Surveillance of avian influenza virus and sequence analysis of H9N2 subtype in live poultry markets in Fujian province, 2021-2023
10.3760/cma.j.cn112866-20240924-00141
- VernacularTitle:2021—2023年福建省活禽市场禽流感病毒监测和H9N2亚型序列分析
- Author:
Jingjing WU
1
;
Yating ZHANG
;
Yuqing YAN
;
Hongbin CHEN
;
Qi LIN
;
Yuwei WENG
Author Information
1. 福建省疾病预防控制中心 福建省人兽共患病研究重点实验室，福州 350012
- Publication Type:Journal Article
- Keywords:
Avian influenza virus;
H9N2;
Surveillance;
Genetic evolution;
Variation
- From:
Chinese Journal of Experimental and Clinical Virology
2025;39(1):41-50
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the epidemiologic characteristics of avian influenza virus and the molecular characteristics and genetic evolution of H9N2 subtype avian influenza viruses in the live poultry markets in Fujian province in 2021-2023.Methods:Six types of specimens were collected from five cities in Fujian province. The specimens were subjected to nucleic acid detection for influenza A viruses, subtypes H5, H7, and H9 by fluorescence quantitative PCR, and the results were analyzed statistically with χ2 test. Specimens with Ct value less than 31 were screened for targeted amplification and next-generation sequencing of the hemagglutinin (HA) and neuraminidase (NA) genes. Reference sequences were downloaded from the databases, and the characteristics of molecular variation and genetic evolution were analyzed by using bioinformatics softwares. Results:From 2021 to 2023, a total of 1 853 specimens were collected from five cities, with a positive rate of 50.94% for influenza A viruses, including 684 specimens of H9 subtype, 23 specimens of H5 subtype, 1 specimen of H7 subtype, 28 specimens of H5 and H9 subtype, 1 specimen of H7 and H9 subtype, and 207 specimens of unclassified A-type. There were significant differences in the positive detection rates of influenza A viruses in different cities( χ2=461.82, P<0.001). Statistically significant differences in influenza A virus positivity rates across years and quarters( χ2=12.26, P=0.002; χ2=30.12, P<0.001), with higher rates of 56.39% and 55.34% in the first and third quarters, respectively. And the differences in the positive rates of influenza A viruses in different types of specimens were statistically significant( χ2=23.05, P<0.001), with specimens on the cage surface having a positivity rate of 56.09%, which was the highest of all types of specimens. A total of 24 strains of HA and NA genes of H9N2 subtype were fully sequenced. Compared with the sequence of NCBI database, the highest identity of HA gene nucleotide sequences ranged from 97.03% to 99.87%, and the highest identity of NA gene nucleotide sequences ranged from 97.50% to 99.78%.Twenty-three strains with both HA and NA genes belonged to the G57 genotype in the Y280-like evolutionary branch of the Eurasian lineage, and one strain belonged to the Y439-like evolutionary branch of the Eurasian lineage. The cleavage sites of all the strains showed the characteristic of low pathogenicity, and most strains had receptor binding sites characterized by avian-derived and human receptors. Conclusions:The overall positive rate of avian influenza viruses in live poultry markets in Fujian province was relatively high, especially in the first and third quarters, with H9 subtype accounting for the main proportion. Most of H9N2 subtype belonged to the Y280-like G57 genotype with a small number of Y439-like evolutionary branches, suggesting the possibility of genetic recombination and the risk of human infection. Thus, surveillance of avian influenza viruses in the live poultry markets as well as mutation analysis should continue to be strengthened.
