Human immunodeficiency virus infection: In situ polymerase chain reaction localization in human placentas after in utero and in vitro infection

OBJECTIVE: We compared localization of human immunodeficiency virus type 1 within human placentas infected in utero with localization within human pla cental explants infected in vitro. STUDY DESIGN: Placental tissues from 3 cases of vertical transmission of hu man immunodeficiency virus type 1 were studied. Human placental explants fr om 6 term pregnancies not complicated by human immunodeficiency virus type 1 infection were infected in vitro with human immunodeficiency virus type 1 (Ba-L). Sections from each placental explant and each placenta infected in utero were analyzed for human immunodeficiency virus type 1 localization by means of in situ polymerase chain reaction. RESULTS: Human immunodeficiency virus type 1 was primarily localized within syncytiotrophoblast, Hofbauer cells, and extravillous mononuclear cells in placental tissue sections from cases of in utero infection. Within placent al explants human immunodeficiency virus type 1 deoxyribonucleic acid was f ound in syncytiotrophoblast and Hofbauer cells. The distributions of viral localization were similar in placentas infected in utero and placental expl ants infected in vitro. CONCLUSION: Human immunodeficiency virus type 1 can be localized to specifi c human placental cells (eg, syncytiotrophoblast) after either in utero or in vitro infection, which demonstrates the specificity and selectivity of h uman immunodeficiency virus infection in the human placenta.