Single and concurrent avian leukosis virus infections with avian leukosis virus-J and avian leukosis virus-A in Australian meat-type chickens.
Australian broiler breeders were screened for avian leukosis viruses (ALVs) (May 2001 to December 2003) as surveillance of measures to reduce the prevalence of ALV-J. Samples of blood (4233), albumen (1122), meconium (99) and tumours (16) were obtained from 93 flocks in six Australian states. Virus isolation was performed in C/O chick embryo fibroblast cultures, which were initially screened by group-specific antigen enzyme-linked immunosorbent assay, with follow-up confirmation using polymerase chain reaction. The chronology of isolations reveals the circulation of both ALV-J and ALV-A during this period. On 16 occasions single isolations were found to contain both ALV-A and ALV-J. This is the first report of dual infections with two subgroups of ALV occurring in the same chicken. The effectiveness of ALV-J eradication measures is indicated by the absence of any ALV-J isolations in late 2003. ALV-A however, continued to be isolated from the broiler population. The detection of dual infections, as well as the ongoing occurrence of ALV-A in meat-type birds, is discussed in the context of ongoing potential for recombinations and the associated threat for the emergence of avian leukosis virus with changes in host range and pathogenicity.
Fenton
Simon P
SP
School of Veterinary Science, University of Melbourne, Parkville, Victoria 3052, Australia. apfenton@unimelb.edu.au
Reddy
Maddula R
MR
Bagust
Trevor J
TJ
D000818:Animals; D001315:Australia / Q000453:epidemiology; D001353:Avian Leukosis / Q000453:epidemiology / Q000821:virology*; D001354:Avian Leukosis Virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D002645:Chickens / Q000821:virology*; D011201:Poultry Diseases / Q000453:epidemiology / Q000821:virology*; D013997:Time Factors