[Genetic characteristics analysis of the VP1 region of coxsackievirus A2 in Guangdong Province, 2008-2024].

Objective: To analyze the epidemic characteristics of coxsackievirus A2 (CV-A2) and the genetic variation pattern of its VP1 region in Guangdong Province from 2008 to 2024. Methods: Pathogenic specimens were collected through the hand, foot and mouth disease (HFMD) laboratory surveillance network from 2008 to 2024. CV-A2 was detected in other enterovirus-positive samples other than EV-A71/CV-A16/CV-A6. Viruses were isolated from human rhabdomyosarcoma cells, and the VP1 region was amplified and sequenced. Mega 12.0 software constructed the phylogenetic tree, and the amino acid mutation sites were analyzed by BioAider 1.727 software. Results: A total of 495 cases of CV-A2 were enrolled, including 1 death and 22 severe cases. The average annual number of cases was 55 during 2017-2024 and 6 during 2008-2016, with a significant difference (χ²=3.84, P<0.001). The phylogenetic analysis of the VP1 region showed that, from 2008 to 2023, all strains except one and subtype C3 belonged to genotype D, while all 10 strains in 2024 belonged to subtype C3. A total of 135 amino acid mutation sites were found, among which N17D, E130A, F252Y, and P282Q were common to all strains. High-frequency mutations were concentrated in sites 101-130 (epitope region) and 195-213 (receptor binding region) of VP1. Q175R, H113Y, S170F, F193S, T148I high-frequency mutations (count ≥10 times) were detected in severe cases, and a Q142-specific deletion mutation was found in death cases. Conclusions: There is a transition from genotype D to C3 in 2024, and the high-frequency mutation in the VP1 region may affect viral antigenicity and pathogenicity. It is necessary to strengthen CV-A2 surveillance to assess better the epidemic risk and the mechanisms underlying severe disease.