Murine AIDS, a key to understanding retrovirus-induced immunodeficiency

A synthetic thiol molecule releasing N-acetyl-l-cysteine and cysteamine drives early up-regulation of immunoproteasome subunits in the lymph nodes of mice infected with LP-BM5 leukemia retrovirus

Thiol molecules have been recently re-considered as drug candidates in viral infections because of their ability to induce redox changes which interfere with virus life cycle and modulate the host immune response. Little is known about the molecular mechanisms of their immunomodulatory properties. Here we show that I-152, a thiol molecule metabolized to release N-acetyl-l-cysteine and cysteamine and acting as a pro-glutathione agent, causes early up-regulation of immunoproteasome subunits in the lymph nodes of murine leukemia virus infected mice. This evidence suggests that the immunoproteasome may be modulated by thiol-based compounds with important implications in understanding redox-controlled immunoregulation.

Sympathetic Nerves and Innate Immune System in the Spleen: Implications of Impairment in HIV-1 and Relevant Models

The immune and sympathetic nervous systems are major targets of human, murine and simian immunodeficiency viruses (HIV-1, MAIDS, and SIV, respectively). The spleen is a major reservoir for these retroviruses, providing a sanctuary for persistent infection of myeloid cells in the white and red pulps. This is despite the fact that circulating HIV-1 levels remain undetectable in infected patients receiving combined antiretroviral therapy. These viruses sequester in immune organs, preventing effective cures. The spleen remains understudied in its role in HIV-1 pathogenesis, despite it hosting a quarter of the body’s lymphocytes and diverse macrophage populations targeted by HIV-1. HIV-1 infection reduces the white pulp, and induces perivascular hyalinization, vascular dysfunction, tissue infarction, and chronic inflammation characterized by activated epithelial-like macrophages. LP-BM5, the retrovirus that induces MAIDS, is a well-established model of AIDS. Immune pathology in MAIDs is similar to SIV and HIV-1 infection. As in SIV and HIV, MAIDS markedly changes splenic architecture, and causes sympathetic dysfunction, contributing to inflammation and immune dysfunction. In MAIDs, SIV, and HIV, the viruses commandeer splenic macrophages for their replication, and shift macrophages to an M2 phenotype. Additionally, in plasmacytoid dendritic cells, HIV-1 blocks sympathetic augmentation of interferon-β (IFN-β) transcription, which promotes viral replication. Here, we review viral–sympathetic interactions in innate immunity and pathophysiology in the spleen in HIV-1 and relevant models. The situation remains that research in this area is still sparse and original hypotheses proposed largely remain unanswered.

The Effects of Curcuma longa L., Purple Sweet Potato, and Mixtures of the Two on Immunomodulation in C57BL/6J Mice Infected with LP-BM5 Murine Leukemia Retrovirus

The immune response is stimulated to protect the body from external antigens and is controlled by several types of immune cells. In the present study, the immunomodulatory effects of Curcuma longa L., purple sweet potato, and mixtures of the two (CPM) were investigated in C57BL/6 mice infected with LP-BM5 murine leukemia virus (MuLV). Mice were divided into seven groups as follows: normal control, infected control (LP-BM5 MuLV infection), positive control (LP-BM5 MuLV infection+dietary supplement of red ginseng 300 mg/kg body weight), the original powder of C. longa L. (C; LP-BM5 MuLV infection+dietary supplement of C 189 mg/kg body weight), the original powder of purple sweet potato (P; LP-BM5 MuLV infection+dietary supplement of P 1811 mg/kg body weight), CPM Low (CPL; LP-BM5 MuLV infection+CPM 2 g/kg body weight), and CPM High (CPH; LP-BM5 MuLV infection+CPM 5 g/kg body weight). Dietary supplementation lasted for 12 weeks. Dietary supplementation of CPM inhibited LP-BM5 MuLV-induced lymphadenopathy and splenomegaly and inhibited reduction of messenger RNA (mRNA) expression of major histocompatibility complex (MHC) I and II. Moreover, CPM reduced the decrease in T- and B cell proliferation, reduced the population of CD4(+)/CD8(+) T cells, and remedied the unbalanced production of T helper-1 (Th1)/T helper-2 (Th2) cytokines in LP-BM5 MuLV-infected mice. In addition, CPM inhibited reduction of phagocytosis in peritoneal macrophages and decreased serum levels of immunoglobulin A (IgA), immunoglobulin E (IgE), and immunoglobulin G (IgG). These results suggest that CPM had a positive effect on immunomodulation in C57BL/6 mice induced by LP-BM5 leukemia retrovirus infection.

