Relative efficiency of test procedures to detect lymphoid leukosis virus infection

A total of 2544 comparisons were used to study the relative efficiency of various test procedures currently used to detect lymphoid leukosis virus infection in chickens. Meconium, blood, cloacal swabs, and egg albumen were collected from day-old chicks and adult hens from four breeder flocks. The phenotypic mixing was used as the biological assay for infectious virus. The complement fixation test and enzyme-linked immunosorbent assays were used as direct assays for the group-specific antigen of the avian leukosis-sarcoma viruses. Analysis of test results of biological assays has shown that blood from virus-infected chicks was more frequently positive than meconium. Also, direct assay for group-specific antigen was as efficient as the biological assays for detection of positive albumen samples from freshly laid eggs. The rate of false-positive reactors recognized by direct assays was lower in albumen samples than in cloacal swabs collected from hens that produce endogenous virus or group-specific antigen. Data also showed a relatively high concordance, ranging from 71 to 100%, between various assays with test materials from adult hens. Progress in reducing rates of exogenous lymphoid leukosis virus infection can be significant if dams are selected on the basis of any one of the test procedures examined. For complete eradication however, day-old chicks should be selected on the basis of the biological assay of blood of individual chicks reared in small groups.