Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2002
Publication Date: N/A
Citation: N/A Interpretive Summary: Subgroup J avian leukosis virus (ALV-J) is an emerging economically important virus infection that can cause cancer-like disease and other production problems in meat-type chickens. Previous observations suggest that the virus is changing (mutating) at a higher rate, however, information regarding the ability of ALV-J to recombine with other subgroups of ALV viruses is not known. Our data show for the first time the diagnosis of ALV-J-like infection and tumors in commercial layers flock. The source of infection with this ALV-J-like virus, probably a recombinant virus, is thought to be the commingling of the day old egg-type chicks with ALV-J infected meat-type chicks in a common hatchery. This new information is significant and useful to scientists in academia and industry who are studying the epidemiology and control of this important virus infection of chickens.
Technical Abstract: Commercial white egg layer flocks being used to produce fertile eggs for human vaccine production exhibited dramatically low peaks in egg production, two to four times higher than normal weekly mortality, and high numbers of cull, non-laying birds after the onset of sexual maturity. These lower production characteristics could not be associated with management related problems. Gross lesions of cull and fresh dead birds necropsied showed approximately 60% to lack ovarian activity and had lesions of a bacterial bursitis or synovitis while the other 40% had tumors of the viscera but not the bursa of Fabricius. Histologic examination of tumor containing tissues showed lesions typical of myelocytomatosis. The diagnosis of myeloid leukosis was confirmed by the isolation of subgroup J-like avian leukosis virus (ALV-J) and by positive a polymerase chain reaction using primers specific for the LTR of ALV-J. The source of the infection is thought to be the commingling of the day old egg- type chicks with ALV-J infected meat-type chicks in a common hatchery.