Secretory IgA as a vaccine carrier for delivery of HIV antigen to M cells.

HIV transmission and spread in the host are based on the survival of the virus or infected cells present in mucosal secretions, and the virus' ability to cross the epithelial barrier and access immune target cells, which leads to systemic infection. Therefore, HIV-specific immunity at mucosal sites is critical for control of infection. Although mucosal delivery would ensure the best onset of protective immunity, most candidate vaccines are administered through the parenteral route. Remarkably, secretory IgA (SIgA) interacts specifically with mucosal microfold (M) cells present in gut-associated lymphoid tissues. Here we evaluate the feasibility of delivering chemically bound p24HIV antigen via SIgA into the intestinal mucosae in mice. After oral administration, p24-SIgA complexes are quickly delivered into the tissue and selectively captured by CX3CR1(+) dendritic cells. Oral immunization with p24gag linked to SIgA (p24-SIgA) adjuvanted with E. coli heat labile enterotoxin (HLT) elicits both humoral and cellular immune responses against p24 at the systemic and mucosal levels and induces efficient protection against rectal challenge with a recombinant vaccinia virus encoding gag. This is the first study which underscores the remarkable potential of SIgA to serve as a vaccine carrier for an HIV antigen in mucosal administration targeting the gastrointestinal environment.

Predicting anticancer peptides with Chou's pseudo amino acid composition and investigating their mutagenicity via Ames test.

Cancer is an important reason of death worldwide. Traditional cytotoxic therapies, such as radiation and chemotherapy, are expensive and cause severe side effects. Currently, design of anticancer peptides is a more effective way for cancer treatment. So there is a need to develop a computational method for predicting the anticancer peptides. In the present study, two methods have been developed to predict these peptides using support vector machine (SVM) as a powerful machine learning algorithm. Classifiers have been applied based on the concept of Chou's pseudo-amino acid composition (PseAAC) and local alignment kernel. Since a number of HIV-1 proteins have cytotoxic effect, therefore we predicted the anticancer effect of HIV-1 p24 protein with these methods. After the prediction, mutagenicity of 2 anticancer peptides and 2 non-anticancer peptides was investigated by Ames test. Our results show that, the accuracy and the specificity of local alignment kernel based method are 89.7% and 92.68%, respectively. The accuracy and specificity of PseAAC-based method are 83.82% and 85.36%, respectively. By computational analysis, out of 22 peptides of p24 protein, 4 peptides are anticancer and 18 are non-anticancer. In the Ames test results, it is clear that anticancer peptides (ARP788.8 and ARP788.21) are not mutagenic. Therefore the results demonstrate that the described computation methods are useful to identify potential anticancer peptides, which are worthy of further experimental validation and 2 peptides (ARP788.8 and ARP788.21) of HIV-1 p24 protein can be used as new anticancer candidates without mutagenicity.

Immunization with HIV Gag targeted to dendritic cells followed by recombinant New York vaccinia virus induces robust T-cell immunity in nonhuman primates.

Protein vaccines, if rendered immunogenic, would facilitate vaccine development against HIV and other pathogens. We compared in nonhuman primates (NHPs) immune responses to HIV Gag p24 within 3G9 antibody to DEC205 ("DEC-HIV Gag p24"), an uptake receptor on dendritic cells, to nontargeted protein, with or without poly ICLC, a synthetic double stranded RNA, as adjuvant. Priming s.c. with 60 µg of both HIV Gag p24 vaccines elicited potent CD4(+) T cells secreting IL-2, IFN-γ, and TNF-α, which also proliferated. The responses increased with each of three immunizations and recognized multiple Gag peptides. DEC-HIV Gag p24 showed better cross-priming for CD8(+) T cells, whereas the avidity of anti-Gag antibodies was ∼10-fold higher with nontargeted Gag 24 protein. For both protein vaccines, poly ICLC was essential for T- and B-cell immunity. To determine whether adaptive responses could be further enhanced, animals were boosted with New York vaccinia virus (NYVAC)-HIV Gag/Pol/Nef. Gag-specific CD4(+) and CD8(+) T-cell responses increased markedly after priming with both protein vaccines and poly ICLC. These data reveal qualitative differences in antibody and T-cell responses to DEC-HIV Gag p24 and Gag p24 protein and show that prime boost with protein and adjuvant followed by NYVAC elicits potent cellular immunity.

Comparable T helper 1 (Th1) and CD8 T-cell immunity by targeting HIV gag p24 to CD8 dendritic cells within antibodies to Langerin, DEC205, and Clec9A.

