US 5,556,744 AGrant
Methods and Compositions for Diagnosing and Treating Certain HIV Infected Patients
Issue Date:1996-09-17
•2 Claims
•3 Drawing Sheets
Abstract
The present invention provides a panel of HIV peptides useful in diagnosing whether or not a patient is of vertical HIV transmission status, methods for diagnosing same, methods for identifying epitopes and peptides associated with non-transmission status, and pharmaceutical and vaccine compositions containing same.
Metadata
Assignees
- The Trustees of the University of Pennsylvania
- The Wistar Institute of Anatomy & Biology
Inventors
- David B. Weiner
- Kenneth E. Ugen
- William V. Williams
Application Information
Application Number:US 2180251
Filing Date:1994-03-24
Priority Date:1992-05-29
Art Unit:183
Classifications
IPC:
C12Q 170
Field of Search:
4355305;7.1;974;975324-328;826
Patent Drawings (3 sheets)
Description
1. Field of the Invention
This invention relates generally to methods for diagnosis, treatment and prophylaxis of certain HIV infections.
2. Background of the Invention
The human immunodeficiency virus (HIV) is the etiologic agent of the acquired immunodeficiency syndrome (AIDS) and related disorders [F. Barre-Sinoussi et al, Science, 220:868-870 (1983); and R. C. Gallo et al, Science, 220:865-867 (1984)]. HIV-1 evades immune surveillance by multiple mechanisms including the inhibition of immune responsiveness through deletion of T helper CD4+ cells and extensive variation of envelope proteins, gp120 and gp41 [W. C. Koff and D. F Hoth, Science, 241:426-432 (1988)]. In fact, the destruction and depletion of CD4+ cells through direct infection by HIV is a hallmark of this disease [H. C. Lane and A. S. Fauci, Ann. Rev. Immunol., 3:477-500 (1985)]. This depletion of the T helper subset ultimately results in profound immunosuppression.
Progression to symptomatic disease states in HIV-infected individuals is correlated with lower humoral and in vitro T cell immune responses. The humoral immune response is an important component of protective immunity against a number of infectious agents. In many cases neutralizing antibodies (which, regardless of the mechanism employed, can inhibit the infection of healthy cells) are generated against the infectious agents. Most of the targets for neutralizing antibodies against HIV-1 reside on the viral envelope gene products (gp120 and gp41).
Several HIV-1 neutralization epitopes have been identified on the external membrane glycoprotein gp120. These include: (a) a region near the amino terminus which has been shown to be important for virus entry; (b) the V3 hypervariable loop; (c) the CD4 binding domain; and (d) a region which spans the carboxy terminus of gp120 and the amino terminus of gp41.
The gp41 transmembrane glycoprotein is involved in the fusion step between HIV and the target cell and it cannot be shed from the surface of virally infected cells. Several domains in the gp41 have been shown to elicit neutralizing antibodies [T. C. Chanh et al, EMBO J., 5:3065-3071 (1986); A. G. Dalgleish et al, Virol., 165:209-215 (1988); E. K. Thomas et al, AIDS, 2:25-29 (1988 )].
Cell-free neutralization assays have been a useful in vitro methods for the analysis of the anti-HIV potential of hyperimmune animal sera or HIV+ sera. In several studies, neutralizing antibodies have been correlated with lesser manifestations and better clinical outcome. In addition, some studies have shown that decreasing neutralizing antibody titers indicate a poor prognosis [J. N. Weber et al, Lancet, 1:119-121 (1987); L. A. Sawyer et al, AIDS Res. Hum. Retroviruses, 6:341-356 (1990)]. However, other investigations have failed to demonstrate a clear correlation between neutralizing antibody activity and clinical state, prognosis or vertical transmission status [J. Goedert et al, cited above; L. K. Vujcic et al, J. Infect. Dis., 157:1047-1050 (1988); I. Wendler et al, AIDS Res. Hum. Retroviruses, 3: 157-163 (1987); G. P. Faulkner-Valle et al, Tumori., 72:219-224 (1986); K. Ljunggren et al, J. Infect. Dis., 161:198-202 (1990)]. Anti-syncytial and group specific neutralization activity are observed more frequently in the asymptomatic patient population than in patients with AIDS. Several peptides corresponding to defined regions of the HIV envelope, including the V3 loop region of gp120, are able to induce protective immune responses in experimental animals.
Pediatric AIDS is an important medical problem [D. Barnes, Science, 232: 1589-1590 (1986)]. The timing and mechanism of viral infection of the fetus or neonate is being intensely investigated but is still incompletely understood. While most infected newborns appear clinically and immunologically normal at birth, studies support vertical transmission of HIV to the fetus in utero and to the neonate at the time of delivery or postpartum.
While it is unknown if free virus can cross the placenta, in utero transmission of HIV is supported by several studies. For example, HIV has been cultured, or HIV DNA detected, in aborted fetuses of less than 15 weeks of gestational age [S. Sprecher et al, Lancet, 2:288-289 (1986); E. Jovaisas et al, Lancet, 2:1129 (1985)]. HIV-1 infection has also been observed by immunochemical and molecular methods in villous trophoblastic derivatives, villous mesenchymal cells and embryonic blood precursors of an eight week gestational fetus [P. Pizzo et al, Am. J. Med., 85 (Suppl 2A):195-202 (1988)]. Additionally, children can become infected despite delivery by Cesarean section [M. C. Cowan et al, Pediatrics, 73:382-386 (1984)].
Some children may be infected following exposure to maternal blood at the time of delivery. In addition, the exchange of blood prior to birth or at birth between the mother and infant has been documented. Infected maternal blood cells, i.e., lymphocytes, can be found postpartum in the circulation of some infants and these cells can support HIV infection in vitro. Postpartum infection has been documented in children exposed to breast milk [J. Ziegler et al, Lancet, 1 :896-897 (1985)].
Despite the evidence that HIV infection of children can occur in utero, 65-80% of all infants seem to escape infection [S. Lewis et al, Lancet, 335:565-568 (1990)]. Little is known about the immune responses that might affect perinatal transmission of HIV. There are data suggestive of a protective role for humoral immunity in vertical transmission of HIV infection. Four studies have suggested a correlation between the presence of certain maternal antibodies to regions of the V3 loop and a reduced incidence of infection in the infant [P. A. Broliden et al, AIDS, 3:577-582 (1989); P. Rossi et al, Proc. Natl. Acad. Sci. USA, 86:8055-8058 (1989); J. Goedert et al, Lancet, 2:1351-1354 (1989); and Y. Devash et al, Proc. Natl. Acad. Sci. USA, 87:3445-3449 (1990)]. In each study, the antibody measured was directed against the gp120 envelope protein. High titer anti-gp120 antibodies against conserved portions of the V3 hypervariable loop of gp120, and high affinity/avidity antibodies against the principal neutralizing domain (PND) of the V3 hypervariable loop have been identified as potential correlates of protection. Other investigators have been unable to confirm the association of non-transmission and high titered responses to V3 [A. Jean-Pierre et al, VII International Conference on AIDS, Abstract W. C. 3263., p 361 (1991) and B. N. Parkeh et al, AIDS, 5: 1179-1184 (1991)].
Maternal antibody may protect the fetus by reducing the quantity of infectious virus in the maternal circulation or by passive transfer of protective antibody to the fetus during the last 3-4 months of pregnancy. One report suggested an increased incidence of HIV infection in premature infants, who may have lower levels of passively acquired maternal antibody [I. Auger et al, Nature, 336:575-577 (1988)]. So far, no information is available to assess the ability of antibodies from an individual mother to neutralize or react with the virus variant transmitted to her own infant. Additionally, there has been no detailed analysis of the contribution of the humoral immune response to regions outside the V3 region and maternal HIV transmission.
There remains a need in the art for compositions and methods for identifying humoral immune responses useful as antibody therapy protective against the vertical transmission of HIV from mother to child and for immune based therapy and vaccinal compositions to prevent prenatal and perinatal transmission of HIV. There also remains a need to determine the likelihood that a given pregnancy in an HIV infected mother will result in infection of the fetus.
Summary of the Invention
In one aspect, the present invention provides a collection or panel of HIV peptides, useful in determining whether or not an HIV infected woman will transmit HIV to her fetus in a given pregnancy and a diagnostic kit for use in clinical laboratories containing these peptides. Desirably, when in the diagnostic kit, the peptides of the collection are associated with a detectable label or label system, capable of providing a conventional diagnostic signal. The kit also contains a standard or control which demonstrates the recognition pattern of a known maternally transmissible serum with the same peptides. These peptide collections are useful in the diagnosis of female HIV patients likely to transmit the infection to their newborns, or in the diagnosis of HIV infection in newborns.
In another aspect, the present invention provides a method for determining whether or not an HIV infected woman will transmit HIV to her fetus in a given pregnancy. This method involves providing a biological sample from said HIV-infected patient, e.g., serum, screening said sample with a collection of HIV peptides as defined above, quantitatively determining the peptides recognized by said sample, and comparing said recognized peptides to the standard. Samples obtained from patients at a low risk for transmitting HIV to the fetus will react with about two to three times more peptides in the collection than recognized by the standard serum from a patient who transmits HIV to her fetus.
