Pig-tailed macaques infected with human immunodeficiency virus (HIV) type 2GB122 or simian/HIV89.6p express virus in semen during primary infection:: New model for genital tract shedding and transmission

Characterizing human immunodeficiency virus (HIV) expression in semen during primary infection remains essential to understanding the risk of sexual transmission. This investigation represents the first systematic evaluation of male genital tract shedding to use a nonhuman primate model, including the impact of exposure route and viral virulence. Male macaques were inoculated with either a chronic disease-causing virus (HIV-2(GB122); n = 4 intravenous; intrarectal) or an acutely pathogenic simian/HIV strain (SHIV89.6P; n = 2 intravenous). All macaques were systemically infected, and seminal plasma virion-associated RNA (vRNA) levels were similar to 10- fold lower than those in blood. In HIV-2(GB122) infection, seminal virus was delayed by 1-2 weeks compared with that in blood. Intrarectal inoculation resulted in a shorter duration of seminal vRNA expression and intermittent seminal cell provirus. No delays, higher peaks (similar to 50- fold), or longer durations in seminal virus expression were noted for SHIV89.6P infection. This novel model definitively establishes that virus dissemination results in early peak seminal levels and provides a basis for evaluating interventions targeting male genital tract expression.