[The diversification of the protein kinase R contributes to the specificity of bat-virus interactions]

Several bat species asymptomatically harbor certain viruses that are highly pathogenic in other mammals. The underlying mechanisms involve an evolutionary balance between tolerance and immune resistance to viral infections. However, how bats innate immunity has evolved in response to viruses remains to be elucidated. Here, we review the evolution of the protein kinase R (PKR) in bats, a major antiviral protein of vertebrate innate antiviral defense. Our recent results indicate that PKR has evolved under selective pressure and has undergone genomic duplications in bats, in contrast to all mammals studied, which possess only a single copy of the gene. The genetic changes in bat PKR are probably partly the result of genetic conflicts with ancient pathogenic poxviruses, shaping a bat-specific host–virus interface. Furthermore, the duplicated PKRs in Myotis species enable them to collectively escape viruses and enhance their viral control. These results suggest that viral adaptations of PKR contribute to the specificity of modern interactions between viruses and bats, and may explain unique antiviral mechanisms in bats.