Development and evaluation of a C-ELISA for rapid detection of antibody to AIV-H7

Since 2013, the H7 subtype avian influenza virus (AIV-H7) has seriously endangered human life and health, and has had a serious impact on the poultry industry in China. A competitive enzyme-linked immunosorbent assay (C-ELISA) which detects the antibody for AIV-H7 was developed, basing on a monoclonal antibody (mAb) against the neutralizing epitopes on hemagglutinin (HA)gene. Twelve hybridoma cell lines were screened by cell fusion. Hemagglutination inhibition (HI) assay and indirect ELISA were used to identify the competitive effect of the mAbs. High-affinity mAb 1H11 was selected as a competitive antibody. The reaction conditions for the C-ELISA were optimized for AIV-H7 antibody detection. The cross-reactivity of the C-ELISA was determined by AIV-(H1-H15), NDV, IBV and IBDV positive serum. A total of 1294 field samples (chicken (462), duck (318), goose (219), quail (203) and pigeon (92) were simultaneously detected by C-ELISA and HI assay. The C-ELISA was found to have a high specificity of 93.23% and a sensitivity of 96.24%. These results reveal a positive coincidence between C-ELISA and HI assay at a coincidence rate of 97.52%. In addition, It confirmed that this method can be used for the diagnosis of AIV-H7 antibodies from chicken, ducks, goose, quail and pigeons.