Molecular and clinical characterization of respiratory syncytial virus genotypes in a medical centre in Central Taiwan across the COVID-19 era.

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of respiratory illness in young children. The COVID-19 pandemic profoundly altered RSV circulation, yet the regional molecular and structural characteristics of circulating RSV strains in Taiwan during this period remain incompletely characterized.

METHODS

We conducted a retrospective study of RSV infections identified by viral culture at a tertiary medical center in Central Taiwan from 2016 to 2023. Epidemiological patterns, clinical features, and outcomes were analyzed. A representative subset of culture-positive isolates underwent F and G gene sequencing, phylogenetic analysis, and AlphaFold2-based structural modeling to examine lineage-specific substitutions in the RSV F protein and their spatial relationship to known antigenic sites.

RESULTS

Among 277 RSV cases, seasonality was markedly disrupted during and after the COVID-19 pandemic, with delayed and altered epidemic peaks. Children aged 1-4 years accounted for the largest proportion of cases (44.6%). Of 25 sequenced isolates, 16 were RSV-A and 9 were RSV-B. RSV-A clustered within the ON1 lineage, whereas RSV-B clustered within the GB5 lineage, consistent with contemporaneous regional surveillance. RSV-B isolates demonstrated slower in vitro replication than RSV-A isolates (8.4 vs. 5.4 days). RSV-A isolates exhibited conserved F protein substitutions, whereas RSV-B isolates showed greater sequence heterogeneity. Structural modeling revealed preservation of the prefusion F protein architecture, with substitutions localized to epitope and non-epitope regions but not overlapping known monoclonal antibody resistance sites.

CONCLUSIONS

RSV epidemiology in Central Taiwan was substantially altered during the COVID-19 era, including a transient RSV-B-dominant period in 2022. Although limited by sample size, integration of genomic and structural analyses provides mechanistic context for regional RSV evolution and complements larger surveillance studies. Continued regional monitoring incorporating structural approaches may inform RSV vaccine and therapeutic strategies.