Fetal human immunodeficiency virus type 1 infection of different organs in the second trimester.

Human immunodeficiency virus type 1 (HIV-1) infection in utero was examined by isolating the virus and detecting the HIV-1 DNA sequence from different fetal tissues. The brain, thymus, lung, liver, spleen, and placenta tissues from fetuses (10-23 weeks of gestation) born to HIV-1-infected asymptomatic mothers were examined. HIV-1 was isolated from 2 of 7, 1 of 7, and 1 of 7 cocultures of splenic, thymic, and trypsin-resistant cells from the liver and placenta, respectively, with peripheral blood mononuclear cells; 20-30% and 40-60% of splenic and of thymic cells were CD4+ lymphoid cells and 40-80% of trypsin-resistant cells were mononuclear phagocytes. The HIV-1 DNA sequence was detected in 4 of 7, 3 of 7, 1 of 7, 1 of 7, 2 of 7, and 2 of 6 samples from the spleen, thymus, brain, lung, liver, and placenta, respectively, using the polymerase chain reaction. In one case, the intensity of the HIV-1 DNA sequence appeared to be correlated with the success of viral isolation. We indicate that fetal HIV-1 infection may frequently occur in the second trimester and the cells responsible for the infection may be CD4+ lymphoid cells and mononuclear phagocytes.