Molecular Epidemiology and Characteristics of Respiratory Syncytial Virus in Guangzhou, China

Background: Human respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection and hospitalization, especially in children. Highly mutagenic nature and antigenic diversity enable the RSV to successfully survive in human population. Regular monitoring of the circulating strains of RSV in different parts of China could assist in the development of more effective vaccines and preventive measures. We performed a molecular epidemiological study during 2017–2021 to investigate the prevalence and genetic characteristics of RSV in China. Methods A total of 6499 nasopharyngeal (NP) swabs were collected from patients suffering from respiratory infections at Department of Pediatrics, Guangdong Provincial Hospital of Traditional Chinese Medicine, Yuexiu District, Guangzhou, Guangdong, China. Results Overall detection rate for respiratory viruses was 16.12% (1048/6499). A total of 405 specimens (6.20%, 405/6499) were found positive for RSV. Seasonal distribution of RSV and other respiratory viruses was variable and highest incidence were recorded in winter. Based on sequencing of hypervariable region of G gene, 93 RSV sequences were sub-grouped into RSV-A (56, 60.2%) and RSV-B (37, 39.8%). There was no coinfection of RSV-A and RSV-B in tested samples. Phylogenetic analysis revealed that RSV-A and RSV-B strains belonged to ON1 and BA9 genotype respectively, indicating predominance of these genotypes in Guangzhou. Deduced amino acid sequence analysis determined several substitutions which may likely change antigenicity and pathogenicity of RSV. Multiple glycosylation sites were observed in the second hypervariable region of the G protein, demonstrating high selection pressure on these genotypes. Conclusion This study illustrated the useful information about epidemiology, genetic characteristics and circulating genotypes of RSV in Guangzhou China which may facilitate policy makers, clinicians, and researchers for a better understanding of the evolution of RSV within and outside of China. Due to emergence of several lineages of ON1 and BA9 genotypes, it is quite possible that new lineages could emerge in near future due to highly mutagenic nature of RSV. Continuous and long-term surveillance programs coupled with clinical data must be initiated in Guangzhou to better understand the pattern of seasonal distribution of circulating genotypes of RSV and find any association between emerging genotypes and disease severity.