Risk factors for HIV-1 shedding in semen

Semen is the body fluid most commonly associated with sexual transmission o f human immunodeficiency virus type-1 (HIV-1). Because the male genitourina ry tract is distinct immunologically from blood, compartment-dependent fact ors may determine HIV-1 shedding in semen. To identify these factors, the a uthors obtained 411 semen and blood specimens from 149 men seen up to three times. Seminal plasma was assayed for HIV-1 RNA and semen was cocultured f or HIV-1 and cytomegalovirus (CMV), which may up-regulate HIV-1 replication . The best multivariate model for predicting a positive semen HIV-1 cocultu re included two local urogenital factors, increased seminal polymorphonucle ar cell count (odds ratio (OR) = 12.6 for each log(10) increase/mL, 95% con fidence interval (CI) 12.2, 134.5) and a positive CMV coculture (OR = 3.0, 95% CI 1.2, 7.7). The best multivariate model for predicting semen HIV-1 RN A included two systemic host factors, CD4+ cell counts <200/mu liter (OR = 3.0, 95 percent CI 1.3, 6.9) and nucleoside antiretroviral therapy (monothe rapy: OR = 0.5, 95% CI 0.3, 1.0; combination therapy: OR = 0.4, 95% CI 0.2, 0.9), and a positive CMV coculture (OR = 1.7, 95% CI 1.0, 3.0). Thus, both systemic and local genitourinary tract factors influence the risk of semen HIV-1 shedding. These findings suggest that measures of systemic virus bur den alone may not predict semen infectivity reliably.