CAS Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China. Electronic address: [Email]
Endogenous retroviruses (ERVs) arise from the infection and integration of past retroviruses into animal hosts. We performed large-scale genomic mining of 101 avian genomes for discovery of ERVs having none-avian origin and investigated the cross-species transmission events. Phylogenetic analysis of the reverse transcriptase (RT) of polymerase gene (pol) and the transmembrane subunit (TM) of the envelope gene (env) supported that avian ERVs with a mammalian env gene existed in at least 15 avian species and can be divided into two major groups: Group-1 were of recombinant ERVs with an alpha-like pol gene and a gamma-like env gene, and Group-2 included ERVs with both gamma-like pol and env genes. Group-1 represented the avian alpharetroviral/mammalian gammaretroviral recombinant while Group-2 documented viral jump from mammals to birds. Molecular dating analysis suggested that Group-1 ERVs had integrated into avian genomes continuously, until recent past. We have expanded the knowledge of ERVs with cross-order transmission.