Abstract
BackgroundSince 2008, avian influenza surveillance in poultry-related environments has been conducted annually in China. Samples have been collected from environments including live poultry markets, wild bird habitats, slaughterhouses, and poultry farms. Multiple subtypes of avian influenza virus have been identified based on environmental surveillance, and an H1N8 virus was isolated from the drinking water of a live poultry market.MethodsVirus isolation was performed by inoculating influenza A-positive specimens into embryonated chicken eggs. Next-generation sequencing was used for whole-genome sequencing. A solid-phase binding assay was performed to test the virus receptor binding specificity. Trypsin dependence plaque formation assays and intravenous pathogenicity index tests were used to evaluate virus pathogenicity in vitro and in vivo, respectively. Different cell lines were chosen for comparison of virus replication capacity.ResultsAccording to the phylogenetic trees, the whole gene segments of the virus named A/Environment/Fujian/85144/2014(H1N8) were of Eurasian lineage. The HA, NA, PB1, and M genes showed the highest homology with those of H1N8 or H1N2 subtype viruses isolated from local domestic ducks, while the PB2, PA, NP and NS genes showed high similarity with the genes of H7N9 viruses detected in 2017 and 2018 in the same province. This virus presented an avian receptor binding preference. The plaque formation assay showed that it was a trypsin-dependent virus. The intravenous pathogenicity index (IVPI) in chickens was 0.02. The growth kinetics of the A/Environment/Fujian/85144/2014(H1N8) virus in different cell lines were similar to those of a human-origin virus, A/Brisbane/59/2007(H1N1), but lower than those of the control avian-origin and swine-origin viruses.ConclusionsThe H1N8 virus was identified in avian influenza-related environments in China for the first time and may have served as a gene carrier involved in the evolution of the H7N9 virus in poultry. This work further emphasizes the importance of avian influenza virus surveillance, especially in live poultry markets (LPMs). Active surveillance of avian influenza in LPMs is a major pillar supporting avian influenza control and response.
Highlights
Since 2008, avian influenza surveillance in poultry-related environments has been conducted annually in China
Homology analysis The avian influenza virus subtype H1N8 identified in this study was named A/Environment/Fujian/85144/ 2014(H1N8); the full genome sequences of the virus have been uploaded to the Global Initiative on Sharing All Influenza Database (GISAID) with accession numbers EPI11315724-EPI11315731
The N30D and T215A substitutions of the M1 protein were found in the H1N8 virus, and this mutation has been reported to be associated with increased pathogenicity of the H5N1 virus in mice [15]
Summary
Since 2008, avian influenza surveillance in poultry-related environments has been conducted annually in China. Multiple subtypes of avian influenza virus have been identified based on environmental surveillance, and an H1N8 virus was isolated from the drinking water of a live poultry market. Both animal and human infections with influenza A virus have been reported. Wild aquatic birds are the major reservoir of avian influenza, harbouring 16 haemagglutinin (HA) and 9 neuraminidase (NA) subtypes of viruses [1]. Human infections have been reported with the H5, H6, H7, H9, and H10 influenza virus subtypes [2, 3]. Exposure to live poultry markets (LPMs) is an important risk factor for highly pathogenic avian influenza infection. Avian influenza surveillance in LPMs provides clues for tracing infection sources and evidence for risk assessment and decision making [7,8,9]
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