In still a further aspect, the invention provides a method for determining the risk of an HIV infection in an infant born to an HIV-infected mother, which consists of employing as a hybridization probe a panel of peptides, which may optionally be labelled, or a multivalent construct of this invention.
In still another aspect, the present invention provides a vaccine composition useful in preventing vertical transmission of HIV comprising a pharmaceutically acceptable carrier and at least one HIV peptide associated with non-transmissibility. Optionally, such a vaccine composition may contain, or be administered in conjunction with, other anti-HIV agents.
In a further aspect, the present invention provides a method of preventing vertical transmission of HIV comprising the step of administering to a pregnant woman a vaccine composition as defined above.
In a further aspect, the invention provides a vaccinal composition useful in conferring passive immunity against HIV infection comprising an antibody directed against a peptide associated with lack of vertical transmission of HIV and,a pharmaceutical composition of this invention.
Other aspects and advantages of the present invention are described further in the following detailed description of the preferred embodiments,thereof .
Brief Description of the Drawings
FIG. 1 provides a linear map of HIV gp120 and gp41 with the amino acid numbers above the map. The approximate location and the designation of the peptides described herein are shown in the map.
FIG. 2A is a bar graph illustrating the binding of maternal serum samples to peptides from the amino terminus of gp120. A closed box indicates the transmission group and an open box indicates the non-transmission group.
FIG. 2B is a bar graph illustrating the binding of maternal serum samples to peptides from the V3 loop of gp120. A closed box indicates the transmission group and an open box indicates the non-transmission group.
FIG. 2C is a bar graph illustrating the binding of maternal serum samples to peptides from the CD4-binding site of gp120. A closed box indicates the transmission group and an open box indicates the non-transmission group.
FIG. 2D is a bar graph illustrating the binding of maternal serum samples to peptides from the carboxyl terminus of gp120. A closed box indicates the transmission group and an open box indicates the non-transmission group.
Detailed Description of the Invention
The present invention provides a collection or panel of HIV peptides useful in distinguishing between an immune maternal status which prevents transmission of HIV infection and immune status which permits maternal transmission of HIV infection (i.e., vertical transmission from mother to child). This invention also provides a means for identifying one or more of the peptides of this panel and/or the epitope(s) to which they correspond, which may, alone, be capable of distinguishing between maternal transmission and non-transmission immune status, and which may be useful in therapeutic and vaccinal compositions.
I. Definitions
As used herein, the term "panel" or "collection" of peptides refers to HIV peptides, fragments, and analogs thereof which, alone or preferably in combination with one another, are useful in identifying or distinguishing a biological sample as being associated with either lack of vertical transmission of HIV infection or the presence of vertical transmission of HIV infection. Preferably, this panel includes between about 5 to about 15 peptides derived from both gp41 and gp120 envelope proteins. More preferably, the panel includes about 10 peptides. Desirably, peptides of the panel are between about 8 to about 50 amino acids in length. More preferably, the peptides are between about 12 to about 20 amino acids in length. Such a collection or panel can include the specific HIV peptides identified in the lists and tables below, as well as other fragments of gp120 and gp41 from HIV isolates. Advantageously, when used in diagnosing whether or not an HIV-infected patient has an immune status which permits vertical transmission of HIV infection at any given time, e.g. during a pregnancy, a sample from a patient having an immune status which does not permit vertical transmission of HIV will recognize at least two-fold more of the peptides of a panel of the invention and exhibit a stronger immune response as reflected in higher antibody titers, as compared to a sample from a subject having an immune status which permits vertical transmission of HIV.
As used herein, the term "vertically transmissible HIV infection" or "transmitter", refer to a patient having an immune status which is such that it permits transmission of HIV infection to a fetus intraplacentally or to a newborn exposed to an HIV-infected mother's milk. The term "vertically non-transmissible HIV infection" or "non-transmitter" refer to a patient having an immune status which prevents vertical transmission of HIV infection.
As used herein, the term "fragment" refers to an amino acid sequence shorter than the HIV peptide from which it is derived, but which retains substantially identical biological activity of the intact peptide. Desirably such a fragment is at least four amino acids in length.
As used herein, the term "analog" refers to variations in the amino acid sequences of the HIV gp160 (gp120+gp41) proteins of this invention, which may typically include analogs that differ by only 1 to about 4 amino acid changes. Other examples of analogs include peptides or polypeptides with minor amino acid variations from the natural amino acid sequence of HIV peptides. In particular, the HIV peptides containing conservative amino acid replacements, i.e., those that take place within a family of amino acids that are related in their side chains, constitute analogs of this invention. Genetically encoded amino acids are generally divided into four families: (1) acidic=aspartate, glutamate; (2) basic=lysine, arginine, histidine; (3) non-polar=alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan; and (4) uncharged polar=glycine, asparagine, glutamine, cysteine, serine, threonine, tyrosine. Phenylalanine, tryptophan, and tyrosine are sometimes classified jointly as aromatic amino acids. For example, it is reasonable to expect that an isolated replacement of a leucine with an isoleucine or valine, an aspartate with a glutamate, a threonine with a serine, or a similar conservative replacement of an amino acid with a structurally related amino acid will not have a significant effect on its activity, especially if the replacement does not involve an amino acid at an epitope of the polypeptides of this invention.
As used herein, the term "homologous peptide" includes peptide fragments which share at least 85% identity at the amino acid level, and preferably 95% identity, and substantially similar biological activity to a reference peptide.
As used herein, the term "standard" includes a pattern of peptide recognition of a sample screened against a selected panel or collection of peptides from a known transmitter, a known non-transmitter, or both. Alternatively, the suitable sample itself, e.g. sera, from transmitters or non-transmitters could be used as a standard.
II. HIV Peptides of the Invention
The following HIV peptides derived from strain HIV IIIB [ATCC CRL 8543] have been found to correlate significantly with lack of vertical transmission of HIV. These peptides are anticipated to be useful in the diagnostic panel, as well as in the therapeutic and vaccinal compositions of the invention.
(a) DYDTEVHNVWATHACV SEQ ID NO: 1
(b) RKSIGIQRGPGR SEQ ID NO: 2
(c) KQFINMWQEVGKAMYAPP SEQ ID NO: 3
(d) CFRPGGGDMRDNWREL SEQ ID NO: 4
(e) QNNLLRAIEAQQHLLQLTVWGI SEQ ID NO: 5
(f) CQNQQEKNEQELLEL SEQ ID NO: 6
(g) ELDKWASLWNWFNITNWLWY SEQ ID NO: 7
(h) VTRIVELLGRRGWEALKYWW SEQ ID NO: 8
(i) TLPCASDAKAYDTEV SEQ ID NO: 10
(j) FSYHRLRDLLLIVTR SEQ ID NO: 30,
(k) NATAIAVAEGTDRVIEVVQGAYRAI SEQ ID NO: 31,
(l) LGIWGCSGKLIC SEQ ID NO: 121,
(m) CNNKTFNGTGFCTNVSTVQ SEQ ID NO:137,
(n) VVQREKRAVGIG SEQ ID NO:133,
(o) YNKRKRIHIQRGPGRAFYTTKNII SEQ ID NO:134,
(p) KQIINMWQEVGKAMYA/CTRPNNNTRKSIRIQRGPG SEQ ID NO:194
(q) YIKIFIMIVGGLVG SEQ ID NO:170
(r) DTSGRLVHGFLAIIW SEQ ID NO:159
(s) HIPTRIRQGLERALL SEQ ID NO:171 and
(t) HMLQLTVWGIKQLQAR SEQ ID NO:165.
Other peptide fragments which are particularly suitable for inclusion in the peptide collection of the invention are illustrated topographically in FIG. 1. The location and strain derivation of these peptides are provided in Tables 2, 9 and 12 below. Further, peptides of the V3 region are also expected to be useful in the peptide collection and methods of the invention. See, SEQ ID NO: 179 to 190. Also expected to be useful in the collection/panel of the invention are the peptides provided in SEQ ID NO:32 through SEQ ID NO:98. Additionally, other suitable peptide fragments identified by SEQ ID NOS, and the amino acid positions of the fragments corresponding with the gp160 sequence of each indicated strain are provided in Table 1 below.
It is anticipated that peptide fragments homologous to the peptide fragments above and which are derived from other HIV strains will similarly correlate specifically with non-vertical transmission of HIV.
Other HIV strains are readily available from depositaries such as the American Type Culture Collection, as well as from academic and commercial sources. Particularly desirable are HIV isolates obtained from infected individuals, e.g. the HIV-I-MN isolate [Y. Devash et al, AIDS Res. and Human Retroviruses, 6(3):307-316 (1990)] or the SF-2 isolate. The IIIB (also known as HXB2), MN and SF-2 sequences can be found in the Human Retroviruses and AIDS I-II, ed. G. Meyers et al, p. IIA-40 through IIA-55 (August 1933). Another useful HIV strain, Z3, is described in K. M. Callahan et al, J. Immunol., 144(9):3341-3346 (May 1, 1990). Additionally, the envelope sequences of strains MN and BH10 are also provided in C. Gurgo et al, Virol., 164:531-526 (1988). These publications are incorporated by reference herein.
