Sperm May Play Leading Role In Transmitting HIV. 1/11/09
In an article which will appear in the November 23 issue of the Journal of Experimental Medicine (online October 26), it is reported that sperm, not just semen, may carry HIV and therefore contribute to the spread of the virus.
According to the article, scientists led by Ana Ceballos at the University of Buenos Aires in Argentina have discovered that sperm can transmit HIV to macrophages, T-cells, and dendritic cells (DCs). “During sexual intercourse, HIV-infected men transmit HIV through their semen, which carries free-floating virus as well as HIV-infected leukocytes. Traces of HIV 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 et al. show that HIV attaches to the surface of sperm and that these HIV carriers pass on the virus to DCs and other HIV targets.”
The authors reported that HIV relies on heparan sulfate to attach to sperm and once attached, the virus was transmitted from sperm to DCs in culture. The DC receptors CD4 and DC-SIGN were required for transmission, suggesting that DCs pick up the virus by binding to sperm rather than by ingesting them. Furthermore, the team found that a slightly acidic pH, similar to the pH in the vagina after sex, promoted HIV-sperm binding and the subsequent rate of sperm-related DC infection.