Hemagglutinin
Hemagglutinin (HA) is the major surface glycoprotein of influenza viruses and one of the principal antigenic determinants targeted by the host immune system.
Hemagglutinin (HA) is the major surface glycoprotein of influenza viruses and one of the principal antigenic determinants targeted by the host immune system. It mediates attachment of influenza A virus and influenza B virus to host-cell receptors containing N-acetyl-β-neuraminic acid, and it is the dominant target of neutralizing antibody responses elicited by infection and vaccination. Because its surface-exposed regions are under strong immune pressure, hemagglutinin undergoes continual antigenic variation, which contributes to seasonal influenza epidemics and the need for updated influenza vaccine formulations.
Structurally and immunologically, hemagglutinin is a central focus of studies of humoral responses, B-cell epitopes, monoclonal antibody binding, and broadly neutralizing monoclonal antibodies. The hemagglutinin head domain is highly immunodominant but variable, while more conserved regions are of interest for cross-subtype immunity and vaccine design. As a result, hemagglutinin is a major component of conventional influenza vaccine, recombinant vaccine, mRNA vaccine, self-amplifying RNA vaccine, and adjuvanted vaccine strategies, including platforms such as mRNA-1010 and FluMist.
Where the papers sit
19 papers from the last 6 months study hemagglutinin directly · updated from PubMed 8 Oct 2026
Study type 1 clinical trial · 2 human data · 16 preclinical
Themes 4 themes · 1 paradigm shift
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Broad Influenza Antibody Protection
Antigenic drift and childhood imprinting are driving efforts to broaden protection beyond variable hemagglutinin head epitopes. Conserved-epitope antibodies, including a bispecific H7 antibody, protect across avian influenza variants and may limit viral escape. Consensus H3N2 immunogens and anti-idiotypic mimics similarly seek wider neutralization. Live-attenuated vaccination adds durable local B-cell memory, but breadth remains strain dependent.
7 papers · 36.8%
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Influenza Vaccine Delivery and Adjuvants
Influenza vaccination is moving toward engineered delivery and immune stimulation rather than hemagglutinin antigen alone. BECC adjuvants, conjugation, outer-membrane vesicles, thermoresponsive microneedles and lipid nanoparticles enhance immunogenicity or protection in preclinical models. Intranasal platforms emphasize mucosal and systemic responses, while epitope mapping supports more focused antigen design. The recurring endpoint is stronger protection with less antigen, although clinical durability remains open.
6 papers · 31.6%
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mRNA Influenza Vaccines
mRNA and self-amplifying RNA platforms are moving influenza vaccination toward dose-sparing, rapidly adaptable formulations. Optimized seasonal mRNA compositions showed safety and enhanced immunogenicity in a phase 2 study, while capless self-amplifying RNA protected mice against H5 virus. The work increasingly targets cross-subtype or multi-respiratory-virus coverage rather than a single strain. Human protection, durability and breadth beyond immunogenicity remain unresolved.
4 papers · 21.1%
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Broadly Reactive Influenza Antigens
Computationally optimized hemagglutinin antigens are being used to widen antibody coverage across influenza subtypes and lineages. COBRA vaccination with a nanoemulsion adjuvant increased protective titers against H1N1 and H3N2 viruses. A retooled influenza B antigen redirects neutralizing antibodies toward B/Victoria strains, showing that antigen design can reshape specificity. Evidence remains centered on antibody responses and preclinical protection rather than clinical efficacy.
2 papers · 10.5%
The hemagglutinin head can support broad cross-subtype immunity rather than being uniformly variable and escape-prone
The H7 avian influenza antibody study and the childhood-imprinting study found, in separate systems, that the hemagglutinin head contains targets capable of broad recognition. In H7 influenza, conserved, functionally constrained head residues supported a bispecific antibody that neutralized divergent H7 subtypes and protected mice from heterologous challenge, while in humans and sequentially exposed ferrets, prior H3N2 exposure generated antibodies recognizing both historical H3 and contemporary H1 head epitopes 42617142Aug 42049037Apr. This challenges the assumption that broadly protective responses must avoid the head because its epitopes are too variable; conserved or exposure-shaped head targets can instead guide broad antibody design and vaccination.
