Serological and Molecular Insights into Respiratory Syncytial Virus B Infections among Pediatric Patients

Respiratory syncytial virus (RSV) remains a leading cause of acute respiratory infections in children globally, yet comprehensive data from India remain limited. This study investigated RSV seroprevalence, molecular and clinical profiles of children aged between 1.5 and 5 years in Maharashtra, India, through IgM ELISA (serology) and whole-genome sequencing (WGS) of RSV-positive nasopharyngeal swabs (n=7). Results revealed high IgM seroprevalence (62.75%), peaking in children aged 2–3 years (33.5%), with no significant gender differences (p=0.81). Molecular screening identified RSV-B exclusively (2.47% positivity), forming a distinct GB5 subclade with unique mutations (A74V, I252T, 165del) in glycoprotein (G) and fusion (F) proteins. Seasonal peaks occurred from September to December, correlating with winter months. Clinically, fever (100%), cough (85.5%), and nasal discharge (94.3%) dominated, while severe cases were rare (1 SARI case). Glycosylation analysis revealed conserved sites (observed in all strains and reported in scientific literature) and a new site observed in the fusion protein F180 site, suggesting immune evasion mechanisms. Phylogenetically, Indian RSV-B strains diverged from global GB5 variants, indicating localised evolution. These findings underscore RSV-B’s predominance in the study area, with implications for vaccine design targeting conserved epitopes (e.g., the Fusion protein conserved area). The study advocates for enhanced surveillance, seasonal prevention strategies, and regionally tailored vaccines to address India’s unique RSV epidemiology.