For use in the compositions and methods of this invention, it is anticipated that the above-described HIV peptides, fragments and analogs thereof, may be designed into conventionally known, alternative constructs to enhance the production of the peptide or its immunogenicity.
For example, multivalent constructs, e.g., associations of the HIV peptides characterized by multiple copies of a single peptide, or preferably, single or multiple copies of several of the above-described peptides may be designed [see, e.g., European Patent Application 0339695, published Nov. 2, 1989, incorporated by reference herein.]
In another form, the peptides may optionally be fused in frame or otherwise conventionally conjugated to a protein/peptide fusion partner. For example, one of skill in the art may design the HIV peptide in association with a selected fusion partner, such as the same or other HIV peptides of this invention, a preferred signal sequence, a sequence which is characterized by enhanced secretion in a selected host cell system (e.g., ubiquitin, .alpha. mating factor, beta-galactosidase and influenza proteins), a sequence which enhances the stability of the HIV peptide, or another peptide or protein which imparts desirable characteristics to the HIV peptide (e.g., tetanus toxoid, keyhole limpet hemocyanin (KLH), bovine serine albumin (BSA), hepatitis B virus core antigen, T cell epitopes). Such peptide or protein fusions may be mediated and preferentially distanced from each other, if desired, through a conventional linker sequence of between about 2 to about 50 amino acids in length. This linker sequence may encode, if desired, a polypeptide which is selectively cleavable or digestible by conventional chemical or enzymatic methods.
Similarly, the peptide of the invention may be associated with a non-protein carrier or compound such as a diagnostic label or immobilizing agent, a polystyrene bead or the like.
Moreover, it is possible, using the basic methods reviewed by L. Reichmann et al, Nature, 332:323 (1988), for a skilled artisan to engineer a peptide of the present invention as an epitope loop into an entire antibody or fragment thereof, e.g., chimeric antibodies.
This invention also encompasses the corresponding nucleotide sequences of the specifically-recited HIV peptides, fragments and multivalent constructs of this invention which are described herein. For example, one of skill in the art can readily determine the nucleotide sequences which encode the HIV peptides (a) through (t), as well as those sequences which encode the other peptide sequences of the invention, including those of FIG. 1. Additionally, the invention encompasses other DNA sequences of the peptides and polypeptides of this invention, such as allelic variations of DNA sequences encoding the various illustrated HIV amino acids, as well as deliberately modified analogs or derivatives thereof are also included in the present invention. Similarly, DNA sequences which code for peptide sequences of the invention but which differ in codon sequence due to the degeneracies of the genetic code or variations in the DNA sequence encoding these peptides which are caused by point mutations or by induced modifications to enhance the activity, half-life or production of the peptide encoded thereby are also encompassed in the invention. These sequences may be used in the recombinant production or chemical synthesis of the peptides by conventional means.
A. Production of HIV Peptides
The HIV peptides, fragments, and analogs thereof, and multivalent peptides, optionally associated with fusion partners of the invention, are preferably synthesized using conventional synthesis techniques, e.g., by chemical synthesis techniques. Alternatively, a skilled artisan may synthesize any of the peptides of the present invention by using an automated peptide synthesizer (e.g., an Applied Biosystems model 430A) using standard t-Boc chemistry as reported by L. A. Carpino, J. Am. Chem. Soc., 79:4427 (1957), the disclosure of which is hereby incorporated by reference.
Alternatively, the peptides and other constructs of the invention may be prepared by known genetic engineering techniques, e.g., recombinant DNA techniques by cloning and expressing within a host microorganism or cell a DNA fragment carrying a coding sequence for the selected peptide or construct. Coding sequences for the HIV peptides, fragments and other proteins, e.g., fusion partners, can be prepared synthetically or can be derived from viral RNA by known techniques, or from available cDNA-containing plasmids.
Systems for cloning and expressing the HIV peptides or polypeptides in various microorganisms and cells, including, for example, E. coli, Bacillus, Streptomyces, Saccharomyces, mammalian, yeast and insect cells, and suitable vectors therefor are known and available from private and public laboratories and depositories and from commercial vendors. Currently, one preferred host is a mammalian cell. Suitable mammalian cells include Chinese Hamster ovary cells (CHO) or COS-1 cells. The selection of other suitable host cells and methods for transformation, culture, amplification, screening and product production and purification can be performed by one of skill in the art by reference to known techniques. See, e.g., Gething and Sambrook, Nature, 293:620-625(1981). Another known expression system includes the baculovirus expression system and vectors. While not preferred, E. coli may also be used for production of the HIV peptides and fragments, where the proper glycosylation and configuration is found to be achieved.
When produced by conventional recombinant means, the HIV peptides may be isolated either from the cellular contents by conventional lysis techniques or from cell medium by conventional methods, such as chromatography. See, e.g., Sambrook et al, Molecular Cloning. A Laboratory Manual., 2d Edit., Cold Spring Harbor Laboratory, New York (1989).
Whether produced recombinantly or synthesized, the peptides of the invention may be purified using conventional means. Desirably, when used in the diagnostic panel of the invention, the peptides are at least about 85% pure. One of skill in the art can readily determine the appropriate level of purity required for the desired application for which the peptides are to be used.
B. Antibody Production
The present invention also provides antibodies capable of recognizing and binding naturally-occurring HIV epitopes on the peptides of the invention, when the virus or particles thereof are present in a biological fluid of a subject. These antibodies may be generated by conventional means utilizing the isolated peptides or multivalent peptide constructs of this invention [See, e.g., PCT published application WO91/04273, published Apr. 4, 1991]. For example, polyclonal antibodies may be generated by conventionally stimulating the immune system of a selected animal with one or more of the above-identified peptides, or multivalent constructs, allowing the immune system to produce natural antibodies thereto, and collecting these antibodies from the animal's blood or other biological fluid. High titer polyclonal antibodies may be obtained by using the multi-valent constructs described above as antigens. The resulting antibodies are capable of binding the selected HIV antigen as it appears in the biological fluids of an infected subject.
Additionally, the peptides of the present invention may also be used to generate antibodies that can be used as templates to generate anti-idiotype antibodies having the internal image of the neutralizing epitope structure contained in the peptide sequence. These antibodies, polyclonal or monoclonal, can then be used in vaccine formulations or in active immunotherapy. Accordingly, the present invention also includes monoclonal or polyclonal antibodies that carry the internal image of the peptides, as well as methods for generating these antibodies [PCT/US90/05393]. This published application is incorporated by reference herein, with particular reference to the discussion of antibodies therein.
Where it is desirable to obtain and utilize monoclonal antibodies (MAb) for the compositions and the methods of this invention, hybridoma cell lines expressing desirable MAbs may be generated by well-known conventional techniques, e.g. Kohler and Milstein, and using available tumor cell lines.
Recombinant antibodies may be generated using known techniques for their production [W. D. Huse et al, Science, 246:1275-1281 (1989)]. Desirable high-titer antibodies may also be generated by applying known recombinant techniques to the monoclonal or polyclonal antibodies developed to these antigens [see, e.g., PCT Patent Application No. PCT/GB85/00392; British Patent Application Publication No. GB2188638A; Amit et al., Science, 233:747-753 (1986); Queen et al., Proc. Nat'l. Acad. Sci. USA, 86:10029-10033 (1989); PCT Patent Application No. PCT/WO9007861; Riechmann et al., Nature, 332:323-327 (1988); and Barbas et al, Proc. Natl. Acad. Sci. USA, 89:4457-4461 (1992)].
These peptides, fragments and antibodies of this invention are thus useful as diagnostic reagents and vaccine components useful in the prophylaxis of HIV. The peptides and antibodies thereto may be associated with a diagnostic label, a chemical moiety, a toxin, another protein or peptide, provided that the peptide associated with such a molecule is characterized by substantially the same biological activity as the original peptide.
III. Identifying HIV Epitopes and Peptides
The present invention also provides a means for identifying additional HIV peptides and epitopes which correlate with predilection for vertical transmission. According to this method, the sites on the HIV-1 envelope to which maternal antibodies bind in biologic assays such as ELISA or radioimmunoassay (RIA) are mapped. As described in greater detail in Examples 3 and 4 below, a wide variety of gp160 envelope peptides within one or more selected HIV-1 isolate(s), e.g., MN strain, are screened by neutralizing antibodies from maternal sera from individuals with known maternally transmissible and non-transmissible HIV. This screen provides two sets of peptide recognition or binding data.
These screens provide peptides which are strongly recognized by neutralizing antibodies from individuals with maternally non-transmissible HIV. Maternally transmissible sera recognizes a smaller subset of the peptides used in the screen at detectably lower titer. The former set of recognized peptides have been shown to have some ability to predict protection from vertical transmission. Examples 3 and 4 demonstrate that women who did not transmit the virus had high titers of neutralizing antibodies to a collection of peptides of this invention, as assessed by a neutralization assay.
