journals.asm.org
Broadly reactive antibodies against influenza B virus hemagglutinin neutralize and protect through distinct structural mechanisms | Journal of Virology
Influenza B viruses cause substantial seasonal illness, particularly in children; however, antibody responses against influenza B virus remain less well understood than those against influenza A virus. Here, we identified four antibodies that broadly recognize influenza B virus hemagglutinin and protect through distinct mechanisms. We determined cryo-electron microscopy structures of three antibody-hemagglutinin complexes to define their epitopes and explain their molecular mechanisms of action. One antibody blocks viral attachment by engaging the receptor-binding site, whereas antibodies targeting the medial junction act through post-entry antiviral activity, neuraminidase inhibition, or immune effector functions. Although the antibodies differed in neutralizing potency, all protected mice when administered before infection, and several remained effective after infection. These findings show that broad protection against influenza B virus can arise through multiple antibody targets and mechanisms, informing the evaluation and design of future vaccines and antibody-based therapies.
