Molecular analysis of human respiratory syncytial virus group B strains isolated in Kenya before and during the emergence of pandemic influenza A/H1N1

Wangui, J., Gachara, G., Mobegi, V., Agoti, C., Otieno, J., Opanda, S., Opot, B., Ngeranwa, J.N., Njeru, R. and Bulimo, W. 2025. Molecular analysis of human respiratory syncytial virus group B strains isolated in Kenya before and during the emergence of pandemic influenza A/H1N1. Influenza and Other Respiratory Viruses 19(2): e70082.

Background: We conducted a retrospective study to explore molecular insights into human respiratory syncytial virus (HRSV) group B strains among patients attending outpatient clinics at government medical facilities both prior and during the onset of Influenza A/H1N1/2009 pandemic outbreak.

Methods: We screened 2300 nasopharyngeal swabs using multiplex real time reverse transcriptase polymerase chain reaction. We amplified a segment of the first and second hypervariable regions, as well as the conserved portion of the third domain of the G-gene using HRSV-B specific primers, sequenced by Sanger di-deoxy chain termination method and thereafter analyzed the sequences.

Results: We characterized the circulating strains into three known genotypes: SAB4 (1.4%), BA7 (1.4%), and multiple variants of BA9 (97.2%). The majority of BA9 viruses were uniquely Kenyan with only 4% aligning with BA9 lineages found elsewhere. The mean evolutionary rate of the HRSV-B was estimated to be 3.08 × 10⁻³ substitutions pe