Immunotherapy of murine retrovirus-induced acquired immunodeficiency by CD4 T regulatory cell depletion and PD-1 blockade

LP-BM5 retrovirus induces a complex disease featuring an acquired immunodeficiency syndrome termed murine AIDS (MAIDS) in susceptible strains of mice, such as C57BL/6 (B6). CD4 T helper effector cells are required for MAIDS induction and progression of viral pathogenesis. CD8 T cells are not needed for viral pathogenesis, but rather, are essential for protection from disease in resistant strains, such as BALB/c. We have discovered an immunodominant cytolytic T lymphocyte (CTL) epitope encoded in a previously unrecognized LP-BM5 retroviral alternative (+1 nucleotide [nt]) gag translational open reading frame. CTLs specific for this cryptic gag epitope are the basis of protection from LP-BM5-induced immunodeficiency in BALB/c mice, and the inability of B6 mice to mount an anti-gag CTL response appears critical to the initiation and progression of LP-BM5-induced MAIDS. However, uninfected B6 mice primed by LP-BM5-induced tumors can generate CTL responses to an LP-BM5 retrovirus infection-associated epitope(s) that is especially prevalent on such MAIDS tumor cells, indicating the potential to mount a protective CD8 T-cell response. Here, we utilized this LP-BM5 retrovirus-induced disease system to test whether modulation of normal immune down-regulatory mechanisms can alter retroviral pathogenesis. Thus, following in vivo depletion of CD4 T regulatory (Treg) cells and/or selective interruption of PD-1 negative signaling in the CD8 T-cell compartment, retroviral pathogenesis was significantly decreased, with the combined treatment of CD4 Treg cell depletion and PD-1 blockade working in a synergistic fashion to substantially reduce the induction of MAIDS.

Impaired memory CD8 T cell responses against an immunodominant retroviral cryptic epitope

The immunodominant cryptic epitope SYNTGRFPPL, encoded within open reading frame 2 of the LP-BM5 retroviral gag gene, is critical for protection against retroviral-induced pathogenesis. The goal of this study was to dissect the memory response against this unique immunodominant cryptic epitope. Unlike the protective acute effector population of SYNTGRFPPL-specific CD8 T cells, long-lived SYNTGRFPPL-specific CD8 T cells lacked the ability to protect susceptible mice infected with LP-BM5 retrovirus. Compared to memory CD8 T cells against a conventional epitope with similar MHC-I specificity, primed and restimulated using similar conditions, long-lived SYNTGRFPPL-specific CD8 T cells were impaired in their ability to recall against antigen, with reduced cytolytic capabilities and cytokine production. Since similar priming and restimulation regimes were utilized to generate each effector CD8 T cell population, this study has potentially broad implications with regard to the selection criteria of potent, highly conserved cryptic epitopes for use in epitope-based vaccines.

Defining the mechanism(s) of protection by cytolytic CD8 T cells against a cryptic epitope derived from a retroviral alternative reading frame

The biological significance of protective CD8 T-cell-mediated responses against non-traditional alternative reading frame epitopes remains relatively unknown. Cytolytic CD8 T cells (CTL) specific for a non-traditional cryptic MHC class I epitope, SYNTGRFPPL, are critically involved in the protection of mice during infection with the LP-BM5 murine retrovirus. The goal of this study was to determine the functional properties of the protective SYNTGRFPPL-specific CTL during LP-BM5 infection of susceptible BALB/c CD8(-/-) mice. Direct infection experiments and adoptive transfer of CD8 T cells derived from perforin (pfp)(-/-), IFN gamma(-/-), FasL(-/-) and, as a positive control, wild-type BALB/c mice, were utilized to assess the effector mechanisms responsible for protection. Our results indicate that SYNTGRFPPL-specific effector CTL preferentially utilize perforin-mediated cytolysis to provide protection against LP-BM5-induced pathogenesis, whereas CTL production of IFN gamma is not required. Our results also suggest a minimal contribution of FasL/Fas-mediated lysis during the effector response. Collectively, these results provide insight into effector mechanisms utilized by protective CTL directed against non-traditional cryptic epitopes during disease protection.

