Sperm -- and not just the fluid it bathes in -- can transmit HIV to macrophages, T cells, and dendritic cells, according to a research team led by Ana Ceballos at the University of Buenos Aires in Argentina. Writing in The Journal of Experimental Medicine, the team says that by infecting dendritic cells, which carry the virus and potently pass it to T cells, sperm may play a leading role in spreading HIV.
During sexual intercourse, infected men transmit HIV through their semen, which carries free-floating virus as well as HIV-infected leukocytes. Traces of the virus have been detected on sperm as well, but the role they play in viral transmission has been a matter of debate. After all, men with vasectomies can transmit HIV. Now Ceballos's team has shown that HIV attaches to the surface of sperm and that these carriers pass on the virus to dendritic cells and other HIV targets.
Sperm might reach dendritic cells by passing through microabrasions in the vaginal or anal lining that often form during intercourse, suggest the authors. Or they might contact the finger-like projections of the dendritic cells that extend to the surface of mucosal linings.
