Emergence of an antigenically drifted and reassorted influenza B virus at the end of the 2024-25 influenza season - PubMed
4 hours ago
- #Vaccine Mismatch
- #Influenza B Virus
- #Antigenic Drift
- A new influenza B virus (IBV) called C.3.1/re emerged late in the 2024-25 Northern Hemisphere season.
- C.3.1/re is a reassorted virus from clades C.3 and C.5.1, with a D197N mutation in hemagglutinin that adds a glycan masking a key antibody site.
- This virus primarily infected children but did not cause more severe disease.
- Vaccination sera from a human cohort showed poor neutralization against C.3.1/re.
- Removing the glycan at residue 197 restored antibody recognition, confirming its role in antigenic drift.
- C.3.1/re is antigenically mismatched with vaccine strains for 2025-2026 seasons in both hemispheres.
- The selected 2026-27 Northern Hemisphere vaccine strain lacks the 197 glycosylation, potentially reducing effectiveness.
- Phylogenetic analysis reveals diversification and multiple reassortments between C.3 and C.5 clades, with independent D197N mutations.
- The findings highlight significant antigenic and genetic expansion of IBV, impacting vaccine strain selection.