The PCR amplified HA1 fragment of H5N1 (H5HA1) avian influenza virus (AIV) hemagglutinin gene was cloned into pET28a (+) expression vector and expressed in Rosetta Blue (DE3) pLysS cells. The recombinant H5HA1 (rH5HA1) protein purified by passive gel elution after SDS-PAGE of the inclusion bodies reacted specifically with H5N1 serum in Western blot analysis. A subtype specific indirect enzyme linked immunosorbent assay (iELISA) using the rH5HA1 protein as the coating antigen was developed for detecting antibodies to H5 subtype of AIV. The assay had 89.04% sensitivity and 95.95% specificity when compared with haemagglutination inhibition test. The Kappa value of 0.842 indicated a perfect agreement between the tests. The iELISA developed can be used for serosurveillance of avian influenza in chickens.
Keywords: AIV H5N1; characterization; expression; haemagglutinin; indirect ELISA.