Improved protein-based vaccines should facilitate the goal of effective vaccines against HIV and other pathogens. With respect to T cells, the efficiency of immunization, or "immunogenicity," is improved by targeting vaccine proteins to maturing dendritic cells (DCs) within mAbs to DC receptors. Here, we compared the capacity of Langerin/CD207, DEC205/CD205, and Clec9A receptors, each expressed on the CD8(+) DC subset in mice, to bring about immunization of microbial-specific T cells from the polyclonal repertoire, using HIV gag-p24 protein as an antigen. α-Langerin mAb targeted splenic CD8(+) DCs selectively in vivo, whereas α-DEC205 and α-Clec9A mAbs targeted additional cell types. When the mAb heavy chains were engineered to express gag-p24, the α-Langerin, α-DEC205, and α-Clec9A fusion mAbs given along with a maturation stimulus induced comparable levels of gag-specific T helper 1 (Th1) and CD8(+) T cells in BALB/c × C57BL/6 F1 mice. These immune T cells were more numerous than targeting the CD8(-) DC subset with α-DCIR2-gag-p24. In an in vivo assay in which gag-primed T cells were used to report the early stages of T-cell responses, α-Langerin, α-DEC205, and α-Clec9A also mediated cross-presentation to primed CD8(+) T cells if, in parallel to antigen uptake, the DCs were stimulated with α-CD40. α-Langerin, α-DEC205, and α-Clec9A targeting greatly enhanced T-cell immunization relative to nonbinding control mAb or nontargeted HIV gag-p24 protein. Therefore, when the appropriate subset of DCs is targeted with a vaccine protein, several different receptors expressed by that subset are able to initiate combined Th1 and CD8(+) immunity.

Surfactant-free anionic PLA nanoparticles coated with HIV-1 p24 protein induced enhanced cellular and humoral immune responses in various animal models.

Microparticles and nanoparticles prepared with poly(D,L-lactide-co-glycolide) (PLGA) or poly(D,L-lactide) (PLA) polymers represent a promising method for in vivo delivery of encapsulated peptide, protein or DNA antigens. However, one major issue that limits the potential of these delivery systems is the instability or the degradation of the entrapped antigen. Charged microparticles carrying surface adsorbed antigen were developed to resolve this problem and appear more suitable for vaccine applications. We describe here new anionic PLA nanoparticles obtained by the dialysis method that are absolutely surfactant-free, which makes them more appropriate for use in humans. The potency of this delivery system as a vaccine carrier was tested in various animal models using HIV-1 p24 protein. p24-coated PLA nanoparticles (p24/PLA) induced high antibody titres (>10(6)) in mice, rabbits and macaques. Moreover, p24/PLA nanoparticles elicited strong CTL responses and a Th1-biased cytokine release (IFNgamma, IL-2) in mice. p24 protein seemed to generate a more Th1-oriented response when administered coated onto the surface of PLA nanoparticles than adjuvanted with Freund's adjuvant. Most importantly, the ability of p24/PLA particles to induce Th1 responses was also confirmed in the macaque model, since high levels of IFNgamma-producing CD4+ T cells and CD8+ T cells could be detected by the ELISPOT assay. This protein delivery system confirms the potential of charged nanoparticles in the field of vaccine development.

Expression of latent HAART-persistent HIV type 1 induced by novel cellular activating agents.

The novel antitumor-promoting phorbol ester, prostratin, was evaluated for its ability to induce the expression of latent, highly active antiretroviral therapy (HAART)-persistent human immunodeficiency virus type I (HIV-1) from specific subsets of patients' peripheral blood cells. This evaluation was performed relative to the use of other cellular activating agents, such as OKT3, a monoclonal antibody against the human T cell receptor, interleukin-2 (IL-2), phytohemagglutinin (PHA), p24 antigen (HIV-1-specific capsid protein), and a molecular relative of prostratin, 12-deoxyphorbol 13-phenylacetate (DPP). Prostratin performed as efficiently as the other cellular activators at inducing the expression of latent HIV-1 from cells of patients on virally suppressive HAART. Of interest was the induction of a novel species of latent virus from the cells of an individual after exposure to the HIV-1-specific capsid protein, p24, relative to virus expression induced by several other cell activators. This suggests that a variety of agents may be available for animal model studies of lentiviral latency and clinical use to broadly induce the expression of latent, HAART-persistent HIV-1 in vivo with the goal of potential HIV-1 reservoir depletion or eradication.

