Genomic Characterization of SARS-CoV-2 NB.1.8.1 and PQ.2 from the Infants and Young Children with Gastrointestinal Symptoms.

PURPOSE: This study investigated the viral genomic characteristics of infants and young children who presented to our hospital with gastrointestinal symptoms during a local COVID-19 epidemic and were confirmed to have SARS-CoV-2 infection.

PATIENTS AND

METHODS

Between May and August 2025, pharyngeal swab samples were collected from four infants and young children who presented to the outpatient department of Meizhou People's Hospital in Meizhou, with gastrointestinal symptoms. Nucleic acid testing and whole-genome sequencing were performed. The viral mutation profile was analyzed, and the potential impact of mutations on protein function was predicted.

RESULTS

Pangolin typing identified the NB.1.8.1 variant in three patients and the PQ.2 variant in one patient. Genome sequences from three of the four viral variants displayed varying degrees of mutation. The nonsynonymous mutations for both variants were concentrated in the spike protein. A comparison with the parental XDV.1.5.1 lineage revealed 14 specific mutations, with 7 nonsynonymous sites conserved across all gene sequences. Five of these mutation sites, NSP12: D284Y, ORF3a: L46F, ORF3a: F207C, N: Q9H, and N: Q384H, were predicted to be functionally deleterious and structurally destabilizing.

CONCLUSION

SARS-CoV-2 variants from specimens obtained from four infants and young children exhibited varying degrees of mutation, providing evidence for the ongoing evolution of emerging variants in pediatric patients. However, monitoring genomic changes of circulating variants requires further clinical specimens, which contributes to understanding the dynamic changes at mutation sites, thereby supporting epidemic prevention and control.