HIV-2 Tropism and Disease
Kelly Cheney and Áine McKnight
from: Lentiviruses and Macrophages: Molecular and Cellular Interactions (Edited by: Moira Desport). Caister Academic Press, U.K. (2010)
Human immunodeficiency viruses (HIV-1 and HIV-2) have evolved from a reservoir of African non-human primate lentiviruses, the simian immunodeficiency viruses. In contrast to the epidemic nature of HIV-1 infections, HIV-2 is restricted in its worldwide distribution, with the lower viral loads established in asymptomatic infection a significant cause of its diminished transmission efficiency. HIV-2 is also much less pathogenic than HIV-1 and results in a reduced rate of progression to AIDS despite a substantial proviral burden. The majority of patients remain asymptomatic and die of causes unrelated to immunodeficiency. The adoption of "accessory genes" by HIV-2 and its more promiscuous pattern of coreceptor usage (including CD4-independence) may assist the virus in its adaptation to avoid innate restriction factors present in host cells. Adaptation to use normal cellular machinery to enable transmission and productive infection has also aided the establishment of HIV-2 replication in humans. A survival strategy for any infectious agent is not to kill its host but ultimately become a commensal organism. Having achieved a low pathogenicity, over time, variants more successful at transmission will be selected read more ...