Oral transmission of primate lentiviruses

Oral transmission of human immunodeficiency virus type 1 (HIV-1) is well do cumented in children who become infected postnatally through breast milk. I n contrast, epidemiologic surveys have yielded conflicting data regarding o ral HIV-1 transmission among adults, even though case reports have describe d seroconversion and the development of AIDS in adults whose only risk was oral-genital contact. To study oral virus transmission in primate models, w e exposed rhesus macaques of various ages to cell-free simian immunodeficie ncy virus (SIV), including uncloned and molecularly cloned viruses. In neon ates, viremia and AIDS developed after nontraumatic oral exposure to severa l SIV strains. Furthermore, chimeric simian human immunodeficiency viruses containing the HIV-1 envelope can also cross intact upper gastrointestinal mucosal surfaces in neonates. In adult macaques, infection and AIDS have re sulted from well-controlled, nontraumatic, experimental oral exposure to di fferent strains of SIV. These findings have implications for the risks of H IV-1 transmission during oral-genital contact.