Pig-tailed macaques infected with human immunodeficiency virus (HIV) type 2(GB122) 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 durin g primary infection remains essential to understanding the risk of sexual t ransmission. This investigation represents the first systematic evaluation of male genital tract shedding to use a nonhuman primate model, including t he impact of exposure route and viral virulence. Male macaques were inocula ted with either a chronic disease-causing virus (HIV-2(GB122); n = 4 intrav enous; intrarectal) or an acutely pathogenic simian/HIV strain (SHIV89.6P; n = 2 intravenous). All macaques were systemically infected, and seminal pl asma virion-associated RNA (vRNA) levels were similar to 10- fold lower tha n 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 duration s in seminal virus expression were noted for SHIV89.6P infection. This nove l model definitively establishes that virus dissemination results in early peak seminal levels and provides a basis for evaluating interventions targe ting male genital tract expression.