Isolation and phylogenetic analysis of hemagglutinin gene of H9N2 influenza viruses from chickens in South China from 2012 to 2013

Abstract

As part of our ongoing influenza surveillance program in South China, 19 field strains of H9N2 subtype avian influenza viruses (AIVs) were isolated from dead or diseased chicken flocks in Guangdong province, South China, between 2012 and 2013. Hemagglutinin (HA) genes of these strains were sequenced and analyzed and phylogenic analysis showed that 12 of the 19 isolates belonged to the lineage h9.4.2.5, while the other seven belonged to h9.4.2.6. Specifically, we found that all of the viruses isolated in 2013 belonged to lineage h9.4.2.5. The lineage h9.4.2.5 viruses contained a PSRSSR↓GLF motif at HA cleavage site, while the lineage h9.4.2.6 viruses contained a PARSSR↓GLF at the same position. Most of the isolates in lineage h9.4.2.5 lost one potential glycosylation site at residues 200-202, and had an additional one at residues 295-297 in HA1. Notably, 19 isolates had an amino acid exchange (Q226L) in the receptor binding site, which indicated that the viruses had potential affinity of binding to human like receptor. The present study shows the importance of continuing surveillance of new H9N2 strains to better prepare for the next epidemic or pandemic outbreak of H9N2 AIV infections in chicken flocks.

Isolation and characterization of avian influenza viruses from raw poultry products illegally imported to Japan by international flight passengers

“…A/chicken/Japan/AQ‐HE14/2015 (Ck/HE14) (H9N2) was closely related to the A/chicken/Guangdong/LZL01/2012 (H9N2). These two related strains were the dominant lineage in Guangdong province in South China in 2012–2013 (Shen et al., ) and classified into another cluster in A/duck/Zhejiang/C1036/2009‐like (Dk/ZJ/09‐like) strains in our phylogenetic tree (Li et al., ) (Figure ). HA genes of Dk/HE5 (H9N2), Dk/HE28 (H9N2) and Ck/HE61 (H9N2) shared 98.0%, 98.2% and 98.2% nucleotide identity with A/chicken/Guangdong/H07/2013 (H9N2), respectively, and the HA gene of Ck/HE14 (H9N2) shared 97.6% nucleotide identity with A/chicken/Guangdong/LZL01/2012 (H9N2).…”

“…Internal gene segments showed diversity at the nucleotide level but were closely related to Dk/ZJ/09‐like strains (see the Supporting Information). The cleavage site of HA protein of all H9 isolates contained a PSRSSR‐GLF motif (Table ) corresponding to the cleavage site motif of H9N2 viruses in China (Shen et al., ).…”

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

“…Previous study had shown that the percentage of H9N2 AIV possessing the PSRSSR↓GLF instead of PARSS-R↓GLF amino acid sequence motif in the HA cleavage site dramatically increased beginning in 2005, and the further investigation indicated that the A316S substitution at cleavage site of HA significantly strengthen the virulence of H9N2 AIV in chickens individually or combined with the 3-amino acid deletion in NA collectively (Sun Y et al 2013). Most of the lineage h9.4.2.5 viruses had the cleavage site motif PSRSSR↓GLF, while for the lineage h9.4.2.6, most viruses harbored PARSSR↓GLF between 2010 and 2013 based on previous studies (Chen et al 2013;Shen et al 2015). It is noteworthy that all of the H9N2 AIV isolated in this study between 2013 and 2015 harbored the A316S substitution at cleavage site.…”

Molecular Epidemiological Investigation of AIV H9N2 Subtype in Broilers in North and Northeast China

“…Since the first H9N2 subtype was isolated in China in 1994, the epidemic situation of avian influenza H9N2 subtype in chickens is relatively serious, especially in broiler industry (Sun et al, 2013). The current preventive and treatment methods are mainly based on vaccine immunization which have achieved good results but because of the characteristics of H9N2 viruses that they mutate easily, the chance of genetic drift in vaccine strain has a high probability (Chen et al, 2011;Shen et al, 2015). The difference of antigenicity result in that although it belongs to the same serotype H9N2 does not give ideal conditions of attack protection and the infection of H9N2 disease occurred frequently in immunized chicken.…”