Retroviral proteomics and interactomes: intricate balances of cell survival and viral replication

Overall changes in the host cellular proteome upon retroviral infection intensify from the initial entry of the virus to the incorporation of viral DNA into the host genome, and finally to the consistent latent state of infection. The host cell reacts to both the entry of viral elements and the manipulation of host cellular machinery, resulting in a cascade of signaling events and pathway activation. Cell type- and tissue-specific responses are also characteristic of infection and can be classified based on the differential expression of genes and proteins between normal and disease states. The characterization of differentially expressed proteins upon infection is also critical in identifying potential biomarkers within infected bodily fluids. Biomarkers can be used to monitor the progression of infection, track the effectiveness of specific treatments and characterize the mechanisms of disease pathogenesis. Standard proteomic approaches have been applied to monitor the changes in global protein expression and localization in infected cells, tissues and fluids. Here we report on recent investigations into the characterization of proteomes in response to retroviral infection.

MAIDS resistance-associated gene expression patterns in secondary lymphoid organs

Murine acquired immunodeficiency syndrome (MAIDS) is caused by exposure to murine leukemia virus and serves as a model to study human AIDS. In MAIDS-susceptible C57BL/6 mice, virus exposure leads to progressive immune deficiency, while resistant strains such as BALB/c recover from infection and develop protective immunity. The goal of this study was to identify early gene expression patterns that may be important in establishing this strain-specific differential response. Total RNA was isolated from spleens and pooled lymph nodes of both mouse strains at 3 and 7 days post virus infection. The complementary DNA generated from this RNA was hybridized to mouse oligonucleotide DNA microarrays using a strategy that controlled for inherent variability and highlighted only virus-induced changes. Fluorescent intensities were normalized and analyzed for statistically significant differential expression between strains across both time points and lymphoid organs. The majority of the resistance-associated genes was identified at day 3 post-infection and demonstrated the highest fold differences between strains, while more susceptibility-associated sequences were seen at 7 days post-infection. Among the most highly differentially expressed sequences seen at the earlier time point were genes related to protein metabolism, especially serine proteases. Differential patterns of chemokine-related genes were observed at the later time point. The overall pattern of expression suggests strain-specific differences in proteases and chemokines within secondary lymphoid organs shortly after infection influence the likelihood of disease progression.

Bacterial lipopolysaccharide enhances cardiac dysfunction but not retroviral replication in murine AIDS: roles of macrophage infiltration and toll-like receptor 4 expression

Cardiovascular disease is an important complication of human immunodeficiency virus/acquired immune deficiency syndrome (AIDS), but the mechanism(s) involved are poorly understood. Although co-infecting pathogens have been implicated as an important factor in AIDS progression, no studies have investigated these interactions in cardiac tissue. We recently demonstrated that the murine AIDS model (LPBM5 retroviral infection) mimics human immunodeficiency virus-related cardiac dysfunction and pathology. We tested the hypothesis that subseptic lipopolysaccharide exposure (LPS) would enhance LPBM5 progression and exacerbate cardiovascular dysfunction during murine AIDS development. LPS (5 mg/kg, Escherichia coli 0111:B4) was administered at 1, 6, and 8 weeks during LPBM5 infection, and cardiac performance was evaluated at 10 weeks using noninvasive echocardiography. LPS alone had no significant effects, whereas it amplified abnormalities in cardiac structure and function observed in murine AIDS. Cardiac dysfunction was associated with selective increases in nonfocal infiltration of CD68(+) cells and correlated with the extent of cardiac dysfunction. Retroviral progression and cardiac retroviral content remained unaltered, but cardiac toll-like receptor 4 was increased in retrovirus + LPS. We provide first-time evidence of multipathogen enhancements to retrovirus-related cardiac complications and implicate innate immune responses, not co-pathogen-induced retroviral replication, as the primary mechanism in this setting.

Cytolytic CD8+T Cells Directed against a Cryptic Epitope Derived from a Retroviral Alternative Reading Frame Confer Disease Protection

Cytolytic CD8(+) T cells (CTL) are key to the immune response that controls virus infections and mediates disease protection. The ability of CTL to induce apoptosis of infected cells and/or limit viral replication is determined by recognition of processed viral peptide epitopes on the surface of the target cell. An understudied source of MHC class I-presented peptides is the aptly named "cryptic epitopes," defined by their nontraditional methods of generation, including derivation from alternative reading frames (ARFs). Although ARF-encoded epitopes have now been documented in a few systems, their potential functional relevance in vivo has been debated. In this study, we demonstrate the physiological significance of an ARF-derived CTL epitope in a retrovirus-induced disease model. We show that disease-susceptible CD8-deficient mice reconstituted with CTL specific for the retroviral ARF-derived SYNTGRFPPL epitope controlled an infection by the LP-BM5 retrovirus isolate, evidently at the level of viral clearance, resulting in protection of these mice from disease. These data indicate that ARF-derived epitopes are indeed relevant inducers of the immune system and demonstrate the importance of atypically generated peptides as functional Ag with a physiologic role in disease protection.