Papers
The 19 papers from the last 6 months that study hemagglutinin directly, newest first, by theme and by study type. Study types come from PubMed publication types and MeSH headings.
By theme
Broad Influenza Antibody Protection (7)
- Anti-idiotypic antibodies as molecular mimics of conserved influenza hemagglutinin epitopes. Protein science : a publication of the Protein Society · 15 Sept 2026 PMID 42742346
- Consensus H3N2 HA immunogens incorporating key antigenic mutations elicit broad-spectrum neutralizing responses. Emerging microbes & infections · 7 Sept 2026 PMID 42703780
- A bispecific antibody targeting conserved hemagglutinin epitopes confers broad protection against H7 avian influenza and accelerates viral clearance via localized respiratory delivery. Emerging microbes & infections · 19 Aug 2026 PMID 42617142
- Neutralizing and protective monoclonal antibodies identify antigenic sites in influenza H7 hemagglutinin and select for amino acid substitutions rarely observed at the global level. Microbiology spectrum · 6 Aug 2026 PMID 42560073
- Emergence of an antigenically drifted and reassorted influenza B virus at the end of the 2024-25 influenza season. mBio · 22 Jun 2026 PMID 42328860
- Local B cell immunity and durable memory after live-attenuated influenza intranasal vaccination of humans. Science translational medicine · 29 Apr 2026 PMID 42054493
- Childhood immunological imprinting of cross-subtype antibodies targeting the hemagglutinin head domain of influenza viruses. Cell host & microbe · 28 Apr 2026 PMID 42049037
Influenza Vaccine Delivery and Adjuvants (6)
- Linear DNA expression cassette encapsulated in lipid nanoparticles confers complete protection against influenza A virus in mice. mSphere · 4 Sept 2026 PMID 42695687
- Mannose-functionalized thermoresponsive microneedles for enhanced antigen delivery and immune activation. Journal of materials chemistry. B · 27 Aug 2026 PMID 42657667
- Identification and computational analysis of B-cell epitopes on the hemagglutinin protein of the H3N2 influenza virus. Archives of microbiology · 5 Aug 2026 PMID 42554770
- Intranasal influenza vaccination using an outer membrane vesicle platform. Vaccine · 26 Jun 2026 PMID 42361782
- BECC-adjuvanted hemagglutinin influenza vaccine promotes enhanced immunogenicity and protective efficacy. Vaccine · 31 May 2026 PMID 42218860
- Conjugate vaccine technology enhances responses to influenza virus. Vaccine · 22 May 2026 PMID 42172691
mRNA Influenza Vaccines (4)
- Capless self-amplifying mRNA vaccine induces dose-sparing protective immunity against HPAI clade 2.3.4.4 H5 virus in mice. Molecular therapy : the journal of the American Society of Gene Therapy · 30 Jul 2026 PMID 42528137
- Optimized seasonal influenza mRNA vaccine compositions demonstrate safety and enhanced immunogenicity in a phase 2 study. Human vaccines & immunotherapeutics · 13 Jul 2026 PMID 42441816
- A subunit vaccine for multiple respiratory viruses. Science advances · 26 Jun 2026 PMID 42361166
- Enhanced immunogenicity and dose-sparing efficacy of self-amplifying RNA vaccines against seasonal influenza across subtypes. Emerging microbes & infections · 4 May 2026 PMID 42081324
Broadly Reactive Influenza Antigens (2)
- Nanoemulsion adjuvanted COBRA HA vaccine enhances protective antibody titers against H1N1 and H3N2 influenza viruses. Human vaccines & immunotherapeutics · 3 Sept 2026 PMID 42691282
- Retooling a novel influenza B hemagglutinin to redirect neutralizing antibodies against B/Victoria strains. Vaccine · 9 May 2026 PMID 42105398
