Abstract: To evaluate the reliability of the positive rate of ALV-A/B specific antibodies detection in chicken serum and illustrate the stability and specificity problems existing in the commercialized Avian Leukosis Virus Subgroup A/B Antibody Test Kit, two batches of serum samples submitted by the company A which had no positive samples detected previously and the company B which had positive samples detected yet were tested using the same lot of ELISA kit by the professional operators. Then, among the positive samples detected for the first time, eight samples from company A and forty samples from company B whose S/P ratio all ranked higher were re-detected triply, and IFA were tested using the forty-eight samples above as first antibodies. The consistence of the results between ELISA and IFA assay was compared. The results demonstrated that, eight samples from company A turned into negative in the re-detection by ELISA kit, and IFA results were negative as well, which indicated stability problems existing in some batches of commercialized kit. Four samples (4/40) form company B turned into negative in the re-detection by ELISA kit, so as IFA results；thirty-six samples (36/40) form company B were positive in the re-detection by ELISA kit, however, twenty of them were IFA positive and sixteen of them were IFA negative, the complicated results indicated non-specificity detection were existed in some batches of commercialized kit except for the stability problem. Therefore, to achieve higher veracity, samples should be determined by both of ELISA and IFA in the massive detection.

Key words: subgroups A/B avian leukosis virus; IFA; ELISA; stability; specificity