A role for T lymphocytes in mediating cardiac diastolic function

The induction of T helper (TH) lymphocytes by distinct TH ligands results in a differentiation to TH1/TH2 subsets based on their unique pattern of cytokine secretion and effector functions. We hypothesized that the relative proportion of TH1/TH2 directly relates to cardiac fibroblast (CF) function and thereby cardiac extracellular matrix (ECM) composition and cardiac diastolic function in the absence of injury or altered wall stress. We compared the effect of selective TH1 with TH2 inducers on cardiac gene expression, ECM composition, and diastolic function in C57BL/J mice. Twelve weeks after immune modulation, the left ventricular stiffness (beta) was significantly increased in the TH1 group and decreased in the TH2 group (P < 0.01). The TH2 group also demonstrated significantly increased end-diastolic and end-systolic volumes (P < 0.01). Cardiac gene expression patterns for pro-matrix metalloproteinase (MMP)-9 and -13 were increased by greater than fivefold in the TH2 group and significantly decreased in the TH1 group (P < 0.05). The total cardiac collagen and cross-linked collagen were significantly increased in the TH1 group and decreased in the TH2 group (P < 0.01). Coculturing lymphocytes harvested from the treated mice with naive primary CF demonstrated a direct control of the lymphocytes on CF pro-collagen, pro-MMP gene expression, and MMP activity. These results suggest that the TH phenotype differentially affects diastolic function through modulating CF pro-collagen and pro-MMP gene expression, MMP activity, and cardiac collagen cross-linking, resulting in altered ECM composition. Thus modulation of TH lymphocyte function could promote adaptive remodeling in heart failure and postmyocardial infarction.

AIDS-related vasculopathy: evidence for oxidative and inflammatory pathways in murine and human AIDS

Increased life expectancy of human immunodeficiency virus (HIV)-positive patients has led to evidence of complications apparently not directly related to immunodeficiency or opportunistic infection, including increased cardiovascular risk. We tested the hypothesis that vascular dysfunction occurs in the murine acquired immune deficiency syndrome (AIDS) model and evaluated potential mechanisms in murine AIDS tissues and relevant human HIV/AIDS vascular tissues. We also investigated endothelial activation and/or endothelial protein nitration and their association with time-dependent vascular dysfunction. At 1 and 5 wk of murine AIDS, statistically significant decreases in KCl contractility and time-dependent contractile deficits in response to phenylephrine were observed. The maximal response (E(max)) was reduced by approximately 40% at 10 wk, and EC(50) values were significantly changed: 102 +/- 7.3 ng for control vs. 190 +/- 37 and 130 +/- 22 ng at 5 and 10 wk, respectively (P < 0.05). Endothelium-dependent relaxation to ACh was decreased (EC(50) = 120 +/- 27 and 343 +/- 94 nM for control and at 10 wk, respectively), whereas the response to an exogenous nitric oxide donor, sodium nitroprusside, remained unchanged, suggesting a specific endothelial dysfunction. Histochemical investigations of the same vascular tissues as well as corresponding coronary endothelium showed an increase in protein 3-nitrotyrosine, intercellular adhesion molecule, and nitric oxide synthase isoforms 2 and 3. These findings were corroborated in concurrent experiments in a cohort of well-cataloged human cardiac microvascular tissues. We have demonstrated, for the first time, a specific functional vasculopathy with endothelial involvement in a murine model of AIDS that was also associated with and correlated to increased oxidative stress and specific endothelial activation. This finding was echoed in a relevant population of human HIV/AIDS patients. Research into sources and intracellular targets of oxidants in this disease could provide important mechanistic insights and may reveal new therapeutic opportunities for this increasingly important cardiovascular disease state.

