Abstract :
Influenza continues to be a major public health issue with the contribution of annual epidemics and sporadic outbreaks. The objective of the study is to investigate and characterize the circulating influenza A virus among pediatric patients over a period of 36 months, from March 2021 to March 2024 at a tertiary care hospital in Karad, India. A total of 160 pediatric patients aged from 1 year and 6 months to 5 years, presented with influenza-like illness, including fever, cough, breathlessness, and runny nose, were included in the study. Nasopharyngeal swab samples from both outpatient and inpatient respiratory illness cases were evaluated and processed for RNA extraction and real-time polymerase chain reaction (RT-PCR) detection of influenza A/B, including pandemic H1N1 and H3N2. Four of the samples tested positive for Influenza A and further nucleotide DNA sequencing and phylogenetic analysis were done at the ICMR-National Institute of Virology, Pune, using Miniseq NGS Platform and MEGA11 software. Sequence analysis revealed mutations in HA with especially three mutations at the receptor-binding domain (RBD); S137P, A141T, and R142K, which improve viral fitness and replication in respiratory epithelial cells. The R223Q mutation correlated with improved viral fitness and enhanced viral replication in human respiratory tract epithelial cells without altering the antigenic properties. Glycosylation site analysis revealed changes that alter virus-host interaction and display possible confirmation of oseltamivir's continued effectiveness. Phylogenetic analysis showed a unique evolving lineage revealing the necessity of regular vaccine updates. Robust surveillance is critical for early detection of emerging strains and guidance.
Keyword :
Influenza A virus, Genomic characterization, Viral mutation, Hemagglutinin, Neuraminidase, Pediatric.