Molecular characterization of human adenovirus associated with pediatric severe acute respiratory infections in a tertiary care hospital in North East India

Purpose The present study explored the molecular characterization of human Adenovirus (HAdV) and its strains among hospitalized SARI cases in the pediatric unit of a tertiary care hospital in North-East India. Methods Nasal and throat swabs were collected from 70 patients of Pediatric Unit, of a tertiary hospital in NE India from April 2023-October 2023. The samples were screened for the presence of HAdV using an adenovirus-specific Real-Time PCR Kit. For molecular characterization, Next Generation Sequencing (NGS) was performed by targeting the hexon gene of HAdV followed by post-sequencing analysis. Results Overall, 18.57% (13/70) of samples were positive for HAdV. In context of the severity of illness, 3/13 adenovirus-positive patients (23.07%) died after hospitalization, had severe pneumonia among which two were of less than one year of age. Molecular characterization using NGS indicated that 4/13 individuals were infected with HAdV-B type 3 and 5/13 patients were infected with HAdV type 7. Notably, 4/7 cases of severe pneumonia were under five years of age and associated with HAdV type 7 infection. The ratio of non-synonymous to synonymous mutation (dN/dS) was comparatively low in HAdV type 7 positive samples (dN/dS=0.31). No non-synonymous mutation was observed in HAdV-B type 3 positive samples. The higher neutrophil percentage among the death cases suggested an acute immune response. Conclusion The study demonstrated HAdV type 7 and HAdV-B type 3 as strains associated with pediatric SARI cases from April 2023-October 2023. Further, HAdV type 7 infection was primarily linked with lower respiratory tract infections mainly severe pneumonia.