ObjectiveTo analyze the test results and genetic characteristics of avian influenza virus in the samples collected from environment and related staff in a farmer’s market in Tongzhou district of Beijing from 2021 to 2022, so as to provide basis for the prevention and control strategy of avian influenza in our city.
MethodsFrom 2021 to 2022, a total of 2 184 swab samples were collected from environment and food and 124 throat swab samples from relevant staff. Real-time RT-PCR was used to detect viral nucleic acid in samples. The next generation sequencing platform from illumina was used in whole genome sequencing for the positive samples with high virus titer and the genetic characteristics were analyzed.
ResultsThe results detected by real-time RT-PCR showed that among samples from environment and food, 2 were positive for H5N8, 78 were positive for H7N9, 177 were positive for H9N2, 2 were co-infected with H5N8 and H9N2 and 1 was co-infected with H7N9 and H9N2. All 124 human samples were negative. The genome sequence analysisof high viral titer samples were performed. The HA gene in one case of H5N8 virus belonged to the 2.3.4.4 clade, and the HA0 cleavage site sequence of the gene consisted of multiple continuous basic amino acids (REKRRKR/ GLF). The HA gene in 2 cases of H7N9 virus belonged to the same branch as Yangtza river delta, and the HA0 cleavage site sequence of the HA gene consists of multiple continuous basic amino acids (VPKRKRTAR/GLF), which belonged to highly pathogenic avian influenza viruses. The results of phylogenetic analysis showed that the HA genes of H5N8 and H7N9 were closely related to the virus strains reported in China.
ConclusionsThe farmer’s market was the main place for the distribution of avian influenza virus. Simultaneous and spatial overlapping infection status of highly pathogenic and low pathogenic avian influenza viruses suggested that surveillance and control of avian influenza virus and propaganda of prevention knowledge should be strengthened.