“Breathing” Hemagglutinin Reveals Cryptic Epitopes for Universal Influenza Vaccine Design

A universal vaccine against influenza remains a critical target, and efforts have recently focused on the stem of the hemagglutinin glycoprotein. In this issue of Cell and a related Cell Host & Microbe article, three studies identify broad protective epitopes in the hemagglutinin head domain that are exposed by trimer “breathing.