The performance of these screens also permitted the identification of certain of the peptides, e.g., SEQ ID NO: 6 in Example 3, to which the neutralizing antibodies bound. This peptide recognition clearly correlated to non-transmission status. For example, humoral antibody responses to several peptides from the gp41 envelope glycoprotein seemed to be mostly associated with protection of the fetus from vertical transmission, e.g., non-transmission status, although there was not a 100% association in this small sample group. More striking was the importance of a combinatorial humoral response, to peptides from both gp41 and gp120 (see Example 3, part C, below). Maternal reactive serum was more likely to be from a non-transmitting mother if antibodies were present to both the gp41 and gp120 envelope proteins rather than if there was a humoral response to only one peptide.
Several HIV peptides have been identified, particularly in those regions outside of the V3 loop of gp120, which appear to have a relationship to transmission status as well as to in vitro anti-HIV-I biological activity. For example, peptides (a) to (t) listed above, correlate well to lack of vertical transmission. These peptides are thus particularly desirable for inclusion in the panel of peptides which is useful for diagnostic purposes, discussed herein. These peptides are also anticipated to be useful in vaccinal compositions and in generating antibodies for use in therapeutic compositions, e.g. passive immunization.
Using the techniques described above, it is anticipated that one of skill in the art could identify other suitable peptides and epitopes. Identification of these peptides and epitopes implicated in non-transmission and maternal humoral immune responses which protect the fetus from vertical transmission permits the use of these peptides in vaccinal and therapeutic, as well as diagnostic methods.
IV. Diagnostic Method and Kit
The present invention provides a method for distinguishing between pregnancies in which there is a high or low rate of vertical transmission making use of the peptide collection of the invention. This method involves, generally, obtaining a sample from a subject known to have, or suspected of being infected with, HIV and screening the sample with a panel of peptides. Samples from individuals having an immune status consistent with low risk of vertical transmission respond to a larger number of peptides, e.g., at least two-fold more peptides, and exhibit a stronger immune response as reflected in higher titers of antibody, in comparison to samples from subjects at high risk of vertical transmission status.
Suitable samples include biological fluids and tissue. For purposes of this invention, the term biological fluids includes plasma, serum, whole blood, saliva, amniotic fluid, tears, urine and vaginal wash samples.
Alternatively, when used individually or in combinations smaller than the HIV panels discussed above, the HIV peptides, multivalent constructs, and/or antibodies of this invention may be useful for a variety of purposes. For example, selected peptides or multivalent constructs may be labeled with conventional diagnostic detectable labels and employed to detect the occurrence of anti-HIV antibodies in patient serum. Conversely, the antibodies of this invention may be employed to detect the occurrence of the naturally-occurring viral peptides in an infected patient's biological fluids. These peptides, constructs and antibodies are thus useful in diagnosis of HIV, particularly the diagnosis of a predilection for vertical transmission.
Utilizing the peptides and antibodies thereto which correlate with vertical transmission status as diagnostic reagents, HIV-infected patients can be readily identified as being at risk of vertically transmitting their infection. This information can be valuable in planning treatment for the infant as well as the mother. For example, the method of the invention can be used to predict whether or not the offspring of an HIV infected mother is itself infected, particularly prior to 24 months of age, by obtaining a suitable sample from either the mother or the infant. Testing of infants did not yield useful results under prior art methods because of the immaturity of the immune system in a newborn. Similarly, such diagnostic uses may be made in the general population, rather than simply in vertical transmission, if the antibodies implicated in vertical transmission are also implicated in horizontal transmission.
For use in diagnostic reagents and assays, the peptides, peptide constructs and antibodies of this invention may be associated with conventional labels which are capable, alone or in concert with other compositions or compounds, of providing a detectable signal. Where more than one antibody is employed in a diagnostic method, the labels are desirably interactive to produce a detectable signal. Most desirably, the label is detectable visually, e.g. colorimetrically. A variety of enzyme systems have been described in the art which will operate to reveal a colorimetric signal in an assay, e.g., glucose oxidase, peroxide, and tetramethyl benzidine (TMB) system, a horseradish peroxidase (HRP) system and similar enzyme systems. Other label systems that may be utilized in the methods of this invention are detectable by other means, e.g., colored latex microparticles [Bangs Laboratories, Indiana], fluorescent compounds, radioactive compounds or elements, or immunoelectrodes.
Detectable labels for attachment to the peptides, constructs and antibodies useful in diagnostic assays of this invention may be easily selected from among numerous compositions known and readily available to one skilled in the art of diagnostic assays. The diagnostic methods and peptides or antibodies of this invention are not limited by the particular detectable label or label system employed.
Various assay protocols may be employed for detecting the presence of naturally occurring antibodies capable of binding the HIV peptides associated with vertical transmission status identified herein or the naturally-occurring HIV peptide sequences as they occur in the biological fluids of HIV infected subjects. Of particular interest is the use of an isolated HIV peptide associated with vertical transmission status of this invention as a labeled reagent, optionally bound to an immobilizing agent, e.g., a well or plate, to determine whether antibody in the biological fluid sample will become bound to (form antigen-antibody complexes with) the identified peptide.
Assays employing an HIV peptide or peptide construct or antibody of the invention can be heterogenous (i.e., requiring a separation step) or homogenous. If the assay is heterogenous, a variety of separation means can be employed, including centrifugation, filtration, chromatography, or magnetism. One preferred assay for the screening of biological fluids is an enzyme linked immunosorbent assay, i.e., an ELISA.
Alternatively, an assay could be performed to determine the presence of the particular HIV peptide as it is naturally associated with the virus in the patient's sample. This assay involves incubating the sample, e.g. serum, with a labeled antibody of this invention such that specific binding occurs (antigen-antibody complex). Subsequently, excess labelled antibody is optionally removed, and the reaction mixture is analyzed to determine the presence or absence of the antigen-antibody complex and the amount of label associated with the antibody.
It should be understood by one of skill in the art that any number of conventional assay formats, particularly immunoassay formats, may be designed to utilize the HIV peptides, constructs therefor, and antibodies of this invention for the detection of HIV infection and the transmission status thereof in humans. This invention is thus not limited by the selection of the particular assay format, and is believed to encompass assay formats which are known to those of skill in the art.
For convenience, reagents for assays according to this invention may be provided in the form of kits. These kits can include microtiter plates to which the HIV peptides or constructs or antibodies of the invention have been pre-adsorbed, various diluents and buffers, labeled conjugates for the detection of specifically bound peptides or antibodies, and other signal-generating reagents, such as enzyme substrates, cofactors and chromogens. Other components of these kits can easily be determined by one of skill in the art. Such components may include polyclonal or monoclonal capture antibodies to the selected HIV peptide or a cocktail of two or more of the antibodies, a suitable standard including a purified or semi-purified HIV peptide standard, MAb detector antibodies, an anti-idiotypic antibody with indicator molecule conjugated thereto, an ELISA plate prepared for absorption, indicator charts for colorimetric comparisons, disposable gloves, decontaminations instructions, applicator sticks or containers, and a sample preparator cup. These kits provide a convenient, efficient way for a clinical laboratory to diagnose various HIV transmissible or non-transmissible infection.
V. Vaccinal Compositions and Immunization
As demonstrated by the results of the examples below, the lack of vertical transmission (referred to as non-transmission) correlates with high viral neutralization activity, but not with antisyncytial activity or binding to the V3 peptides examined. Also, the transmission group bound to fewer gp41 peptides when compared to the non-transmission group, further supporting the conclusion immune responses to gp41 are important in preventing transmission.
A. Active Immunization
Thus, the present invention also provides vaccine compositions useful for preventing transmission of HIV from a mother to her offspring. Such vaccine compositions contain an HIV peptide, fragment or analog of the invention correlating with either vertical transmission or lack of vertical transmission identified herein, combinations thereof or multivalent peptide constructs of the invention. Such a vaccine composition may contain the HIV peptide or construct according to the invention together with a pharmaceutically acceptable carrier or diluent suitable for administration as a composition for prophylactic treatment of HIV infections. Suitable pharmaceutically acceptable carriers facilitate administration of the proteins but are physiologically inert and/or nonharmful.
Carriers may be selected by one of skill in the art. Exemplary carriers include sterile saline, lactose, sucrose, calcium phosphate, gelatin, dextrin, agar, pectin, peanut oil, olive oil, sesame oil, and water. Additionally, the carrier or diluent may include a time delay material, such as glycerol monostearate or glycerol distearate alone or with a wax. In addition, slow release polymer formulations can be used.
This vaccine composition may contain one, or preferably more than one, non-transmissible HIV peptide, fragment and/or peptide constructs of the invention which is associated with non-transmission status. Such a vaccine may be useful in uninfected individuals to induce protective titers of neutralizing anti-HIV antibodies. In one embodiment, a vaccine composition may contain a `cocktail` of multiple individual peptides (a) through (t) above, selected for their relationship to non-transmissible status. In another embodiment the cocktail may contain the other transmission-associated HIV peptides identified in Table 2 below. In still another embodiment multiple copies of a single HIV peptide of this invention, or multiple copies of more than one of these peptides may be employed in a single construct. For example, the peptides may be fused in frame to each other, or via a linker. Alternatively, multiple HIV peptides of this invention may be present in a multivalent peptide construct which contains multiple copies of one or more than one, of the peptides of this invention fused or linked to an inert carrier, to another protein, or to a lysine core.
