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October 2, 2009

Immune surveillance below the radar: study offers explanation for acyclovir’s failure to reduce HIV risk

"The background to the work is that HSV-2 infection has been consistently associated with a 2 to 3-fold increased risk of acquiring HIV; a meta-analysis published in 2006 reported a relative risk of 3.1, 2.7 and 1.7 for women, heterosexual men and men who have sex with men, respectively. [3]

"Recently analysed data from the Merck vaccine trial are consistent with these findings in that HSV-2-infected participants were found to have approximately double the risk of acquiring HIV infection during the study.

"The mechanism by which HSV-2 infection increases HIV acquisition risk is not so clear, however, and has been the subject of debate.


"The researchers acknowledge in the conclusion to the paper that the number of participants was small, but nevertheless state: “we feel that our central finding – that HSV reactivation leaves a residual inflammatory response not appreciated clinically – is typical of HSV-2 genital lesions.” They also note that “the wide anatomical distribution of HSV-2 in the male and female genital tract underscores the importance that these localized reservoirs of inflammatory cells are likely to have in HIV acquisition.”"

Read more in i-base, September/October 2009.