Identification of broiler breeders congenitally transmitting avian leukosis virus by enzyme-linked immunosorbent assay.

Seventy-two female broiler breeders produced 500 pedigreed chicks that were classified as infected or free of avian leukosis virus (ALV) by assay for ALV in their meconia. The albumen of one egg produced by each dam was assayed for group-specific (gs) antigen by the complement fixation (CF) test and enzyme-linked immunosorbent assay (ELISA). Cloacal swabs of dams were assayed for gs antigen by ELISA. Assays on albumens differentiated between transmitting and nontransmitting dams slightly better than swabs. The ELISA was more sensitive than the CF test on albumens, but more nontransmitting dams were positive by ELISA. The ELISA and virus assay on the same samples of swabs and meconia were highly correlated.