Molecular typing and epidemiological profiles of human respiratory syncytial virus infection among children with severe acute respiratory infection in Huzhou, China

Background: Human respiratory syncytial virus (HRSV) is an important pathogen causing severe acute respiratory infection (SARI), particularly in children under 5 years old. We investigated the HRSV infection status and genogroups in pediatric patients with SARI between January 2019 and December 2022 in Huzhou, China. Methods: Nasopharyngeal swabs (NPSs) were collected from pediatric patients in the First People's Hospital of Huzhou. Real-time quantitative RT-PCR for respiratory syncytial virus (A/B)was performed with an QuantStudio 7 Flex Real-Time PCR System. For genotyping, the primer sets A-F/A-R and B-F/B-R were used to amplify the G protein sequences of HRSV-A and HRSV-B, respectively. Phylogenetic analysis was performed using MEGA software. Results: In total, 973 NPSs were collected between January 2019 and December 2022, and 63 samples were positive for HRSV nucleic acid, representing a detection rate of 6.47%. Of the positive specimens, 28 were classified as HRSV-A and 35 were classified as HRSV-B. Infection with HRSV was found in all age groups tested, with children < 5 years old accounting for 88.89% of the positive cases. The detection rate was high from November to the following March. Phylogenetic analysis clustered HRSV-A strains into the ON1 genogroup and HRSV-B strains belonged to the BA9 genogroup. Conclusions: HRSV is an important respiratory pathogen among children in Huzhou, China, with a high incidence in children under 5 years old between winter and spring. HRSV subgroups A and B were co-circulating, and ON1 and BA9 were the two main genogroups identified in this study