Advances on ALV-J in China over the past two decades

Avian leukosis is an important tumorigenic disease caused by the avian leukosis virus (ALV) in poultry. ALVs belong to the retroviral family and are classified into 11 subgroups (ALV-A to ALV-K). Among them, ALV-J was first introduced into China in 1999, spreading widely and evolving from infecting meat-type chickens to layer chickens and Chinese local chickens. ALV-J typically induces myeloid leukosis in infected chickens, but also induces a high proportion of hemangiomas in infected layer chickens, posing a serious threat to poultry breeds in China. As a retrovirus, the genome of ALV-J has undergone significant mutations, which may be related to the expansion of the infection host range and increased pathogenicity of ALV-J. Over the last two decades, the introduction and spread of ALV-J in China have caused substantial losses to the poultry industry. Specialized detection assays have been developed to combat ALV-J infections in China. Additionally, ongoing research aims to employ gene-editing technology as a novel antiviral strategy to control the spread of ALV infections. This review highlights the importance of understanding the impact of ALV-J on the Chinese poultry industry and emphasizes the need for ongoing research and innovation to safeguard poultry health and promote sustainable poultry farming practices in China.