By study type
Clinical trials (1)
- Optimized seasonal influenza mRNA vaccine compositions demonstrate safety and enhanced immunogenicity in a phase 2 study. Human vaccines & immunotherapeutics · 13 Jul 2026 PMID 42441816
Human data, design not indexed (2)
- Emergence of an antigenically drifted and reassorted influenza B virus at the end of the 2024-25 influenza season. mBio · 22 Jun 2026 PMID 42328860
- Local B cell immunity and durable memory after live-attenuated influenza intranasal vaccination of humans. Science translational medicine · 29 Apr 2026 PMID 42054493
Preclinical: animal, cell and lab studies (16)
- Anti-idiotypic antibodies as molecular mimics of conserved influenza hemagglutinin epitopes. Protein science : a publication of the Protein Society · 15 Sept 2026 PMID 42742346
- Consensus H3N2 HA immunogens incorporating key antigenic mutations elicit broad-spectrum neutralizing responses. Emerging microbes & infections · 7 Sept 2026 PMID 42703780
- Linear DNA expression cassette encapsulated in lipid nanoparticles confers complete protection against influenza A virus in mice. mSphere · 4 Sept 2026 PMID 42695687
- Nanoemulsion adjuvanted COBRA HA vaccine enhances protective antibody titers against H1N1 and H3N2 influenza viruses. Human vaccines & immunotherapeutics · 3 Sept 2026 PMID 42691282
- Mannose-functionalized thermoresponsive microneedles for enhanced antigen delivery and immune activation. Journal of materials chemistry. B · 27 Aug 2026 PMID 42657667
- A bispecific antibody targeting conserved hemagglutinin epitopes confers broad protection against H7 avian influenza and accelerates viral clearance via localized respiratory delivery. Emerging microbes & infections · 19 Aug 2026 PMID 42617142
- Neutralizing and protective monoclonal antibodies identify antigenic sites in influenza H7 hemagglutinin and select for amino acid substitutions rarely observed at the global level. Microbiology spectrum · 6 Aug 2026 PMID 42560073
- Identification and computational analysis of B-cell epitopes on the hemagglutinin protein of the H3N2 influenza virus. Archives of microbiology · 5 Aug 2026 PMID 42554770
- Capless self-amplifying mRNA vaccine induces dose-sparing protective immunity against HPAI clade 2.3.4.4 H5 virus in mice. Molecular therapy : the journal of the American Society of Gene Therapy · 30 Jul 2026 PMID 42528137
- Intranasal influenza vaccination using an outer membrane vesicle platform. Vaccine · 26 Jun 2026 PMID 42361782
- A subunit vaccine for multiple respiratory viruses. Science advances · 26 Jun 2026 PMID 42361166
- BECC-adjuvanted hemagglutinin influenza vaccine promotes enhanced immunogenicity and protective efficacy. Vaccine · 31 May 2026 PMID 42218860
- Conjugate vaccine technology enhances responses to influenza virus. Vaccine · 22 May 2026 PMID 42172691
- Retooling a novel influenza B hemagglutinin to redirect neutralizing antibodies against B/Victoria strains. Vaccine · 9 May 2026 PMID 42105398
- Enhanced immunogenicity and dose-sparing efficacy of self-amplifying RNA vaccines against seasonal influenza across subtypes. Emerging microbes & infections · 4 May 2026 PMID 42081324
- Childhood immunological imprinting of cross-subtype antibodies targeting the hemagglutinin head domain of influenza viruses. Cell host & microbe · 28 Apr 2026 PMID 42049037
Written from 19 PubMed abstracts, each one listed by PMID above. Published: 2026-08-13. Last written: 2026-09-05 by GPT. Drafted by language models from published abstracts; not medical advice.