HIV-2 does not protect against HIV-1 infection

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Infection with HIV-2 does not protect against HIV-1 infection, and people with HIV-2 may be at increased risk of HIV-1 infection compared to those without HIV-2, according to findings from Guinea-Bissau reported at a UK Medical Research Council symposium last week in London by Dr Maarten van der Loeff . Many researchers had previously believed that HIV-2 infection might confer some protection against HIV-1.

Researchers from the MRC's Gambia unit looked at villages in the Caio region of Guinea-Bissau, one of the West African countries where HIV-2 is commonly found. They identified 248 HIV-2 infected individuals and 159 uninfected controls, and carried out blood tests more than a year apart to evaluate whether HIV-2 infection reduced the risk of subsequent HIV-1 infection.

They found an HIV-1 incidence of 1.6% and an HIV-2 incidence of 2.6%, and found that 1.1% became dually infected during the follow-up period. The major risk factors for HIV-1 infection were commercial sex work and prior HIV-2 infection. Adjusting for commercial sex work experience, HIV-2 infection in itself increased the risk of HI-1 infection 3.5-fold, regardless of age or sex, suggesting that HIV-2 infection is a predisposing factor for HIV-1 infection rather than being a marker for sexual activity.