Genetic evolution of respiratory syncytial virus in pediatric acute respiratory infections: Insights from a non-epidemic season.

BACKGROUND

Respiratory syncytial virus (RSV) is an important cause of acute respiratory infections (ARI) in children, with recent outbreaks increasing the global burden. The 2021 season saw a significant increase in cases from June to August, possibly due to COVID-19 control measures. The RSV-G region contributes to significant strain variation that can lead to severe epidemics. Understanding the impact of RSV genetic diversity on epidemics and disease severity is critical for prevention and management. This study aimed to investigate the genomic characteristics of RSV-G and provide insights for vaccine development and RSV control.

METHODS

Seventy-four hospitalized ARI cases were identified from May to July 2021. Nasopharyngeal swab samples were collected for RSV-A and RSV-B detection by RT-qPCR. G-gene amplification, sequencing, and alignment were performed for genetic analysis. Phylogenetic trees were constructed, and whole genome sequencing was performed.

RESULTS

Of the 74 cases, 35.1 % were infants under 1 year old, and 6.76 % were severe RSV infections. RSVA accounted for 56.76 % of cases, while RSVB accounted for 43.24 %. Unique mutations were observed, possibly related to epidemic trends and disease severity. Phylogenetic analysis revealed significant differences from reference strains, particularly in a unique combination of three amino acid sites in the RSV-A G protein associated with disease severity.

CONCLUSIONS

This study provides insights into the genetic diversity of RSV during the 2021 off-season epidemic in Shenzhen and reveals the emergence of a new phylogenetic sublineage. Understanding the genetic diversity of RSV is critical for developing effective vaccines and controlling RSV outbreaks.