Molecular characteristics of HA1 and NA genes of influenza A (H3N2) virus in Yancheng city from 2022 to 2024
10.3760/cma.j.cn112866-20240429-00076
- VernacularTitle:2022—2024年盐城市甲型H3N2流感病毒HA1和NA基因分子特征
- Author:
Chunxiang LI
1
;
Xiongying SUN
;
Min YANG
;
Peng SHEN
;
Jiajing YUAN
;
Min ZHANG
;
Chen CHEN
;
Changcheng LI
;
Guoqing CHEN
Author Information
1. 盐城市妇幼保健院，盐城 224002
- Keywords:
Influenza A/H3N2 virus;
RT-PCR;
Hemagglutinin gene;
Neuraminidase gene;
Sequencing
- From:
Chinese Journal of Experimental and Clinical Virology
2024;38(4):446-453
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the molecular evolutional characteristics of the hemagglutinin and neuraminidase genes of influenza A (H3N2) viruses isolated in Yancheng from 2022 to 2024.Methods:The throat swab specimens of influenza-like illness ( ILI) from sentinel surveillance hospital and outbreak sites were detected using the method of real time Rt-qPCR. The influenza A(H3N2) viruses were isolated using MDCK cells culture method from April 2022 to Marh 2024. The strains isolated from 2022 to 2024 were selected randomly and their sequences of the HA1 and NA genes were amplified through one step RT-PCR method and the PCR products were sequenced.The nucleotide and amino acid site variations and evolutionary characteristics of the genes were analyzed using relevant bioinformatics software. The mutations of genes and nucleic acid locus were analyzed and the evolutional trees were generated using bioinformatics software.Results:A total of 5 020 samples were collected between April 2022 and March 2024, the positive detection rate of influenza virus nucleic acid was 18.59%(933/5 020).The winter and spring influenza peaks were obvious in the two monitoring seasons from April 2022 to March 2024. Among them, the summer influenza peak was obvious in the monitoring season from April 2022 to March 2023, and the H3N2 subtype influenza virus was the dominant epidemic strain in the two monitoring seasons. Genetic evolution tree displayed: the clustering relationships of the respective branches of HA1 and NA genes of 32 strains isolated in Yancheng were basically the same.The HA1 and NA genes of 24 strains isolated from 2023-2024 in Yancheng and the 2022-2024 Northern Hemisphere vaccine strain A/Darwin/9/2021 (H3N2) were located in the 3C.2a1b2a.2a.3a.1 evolutionary lineage, while the 8 strains isolated in the 2022 in Yancheng and the 2021-2022 Northern Hemisphere vaccine strain A/Cambodia/e0826360/2020 (H3N2) were located in the 3C.2a1b.2a.1a evolutionary lineage.The 6 strains (A/JSTH/11735/2023, A/JSTH/11788/2023, A/JSTH/11974/2023, A/JSYD/353/2023, A/JSYD/354/2023, A/JSTH/138/2023) all exhibited variations in the F79L, N122D, P239S, and K276E amino acid sites, which were present in both sporadic and outbreak strains. Because the strains of the antigen epitopes, receptor binding sites and glycosylation sites in the HA1 genes had a certain degree of variations in Yancheng in the 2022-2024 year, the immunogenicity matching between the 24 strains isolated in the 2023-2024 and the Northern Hemisphere vaccine strain A/Darwin/9/2021 was good, while the immunogenicity matching between the 8 strains isolated in the 2022 and the Northern Hemisphere vaccine strain A/Cambodia/e0826360/2022 was good; 32 strains isolated from 2022 to 2024 had no mutations in catalytic residues and drug resistant sites of NA genes.Conclusion:These result indicated that the HA1 and NA genes of influenza A/H3N2 viruses circulated in Yancheng city from 2022 to 2024 are changed gradually.The accumulation of these mutations would result in antigenic drift of influenza A(H3N2) viruses and increase the mismatching of the recommended vaccine strain.Compared with the vaccine strain A/Darwin/9/2021(H3N2), the strains isolated in the 2022 had substantially result in antigenic drift on the whole.The influenza A(H3N2) viruses surveillance should be strengthened to find the new mutant of virus in time.