Prognostic value of proliferative responses to HIV-1 antigen in chronically HIV-infected patients under antiretroviral therapy.

BACKGROUND: In the chronic stage of HIV infection T cell proliferative responses to HIV antigens are rare, mostly of low level, and the influence of responses on antiretroviral therapy is not known. OBJECTIVES: To determine a potential correlation between HIV-specific proliferative responses and the subsequent course of infection under antiretroviral therapy. STUDY DESIGN: Proliferation assays were performed with freshly isolated blood mononuclear cells from 45 chronically HIV-infected HAART treated individuals using HIV-p24, other recall antigens, and mitogens as stimulants. Virus load was monitored at the time of stimulation and during 33 months follow-up. RESULTS: A proliferative response to HIV antigen stimulation was detectable in 7 of 45 patients (15.5% responders). This group showed elevated reactions against tetanus toxoid and tuberculin, whereas reactions against standard mitogens were equal in the HIV responder and nonresponder groups. None of the seven HIV-specific responders had a blood virus load rebound of more than 1000 genome copies/ml during follow-up, whereas in 50% of the non-responders higher virus rebounds occurred. CD4 cell levels were slightly higher in the responder group, but mostly independent of virus rebound within the non-responders. Only four patients with high and continuous virus rebound experienced a significant CD4 cell decline. CONCLUSIONS: In patients under HAART, HIV-specific proliferative response is frequently related to anamnestic antigen responses and an enduring control of virus replication.

Association of strong virus-specific CD4 T cell responses with efficient natural control of primary HIV-1 infection.

OBJECTIVE: To investigate whether there are differences in the virus-specific CD4 T cell response during primary HIV-1 infection in patients who naturally (without antiretroviral intervention) control viral replication with differing efficiencies. METHODS: CD4 T cell responses to recombinant HIV proteins (Gag p24 and p55 and Env gp160) and an inactivated HIV-1 preparation were analysed using interferon-gamma ELISPOT assays (with CD8-depleted peripheral blood mononuclear cells) and by intracellular interferon-gamma staining and fluorescent-activated cell sorting. RESULTS: Strong HIV-specific CD4 T cell responses were detected from the earliest time-points analysed in primary infection in patients who naturally established low persisting viral loads. By contrast, HIV-specific CD4 T cell responses were weaker (at or just below the limit of detection in our assays) at similar time-points in patients who went on to establish high persisting viral loads. Statistical analysis revealed a highly significant difference (P < 0.001) between the magnitudes of the Gag p24-specific response at the earliest time-point analysed in primary infection in the two sets of patients. CONCLUSIONS: Strong HIV-specific CD4 T cell responses are associated with efficient natural control of primary HIV-1 infection.

Multiple effector functions mediated by human immunodeficiency virus-specific CD4(+) T-cell clones.

Mounting evidence suggests that human immunodeficiency virus type 1 (HIV-1) Gag-specific T helper cells contribute to effective antiviral control, but their functional characteristics and the precise epitopes targeted by this response remain to be defined. In this study, we generated CD4(+) T-cell clones specific for Gag from HIV-1-infected persons with vigorous Gag-specific responses detectable in peripheral blood mononuclear cells. Multiple peptides containing T helper epitopes were identified, including a minimal peptide, VHAGPIAG (amino acids 218 to 226), in the cyclophilin binding domain of Gag. Peptide recognition by all clones examined induced cell proliferation, gamma interferon (IFN-gamma) secretion, and cytolytic activity. Cytolysis was abrogated by concanamycin A and EGTA but not brefeldin A or anti-Fas antibody, implying a perforin-mediated mechanism of cell lysis. Additionally, serine esterase release into the extracellular medium, a marker for cytolytic granules, was demonstrated in an antigen-specific, dose-dependent fashion. These data indicate that T helper cells can target multiple regions of the p24 Gag protein and suggest that cytolytic activity may be a component of the antiviral effect of these cells.

HIV-1-Specific CD4 helper function in persons with chronic HIV-1 infection on antiviral drug therapy as measured by ELISPOT after treatment with an inactivated, gp120-depleted HIV-1 in incomplete Freund's adjuvant.

