HIV-1 and HIV-2: A Tale of Two Viruses

Charles B. Hicks, MD


AIDS Clinical Care 

In This Article

Abstract and Introduction


Patients infected with both viruses had slower disease progression than those infected with HIV-1 only.


HIV-1 infection causes most AIDS cases worldwide, but in West Africa, HIV-2 is also prevalent. The natural history of HIV-2 infection tends to be more benign than that of HIV-1, and most patients infected solely with HIV-2 do not progress to AIDS. Previous research suggests that HIV-2 infection protects against subsequent HIV-1 infection and, in cases of dual infection, slows the rate of HIV-1 disease progression. Researchers recently tested this hypothesis using a long-term cohort of untreated individuals infected with one or both viruses.

From 1990 through 2007, all persons employed by the Guinea-Bissau police force were offered enrollment in a prospective study of HIV infection that included blood collection every 12 to 18 months. A total of 223 participants became infected with HIV-1 after enrolling: 191 with HIV-1 only and 32 with both HIV-1 and HIV-2. Of the 32 individuals with dual infection, 20 were infected with HIV-2 first, and 12 had concomitant seroreactivity.

Patients with dual infection had a significantly longer median time to AIDS diagnosis than those infected with HIV-1 only (104 vs. 68 months). They also had a significantly higher mean CD4-cell percentage at the extrapolated time of seroconversion (31% vs. 23%) and a significantly slower increase in CD8-cell percentage over time. Furthermore, their HIV-1 viruses exhibited significantly less genetic diversity over time, which also suggests an attenuating effect of HIV-2 on HIV-1 disease progression. The 20 participants who were infected with HIV-2 before HIV-1 had the longest median time to AIDS diagnosis (129 months) and also the highest mean CD4 percentage at seroconversion (32%).


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