Establishment of an indirect-blocking ELISA for detection of antibody against matrix protein 1 (M1) of avian influenza virus.

An indirect-blocking ELISA was established using recombinant avian influenza virus(AIV)matrix protein 1(M1)as detection antigen,and using rabbit antiserum against the M1 protein as blocking antibody.The optimal concentration of the coating antigen was 0.78 μg/mL,the optimal dilution of the blocking antibody was 1∶15 000,and the optimal dilution of the serum was 1∶10.38 AIV positive samples and 26 AIV negative samples were detected by the indirect-blocking ELISA,indicating that the sensitivity of the indirect-blocking ELISA was 97.37%,and the specificity was 96.15%.Cross-reaction test showed that this method had no cross-reaction with positive sera against Newcastle disease virus,Marek's disease virus,infectious bronchitis virus,infectious bursal disease virus,infectious laryngotracheitis virus,duck plague virus,gosling plague virus,and goose paramyxovirus,respectively.The coincidence of the indirect-blocking ELISA with the hemagglutination inhibition(HI)test was over 92% for the detected 268 clinical samples.The results indicated that this method could be used for antibody detection and epidemiological investigation on AIV.