Different genetic barriers for resistance to HA stem antibodies in influenza H3 and H1 viruses

Resistance to influenza antibodies Broadly neutralizing human antibodies (bnAbs) to the stem of hemagglutinin (HA), a trimeric glycoprotein found on the surface of influenza viruses, are valuable therapeutics and can guide the development of universal influenza vaccines. For their use in therapy development, it is important to understand the extent to which HA stem variants with resistance to bnAbs can develop. Wu et al. used saturation mutagenesis combined with next-generation sequencing to systematically search for resistance mutations to prototypic bnAbs in two influenza subtypes, H3 and H1. They found that the genetic barrier to resistance to stem bnAbs was low for the H3 subtype but higher for the H1 subtype. The ability of H3 to develop resistance to bnAbs presents a challenge in the development of a universal influenza vaccine. Science , this issue p. 1335