Current view on HIV-2 - epidemiology, diagnosis and treatment.

Human immunodeficiency virus 2 (HIV-2) is a retrovirus related to HIV-1. It is believed to have evolved from the simian immunodeficiency virus (SIV). The disease caused by HIV-2 is manifested by a slower progression compared to HIV-1. Data from West Africa show that 37% to 50% of HIV-2 infected people have undetected or very low viremia and if left untreated, have a much more gradual decline in CD4 T lymphocytes, thus longer survival. However, treatment should not be postponed even in this case, because the course of immune reconstitution inflammatory syndrome (IRIS) in people with HIV-2 is more severe than in HIV-1, and also the year-on-year increase in the number of CD4 T lymphocytes is approximately half that of HIV-1. Approximately 6% of people living with HIV-2 (PWH2) can be defined as non-progressors and 9% as elite controllers. However, most untreated PWH2 develop AIDS.