Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2007
Publication Date: 9/1/2007
Citation: Pandiri, A.R., Reed, W.M., Mays, J.K., Fadly, A.M. 2007. Influence of strain and dose of virus and age at inoculation on subgroup J avian leukosis virus persistence, antibody response and oncogenicity in commercial meat-type chickens. Avian Diseases. 51(3):725-732. Interpretive Summary: Subgroup J avian leukosis virus (ALV J) is an infection that can cause cancer like disease and other production problems in meat type chickens. The virus was first reported in 1991 in the United Kingdom and in 1993 in the United States. Previous observations suggest that the virus is mutating (changing) at a higher rate, however, information regarding the effects of strain and dose of virus, and age at infection on virus persistence, development of immune response, and tumors in commercial meat-type chickens is poorly understood. Our data demonstrate that strain of virus and dose and age at infection influence virus persistence, antibody response and tumors in commercial meat-type chickens. Results also indicate that development of an immune response against virus did not always lead to viremia-free status, as a high percentage of chickens had concurrent viremia and antibody. This information is significant and should be useful to primary poultry breeders who are implementing programs to eradicate this virus from their breeding stocks.
Technical Abstract: The effects of viral strain and dose, and age at inoculation on Subgroup J avian leukosis virus (ALV J) persistence, neutralizing antibody (NAb) response, and tumors were studied in commercial meat-type chickens. Chickens were inoculated on the 5th day of embryonation (5 ED) or on day of hatch (DOH) with either 100 or 10,000 TCID50 of one of three ALV J strains, namely ADOL Hc1, ADOL 6803, and ADOL 4817. At 1, 3, 7, 11, 15, 19, 23, 27 and 32 weeks post hatch, chickens were examined for ALV J viremia (V) and NAb against the inoculated strain of ALV J. Tumor response was determined on the basis of gross and microscopic examinations of affected tissues. A high incidence (83-100%) of ALV J persistence was observed in chickens infected with ALV-J either at 5 ED or DOH, regardless of strain and dose of virus. Development of NAb did not always lead to viremia-free status, as a high percentage (up to 75%) of chickens had concurrent viremia and antibody (V+A+). The incidence of antibody response, as well as the ability of antibody to clear virus infection varied with viral strain. Chickens infected with ADOL 6803 had the highest incidence of antibodies (up to 75%). However, the NAb against ADOL Hc1 (17%) were more successful in clearing virus infection than NAb against ADOL 6803 (6%) and ADOL 4817 (0%). Chickens inoculated with 100 TCID50 (34-75%) had higher NAb response than chickens inoculated with 10,000 TCID50 (0-26%). Chickens inoculated at DOH (up to 17%) were more successful in clearing virus infection than chickens inoculated at 5ED (up to 10%). Incidence of ALV J-induced tumors and tumor spectrum were also influenced by strain and dose of virus, age at inoculation and antibody response. The data demonstrate that strain and dose and age at inoculation may influence ALV J persistence, antibody response and oncogenicity in commercial meat-type chickens.