[Human Immunodeficiency Virus type 1 variants of groups N, 0 and P]

The HIV pandemic is caused by viruses of type 1 group M (HIV-M). Beside the majority of these viruses, there are many divergent variants, leading to the definition of HIV-2 and group N, O and P in HIV-1. HIV-1 groups are the result of independent cross-species of viruses from chim- panzees and gorillas living in Western Central Africa. These simian origins and the necessary adaptation to the human species are the sources of genomic characteristics, phylogenetic and viral properties, specific to each group. The natural history of the infections associated to these variants nevertheless seems similar to that of HIV-M, with a high viral replication in vivo associated with immunosuppression. These non-M variants all have been described for the first time in patients of Cameroonian origin. The Western Central Africa is the epicenter of the epidemics of non-M variants, and the diffusion outside this area is anecdotal, except in France. In Cameroon, the origin of all groups cur- rently described, HIV-O infections account for 1% of HIV infections, while only 15 cases of HIV-N infections and two HIV-P infections have been repor- ted to date. If the important genetic diversity of these variants requires the use of specific tools for serological identification and molecular characterization, diagnosis and virological monitoring of these infections now appear possible with current commercial kits; however, very little data are available on the response to antiretroviral therapy and no recommendations are defined in case of failure. Despite improved knowledge on these rare variants, many fascinating questions persist about their origin, genetic evolution and reasons for their low epidemiological spread. Their discovery, and the description of many simian viruses, demonstrates a dynamic transmission to humans, making it likely that other variants may exist; we should therefore pursue a careful surveillance, especially when faced to discrepancy between screening and therapeutic management of HIV infections.