About Influenza A Hemagglutinin (HA) (A/District of Columbia/27/2023, H3N2) Recombinant Protein

Influenza A (H3N2) viruses are among the most clinically important causes of seasonal influenza, contributing to significant morbidity and mortality worldwide. The A/District of Columbia/27/2023 (H3N2) strain was selected by the World Health Organization (WHO) as a recommended cell-based vaccine reference strain for the 2025–2026 Northern Hemisphere influenza season, reflecting its close antigenic relationship to circulating H3N2 viruses.

The viral hemagglutinin (HA) glycoprotein is the major surface antigen of influenza A virus and mediates attachment to α2,6- and α2,3-linked sialic acid receptors on host epithelial cells, initiating viral entry through receptor-mediated endocytosis and membrane fusion. Because HA is the principal target of neutralizing antibodies and the primary antigen incorporated into seasonal influenza vaccines, recombinant HA proteins are indispensable tools for vaccine research, serological assays, structural biology, and antiviral therapeutic development. eEnzyme's Influenza A Hemagglutinin (HA) (A/District of Columbia/27/2023, H3N2) Recombinant Protein is expressed in HEK293 cells and consists of the full-length ectodomain (amino acids 17–529) with a C-terminal 8×His tag and an engineered trimerization domain to stabilize the native trimeric HA structure. The purified protein exhibits >95% purity (SDS-PAGE) and preserves native mammalian glycosylation, making it suitable for ELISA, Western blotting, neutralizing antibody characterization, receptor-binding studies, vaccine development, and diagnostic assay development.

Applications

Biological Significance of Influenza A H3 Hemagglutinin

Hemagglutinin is the primary determinant of influenza virus attachment and entry into host cells. Following receptor binding, HA undergoes low pH-induced conformational changes within endosomes that drive fusion of the viral and host cell membranes, enabling viral genome release into the cytoplasm. Because HA is exposed on the virion surface, it is the dominant target of protective humoral immunity and the principal antigen used in seasonal influenza vaccines. Continuous antigenic drift within the H3 hemagglutinin protein leads to the emergence of new variants that escape pre-existing immunity, requiring frequent updates to vaccine formulations. The A/District of Columbia/27/2023 (H3N2) HA has therefore become an important reference antigen for vaccine potency testing, antigenic surveillance, therapeutic antibody evaluation, and studies of influenza virus evolution.

The Influenza A Hemagglutinin (HA) (A/District of Columbia/27/2023, H3N2) Recombinant Protein provides a high-quality research reagent for investigating influenza virus biology, evaluating vaccine-induced immune responses, screening broadly neutralizing antibodies, and supporting the development of next-generation influenza vaccines, diagnostics, and antiviral therapeutics. Its mammalian expression system, native glycosylation, and stabilized trimeric structure make it particularly valuable for immunological, structural, and translational influenza research.