Detection of H6 influenza antibody by blocking enzyme-linked immunosorbent assay

Low pathogenic H6N1 avian influenza viruses (AIVs) have circulated in domestic chickens since 1972 in Taiwan. Detection of avian influenza (AI) antibody is a routine work for AI control in Taiwan. The currently available commercial enzyme-linked immunosorbent assays (ELISAs) are unable to differentiate antibody responses between different subtypes. To this end, a panel of monoclonal antibodies (mAbs) to A/chicken/Taiwan/2838V/00 (H6N1) was developed and implemented a blocking ELISA (bELISA) to detect the H6 antibody. These mAbs were confirmed specific to H6 AIVs. One monoclonal antibody was purified and labeled with horseradish peroxidase to set up a bELISA. The cut-off value was calculated to be 30% inhibition percentage from 138 H6-negative sera. The sensitivity and specificity of the bELISA were 100% and 97%, respectively. The bELISA detected seroconversion in H6-infected farms earlier than hemagglutination inhibition test. The results show that this bELISA could be used to detect H6 infection in the field.