Evaluation of a conserved HA_274–288 epitope to detect antibodies to highly pathogenic avian influenza virus H5N1 in Indonesian commercial poultry

Abstract

A peptide enzyme linked immunosorbent assay (ELISA) based on an epitope in the haemagglutinin (HA) of avian influenza virus H5N1, amino acid positions 274-288 (HA274-288) was evaluated for detection of H5N1-specific antibodies. An optimized ELISA based on the tetrameric form of the HA274-288 epitope designated MP15 gave low background with non-immune chicken sera and detected vaccinated and infected birds. The HA274-288 epitope was highly conserved in Indonesian H5N1 strains and antibody responses were detected in the majority of the vaccinated chickens regardless of the H5N1 strain used for vaccination. The HA274-288 epitope was also conserved in the majority of H5N1 strains from the neighbouring Asian region, and other H5 subtypes potentially allowing for a wider use of the MP15 ELISA in H5N1 vaccinated and infected flocks. The MP15 ELISA results correlated significantly with haemagglutination inhibition (HI) test results and test sensitivity and specificity were 87% and 92%, respectively. The MP15 ELISA titres were significantly higher than the HI titres in all immune sera allowing for sera to be tested at a single dilution of 1:400 which is of advantage in routine surveillance. The study indicated that the MP15 ELISA is potentially useful for serological detection of H5N1 vaccinated or infected poultry and to have some advantages over the standard HI test for routine monitoring of flocks' immunity after vaccination.

Epitopes in the HA and NA of H5 and H7 avian influenza viruses that are important for antigenic drift

“…Characterization of antigenic escape mutants revealed residues 53, 83 (which is not located in antigenic site C but mapped to H1 antigenic site Cb), 274, and 276 (H5: 43, 75, 271, and 273; H7: 43, 73, 265, and 267) were critical for neutralizing antibody recognition (Zhu et al 2013 ). Subsequently, another conserved epitope partially overlapping this region has been described (H3: HA 277-291 ; H5: HA 274-288 ; H7: HA 268-282 ) (Wawegama et al 2016 ). Despite a general trend for conservation in antigenic site C, some subsites are under positive selection in H5N1 viruses isolated from humans (H3: 272 and 275; H5: 269 and 272; H7: 263 and 266) (Duvvuri et al 2009 ), H7 AIVs isolated up until 2012 (H3: 275; H5: 272; H7: 266) (Xiong et al 2019 ) and may play a host-specific role in adaptation (H3: 276; H5: 273; H7: 267) (He et al 2020 ).…”

Characterization of Monoclonal Antibodies against σA Protein and Cross-Reactive Epitope Identification and Application for Detection of Duck and Chicken Reovirus Infections

“…Therefore, alternative serological tests would be necessary to target virus specific antigenic epitopes to avoid the disadvantages. Many epitope-based enzyme immunoassays have been successfully developed for the detection of virus-specific antibodies in serum samples [32,33,34,35]. Therefore, for increasing the specificity of the diagnosis method, screening of single molecules with potential as diagnosis antigen should be explored.…”