Detection of avian leukosis virus subgroup J in chicken flocks from Malaysia and their molecular characterization.

Previously we have shown that avian leukosis virus subgroup J (ALV-J) might be present in chicken flocks from Malaysia based on serological study and also on detection of tissue samples with myelocytic infiltration. In this study, the polymerase chain reaction was used to detect ALV-J sequences from archived frozen samples. Out of 21 tissue samples examined, 16 samples were positive for proviral DNA and four samples for ALV-J RNA. However, only nine samples were found positive for myelocytic infiltration. A total of 465 base pairs equivalent to positions 5305 to 5769 of HPRS-103 from each of the viral RNA positive samples were characterized. Sequence analysis indicated that the samples showed high identity (95.9 to 98.2%) and were close to HPRS-103 with identities between 97.4 and 99.3%. This study indicates that ALV-J-specific sequences can be detected by polymerase chain reaction from frozen tissue samples with and without myelocytic infiltration.