Sequence and phylogenetic analysis of hemagglutinin genes of H9N2 influenza viruses isolated from chicken in China from 2013 to 2015

Abstract

H9N2 avian influenza virus (AIV) infection is a major problem in poultry industry worldwide. In this study, molecular characterizations and phylogenetic relationships of hemagglutinin (HA) gene sequences of H9N2 AIV of 5 Chinese isolates in 2014 recently available in GenBank, 3 widely used vaccine strains, and 52 novel isolates in China from 2013 to 2015 were analyzed. The homology analysis showed that the nucleotide sequences of HA gene of these recent Chinese H9N2 AIV isolates shared homologies from 94.1 to 99.9%. Phylogenetic analysis showed that all isolates belonged to AIV lineage h9.4.2.5. Fifty-six out of the 57 recent Chinese H9N2 AIV isolates had the motifs PSRSSR↓GLF at the cleavage sites within the HA protein, while one isolate PWH01 harbored LSRSSR↓GLF. Remarkably, all of the recent Chinese H9N2 AIV strains had the Q216L substitution in the receptor binding site, which indicated that they had potential to infect humans. Most of recent Chinese H9N2 AIV isolates lost the potential N-linked glycosylation site at residues 200-202 compared with vaccine strains. This present study demonstrated that AIV lineage h9.4.2.5 was more predominant in China than other lineages as it harbored all the H9N2 AIV isolated between 2013 and 2015. Also we showed the importance of continuous surveillance of emerging H9N2 AIV in China and update of vaccine formulation accordingly in order to prevent and control H9N2 AIV.

Avian Influenza Virus Subtype H9N2 Affects Intestinal Microbiota, Barrier Structure Injury, and Inflammatory Intestinal Disease in the Chicken Ileum

“…The avian influenza strain A/Chicken/Henan/SH01/2015 (SH0115) subtype H9N2 (GenBank No. KT023065) was used in all relevant experiments and isolated from chickens in poultry flocks [ 22 ], which caused high morbidity and mortality due to diarrhea and secondary bacterial infections such as Escherichia coli . One-day-old specific pathogen-free (SPF) chickens were purchased from WENS (Yunfu, China).…”

Genetic Characteristics and Pathogenicity Analysis in Chickens and Mice of Three H9N2 Avian Influenza Viruses

“…Compared to the H9N2 reference viruses, six potential glycosylation sites (PGS) (N-X-S/T) were conserved at positions 11(NST), 64(NPS), 123(NVS), 200(NRT), 280(NTT), and 287(NVS) in the HA1 protein of the AV1534, AV1535, and AV1548 viruses. Interestingly, the amino acid P to S change at position 297 led to the addition of one potential PGS in the AV1534, AV1535, and AV1548 viruses, which has been found in the HA1 protein of the recent H9N2 viruses isolated from chickens [17][18][19]. Remarkably, all of the three H9N2 viruses had a human-like motif 216-Leu (H9 numbering) at the receptor binding site.…”