An alternative, desirable vaccine composition may contain a conventional bio-expression vector, such as an adenovirus, poliovirus, vaccinia virus or retrovirus, into which the sequences of one or more of the HIV peptides or antibodies, or functional fragments thereof are inserted under the control of the viral expression regulatory sequences [see, e.g., U.S. Pat. No. 4,920,209]. Such viral vector compositions can be employed to deliver the relevant peptide or antibody sequences to the patient.
Optionally, the vaccine composition may further contain adjuvants, preservatives, chemical stabilizers, or other antigenic proteins. Typically, stabilizers, adjuvants, and preservatives are optimized to determine the best formulation for efficacy in the vaccinee. Suitable preservatives include chlorobutanol, potassium sorbate, sorbic acid, sulfur dioxide, propyl gallade, the parabens, ethyl vanillin, glycerin, phenol, parachlorophenol.
One or more of the above described vaccine components may be admixed or adsorbed with a conventional adjuvant. The adjuvant is used as a non-specific irritant to attract leukocytes or enhance an immune response. Such adjuvants include, among others, mineral oil and water, BCG, aluminum hydroxide, Avridine, L121/squalene, D-lactide-polylactide/glycoside, muramyl dipeptide, killed Bordetella, saponins, as Quil A.
Suitable amounts of the active ingredient can be determined by one of skill in the art based upon the level of immune response desired. In general, however, the vaccine composition contains between 1 ng to 1000 mg peptide and more preferably, 0.05 .mu.g to 1 mg per mL, whether a single HIV peptide of the invention or a combination of these peptides or peptide constructs is employed. Antigens to other pathogens, such as measles, mumps, and rubella (MMR) vaccines, may be combined in a vaccine composition of the invention.
Suitable doses of the vaccine composition of the invention can be readily determined by one of skill in the art. Generally, a suitable dose is between 0.1 to 5 mL of the vaccine composition. Further, depending upon the patient being treated, i.e. weight, age, sex and general health, the dosage can also be determined readily by one of skill in the art.
The present invention also provides a prophylactic method entailing administering to a subject an effective amount of such a composition. For example, for prevention of vertical transmission, a vaccine composition of the invention could be administered either to a pregnant HIV-infected woman or an HIV-infected woman of child-bearing age. In general, the vaccine will be administered once, or preferably, more frequently depending on the likelihood of exposure to the virus. Where desirable, boosters may be administered. The vaccine may be administered by any suitable route. However, parenteral administration, particularly intramuscular, and subcutaneous, is the preferred route. Also preferred is the oral route of administration.
B. Passive Immunization
The present invention further provides pharmaceutical compositions useful in providing passive immunity against HIV. Such compositions are useful for administration to individuals anticipating risk of exposure to the HIV virus, e.g., prior to surgery or for health-care workers.
These compositions comprise one or more antibodies of the invention and a suitable carrier or diluent. These carriers, as well as suitable optional ingredients are as defined above with regard to vaccinal compositions for active immunization.
Additionally, this composition may further contain other active ingredients including, for example, AZT, DDC, DDI, biological response modifiers, such as interleukins, colony stimulating factors, especially GM-CSF, IFNs, and other immunostimulatory cytokines, as well as preservatives, or chemical stabilizers.
Suitable dosages can be determined by the attending physician, with reference to the discussion herein relating to appropriate doses for the therapeutic and vaccinal compositions of the invention. The composition administration may be by any appropriate route and repeated as necessary.
VI. Therapeutic Compositions
The peptides identified herein as correlating with maternal non-transmission status can be used in active immunotherapy of HIV-positive individuals to initiate or boost their immune response of neutralizing antibodies.
Thus, the peptides, multivalent constructs and antibodies of this invention may also be used in therapeutic compositions for treating subjects who test positive for, or, prior to testing, exhibit symptoms of, AIDS or a related non-symptomatic condition. In one therapeutic embodiment, one or more antibodies of this invention, preferably directed to more than one of the non-transmission associated or the transmission associated peptides, may be used therapeutically as targeting agents to deliver virus-toxic or infected cell-toxic agents to HIV infected cells. Rather than being associated with labels for diagnostic uses, a therapeutic agent employs the antibody linked to an agent or ligand capable of disabling the replicating mechanism of the virus or of destroying the virally-infected cell. The identity of the toxic ligand does not limit the present invention. It is expected that preferred antibodies to the HIV peptides may be screened for the ability to internalize into the infected cell and deliver the ligand into the cell.
Such a therapeutic composition may be formulated to contain a carrier or diluent and one or more of the antibodies of the invention. Such carriers are discussed above in connection with vaccinal compositions.
Alternatively, or in addition to the antibodies of the invention, antagonists to the HIV peptides of the invention are expected to be useful in reducing and eliminating disease symptoms. It should be noted that the antibodies, peptides and constructs of this invention may be used for the design and synthesis of either peptide or non-peptide compounds (mimetics) which would be useful in the same therapy as the antibodies [See, e.g., Saragovi et al., Science, 253:792-795 (1991)]. The development of therapeutic compositions containing these agents is within the skill of one of skill in the art in view of the teaching of this invention.
Optionally, this composition may also contain other therapeutic agents useful in treating HIV infection, such as those discussed above in connection with compositions for passive immunization. Suitable non-therapeutic ingredients which may be used in a therapeutic composition in conjunction with the antibodies of the invention include, for example, casamino acids, sucrose, gelatin, and phenol red.
According to the method of the invention, a person may be treated for HIV infection by administering an effective amount of such a therapeutic composition. Preferably, such a composition is administered parenterally, preferably intramuscularly or subcutaneously. However, it may also be formulated to be administered by any other suitable route, including orally or topically.
A therapeutic composition of the invention may contain between about 0.05 .mu.g/mL to about 1000 .mu.g/mL of an antibody of the invention. Such a composition may be administered 1-3 times per day. However, suitable dosage adjustments may be made by the attending physician depending upon the age, sex, weight and general health of the patient.
The following examples illustrate the preferred methods for identification and selection of HIV peptides which correlate with lack of vertical transmission of HIV from mother to infant and which are thus useful in the diagnostic panels and/or vaccinal and therapeutic compositions of the invention. Examples 1-4 illustrate one experiment, which used fourteen peptides, spanning 46% (a total of 239 amino acids) of the gp120 external membrane glycoprotein and seventeen peptides spanning 66% (a total of 236 amino acids) of the gp41 transmembrane glycoprotein were used in binding assays of the maternal serum samples. Binding was examined by radioimmunoassay (RIA) or enzyme-linked immunosorbant assay (ELISA), as described in Example 3 below. A list of the gp120 and gp41 peptides tested, their location in the envelope glycoprotein and sequences are presented in Table 2 of Example 2. Example 5 provides another experiment using an expanded peptide panel. See Table 9. Example 6 provides yet another study using an expanded peptide panel and an expanded number of sera samples. See Table 12 and FIG. 1. These examples are illustrative only and do not limit the scope of the invention.
Example 1
Origin and Classification of Patient Samples
The maternal sera and plasma samples were obtained through a collaborative investigation with the Mothers/Infants Cohort Study [J. Goedert et al, cited above]. Briefly, the Mothers/Infants Cohort Study is a prospective investigation and the sera samples in this study were from women attending obstetric clinics in New York City. All the women were drug abusers and/or Haitian. They were all established to be HIV seropositive by ELISA and Western blot analysis during the first trimester [Centers for Disease Control, "Interpretation and use of the Western blot assay for serodiagnosis of human immunodeficiency virus type 1 infections." MMWR, 38: S1-7 (1989); CDC, "Update: serological testing for antibody to human immunodeficiency virus." MMWR, 36:833-845 (1988)].
Sample number 13 was from a mother in the process of seroconverting late in the third trimester and this particular sample, although weakly reactive in enzyme linked immunosorbent assay against viral lysate and several peptides, was not unequivocally positive by standard whole virus Western blot.
In addition, information on the HIV infected status of the offspring of these women was also available. Seropositive mothers whose infants are found to meet the Centers for Disease Control (CDC) definition of perinatal HIV-1 infection are classified as transmitting mothers, whereas seropositive mothers of children with no sign of infection and who have lost maternal antibody are classified as non-transmitting mothers [CDC, "Classification system for human immunodeficiency virus (HIV) infection in children under 13 years of age." MMWR, 36:225-236 (1987)]. In this study, 13/20 of the mothers (65%) were classified as transmitters, whereas 7/20 of the mothers (35%) were classified as non-transmitters. Of the seven infected children, 2 had asymptomatic infection (CDC Classification P-1) while 5 had symptomatic infection (CDC Classification P-2). All of the maternal serum samples tested in this study were drawn during the last trimester of pregnancy. These patient samples were heat inactivated for 60 minutes at 56.degree. C. before use in peptide binding or biological characterization assays of Examples 3 and 4.
Example 2
Sources of Cell Lines and Peptides
The H9 cell line (a cutaneous T lymphoma line) infected by HIV-IIIB [ATCC CRL 8543] was used in the neutralization assay. The H9 cell line infected by HIV-MN was used in the anti-syncytial assays. SupT1 and Hut78 cells were used as the target cell lines for the anti-syncytial and neutralization assays. All cell lines were obtained from the National Institutes of Health AIDS Repository (Bethesda, Md.).
