ABSTRACT
Background@#The H5 avian influenza viruses (AIVs) of clade 2.3.4.4 circulate in wild and domestic birds worldwide. In 2017, nine strains of H5N6 AIVs were isolated from aquatic poultry in Xinjiang, Northwest China. @*Objectives@#This study aimed to analyze the origin, reassortment, and mutations of the AIV isolates. @*Methods@#AIVs were isolated from oropharyngeal and cloacal swabs of poultry. Identification was accomplished by inoculating isolates into embryonated chicken eggs and performing hemagglutination tests and reverse transcription polymerase chain reaction (RT-PCR). The viral genomes were amplified with RT-PCR and then sequenced. The sequence alignment, phylogenetic, and molecular characteristic analyses were performed by using bioinformatic software. @*Results@#Nine isolates originated from the same ancestor. The viral HA gene belonged to clade 2.3.4.4B, while the NA gene had a close phylogenetic relationship with the 2.3.4.4C H5N6 highly pathogenic avian influenza viruses (HPAIVs) isolated from shoveler ducks in Ningxia in 2015. The NP gene was grouped into an independent subcluster within the 2.3.4.4B H5N8 AIVs, and the remaining six genes all had close phylogenetic relationships with the 2.3.4.4B H5N8 HPAIVs isolated from the wild birds in China, Egypt, Uganda, Cameroon, and India in 2016–2017, Multiple basic amino acid residues associated with HPAIVs were located adjacent to the cleavage site of the HA protein. The nine isolates comprised reassortant 2.3.4.4B HPAIVs originating from 2.3.4.4B H5N8 and 2.3.4.4C H5N6 viruses in wild birds. @*Conclusions@#These results suggest that the Northern Tianshan Mountain wetlands in Xinjiang may have a key role in AIVs disseminating from Central China to the Eurasian continent and East African.
ABSTRACT
Background@#The H5 avian influenza viruses (AIVs) of clade 2.3.4.4 circulate in wild and domestic birds worldwide. In 2017, nine strains of H5N6 AIVs were isolated from aquatic poultry in Xinjiang, Northwest China. @*Objectives@#This study aimed to analyze the origin, reassortment, and mutations of the AIV isolates. @*Methods@#AIVs were isolated from oropharyngeal and cloacal swabs of poultry. Identification was accomplished by inoculating isolates into embryonated chicken eggs and performing hemagglutination tests and reverse transcription polymerase chain reaction (RT-PCR). The viral genomes were amplified with RT-PCR and then sequenced. The sequence alignment, phylogenetic, and molecular characteristic analyses were performed by using bioinformatic software. @*Results@#Nine isolates originated from the same ancestor. The viral HA gene belonged to clade 2.3.4.4B, while the NA gene had a close phylogenetic relationship with the 2.3.4.4C H5N6 highly pathogenic avian influenza viruses (HPAIVs) isolated from shoveler ducks in Ningxia in 2015. The NP gene was grouped into an independent subcluster within the 2.3.4.4B H5N8 AIVs, and the remaining six genes all had close phylogenetic relationships with the 2.3.4.4B H5N8 HPAIVs isolated from the wild birds in China, Egypt, Uganda, Cameroon, and India in 2016–2017, Multiple basic amino acid residues associated with HPAIVs were located adjacent to the cleavage site of the HA protein. The nine isolates comprised reassortant 2.3.4.4B HPAIVs originating from 2.3.4.4B H5N8 and 2.3.4.4C H5N6 viruses in wild birds. @*Conclusions@#These results suggest that the Northern Tianshan Mountain wetlands in Xinjiang may have a key role in AIVs disseminating from Central China to the Eurasian continent and East African.
ABSTRACT
Objective:To analyze phylogenetic structure and molecular characteristics of H5N6 avian influenza virus (AIVs) isolated from live poultry market (LPM).Methods:Oropharyngeal and cloacal swabs from poultry, and environmental samples were collected from LPM in Urumqi in December 2018, AIVs were isolated and identified by inoculation of chicken embryo, hemagglutination test and RT-PCR, the viral whole genome was amplified with the universal primers of influenza A virus, and then sequenced, pairwise sequence alignments, phylogenetic and molecular characteristics analysis were performed by BLAST, Clustal W, MEGA-X and DNAStar software.Results:Six strains of H5N6 AIVs were isolated from poultry samples, the identity between the viral genes was high (99.4%-100.0%), so the isolates were the same source. BLAST analysis revealed that the viral NP sequence had the highest identity (99.7%) with H5N6 AIVs isolated from poultry in Suzhou, while the sequence of the remaining 7 viral genes had the highest identity (99.0%-100.0%) with H5N6 AIVs isolated from environment in Guangdong during 2017 to 2018. Phylogenetic analysis showed that the viral HA belonged to Clade 2.3.4.4C, and the viral HA, NA, PB1, PA, NP, and MP were all clustered together with H5N6 AIVs isolated from mink in Eastern China in 2018, while the PB2 and NS were clustered together with H5N6 AIVs isolated from environment in Guangdong from 2017 to 2018. The HA cleavage site contained multiple basic amino acid residues, which was highly pathogenic AIVs (HPAIVs). S137A and T160A mutations of HA could increase binding to human-type receptor SAα2, 6-Gal. Additionally, the viral multiple mutations, including 59-69 deletion in NA, the L89V, G309D, R477G, I495V, I504V, D391E, and A661E in PB2, as well as the P42S, D92E, and 80-84 deletion in NS1, could enhance the viral virulence and pathogenicity to mammals. Conclusions:The 6 strains of H5N6 HPAIVs isolated from LPM have relatively close genetic relationship with H5N6 AIVs isolated from mink in Eastern China and environment in Guangdong during 2017 to 2018, the viral multiple mutations could increase its pathogenicity to mammals, which could pose a potential risk to public health.