OBJECTIVE: We hypothesized that treatment of HIV-1-seropositive study subjects receiving potent antiviral therapy with an HIV-specific immune-based therapy would increase HIV-1-specific T-helper immune function. DESIGN: 10 HIV-1-seropositive study subjects receiving antiretroviral therapy were treated with an inactivated, gp120-depleted immunogen in IFA (HIV-1 immunogen, Remune) at baseline, week 12, and week 24. METHODS: The frequency of HIV-1 antigen-stimulated interferon-gamma (IFN-gamma)-producing cells was determined by the ELISPOT assay. RESULTS: Study subjects significantly increased their frequency of HIV-1-stimulated (p <. 001) or p24 antigen-stimulated (p <.01) IFN-gamma-producing cells after one, two, and three treatments of HIV-1 immunogen. Depletion of CD4 cells resulted in the strongest abrogation of the IFN-gamma response. The frequency of HIV-1 (r = 0.64; p =.0002) and p24 (r = 0. 72; p <.001) antigen-stimulated IFN-gamma-producing cells in the CD8-depleted population before and after treatment was associated with the lymphocyte-proliferative response. CONCLUSIONS: Treatment with HIV-1 immunogen significantly enhanced the frequency of HIV-1-specific IFN-gamma-producing cells. Studies are ongoing to determine the relationship between this reversal of HIV-specific anergy and virologic outcomes.

Reversal of human immunodeficiency virus type 1 protein-induced inhibition of natural killer cell activity by alpha interferon and interleukin-2.

A recombinant fusion peptide, Env-Gag, derived from the human immunodeficiency virus type 1 (HIV-1) genome corresponding to a defined portion of the envelope (Env) and internal core (Gag) proteins was examined for immunoregulatory effects on the cytotoxic activity of natural killer (NK) cell-enriched, large granular lymphocytes (LGL) from healthy donors. Percoll-separated, NK cell-enriched LGL precultured for 24 h with Env-Gag at 10- and 50-ng/ml concentrations, which significantly stimulated lymphocyte proliferation, caused significant suppression of NK cell activity. Denatured Env-Gag did not cause any effect on the NK cell activity of LGL. Two other control peptides, one derived from the Escherichia coli vector used to clone the HIV Env-Gag fusion peptide and the other derived from a non-HIV-1 viral antigen (rubeola virus), did not produce any observable effect on the NK cell activity of LGL, demonstrating the specificity of the effect produced by Env-Gag. Subsequent treatment of LGL with alpha interferon (IFN-alpha) or interleukin 2 (IL-2) alone partially reversed the Env-Gag-induced suppression of NK cell activity. However, LGL treated with both IFN-alpha and IL-2 completely reversed the suppression of NK cell cytotoxicity by Env-Gag. The combined effect of IFN-alpha and IL-2 in enhancing NK cell activity may provide a novel therapeutic approach to the restoration of depressed NK cell activity observed in HIV-infected patients.

Increased PGE2 production mediates the in vitro inhibitory effect of the human immunodeficiency virus P24 immunosuppressive heptapeptide Ch7.

Previous work from our laboratory demonstrated that a synthetic heptapeptide (Ch7), corresponding to a conserved sequence of human immunodeficiency virus (HIV) core protein p24 (amino acids 232-238), was able to specifically abrogate antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PBL). Addition of recombinant human interferon-gamma (IFN-gamma) to Ch7-suppressed cultures restored the capacity to mount an antigen-specific antibody response, suggesting that a cytokine imbalance may be at the basis of the Ch7 immunosuppressive activity. In the present paper we show that the Ch7-dependent in vitro immunosuppression was accompanied by a significant up-regulation of prostaglandin E2 (PGE2) production and induction of interleukin-10 (IL-10)-secreting cells. In the presence of the PGE2 inhibitor indomethacin, IL-10 up-regulation was prevented and the induction of a specific antibody response was partially restored. PGE2 is indeed an important regulator of immune responses with the ability to differentially affect cytokine production. Thus, our results demonstrate that the Ch7 immunosuppressive epitope may primarily act by up-regulating PGE2 production and, through this mediator, by causing a cytokine dysregulation, finally responsible for immune response suppression.

Suppression of HIV-2 replication by HIV-1 gag mutants.

Gag gene mutants of human immunodeficiency virus type 1 (HIV-1) were analyzed for their potentials of inhibiting the replication of wild-type (wt) HIV-2, the second AIDS virus, in a single-round of viral replication. Of twenty-two HIV-1 gag mutants examined, seven were found to efficiently interfere with the replication of wt HIV-2. Some mutants, which can suppress the replication of wt HIV-1, did not show this inhibitory effect. These mutants were defective at the late phase of viral replication. A mutant designated NL-C1a was demonstrated to be very effective against the replication of HIV-1 and HIV-2 in monocytic cells as well as in lymphocytic cells.