Synthetic peptides were developed according to methods described by C. Romano et al, J. Neurochem., 53:362-369 (1989). The gp120 and gp41 peptides used in these assays are listed in Table 2 below. They were synthesized based on the sequence of the IIIB isolate of HIV-1. Each of the peptides was at least 80% pure, making them suitable for ELISA/RIA assays. The following peptides used in this study were generous gifts of Dr. Jay Berzofsky of the National Institute of Health: 35, 36, 40, 41, 93, 94, 95, 96, 97, 106, 107, 117, 120, 121, 123, 128, 129, and 132 [SEQ ID NOS: 5, 24, 25, 26, 10, 1, 11, 12, 13, 15, 16, 19, 21, 22, 23, 28, 29, and 30, respectively]. These sequences can be found in Human Retroviruses and AIDS, cited above.
Example 3
RIA and ELISA Binding Assays
Radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) were performed by standard methodologies [E. Engvall, Meth. Immunol., 70:419-439 (1980); S. K. Pierce et al, J. Exp. Med., 144:1254-1262 (1976)]. Peptides were dissolved in 0.05M carbonate-bicarbonate buffer (pH 9.6) at a concentration of 10 .mu.g/ml. Fifty .mu.l (500 ng) of the peptides were immobilized in 96 well polyvinylchloride plates (Dynatech Laboratories, Inc.) overnight at 4.degree. C. Plates were washed and non-specific sites were blocked with PBS containing 1% BSA overnight at 4.degree. C.
Dilutions of HIV positive maternal sera were made in blocking buffer at dilutions of 1:50 and 1:500 and incubated in peptide coated plates overnight at 4.degree. C. Plates were washed with PBS and incubated with 75,000 cpm of .sup.125 I-labelled goat anti-human IgG. The antibody was iodinated by a chloramine T method [W. V. Williams et al, Proc. Natl. Acad. Sci. USA, 85:6488-6492 (1988)]. Plates were washed, dried and counted in a gamma counter to measure specific binding. Normal human serum (i.e., HIV seronegative) was used as a control.
Alternatively, ELISA assays were performed in polystyrene plates (Dynatech Laboratories, Inc) in which 0.05% Tween 20 (Sigma Chemical Co.) was included in the washing, blocking and dilution buffers. The secondary antibody used was goat anti-mouse Ig conjugated to horseradish peroxidase (HRP) (Sigma Chemical Co). The substrate used for color development was 3,3',5,5' tetramethyl-benzidine dihydrochloride (TMB) (Sigma Chemical Co). Absorbance of samples was measured in a Dynatech MR5000 (Dynatech Laboratories, Inc.) plate reader and expressed as an optical density at wavelength of 450 nm (OD.sub.450).
The results of the binding assays are represented in Tables 3, 4, 6 and 7. The following key is used for the designation of specific binding of the maternal sera samples to the peptides: The minus sign, -, is equivalent to the specific OD.sub.450 or cpm of sera sample binding to peptide divided by the specific OD.sub.450 or cpm of NHS sample binding to peptide, which value is less than 2. The plus sign, +, is equivalent to the specific OD.sub.450 or cpm of sera sample binding to peptide divided by the specific OD.sub.450 or cpm of NHS sample binding to peptide, which value is between 2 to 3. The double plus sign, ++, is equivalent to the specific OD.sub.450 or cpm of sera sample binding to peptide divided by the specific OD.sub.450 or cpm of NHS sample binding to peptide, which value is greater than 3.
Specific binding is defined as the difference between the OD.sub.450 or cpm of sera to wells with peptide and the OD.sub.450 or cpm of sera to wells without peptide.
Comparisons of number of peptides which bound maternal serum samples were made between the transmission group and the nontransmission group. The data was analyzed using the unpaired student's test. For the determination of differences in the binding of specific peptides between transmission and non-transmission groups, the Spearman's rank-order correlation test was performed.
A. Binding of Maternal Sera to gp 120 peptides
Tables 3 and 4 summarize binding data of the maternal sera samples to the peptides from gp 120.
i. Peptides from gp120 amino terminus
Several maternal serum samples had reactivity to one or more of three peptides spanning amino acid 51 through 85 of the amino terminus of gp120 HIV strain IIIB (peptides 93, 94 and 95 [SEQ ID NOS: 10, 1, and 11, respectively], Tables 2 and 3). No binding of maternal sera to four peptides from the amino terminus of HIV strain IIIB (peptides 59, 60, 96 and 97 [SEQ ID NOS: 14, 9, 12, and 13, respectively], Tables 2 and 3) was observed. Peptides 96 and 97 [SEQ ID NOS: 12 and 13, respectively] are from a region near to the putative sites for the binding of gp120 to gp41 of HIV strain IIIB; and deletion of the amino acid residues within this region of gp120 inhibits viral receptor binding of the CD4 molecule [D. P. Bolognesi, AIDS, 3:S111-S118 (1989)].
Of the six maternal sera binding to peptide 93 [SEQ ID NO: 10], 1(17%) was from the vertical transmission group and 5(83%) were from the non-transmission group. In addition, 3(50%) and 6(100%) of the six samples which bound possessed neutralization and anti-syncytial activity, respectively. Of the two maternal sera binding to peptide 94 [SEQ ID NO: 1], neither were from the vertical transmission group. Of the three maternal sera binding to peptide 95 [SEQ ID NO: 11], one was from the vertical transmission group.
ii. Peptides from the V3 loop of gp120
There was significant binding of a number of the maternal serum samples to peptides from the V3 loop of gp120 (HIV strain IIIB). The peptides 106, 107, 1029-33 and p18p [SEQ ID NOS: 15, 16, 2, and 17, respectively] span amino acids 296-322 and 30%, 95%, 50% and 35% of the maternal serum samples bound to these peptides respectively. See Table 5 below, in which values are the percentages of sera samples from each group demonstrating binding to peptide.
The data presented herein do not support the observation in the prior art [see, e.g., Rossi et al, Goedert et al, and Devash et al, cited above] of an association between binding to V3 and protection from vertical transmission. One potential reason for this discrepancy was the use of different V3 peptides in this example compared with those where an association was found. Neutralizing epitopes other than V3 epitopes could be involved or conformational epitopes (which may or may not involve anti-V3 responses) and may collectively mediate protection from vertical transmission.
The observation of neutralizing activity in one transmitting mother does not necessarily diminish the importance of this observation. Minor trauma or cell spread with or without trauma across the placenta may account for such transmission in the presence of neutralizing levels of antibodies.
iii. Peptides from the CD4 binding site.
Peptide B138 [SEQ ID NO: 3] spans amino acid 421 through 438 of HIV IIIB. Seven of the maternal samples reacted to peptide B138 [SEQ ID NO: 3], in contrast to prior observations that this region has appeared to be immuno-silent in HIV infected patients. Of those samples which bound, two were from the vertical transmission group.
iv. Peptides from the carboxy terminus.
Sixteen (80%) of the maternal sera samples bound to peptide 497 [SEQ ID NO: 18] which spans amino acid 499-511 of the carboxy terminus of gp120 of HIV IIIB. Seventy-seven and 71% of the samples from the transmission and non-transmission groups, respectively, bound to this peptide. This region is immunoactive but antisera generated to this peptide do not demonstrate neutralizing activity.
In addition, 15% of the maternal serum samples demonstrated reactivity to peptide 466 [SEQ ID NO: 4], which spans amino acid 468 through 483 of gp120. Zero and three of the maternal samples from the transmission and non-transmission groups, respectively, bound to this peptide. Of the three maternal samples which bound to peptide 466 [SEQ ID NO: 4], all of them demonstrated neutralizing and anti-syncytial activity. Antisera generated in animals against this peptide have been demonstrated to exhibit neutralizing activity [K. E. Ugen et al, "Inhibition of HIV-1 Cellular Infection by Immunologic Reagents", Vaccines 91. Modern Approaches to New Vaccines Including Prevention of AIDS., R. M. Chanock et al, (eds), Cold Spring Harbor Laboratory Press, pp. 115-121 (1991)]. In particular, one maternal serum (No.9) demonstrated very strong binding to peptide 466 [SEQ ID NO: 4] and also demonstrated high neutralizing and anti-syncytial activity. It is not clear whether this activity is due to binding to peptide 466 [SEQ ID NO: 4].
B. Binding of Maternal Sera to Peptides from gp41
Tables 6 and 7 summarize binding data to the peptides from gp41.
In examining the binding of the maternal sera to peptides from gp41, it is evident that major reactivities to three peptides occur. Peptides 121 [SEQ ID NO: 22] (amino acid 581-595), 649 [SEQ ID NO: 6] (amino acid 649-663) and 1103/55 [SEQ ID NO: 31] (amino acid 817-841) demonstrated binding of 35%, 70% and 45% of the maternal sera samples, respectively. Spearman rank-order correlation coefficient analysis of the binding data indicates that there is a significant statistical difference in binding of samples from the transmission group to peptide 649 [SEQ ID NO: 6], compared to the non-transmission group, suggesting that binding to this peptide is correlated with non-transmission status.
