Identification of immunodominant epitopes in the HA2 subunit of H5N1 haemagglutinin by immunoassay using synthetic peptides as antigens

Abstract

H5N1 causes high mortality in domestic poultry. It is the causative agent of H5N1 flu and is the world's largest current pandemic threat. Haemagglutinin (HA) is a surface glycoprotein of the virus which facilitates viral attachment to target cell and its entry. HA frequently accumulates mutation to escape immune response of host. In this study, conserved amino acid sequences in HA2 subunit of H5N1 HA protein of both clade 2.2 and 2.3 were identified and the conserved sequence was further analyzed in silico for its antigenic index, hydrophilicity and surface probability. Six peptides showing potential antigenicity were selected and synthesized. Reactivity of the peptides were analysed by indirect ELISA using antisera against different subtypes of avian influenza. Five out of the six peptides showed reactivity. Thus, five epitopes in the conserved region of HA2 subunit of H5 could be identified which can detect positive serum against avian influenza.