HIV Viral Populations in Semen Different Than in Blood

Research sheds light on how HIV gets into semen, a major vehicle for spreading AIDS

FRIDAY, Aug. 20 (HealthDay News) -- HIV-1 living in the genital tract displays genetic differences from HIV-1 in the bloodstream, suggesting three mechanisms leading to the virus getting into semen, according to a study published online Aug. 19 in PLoS Pathogens.

Jeffrey A. Anderson, M.D., of the University of North Carolina at Chapel Hill, and colleagues sampled blood and semen in 16 HIV-infected men who had not been treated, and used single genome amplification to generate and compare the env gene and viral RNA populations from the two sites.

Based on the comparisons, the researchers proposed three mechanisms leading to viral populations in semen: direct import of the virus from the bloodstream, oligoclonal amplification of a subset of genotypes within the seminal tract, or sustained replication and evolution of a distinct virus in the seminal tract resulting in compartmentalization. Also, there was a significant enrichment of cytokines and chemokines in semen, compared to blood, of both HIV-infected and uninfected men, creating an environment conducive to viral replication. The researchers note that the concentration of immune modulators in the seminal plasma probably enhances the potential for viral replication by creating an environment where target cells are maintained in an activated state.

"These data define new and distinct features of virus:host interactions and represent a significant advance in our understanding of HIV-1 replication in the male genital tract," the authors write.

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