C. Comparison of Binding to gp120 and gp41
Quantitative analysis of binding to the peptides is as follows:
Of the 13 maternal sera samples from the non-transmission group, 100% demonstrated binding to at least one peptide of both the gp41 and gp120 peptide groups. In contrast, of the 7 maternal samples from the transmission group, 100% demonstrated binding to at least one of the gp120 peptides; but only 43% (3 samples) bound to at least one of the gp41 peptides. On average, sera from the non-transmission group bound to approximately 33% more peptides than the samples from the transmission group.
There appears to be quantitative (number of peptides bound) differences in binding to gp41 and gp120 between the transmission and nontransmission groups. The following relationships can be determined, with average number expressed as the mean.+-.standard error of the mean:
The seven transmission group sera samples bound to an average of 1.1.+-.0.45 (or 24%) gp41 peptides and an average of 3.4.+-.0.37 (or 76 %) gp120 peptides, for a total of 4.5.+-.0.75.
Conversely, the thirteen non-transmission group sera samples bound to an average of 2.4.+-.0.40 (or 36%) gp41 peptides and to an average of 4.2.+-.0.35 (or 64%) gp120 peptides, for a total of 6.6.+-.0.57. Statistically, there was a significantly higher average number of gp41 and combined (gp41+gp120) peptides to which the sera from the non-transmission group bound compared to the transmission group, i.e., p<0.05 by the unpaired Student's t-test. These data suggest that immune responses directed against gp41 are involved in protection of the fetus from infection by HIV-1.
Example 4
Anti-Syncytial and Neutralization Assays
To analyze the effect of the maternal serum samples on HIV-1 fusion, SupT1 cells were used as target cells in an anti-syncytial assay. Dilutions of the different maternal serum samples were made in 96 well plates in RPMI 1640 media containing 10% fetal calf serum at final dilutions of 1:4, 1:8, 1:16, 1:32, 1:64, 1:128, 1:256 or 1:512. HIV-1 infected cells (MN isolate) were then plated in the wells at a density of approximately 10.sup.4 cells per well. SupT1 target cells were then added at 5.times.10.sup.5 /well and the number of syncytia are determined after 3 days of incubation. Inhibition of syncytium formation by a serum sample was considered significant if the dilution which yielded a 50% reduction in the number of syncytia when compared to control was greater than 1:32. The average number of syncytia in the control (normal human serum) wells at the above dilutions were: 45.5, 48.5, 44, 48, 48.5, 41.5, 42 and 45.5 respectively.
In a neutralization assay, 20 .mu.l of maternal sera samples was placed in 96 round bottom well plates at final dilutions of 1:10, 1:90 and 1:810 in RPMI. The HIV-IIIB viral isolate was diluted in RPMI to a TCID.sub.50 of 100 units/ml. Twenty .mu.l of the virus solution was placed in each well and the plate was incubated for one hour at 4.degree. C. Hut-78 cells were incubated with 2 .mu.g/ml of polybrene for one hour at 37.degree. C. in a CO.sub.2 incubator. The HUT-78 cells were washed and resuspended in fresh RPMI to a final concentration of 4.times.10.sup.6 cells/ml. Ten .mu.l of the cell suspension was added to each well and the plate was incubated for one hour in a 37.degree. C., CO.sub.2 incubator.
Fifteen .mu.l of the serum/cell/virus solution was aliquoted to a new plate containing 200 .mu.l of fresh RPMI and incubated for 6 days. After 6 days, 100 .mu.l was used to analyze for p24 antigen. The p24 capture ELISA assay kit (Coulter Corporation, Hialeah, Fla.) was used to perform the measurements.
Further, sera samples at the same dilutions as described above were tested for residual p24 core protein or antibody to insure the results were due only to viral infection. All samples failed to demonstrate residual p24 antigen or anti-p24 antibody at the above dilutions when tested in the p24 ELISA assay kit.
Table 8 summarizes data on anti-syncytial and neutralization activity for each of the maternal serum samples. In addition, these data are shown in relationship to gp41 and gp120 binding reactivities for each of the sera samples.
There appears to be no correlation between anti-syncytial activity of the maternal serum samples and vertical transmission and non-transmission of HIV-1 infection. By the definition established for anti-syncytial activity (titer>1:32), all maternal sera samples except No. 2 possessed significant anti-syncytial activity. These data suggest that anti-syncytial assays are not a useful means for identifying mothers who do not transmit HIV-1 infection to their offspring.
Neutralizing activity by a serum sample was considered significant if the dilution which yielded a 50% reduction in OD.sub.450 (a measure of p24 antigen levels) when compared to control was greater than 1:10 (i.e. in this assay dilutions of 1:0.90 or 1:810). According to this definition established for neutralizing ability, 9/13 (69.2%) of non-transmitting mothers exhibited significant neutralizing activity. In contrast, 1/7 (14.3%) of transmitting mothers possessed significant neutralizing activity.
Absent unusual bias in the sample population, this observation has direct importance for understanding the role of anti-HIV envelope humoral immune responses in preventing vertical transmission. These data indicate a relationship between high neutralization titers of maternal sera and non-transmission status.
Example 5
Screening of Maternal Sera with Alternate Peptide Collection
A. Peptide Collection
The gp120 and gp41 peptides used in this experiment include peptides 60 [SEQ ID NO:9], 93 [SEQ ID NO:10], 94 [SEQ ID NO:1], 95 [SEQ ID NO:11], 96 [SEQ ID NO:12], 97 [SEQ ID NO:13], 59 [SEQ ID NO:14], 106 [SEQ ID NO:15], 107 [SEQ ID NO:17], 1029/33 [SEQ ID NO:2], p18p [SEQ ID NO:17], B138 [SEQ ID NO:3], 466 [SEQ ID NO:4], 497 [SEQ ID NO:18], 117 [SEQ ID NO:19], F560 [SEQ ID NO:20], 35 [SEQ ID NO:5], 120 [SEQ ID NO:21], 121 [SEQ ID NO:22], 123 [SEQ ID NO:23], 36 [SEQ ID NO:24], 40 [SEQ ID NO:25], 41 [SEQ ID NO:26], 649 [SEQ ID NO:6], 53 [SEQ ID NO:7], 55 [SEQ ID NO:27], 128 [SEQ ID NO:28], 129 [SEQ ID NO:29], 132 [SEQ ID NO:30], 57 [SEQ ID NO:8], and 1103/55 [SEQ ID NO:31] from Table 2. The remainder of the peptides used in the study are provided in the following Table 9. These peptides were synthesized based on the same HIV IIIB isolate as were the peptides of Table 2. Alternative designations for these peptides are provided in brackets.
Each of the peptides was at least 85% pure, making them suitable for ELISA analyses. The average length of these peptides was 18 amino acid residues, which allows for a certain degree of local flexibility and conformational folding, thus facilitating detection of antibody species with reactivities to shaped structures.
B. Patient Samples
The maternal serum samples were obtained from the Mothers/Infants Cohort Study described in Example 1. For the ELISA peptide-binding analyses performed essentially as described in Example 3, maternal serum samples were diluted to 1:50 or 1:500 with blocking buffer (1% bovine serum albumin in phosphate-buffered saline containing 0.05% Tween 20). Binding was measured using 10 .mu.g/mL peptide per well and was considered positive if the experimental/control OD.sub.450nm ratio was .gtoreq.2. Normal (HIV seronegative) human sera were used as controls.
C. Results
FIGS. 2A-2D depict the results of analysis of the gp120 peptide reactivities determined for this serum panel. Displayed is the percentage of serum samples from the transmission and non-transmission groups that binds to the V3 loop, CD4-binding site, and carboxyl and amino termini of gp120. No difference was observed between the two groups among the five different V3 peptides tested in this study.
Also examined was the binding to the putative CD4-binding region of gp120. No significant differences were observed in binding to any of these peptides between the two studied groups. Two epitopes from the carboxy-terminal region of gp120 have been examined. High reactivity but no difference between the two groups was observed in the binding of the panel to peptide 497, a peptide that can assume a type-2 .beta. conformation and is located at the very terminal region of gp120. In contrast, the immune response of this panel to peptide 466 may have importance. For example, 3 of 13 non-transmission sera reacted with this peptide. All 3 of these sera exhibited neutralizing activity and possessed, to varying degrees, antisyncytial activity as well. With regard to peptide 466, it has been demonstrated that this peptide can elicit both antisyncytial and neutralizing activities. Differences in binding between the transmission and non-transmission groups are noted with peptides 93 and 95 in the amino terminus of gp120.
The reactivity to peptides derived from gp41 has also been examined. In general, ten peptides were recognized by the non-transmission group but were not recognized by the transmission group. However, six of the peptides were recognized by both groups. These included an immunodominant region peptide designated 41-2 (SEQ ID NO: 121) to which 90% of both groups bound and a peptide from the carboxyl region of gp41 designated 56 (SEQ ID NO: 124) to which more than 50% of both groups bound.
