Triggering the new studies was the recent finding that semen contains a factor -- dubbed semen-derived enhancer of virus infection (SEVI) -- that escorts HIV to the front door of the cells it likes to infect.
SEVI is a beta-amyloid fibril formed from a prostate protein common in semen. Other beta-amyloids are implicated in neurological diseases such as Alzheimer's and Parkinson's. Among the compounds that fight beta-amyloid formation is EGCG -- a highly studied molecule from green tea.
Might green tea block SEVI and fight HIV infection? Yes, find researchers Ilona Hauber, PhD, of the Heinrich-Pette Institute for Experimental Virology and Immunology in Hamburg, Germany, and colleagues.
In lab studies, Hauber and colleagues showed that EGCG degraded fibrils formed from prostate peptides and stopped semen from enhancing HIV infection. The green-tea molecule did not harm human cells.
One of the Holy Grails of AIDS research has been the search for a vaginal gel that women could use to protect themselves from HIV infection during sex. Such a gel would have to cause no irritation, and the active ingredients must thrive in the acidic vaginal environment.
EGCG is stable in acidic environments, so Hauber and colleagues suggest that it would be an important addition to anti-HIV vaginal gels, possibly in combination with an anti-HIV drug.
Moreover, the researchers note, EGCG appears to have some anti-HIV activity of its own.
"EGCG, a natural ingredient of green tea, may be a valuable and cost-efficient inhibitor of semen-mediated enhancement of virus infection, and hence of sexual transmission of HIV," they conclude.
The findings appear in the online early edition of the Proceedings of the National Academy of Sciences.