Detection of avian leukosis virus in the laboratory and in naturally infected poultry flocks using the polymerase chain reaction.

Abstract

Commercial poultry operations continuously test for the presence of avian leukosis virus (ALV) in their flocks. Tests currently in use for detecting ALV are ELISA (enzyme-linked immunosorbent assay)-based and detect either specific viral proteins or antibodies that are raised against ALV upon infection. Regions of the ALV genome have been identified which differentiate endogenous from exogenous ALV and these areas have been targeted with PCR primers. Using semi-nested PCR amplification of the LTR (long terminal repeats), we were able to detect all four subgroups of exogenous viruses affecting chickens (A, B, C and D). Two other sets of semi-nested primers targeted within the variable regions of the env (envelope) gene are able to determine the subgroup, A or B (the predominant subgroups infecting North American flocks), of the infecting virus. These sets of primers were first tested on chick embryo fibroblasts (CEF) not carrying any ev genes. The cells were infected with viral isolates of subgroups A (RAV-1), B (RAV-2), C (RAV-49) and D (RAV-50). The LTR primers detected all four subgroups, while the env primers detected only the virus of the subgroup for which they were designed. (Abstract shortened by UMI.)