Chronic methamphetamine exposure alters immune function in normal and retrovirus-infected mice

Methamphetamine (MA) abuse represents a growing problem in the USA with an increase of sudden death. To evaluate the immune function alterations due to chronic methamphetamine use, we examined C57BL/C mice with LP-BM5 retrovirus infection plus methamphetamine exposure. Mice were randomly assigned to the following groups: placebo, placebo retrovirus-infected, uninfected MA treated and retrovirus-infected MA treated. Placebo, MA-treated groups were intraperitoneally injected with saline, MA, respectively, with a gradually increasing dose from 15 to 40 mg/kg for 12 weeks (5 days/week). Con A- and LPS-induced mitogenesis of splenocytes, cytokine production by splenocytes culture and lipid peroxides in the liver were measured. Heart tissue histopathology was analyzed in all the groups with murine cytomegalovirus (CMV) superinfection. Our data showed that MA treatment significantly decreased production of IL-2 and interferon gamma (IFN-gamma) in uninfected mice but did not further suppress the reduced Th1 cytokines in retrovirus-infected mice. There were no significant effects on cytokines IL-4 and IL-6. However, tumor necrosis factor (TNF-alpha) was significantly increased in both uninfected and infected mice due to MA treatment. Lipid peroxides in liver were significantly increased both in uninfected and retrovirus-infected mice due to MA exposure. Vitamin E levels in liver were significantly decreased in uninfected mice due to MA treatment. CMV superinfection greatly increased the cardiac lesions in retrovirus-infected mice while no significant histopathology changes were detected due to MA treatment. Our data suggest that MA has immunomodulation activity, suppressing Th1 cytokine production and enhancing some Th2 cytokine secretion, as well as increasing lipid peroxides in uninfected mice. The interaction between LP-BM5 and MA remains unclear.

Side-stream cigarette smoke accentuates immunomodulation during murine AIDS

Side-stream cigarette smoke has become a hotly debated social, political, and scientific health and safety issue for nonsmokers. The harmful influences of side-stream cigarette smoke on human health are its adverse effects on the immune system, especially when already compromised by other agents. Acquired immune deficiency syndrome (AIDS) is a clinical disorder caused by human immunodeficiency virus (HIV). To facilitate studies, murine AIDS was induced in C57BL/6 mice by LP-BM5 murine leukemia virus infection, which mimics human AIDS. After 2 weeks of retroviral infection, the mice were exposed to side-stream cigarette smoke for 30 min, 5 days/week for 12 weeks using a side-stream cigarette smoke exposure system. Murine retrovirus infection reduced the in vitro proliferation of T lymphocytes stimulated by concanavalin A, increased the release of pro-inflammatory cytokine interleukin-6 (IL-6) tumor necrosis factor-alpha (TNF-alpha), increased the hepatic lipid peroxidation and decreased the alpha-tocopherol levels in liver, lung and heart. Concomitant side-stream cigarette smoke exposure for 12 weeks further inhibited the proliferation of T cells, increased the release of TNF-alpha, IL-6 cytokines and enhanced the hepatic lipid peroxidation from retrovirus infected mice. The loss of alpha-tocopherol was also further enhanced by side-stream cigarette smoke exposure during retrovirus infection. Our conclusions are that side-stream cigarette smoke induced increasing oxidative stress, reducing nutrient concentrations and suppressing immune function could make mice with murine AIDS more susceptible to opportunistic infections, potentially accelerating murine AIDS progression. Thus, the reduction of side-stream cigarette smoke exposure is an important health issue in AIDS patients to improve the quality and quantity of their lives.

Immunomodulatory effect of gold sodium thiomalate on murine acquired immunodeficiency syndrome

Induction of IL-2 production and increased expression of CD25 were observed in C57BL/10 mice after weekly treatment with gold sodium thiomalate (GST). LP-BM5 murine leukemia virus (MuLV) infected mice treated with GST survived longer, had less cervical lymph node swelling, lower spleen weight, and fewer abnormalities in the expression of the cell surface markers, CD4, CD8a and CD45R/B220 on spleen cells than those that were not treated with GST. Thus, GST treatment may be beneficial through a decrease in disease progression via IL-2 induction in MuLV infected mice. This may have application in human immunodeficiency virus-infected individuals.

Cocaethylene and heart disease during murine AIDS

Cocaethylene is an active cocaine metabolite believed to play a causative role in the increased incidence of sudden cardiac death in individuals who co-administer alcohol and cocaine. Prolonged and excessive abuse of cocaine and alcohol will result in marked alteration of host immunity to increased susceptibility to infection. To test the chronic direct effect of cocaethylene on the heart function, a conductance catheter system (CCS) was used in vivo in this study. To test whether cocaethylene injection exacerbates coxsackievirus B3 (CVB3) or cytomegalovirus (CMV) cardiomyopathy during murine AIDS, female C57BL/6 mice were infected with LP-BM5 retrovirus and superinfected with CVB3 or CMV. Daily, mice were injected intraperitoneally with cocaethylene in 0.9% saline solution (concentration increased gradually from 15 to 25 mg/ml). Histopathology of heart tissue was analyzed in all groups, and cytokines of spleen were measured in the CMV-infected groups. Results showed there was little effect on the cardiovascular system after cocaethylene injection. Cocaethylene injection during murine retrovirus infection greatly exacerbated the pathogenesis of CVB3 or CMV infection, whereas CMV-infected mice showed relatively moderate cardiac pathology compared with CVB3 infection. Both CMV and retrovirus infection suppressed the Th1 response. Our data suggest that cocaethylene treatment shifts the cytokine balance and suppresses Th1 response particularly, facilitating increased CVB3- or CMV-induced myocarditis.

