Characterization of a maternal-fetal HIV transmission model using pregnantmacaques infected with HIV-2(287)

To study mechanisms involved in mother-to-fetus transmission of human immun odeficiency virus (HIV) in utero, we have developed a chronically catheteri zed pregnant macaque model that permits, simultaneous and sequential determ ination of virus in maternal and, fetal blood and amniotic fluid during pre gnancy. 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 patho genic HIV2(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 t o be HIV-RNA-positive by reverse transcriptase-polymerase chain reaction (R T-PCR). However, HIV-infected cells were detected only in the blood of thos e 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 pl asma, although neither 1 HIV-infected cells nor CD4(+) T-cell depletion was detectable. However, 1 all infants developed HIV-2-specific antibody at va rious 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.