An interferon-gamma (IFN-gamma) based whole blood assay to detect T cell response to antigens in HIV-1 infected patients.

Recently it has been reported that cytokine production by T cells in response to antigens may be more sensitive test than lymphoproliferation. T cell reactivities to antigens is usually performed on isolated PBMCs, however whole blood is being used frequently for cytokine production studies. A whole blood assay is described to measure T cell mediated immune responses to HIV-1 and recall antigens. The cultures were performed in 96-well plates in which only 25 microliters of whole blood was required. We studied the production of IFN gamma in short term culture (24 hours) of 1/10 diluted heparinized whole blood (HWB) from 22 HIV-1 (+) patients grouped according to the 1993 classification of the CDC. IFN gamma was measured with an immunoassay in supernatants of HWB cultured in parallel experiments in the presence of supernatant of HIV-1LAI infected CD4+ T cells, p24 HIV antigen, PPD, tetanus toxoid (TET) and PHA. We found no production of IFN gamma in response to HIV-1 antigens in 15 HIV-1 (-) subjects; whereas a specific IFN gamma production in the presence of HIV-1 antigen was obtained in all of the 9 group A patients, in 7 of 8 group B patients and in 2 of 5 group C patients. In response to recall antigens (TET, PPD), we obtained IFN gamma production in 6 of 9 group A patients, 5 of 8 group B patients and in 1 of 5 group C patients, the response to PHA decreased but remained preserved until late in the disease. The HWB assay is a quick and simple potentially valuable tool for assessing cellular immune function in HIV-1+ patients.

A pilot phase II study of the safety and immunogenicity of HIV p17/p24:VLP (p24-VLP) in asymptomatic HIV seropositive subjects.

The aim of this phase II study was to evaluate the safety, immunogenicity and tolerability of the yeast-derived virus-like particle immunogen, Ty.p24.VLP (p24-VLP), in HIV-antibody-positive asymptomatic volunteers. Fifteen informed and consented volunteers, with p24 Antibody titres >1/100, p24 Antigen <20 pg/l, and CD4>350 x 10(9)/l were enrolled. Five were immunized with aluminium hydroxide placebo, five with 25 microg, and five with 100 microg p24-VLP in Alum adjuvant at weeks 0 and 4 by the intramuscular route. Patients were followed for 16 weeks post vaccination and the main outcome assessments were CD4 and CD8 lymphocyte counts, p24 antigen and antibody, Ty antibody and quantitative viral cultures. No serious adverse events were observed in any of the groups. There were increases in CD4 counts in the treated groups but not in the controls, although these changes were not statistically significant. There were no significant intrasubject or intergroup changes in the other parameters, such as p24 antigen and antibody. No pattern of change in plasma viraemia was detected, and most cultures were negative. Therefore we conclude that p24-VLP immunizations of 25 microg and 100 microg are well tolerated, and the CD4 changes are encouraging, but higher doses and larger numbers are required to see if there are significant humoral or cellular responses, and extended phase II studies are now in progress.

Interferon-gamma (IFN-gamma) can counteract the in vitro inhibitory effect of an HIV p24 immunosuppressive heptapeptide.

Previous work from our laboratory demonstrated that a synthetic heptapeptide (Ch7), corresponding to a conserved sequence of HIV core protein p24 (aa 232-238), was able to specifically abrogate antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PBL). In the present study we show that Ch7 did not inhibit the induction of IFN-gamma-secreting cells nor the accumulation of IFN-gamma mRNA in antigen-stimulated cultures. However, delayed addition of recombinant human IFN-gamma to Ch7-suppressed cultures was able to restore fully the capacity to mount an antigen-specific antibody response. Thus, although the Ch7 immunosuppressive effect may not be directly related to a decreased production of IFN-gamma, an increased level of this cytokine is certainly able to counteract the negative effect of the peptide.

Antibodies to p24 antigen do not specifically detect HIV-infected lymphocytes in AIDS patients.

A flow cytometric assay (FCA), which detects the p24 antigen in HIV-infected cell lines and in peripheral blood mononuclear cells (PBMC) of AIDS patients, has been described in several studies. However, the results presented here clearly show that this p24-FCA, although useful for the analysis of HIV infection of cells in vitro, does not specifically detect HIV-infected PBMC from patients. Isotype control antibodies also stained PBMC from HIV-infected patients to a greater degree than the PBMC from healthy controls. Furthermore, the CD4-negative lymphocytes, which are generally not infected with HIV, were also found to stain with anti-p24. Finally, no enrichment of HIV-infected cells was found in the FACS-purified CD4+p24+ lymphocytes, compared to the CD4+p24- cell fraction. The p24-FCA, therefore, was not useful for determining the percentage of infected PBMCs from HIV-infected individuals.

