Avian leukosis virus subgroup A and B infection in wild birds of Northeast China

To analyze the status of wild birds infected with avian leukosis virus (ALV) in China, we collected 300 wild birds from various areas. Virus isolation and PCR showed that wild birds were infected by ALV-A and ALV-B. Two ALV-A and 4 ALV-B env sequences were obtained by PCR using primers designed to detect ALV-A and -B respectively. Our results showed that the gp85 genes of the 2 ALV-A strains have the highest homology with RAV-1, 99.8%, and more than 92% homology with other American strains. However, the gp85 genes of the two ALV-A strains showed slightly lower homology with Chinese strains (87.2–92.6%). Additionally, the 4 ALV-B strains have high homology with the prototype strain (RAV-2), from 99.1 to 99.4%, but they have slightly lower identity with Schmidt-Ruppin B and Prague subgroup B, from 93.3 to 98.4%. The 4 ALV-B strains showed the lowest identity with SDAU09C2 and SDAU09E3 (90%). In total, these results suggested that avian leukosis virus has infected wild birds in China.