{
  "abstract": "The highly conserved influenza virus hemagglutinin (HA) stem domain is a major target for broadly neutralizing antibodies (bnAbs). However, despite being discovered more than a decade ago, the IGHV1-69-encoded CR9114 remains the only HA stem bnAb that cross-reacts with both influenza A and B viruses. To investigate the constraints on the breadth evolution of CR9114, this study performs four deep mutational scanning experiments to compare the binding affinity landscapes of the germline and somatic CR9114 against H1 HA, H3 HA, and influenza B virus HA. Many mutations that minimally affect or even improve the H1 HA binding are detrimental for binding to H3 HA and influenza B virus HA. We further reveal the prevalence of epistasis in IGHV1-69 HA stem bnAbs. Overall, our findings provide a mechanistic explanation for the scarcity of HA stem bnAbs with cross-reactivity against both influenza A and B viruses, and have important implications for developing broadly protective influenza vaccines.\n\nBroadly neutralizing flu antibodies able to recognize both influenza A and B viruses are exceptionally rare. This study shows that mutations which preserve or improve binding to one flu virus can weaken recognition of others, constraining antibody cross-reactive breadth.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America",
    "Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida, United States of America",
    "Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America",
    "Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America",
    "Carle Illinois College of Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America"
  ],
  "article_type": "Research Article",
  "arxiv": null,
  "author_total": 10,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Katrine E. Dailey"
    },
    {
      "affs": [
        1
      ],
      "name": "Yiquan Wang"
    },
    {
      "affs": [
        2
      ],
      "name": "Qi Wen Teo"
    },
    {
      "affs": [
        3
      ],
      "name": "Chaoyang Wang"
    },
    {
      "affs": [
        4
      ],
      "name": "Huibin Lv"
    },
    {
      "name": "Ruipeng Lei"
    },
    {
      "name": "Meixuan Tong"
    },
    {
      "name": "Lucia A. Rodriguez"
    },
    {
      "name": "Letianchu Wang"
    },
    {
      "name": "Nicholas C. Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c1wm2damxjyrd.bib",
  "cited_by": 0,
  "doi": "10.1371/journal.pbio.3004021",
  "fulltext_url": "https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3004021",
  "id": "c1wm2damxjyrd",
  "issns": [
    "1545-7885"
  ],
  "landing_url": "https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3004021",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2713|Influenza Virus Research Studies"
    ],
    [
      "plos",
      "/Biology and life sciences/Biochemistry/Proteins/Immune system proteins/Antibodies"
    ],
    [
      "plos",
      "/Biology and life sciences/Genetics/Gene identification and analysis/Mutation detection"
    ],
    [
      "plos",
      "/Biology and life sciences/Genetics/Heredity/Epistasis"
    ],
    [
      "plos",
      "/Biology and life sciences/Genetics/Mutation/Nonsense mutation"
    ],
    [
      "plos",
      "/Biology and life sciences/Genetics/Mutation/Somatic mutation"
    ],
    [
      "plos",
      "/Biology and life sciences/Immunology/Immune system proteins/Antibodies"
    ],
    [
      "plos",
      "/Biology and life sciences/Microbiology/Medical microbiology/Microbial pathogens/Viral pathogens/Orthomyxoviruses/Influenza viruses/Influenza A virus"
    ],
    [
      "plos",
      "/Biology and life sciences/Organisms/Eukaryota/Fungi/Yeast"
    ],
    [
      "plos",
      "/Biology and life sciences/Organisms/Viruses/RNA viruses/Orthomyxoviruses/Influenza viruses/Influenza A virus"
    ],
    [
      "plos",
      "/Biology and life sciences/Organisms/Viruses/Viral pathogens/Orthomyxoviruses/Influenza viruses/Influenza A virus"
    ],
    [
      "plos",
      "/Biology and life sciences/Physiology/Immune physiology/Antibodies"
    ],
    [
      "plos",
      "/Medicine and health sciences/Immunology/Immune system proteins/Antibodies"
    ],
    [
      "plos",
      "/Medicine and health sciences/Medical conditions/Infectious diseases/Viral diseases/Influenza"
    ],
    [
      "plos",
      "/Medicine and health sciences/Pathology and laboratory medicine/Pathogens/Microbial pathogens/Viral pathogens/Orthomyxoviruses/Influenza viruses/Influenza A virus"
    ]
  ],
  "openalex": "W7214651483",
  "pdf_url": "https://journals.plos.org/plosbiology/article/file?id=10.1371/journal.pbio.3004021&type=printable",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-28",
  "publisher": "Public Library of Science",
  "ris": "https://research.draconitic.com/paper/c1wm2damxjyrd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:37Z",
      "native_id": "10.1371/journal.pbio.3004021",
      "source": "plos",
      "url": "https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3004021"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "plos:genetics",
      "subfield": "genetics-genomics"
    },
    {
      "field": "biology",
      "origin": "plos:immunology",
      "subfield": "immunology"
    }
  ],
  "title": "Epistasis and pleiotropy constrain the evolution of cross-reactive breadth in a broadly neutralizing influenza antibody",
  "title_text": "Epistasis and pleiotropy constrain the evolution of cross-reactive breadth in a broadly neutralizing influenza antibody",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:17:37Z",
  "url": "https://research.draconitic.com/paper/c1wm2damxjyrd",
  "venue": "PLOS Biology",
  "versions": []
}