Induction of IL-6 and IL-10 production by recombinant HIV-1 envelope glycoprotein 41 (gp41) in the THP-1 human monocytic cell line.

Elevated levels of circulating monokines (IL-6, IL-1, and TNF alpha) have been seen in HIV-1 infection, and the overproduction of these cytokines could contribute to AIDS pathogenesis in various ways. In previous work, we had seen that exposure of human monocytes to HIV-1, including inactivated, noninfectious HIV, led to rapid IL-6 gene expression and secretion. To investigate cytokine production in response to components of HIV by monocytes/macrophages, production of IL-6 and IL-10 were examined in a human monocytic cell line, THP-1, stimulated by HIV proteins. IL-6 production was induced in THP-1 cells by a detergent lysate of HIV, particularly fractions at molecular weight of 25-50 kDa. Recombinant HIV envelope glycoprotein 41 (gp41), but not gp120 or p24, also was seen to induce significant IL-6 production by THP-1 cells. These results suggest that gp41, transmembrane protein, is the primary HIV-encoded protein involved in inducing IL-6 production. IL-10 was also produced with delayed kinetics, following IL-6 production in THP-1 cells stimulated by gp41. To investigate a possible regulatory role for IL-10 in HIV-induced monokine production, recombinant IL-10 was added to gp41-exposed THP-1 cells. IL-10 inhibited gp41-induced IL-6 production and reduced the expression of IL-6 mRNA. When anti-human IL-10 neutralizing antibody was added to THP-1 cells, IL-6 production was enhanced. These results suggest that the IL-6 production may be downregulated by endogenously produced IL-10 and that IL-10 may downregulate cytokine production by HIV-activated monocytes via an autoregulatory mechanism.

An HIV p24 heptapeptide down-regulates antigen-specific responses in vitro interfering at the level of the T3-Ti complex.

Ch7 (RGSDIAG), a synthetic heptapeptide derived from a conserved region of HIV p24 (aa 232-238), was previously shown to suppress antigen-induced responses in cultures of normal human peripheral blood lymphocytes (PBL). We show in this paper that Ch7 is the shortest peptide retaining full inhibitory capacity. Further, the peptide inhibited efficiently and in a dose-dependent manner the induction of a specific antibody response to the antigens SRC (sheep red cells) and Candida albicans but did not exert any effect on the induction of immunoglobulin-secreting cells in PWM-stimulated cultures. Finally, Ch7 inhibited anti-CD3-induced lymphoproliferation but did not affect anti-CD2 activation. These results suggest that a conserved epitope of HIV p24 may be able to prevent the induction of antigen-specific antibody responses by interfering with lymphocyte activation via the T3-Ti complex, resulting in the abrogation of immune functions that are defective in HIV-infected individuals.

Selective effect of alcohol on cellular immune responses of lymphocytes from AIDS patients.

In this study we examined the in vitro effects of alcohol on the proliferative responses of lymphocytes from healthy donors and AIDS patients to a recombinant fusion peptide, env-gag, corresponding to portions of the gp41 envelope (env) and internal core (gag) proteins of HIV. The effects of alcohol (ETOH) on the natural killer (NK) cell activities of lymphocytes from healthy donors and patients with AIDS were also investigated. Peripheral blood mononuclear cells from both normal donors and AIDS patients produced significant levels of lymphocyte proliferative responses to the HIV env-gag peptide; however, these responses were significantly higher in patients with AIDS, showing the specificity of the response. The env-gag-induced proliferative responses of lymphocytes from normal subjects were significantly suppressed when cultures contained only higher levels of ETOH (0.2% and 0.3%), whereas ETOH even at a lower level (0.1%) produced significant suppression of the env-gag-induced proliferation of lymphocytes only from AIDS patients. Direct addition of ETOH at concentrations of 0.1%, 0.2%, and 0.3% to cultures of lymphocytes from normal donors and NK target cells did not produce significant suppression of NK cell activities. However, ETOH at concentrations of 0.2% and 0.3% significantly suppressed the NK activities of lymphocytes from AIDS patients, and the suppressive effect was observed at all E:T cell ratios examined. Control peptide from the Escherichia coli expression vector did not produce any significant effect on lymphocyte proliferative responses or NK activity of both normal donors and AIDS patients.(ABSTRACT TRUNCATED AT 250 WORDS)