We have examined the effects of interferon (IFN)-alpha/beta on HIV-1 and SIV replication in CD4+ T-cell lines. To enable us to examine these effects on a single cycle of virus replication, cells were synchronously infected with HIV-1 LAI or SIV mac251. Cell lines included MT4 cells which were responsive to IFN and, as controls, C8166 cells which failed to respond to interferon treatment. Similar to previous reports, we found that replication of both HIV-1 and SIV was markedly inhibited in responsive MT4 cell lines treated with IFN. No such decreases were observed in HIV-1-infected, IFN-treated C8166 cells. Levels of both intracellular and extracellular viral antigens decreased in both HIV-1- and SIV-infected MT4 cells treated with IFN. Whereas steady state levels of viral-specific RNAs dramatically declined in SIV-infected cells, no such decrease was observed in IFN-treated HIV-1-infected cells. In accordance with these data, the rate of viral protein synthesis did not significantly change in HIV-1-infected, IFN-treated MT-4 cells. Western blot analysis of extracts prepared from IFN-treated HIV-1-infected cells revealed a decreased accumulation of most HIV-1-specific glycoproteins and proteins with the exception of the pr55 gag precursor. Pulse-chase experiments confirmed the enhanced stability of pr55 in IFN-treated cells, but also unexpectedly demonstrated the accelerated and quantitative processing of the p26 precursor (p24 capsid [CA] plus p2) to the final processed p24 (CA) polypeptide. These data, taken together, suggest that IFN deregulated viral protein processing and caused reduced protein stability in HIV-1-infected cells while inhibiting an earlier stage of replication in SIV-infected cells.

T cell responses are correlated with recovery from and resistance to leishmaniasis. Antigens of Leishmania chagasi were evaluated by determining their ability to elicit in vitro proliferation and cytokine production in peripheral blood lymphocytes and in T cell lines and clones from patients with histories of leishmaniasis or Chagas' disease. Antigens tested were selected by their reactivity with patient antibodies. Several of the antigens induced proliferative responses in peripheral blood lymphocytes from patients recovered from visceral or cutaneous leishmaniasis or with chronic Chagas' disease. Two purified glycoproteins, 30 and 42 kD, were consistently among the most effective in eliciting high proliferative responses and IL-2 production. Lymphocytes from a recovered visceral leishmaniasis patient were used to produce T cell lines against either the 30-or 42-kD antigen. Each of the lines responded to both of these antigens as well as to crude leishmania lysate. Cb4+ T cell clones specific for either or both of these antigens were also isolated from a visceral leishmaniasis patient. In contrast, rabbit antisera produced against these two antigens were not crossreactive. Both antigens were effective in inducing the production of IFN-'y from T cell lines from both leishmaniasis and Chagas' disease patients. These studies demonstrate the potential for defining parasite antigens with broad immunostimulatory capabilities. (J. Clin. Invest. 1990. 85:690-696.) leishmania * antigens -T cells * leishmaniasis

A model of vertical HIV transmission was developed using oral HIV-2(287) exposure of newborn Macaca nemestrina. The minimal Animal Infectious Dose for this oral route was found to be 10-fold higher than that for atraumatic viral transmission across other mucosal membranes (vaginal/rectal) of juvenile macaques. However, once infection was established, viral replication was rapid and plasma viremia could be detected by reverse-transcriptase polymerase chain reaction and viral co-culture within 1 week following exposure. No animal was resistant to infection and all macaques initially exposed to a subinfectious viral inoculum were subsequently infected by re-exposure of mucosal membranes. Higher viral load during primary infection correlated with a more rapid CD4 depletion; however, all HIV-2(287)-infected animals developed CD4 depletion during the observation period. This animal model can now be used to study early viral replication in the presence and absence of anti-retroviral agents to help identify conditions to reduce vertical HIV transmission in human newborns.

Recently, we developed a maternal-fetal macaque model using a highly pathogenic HIV-2 strain, HIV-2287, to study the time course of HIV transmission in utero. Most pregnant macaques (Macaca nemestrina) infected with HIV-2287 (10-103 infective doses) transmitted HIV to their fetuses, as verified by positive identification of virus-infected mononuclear cells and free viral RNA in fetal blood. To determine whether an antiretroviral drug combination therapy composed of two dideoxynucleosides, azidothymidine (15 mg/kg) and dideoxyinosine (15 mg/kg), and a protease inhibitor, indinavir (25 mg/kg), could completely inhibit mother-to-fetus HIV transmission, we administered these drugs orally through gastric catheters to five pregnant macaques infected with 10 infective doses of HIV-2287. Beginning 30 minutes after HIV inoculation, the dams were given the combination antiviral therapy three times daily until delivery by cesarean section. Drug treatment reduced the maternal virus load to a minimally detectable level but did not prevent primary HIV-2287 infection. All fetal and infant blood samples were virus negative by internally controlled RNA polymerase chain reaction (QC-RNA-PCR) and virus coculture assays. Fetal and infant CD4+ T-cell levels remained normal throughout the experiment. These findings strongly suggest that combination chemotherapy with azidothymidine, dideoxyinosine, and indinavir can suppress maternal viral load enough to prevent mother-to-fetus transmission of HIV.

To study mechanisms involved in mother-to-fetus transmission of human immunodeficiency virus (HIV) in utero, we have developed a chronically catheterized pregnant macaque model that permits simultaneous and sequential determination of virus in maternal and fetal blood and amniotic fluid during pregnancy. In this report, we have characterized this model using three groups of pregnant macaques designed to sample: (1) maternal blood, fetal blood, and amniotic fluid (n = 6); (2) maternal blood and amniotic fluid (n = 6); or (3) maternal blood only (n = 2). After inoculation with the highly pathogenic HIV-2(287), all pregnant macaques developed brief but intense viremias followed by precipitous CD4+ T-cell declines within 2-3 weeks. While all the infants born to dams of the three groups were HIV positive, the degree of infection and outcome of HIV infection varied. All infants were shown to be HIV-RNA-positive by reverse transcriptase-polymerase chain reaction (RT-PCR). However, HIV-infected cells were detected only in the blood of those born to dams enrolled in groups 1 and 2: most of these infants progressed to CD4+ T-cell depletion. The infants in group 3 exhibited HIV-RNA in plasma, although neither HIV-infected cells nor CD4+ T-cell depletion was detectable. However, all infants developed HIV-2-specific antibody at various levels by 2 months of age. Together, the data suggest that, while the degree of instrumentation may modulate intensity of virus transmission to fetus, the highly pathogenic HIV-2(287) exhibited a high frequency of virus transmission from the mother to fetus.