Two novel avian leukosis viruses (ALVs) were isolated from 1380 whole blood samples taken from domestic chicken breeds in China. The two ALVs were uniquely different from the env (Envelope) genes of ALV A-J and carried an LTR (long terminal repeat) cluster from ALV-E. Large scale sequence analysis further showed that these ALVs (with different env and LTRs) were recently endemic in domestic chicken breeds in both China and Japan. The emergence of these novel ALVs is challenging the current ALV eradication program, and as such novel ALVs should be monitored in a timely and careful manner to stop their transmission and further recombination in the future.
Keywords: China; Domestic chicken breeds; Novel avian leukosis virus.