Submitted to: Poultry Health Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: October 14, 1998
Publication Date: N/A
Technical Abstract: Exogenous avian leukosis viruses (ALV) from chickens are classified into five subgroups, A, B, C, D and J. ALV-J was first described in the United Kingdom and found to be associated with myeloid leukosis (ML) in meat-type chickens. Recently, ALV-J infection has emerged as a serious cause of mortality and other production problems in broiler breeder flocks in many countries around the world including the U.S. Field observations suggest that ALV-J, previously not identified in flocks in the U.S., is gaining virulence, as losses in affected flocks are occurring earlier and at a higher rate. Further, ALV-J infection has recently been diagnosed in commercial broiler flocks. During the last three years, several ALV-J were isolated from broiler breder and commercial broiler flocks experiencing a relatively high incidence of ML in the U.S. ALV isolates were classified as subgroup J by: 1) their ability to propagate in CEF that are resistant to subgroup A and E ALV (C/AE); 2) positive reaction in a polymerase chain reaction using primers specific for ALV-J (14); and 3) positive reaction in a virus neutralization tests using antibody specific for ALV-J. ALV-J induced ML was diagnosed in affected flocks at 4 weeks of age or older.