Annual influenza epidemics and episodic pandemics continue to cause widespread illness and mortality. The World Health Organization estimates that annual influenza epidemics cause around 3–5 million cases of severe illness and up to 650,000 deaths worldwide. Seasonal influenza vaccination still remains the best strategy to prevent infection, but the vaccines that are available now offer a very limited breadth of protection. Human broadly neutralizing antibodies (bnAbs) that bind to the hemagglutinin (HA) stem region provide hope for a universal vaccine (Figure 1a)1,2. Binding of these bnAbs prevents the pH-induced conformational changes that are required for viral fusion in the endosomal compartments of target cells in the respiratory tract and, hence, viral entry in our cells.
Image: Complex of Influenza virus HA with (a) Fab CR6261, (b) llama single domain antibody SD36, and (c) JNJ4796.