Anti-inflammatory effects of theophylline: modulation of immune functions during murine leukemia virus infection

LP-BM5 murine leukemia virus induces immune dysfunction leading to B cell leukemia and murine AIDS with cytokine dsyregulation. Theophylline induces apoptosis of leukemia cells in humans. Therefore the effects of theophylline on immune dysfunction in a murine model of leukemia were investigated. C57BL/6 mice consumed drinking water containing 0.3% theophylline beginning 2 weeks after murine retrovirus infection for 4 months. Theophylline largely prevented the retrovirus induced splenomagaly, lymphodenopathy, reduction in B and T cell proliferation, and suppression of Thl cytokines (IL-2) secretion. It also suppressed Th2 cytokine (IL-4, TNF-alpha, and IL-10) production, which was otherwise stimulated by retrovirus infection. These data suggest that immune dysfunction, induced by murine retrovirus infection, was largely prevented by theophylline treatment.

Cocaine injection and coxsackievirus B3 infection increase heart disease during murine AIDS

Coxsackievirus initiates myocarditis especially in the immunologically deficient or immature. To test whether Coxsackievirus B3 (CVB3) induced pronounced cardiomyopathy during severe immune dysfunction of murine AIDS, female C57BL/6 mice were infected with LP-BM5 retrovirus and superinfected with CVB3. Some were also injected daily with cocaine hydrochloride in 0.9% saline solution (30 mg/kg) intraperitoneally, because cocaine also suppresses cellular immune response. Heart tissue was analyzed histopathologically. Mice experiencing concurrent retrovirus and Coxsackievirus infection had a high degree of cardiac lesions consistent with myopathy compared with findings in uninfected animals (p <.05). Cocaine injection during murine retrovirus infection greatly exacerbated the pathogenesis of Coxsackievirus infection. C57BL/6 mice, essentially resistant to Coxsackievirus-induced cardiomyopathy, became susceptible during the immune dysfunction in murine AIDS. This suggests that retrovirus infection causes conditions favoring Coxsackie-induced cardiac lesions. Interleukin (IL)-2 and IL-4 expression by splenocytes from the dually infected retrovirus and Coxsackievirus group showed no significant differences when the animals were also cocaine treated. However tumor necrosis factor TNF-alpha production was significantly decreased in dually infected retrovirus + Coxsackievirus mice treated with cocaine, compared with findings in various controls (p <.05).

Prevention of immune dysfunction and vitamin E loss by dehydroepiandrosterone and melatonin supplementation during murine retrovirus infection

Female C57BL/6 mice infected with the LP-BM5 leukaemia retrovirus developed murine acquired immune-deficiency syndrome (AIDS). Dehydroepiandrosterone (DHEA) and melatonin (MLT) modify immune dysfunction and prevent lipid peroxidation. We investigated whether DHEA and MLT could prevent immune dysfunction, excessive lipid peroxidation, and tissue vitamin E loss induced by retrovirus infection. Retrovirus infection inhibited the release of T helper 1 (Th1) cytokines, stimulated secretion of Th2 cytokines, increased hepatic lipid peroxidation, and induced vitamin E deficiency. Treatment with DHEA or MLT alone, as well as together, largely prevented the reduction of B- and T-cell proliferation as well as of Th1 cytokine secretion caused by retrovirus infection. Supplementation also suppressed the elevated production of Th2 cytokines stimulated by retrovirus infection. DHEA and MLT simultaneously reduced hepatic lipid peroxidation and prevented vitamin E loss. The use of DHEA plus MLT was more effective in preventing retrovirus-induced immune dysfunction than either DHEA or MLT alone. These results suggest that supplementation with DHEA and MLT may prevent cytokine dysregulation, lipid oxidation and tissue vitamin E loss induced by retrovirus infection. Similarly, hormone supplementation also modified immune function and increased tissue vitamin E levels in uninfected mice.