The HIV-2 virus is not widely spread worldwide, with only one to three million infected people, mainly in West Africa. HIV-2 is responsible for an attenuated infection compared to HIV-1. Thus, HIV-2 infection is characterized by low and frequently undetectable viral loads and a slower course to AIDS. Describing the infection natural history differences between these two viruses, and then determining the mechanisms underlying the HIV-2 lower pathogenicity, is essential to identify the mechanisms underlying the immunopathogenicity of HIV infection. Studies conducted to date have identified both host-related and virus-related factors contributing to an improved immune control and the attenuated viral replication. In this review, we summarize the origins and epidemiology of HIV-2, the natural history of infection, the main virological tools for monitoring the infection course, and the main mechanisms explaining the attenuated infection of HIV-2. We also indicate the points remaining to be explored.
Keywords: HIV-2; epidemiology; physiopathology; virulence.