Table 10 below summarizes the reactivity of sera from the transmission and non-transmission groups that bind to all the peptides examined. Importantly, there are clear differences in peptide reactivity between the two groups. The difference was particularly apparent in analysis of reactivity to gp41. The transmission group reacted with 2.5.+-.0.4 peptides, whereas the non-transmission group reacted with 3.9.+-.0.5 peptides. Virtually all samples reacted with the immunodominant peptide from gp41, peptide 41-2. Therefore, if this peptide is removed from both groups, the difference in reactivity changes to 1.5 and 2.9 reactive peptides in the transmission and non-transmission groups, respectively. By this analysis, virtually twice the peptide reactivity is observed in the non-transmission group. In addition, overall reactivity to gp41 was also decidedly different. Only 6 of the peptides from gp41 were recognized by the transmission group (peptides 56, 58, 1103.55, 121, 41-2, and 649), whereas 16 peptides, including all of the 6 above, were recognized by some individuals in the non-transmission group.
Analysis of the relationship between neutralization and antisyncytial activity was also examined (See Table 11 below). Neutralization activity correlated exceptionally well with non-transmission status. Retrospectively, a mother was less likely to transmit infection prenatally if her serum contained neutralizing activity than if her serum had no neutralizing activity. Surprisingly, there was no correlation between antisyncytial activity and transmission status.
Example 6
Screening of Maternal Sera with Peptide Collection
This study analyzes the binding of a larger population of maternal sera from vertical transmitter and non-transmitter mothers to a larger library of peptides from the envelope glycoprotein of HIV-1 than illustrated in the previous examples.
A. Patient Sera Samples
A total of 86 maternal sera samples obtained from patients of the Hospital of the University of Pennsylvania during the third trimester of pregnancy were used in this study 58 (67%) were non-transmitters and 28 (33%) were transmitters. This is approximately consistent with the national average (i.e. a rate of transmission between 25-30%). Transmission status was based upon serological or molecular diagnosis of children (at an age of greater than 15 months) born to these mothers. Because of the constraints on the volume of serum available for many of these samples, not all sera were analyzed with all the peptides. However, each sera sample was run with at least 40 peptides.
B. Peptide Reagents and Analysis
The peptides used in this study are among those shown topographically in FIG. 1. The location and sequences of these peptides are provided in Table 1, Table 2, Table 9, and in the following Table 12.
These peptides are of an average length of 16 amino acids and covered the entire external as well as the transmembrane glycoprotein of HIV-1. Peptide binding was analyzed by ELISA essentially as described in Example 3.
C. Results
The results of one study, using some of the peptides identified above among others, is provided in Table 12, which illustrates the number and percent of non-transmitters which bound to the tested peptide. The percentage designation refers to the percentage of sera samples which bound to a particular peptide. A value of greater than 0% means that at least one of the samples bound to the particular peptides.
Within this sample group, peptides C19Q SEQ ID NO:137] and 510 [SEQ ID NO:133] both bind to non-transmitter at least 30% without any binding of the transmitter samples (i.e. 0%). Additionally, AID-PND SEQ ID NO:134] and 1/SP10 IIIB [SEQ ID NO:194] also appear to selectively correlate with non-transmitters, as these two peptides bound greater than 50% of the nontransmitters and these percentages were at least two fold greater than binding exhibited by the transmitters.
Table 13 below illustrates sera binding to peptides, expressed in terms of the average number of peptides bound, for non-transmitter and transmitter group. The transmission versus non-transmission groups in these studies will be compared using the nonparametric Mann-Whitney test or student t-test.
These results indicate that the average number of peptides bound by sera from transmitting mothers is significantly lower than sera from non-transmitting mothers whether designated in terms of gp120 peptides only, gp41 peptides only, or gp 120+gp41 peptides combined, with the transmitter group being significantly lower.
Example 7
Screening of Maternal Sera with Another Peptide Collection
This example provides additional sera screens using peptides corresponding to sequences of the MN strain. The sera samples (5 transmitters and 5 non-transmitters) were obtained from the NIH and differ from those screened in the previous studies. Peptide binding was analyzed by ELISA as described in Example 3. These results are provided in Table 14 below. This data reports on peptides of gp41 covering 67% of the gp41 transmembrane glycoprotein.
From this data, peptides MN-17, MN-8, MN-11 and MN-15 are shown to selectively correlate with non-transmission. This study further indicates that sera immunoglobulins from mothers who are non-transmitters have a broader reactivity to both gp120 and gp41 in terms of binding to peptides than do transmitter mothers.
Numerous modifications and variations of the present invention are included in the above-identified specification and are expected to be obvious to one of skill in the art. Such modifications and alterations to the methods of the present invention are believed to be encompassed in the scope of the claims appended hereto.
Claims
What is claimed is:
1. A method for determining whether or not a mother will transmit HIV-1 to a fetus in a given pregnancy comprising: (a) providing a biological sample from an HIV-infected woman; (b) incubating said sample with a collection of HIV peptides comprising at least one peptide selected from the group consisting of gp120-derived peptides: SEQ ID NO: 1: YDTEVHNVWATHACV, SEQ ID NO: 2: RKSIGIQRGPGR, SEQ ID NO: 3: KQFINMWQEVGKAMYAPP, SEQ ID NO: 4: CFRPGGGDMRDNWREL, SEQ ID NO: 10: TLPCASDAKAYDTEV, SEQ ID NO:137: CNNKTFNGTGFCTNVSTVQ, SEQ ID NO:133: VVQREKRAVGIG, SEQ ID NO:134: YNKRKRIHIQRGPGRAFYTTKNII, SEQ ID NO:194: KQIINMWQEVGKAMYACTRPNNNTRKSIRIQRGPG, and at least one peptide selected from the group consisting of gp41-derived peptides: SEQ ID NO: 5: QNNLLRAIEAQQHLLQLTVWGI, SEQ ID NO: 6: CQNQQEKNEQELLEL, SEQ ID NO: 7: ELDKWASLWNWFNITNWLWY, SEQ ID NO: 8: VTRIVELLGRRGWEALKYWW, SEQ ID NO: 30: FSYHRLRDLLLIVTR, SEQ ID NO: 31: NATAIAVAEGTDRVIEVVQGAYRAI, SEQ ID NO: 121: LGIWGCSGKLIC, SEQ ID NO:170: YIKIFIMIVGGLVG, SEQ ID NO:159: DTSGRLVHGFLAIIW, SEQ ID NO:171: HIPTRIRQGLERALL, and SEQ ID NO:165: HMLQLTVWGIKQLQAR; (c) determining the number of peptides in said collection reacted with said sample; (d) comparing the number of reacting peptides to a standard, wherein said standard provides a pattern of peptide reaction with a sample from a patient of transmission status, wherein a non-transmissible HIV sample is indicated by reaction of said sample with at least about two fold more peptides than react with said standard.
2. A method for diagnosing HIV infection in an infant born to an HIV-infected mother comprising the steps of: (a) providing a sample from said HIV-infected woman or said infant; (b) incubating said sample with a collection of HIV peptides comprising at least one peptide selected from the group consisting of gp120-derived peptides: SEQ ID NO: 1: YDTEVHNVWATHACV, SEQ ID NO: 2: RKSIGIQRGPGR, SEQ ID NO: 3: KQFINMWQEVGKAMYAPP, SEQ ID NO: 4: CFRPGGGDMRDNWREL, SEQ ID NO: 10: TLPCASDAKAYDTEV, SEQ ID NO:137: CNNKTFNGTGFCTNVSTVQ, SEQ ID NO:133: VVQREKRAVGIG, SEQ ID NO:134: YNKRKRIHIQRGPGRAFYTTKNII, SEQ ID NO:194: KQIINMWQEVGKAMYACTRPNNNTRKSIRIQRGPG, and at least one peptide selected from the group consisting of gp41-derived peptides: SEQ ID NO: 5: ONNLLRAIEAQQHLLQLTVWGI, SEQ ID NO: 6: CQNQQEKNEQELLEL, SEQ ID NO: 7: ELDKASLWNWFNITNWLWY, SEQ ID NO: 8: VTRIVELLGRRGWEALKYWW, SEQ ID NO: 30: FSYHRLRDLLLIVTR, SEQ ID NO: 31: NATAIAVAEGTDRVIEVVQGAYRAI, SEQ ID NO: 121: LGIWGCSGKLIC, SEQ ID NO:170: YIKIFIMIVGGLVG, SEQ ID NO:159: DTSGRLVHGFLAIIW, SEQ ID NO:171: HIPTRIRQGLERALL, and SEQ ID NO:165: HMLQLTVWGIKQLQAR; (c) determining the number of peptides reacting with said sample; (d) comparing the number of reacting peptides to a standard, wherein said standard provides a pattern of peptides reacting with a sample from a patient of transmission status, wherein non-transmission status is indicated by reaction with said sample of at least about two fold more peptides than react with said standard, and where the non-transmission status of the mother corresponds to the HIV diagnosis in the infant.
Patent Citations (8)
| Patent | Date | Inventor | Cited By |
|---|---|---|---|
| EPX273716 | 1988-07-01 | ||
| EPX279688 | 1988-08-01 | ||
| EPX306219 | 1989-03-01 | ||
| EPX328403 | 1989-08-01 | ||
| EPX330359 | 1989-08-01 | ||
| EPX462551 | 1991-12-01 | ||
| EPX471407 | 1992-02-01 | ||
| WOXWO91/04273 | 1991-04-01 |
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