Development and validation of an indirect enzyme-linked immunosorbent assay for the detection of Avian leukosis virus antibodies based on a recombinant capsid protein

Avian leukosis virus (ALV) is associated with tumor development and growth retardation in poultry. Eradication of virus infection at the primary breeder level is the principal method for controlling ALV infection in chickens. An indirect enzyme-linked immunosorbent assay (iELISA) method that utilized the prokaryotically expressed and affinity-purified viral capsid protein antigen p27 was developed for the detection of ALV-specific antibodies in chicken sera. The protocol of iELISA was validated and resulted in a higher agreement value than fluorescent antibody test (FAT) and was shown to be more sensitive and specific compared to the commercial ALV antibody test kit when FAT was used as a reference test. The main advantage of this method is the use of a single immunogenic protein to detect antibodies against all ALV exogenous subgroups. The results show that the developed iELISA is an inexpensive alternative and can potentially be used as a confirmatory test for the presence of anti-ALV antibodies on a large scale.