Heterophil function and resistance to staphylococcal challenge in broiler chickens naturally infected with avian leukosis virus subgroup J

Avian leukosis virus subgroup J has a high tropism for myeloid lineage cell s and frequently induces neoplastic transformation of myelocytes. The impac t of congenital avian leukosis virus subgroup J infection on the function o f circulating heterophils and susceptibility to staphylococcal infection wa s investigated. Six-week-old broiler chickens negative for exogenous avian leukosis viruses or congenitally infected with avian leukosis virus subgrou p J were inoculated intravenously with 106 colony-forming units of Staphylo coccus aureus, and pre- and postinoculation heterophil function was assesse d. All chickens developed a leukocytosis with heterophilia after inoculatio n, but total leukocyte and heterophil counts were significantly higher in l eukosis-negative chickens than in virus-infected chickens. Tenosynovitis wa s more severe in leukosis-negative chickens, and 2/10 (20%) of the virus-in fected chickens had no histologic evidence of tenosynovitis. Osteomyelitis in the tibiotarsus or tarsometatarsus developed in 5/10 (50%) of the chicke ns in each group. S. aureus was recovered from the hock joint of 6/10 (60%) of the chickens in each group. Heterophils from all chickens exhibited sim ilar phagocytic ability pre- and postinoculation. Heterophils from virus-in fected chickens exhibited less bactericidal ability preinoculation than did heterophils from leukosis-negative chickens. However, postinoculation bact ericidal ability was similar in both groups. Avian leukosis virus subgroup J provirus was present in heterophils isolated from congenitally infected c hickens. Heterophils isolated from broiler chickens congenitally infected w ith avian leukosis virus subgroup J exhibit no significant functional defic its, and infected and uninfected chickens exhibit similar susceptibility to staphylococcal infection.