Identification of avian leukosis virus shedding hens. Comparison of ALV gs-antigen levels in various test samples.

Various materials from two White Leghorn basic breeder flocks were tested by the enzyme-linked immunosorbent assay (ELISA), the complement fixation test (CFT) for detection of avian leukosis/sarcoma virus (ALV) group-specific (gs) antigens and the phenotypic mixing test (PMT) to compare the applicability of these techniques for the identification of hens which congenitally excrete exogenous ALV. The predictive value of each test was evaluated on the basis of association between ALV gs-antigen detection and ALV recovery and congenital virus transmission demonstrable in the hens. In materials from two flocks under study a close correlation was observed between congenital transmission of exogenous ALV to embryos and ALV gs-antigen detection in albumen samples. Results of examinations of vaginal/cloaca swabs and meconium samples were poorly associated with congenital virus excretion. ALV gs-antigen levels were generally higher in embryos than in albumen samples. Considerable variations in gs-antigen levels were observed in embryos and albumen samples from eggs of individual ALV shedding hens and also within a series of embryos from eggs of one hen.