Open AccessOral presentation Adaptive evolution of the virus resistance gene Apobec in the genus

APOBEC3 (A3) is a cytidine deaminase gene with antiviral activity. It was originally discovered as a human cell factor that inhibits the replication of vif-defective HIV-1. A3 can be packaged in virions and subsequently blocks infection by causing G to A hypermutation following reverse tran-scription. Humans carry a tandem array of 7 hA3 genes most of which have antiviral activity, whereas the mouse has only a single copy. Several observations indicate that mA3 functions in anti-viral defense: mA3 inhibits infec-tion by several viruses including HIV-1, mA3 knockout mice are more susceptible to MMTV infection and tumor-igenesis, and mA3 restricts Friend MLV and virus-induced disease and may encode the resistance factor Rfv3 (recov-ery from Friend virus 3). In Friend virus sensitive and resistant mice, mA3 differs in expression level, splicing