| Project1.Surveillance of avian influenza virus in live poultry markets in Guangdong Province2.Research on critical point of pollution and transmission of avian influenza virus in poultry breeding and trade chainsPurpose1.Understand the pollution and distribution of different subtypes of avian influenza viruses in live poultry markets in Guangdong Province from September 2016 to August 2018.2.To clarify the main source of avian influenza virus.This article mainly explores the reassortment of H3N2 subtype avian influenza virus.3.Monitor the variation of avian influenza virus.This article mainly studies the variation of hemagglutinin gene of H5N6 subtype avian influenza virus.Method1.Etiology monitoring.The influenza surveillance network laboratories in the 21 cities of Guangdong Province took the poultry markets as the main monitoring points,collected environmental samples and live poultry samples,and performed type A and H5,H7,and H9 typing tests.An epidemiological descriptive study was conducted on the data of monitoring sites in 21 cities in Guangdong Province which can grasp the pollution status of avian influenza in the environment.2.Virus isolation and identification.Avian influenza virus positive samples were isolated from chicken embryos.After red blood cell agglutination test,nucleic acid extraction,PCR amplification,and capillary electrophoresis identification,they were sequenced on the PGM platform to obtain the viral gene sequences.3.Bioinformatics analysis.Use the Ion PGM system and CLC Genomics Workbench v7.51 for data processing and sequence splicing,BioEdit v7.1.3 for sequence editing and homology analysis,Muscle3.8.31 for sequence alignment,iqtree v1.6.3 for establishing Maximum Likelyhood phylogenetic tree,FigTree v1.4.2 and Adobe Illustrator CS5 for editing and optimization the tree.Result1.From September 2016 to August 2018,the live poultry markets in 21 cities in Guangdong Province were used as the main monitoring sites.A total of 51,054 samples of environmental and live poultry samples were collected,in which 9,390 cases were positive for influenza A,with a positive rate of 18.39%.2.A total of 3887 chicken embryos were inoculated with positive samples,and 1132 avian influenza virus isolates were obtained,with an isolation rate of 29.1%.The subtypes and quantity of virus obtained by sequencing are as follows:H5N6（73 strains）,H7N9（77 strains）,H9N2（220 strains）,H1N3（1 strains）,H3N2（7 strains）,H3N3（1 strains）,H3N6（5 strains）,H3N8（4 strains）,H3N9（1 strain）,H5N2（2 strains）,H6N2（24 strains）,H6N6（54 strains）and H9N9（1 strain）.3.The seven strains of H3N2 subtype avian influenza viruses were all reassortant viruses with antigenic shift,and the sources of their segments were mainly derived from avian H3N2 and then H1N2 subtype.Results of H5N6 subtype avian influenza virus agglutination inhibition tests,phylogenetic tree of hemagglutinin gene,and amino acid analysis showed that the H5N6 virus prevalent in Guangdong from 2017 to 2018 has emerged antigenic drift compared with vaccine strain Re-8.ConclusionFrom September 2016 to August 2018,the positive rate of avian influenza virus in the live poultry markets in Guangdong Province was high（18.39%）,and the positive samples contained many avian influenza virus subtypes（13 types）,of which the H9N2 subtype was main subtype.This study assisted in building an avian influenza virus bank in Guangdong Province,which was sourced from the live poultry markets.The study confirmed the presence of the H3N2 subtype avian influenza virus in the live poultry markets in Guangdong Province and clarified their genetic rearrangement.After the implementation of the vaccine policy in July 2017,the positive rate of H7 subtype avian influenza virus decreased rapidly,and the positive rate of H5 subtype avian influenza virus did not change significantly.In 2017-2018,the H5N6 virus circulating in Guangdong Province showed an antigenic drift.The above conclusions can provide a basis for avian influenza prevention and control in Guangdong Province. |
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