title: The inherent mutational tolerance and antigenic evolvability of influenza hemagglutinin.
abstract: 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 ≈10(4) 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.
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.
authors.forename: Bargavi
authors.identifier: http://orcid.org/0000-0003-3871-6410
authors.initials: B
authors.lastname: Thyagarajan
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.
authors.forename: Jesse D
authors.identifier: http://orcid.org/0000-0003-1267-3408
authors.initials: JD
authors.lastname: Bloom
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000235:genetics*; D003062:Codon; D004252:DNA Mutational Analysis; D019143:Evolution, Molecular; D015723:Gene Library; D014644:Genetic Variation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D059014:High-Throughput Nucleotide Sequencing; D008969:Molecular Sequence Data; D009154:Mutation; D009975:Orthomyxoviridae / Q000235:genetics*; D010802:Phylogeny
chemical_list: D000956:Antigens, Viral; D003062:Codon; D019267:Hemagglutinin Glycoproteins, Influenza Virus
keywords: antigenic evolution; deep mutational scanning; evolutionary biology; evolvability; genomics; hemagglutinin; infectious disease; influenza; microbiology; phylogenetics; viruses