Infection of Macaca nemestrina neonates with HIV-1 via different routes of inoculation

Objectives: Receptive anal intercourse but not orogenital sex has been identified as a major risk factor for transmission of HIV-1. Recent studies using simian immunodeficiency virus (SIV) in rhesus macaques have demonstrated relatively efficient infection following oral administration, indicating that modes of transmission may vary between HIV-1 and SIV. Here, vie investigate whether HIV-1 infection of macaques via the oral route is more efficient than via the rectal route. Design: Eleven Macaca nemestrina neonates were Exposed to HIV-1 via different routes (foul-oral, two intravenous, and five I-ectal). One animal was orally inoculated with a sham inoculum and two control animals were not exposed. Methods: All animals were followed for virological signs of infection, and for pathogenesis associated with HIV-1 infection by general physical examinations, complete blood cell counts and lymphocyte subset analysis, and full necropsies. Results: Three out of five rectally exposed macaques and both of the intravenously inoculated animals became infected with HIV-I, whereas none of the orally exposed animals showed evidence of HIV-I infection. Clinical observations following exposure included failure to thrive in the orally inoculated animals and low CD4/CD8 ratios in the rectally exposed macaques. Conclusions: The finding that, contrary to what has been reported for SIV, transmission of HIV-1 via the oral route is not more efficient than via the rectal route, indicates important biological differences between HIV-T and SIV, with direct implications for the spread of HIV and associated AIDS, and for development of anti-HIV-l vaccines.