RT Journal Article SR Electronic T1 The inherent mutational tolerance and antigenic evolvability of influenza hemagglutinin JF bioRxiv FD Cold Spring Harbor Laboratory SP 005041 DO 10.1101/005041 A1 Bargavi Thyagarajan A1 Jesse D. Bloom YR 2014 UL http://biorxiv.org/content/early/2014/06/23/005041.abstract AB Influenza is notable for its evolutionary capacity to escape immunity targeting the viral hemagglutinin. We used deep mutational scanning to examine the extent to which a high inherent mutational tolerance contributes to this antigenic evolvability. We created mutant viruses that incorporate most of the ≈ 104 amino-acid mutations to hemagglutinin from A/WSN/1933 (H1N1) influenza. After passaging these viruses in tissue culture to select for functional variants, we used deep sequencing to quantify mutation frequencies before and after selection. These data enable us to infer the preference for each amino acid at each site in hemagglutinin. These inferences are consistent with existing knowledge about the protein’s structure and function, and can be used to create a model that describes hemagglutinin’s evolution far better than existing phylogenetic models. We show that hemagglutinin has a high inherent tolerance for mutations at antigenic sites, suggesting that this is one factor contributing to influenza’s antigenic evolution.