T-cell receptor on CD4+, CD8+, and γδ T cells recognizing H5N1 HA-derived peptides (H5N1 HA-specific TCR)

The T-cell receptor (TCR) on CD4+, CD8+, and γδ T cells that recognizes H5N1 hemagglutinin (HA)-derived peptides is a critical mediator of the cellular immune response against highly pathogenic avian influenza (HPAI). CD4+ and CD8+ T cells utilize their αβ TCRs to recognize specific HA peptides presented by MHC Class II and Class I molecules, respectively, which triggers the secretion of pro-inflammatory cytokines such as IFN-γ and TNF-α and induces direct cytotoxic activity against infected host cells (2.2.1, 2.2.2). Uniquely, γδ T cells can be directly activated by HA trimers in a sialic acid-dependent manner, bypassing traditional MHC restriction to provide a rapid, innate-like defense (3.2.1). This target is central to the development of H5N1 vaccines and universal influenza strategies, which aim to elicit or boost cross-reactive T-cell populations that can recognize conserved epitopes across different viral clades (2.3.1, 3.3.1). Research indicates that many individuals possess pre-existing cross-reactive TCRs from prior seasonal influenza exposure, which may help blunt the severity of H5N1 infection (2.1.4, 3.1.2). However, therapeutic challenges include the phenomenon of "original antigenic sin," where the immune system preferentially responds to previously encountered seasonal antigens rather than the novel H5N1 epitopes, potentially limiting the efficacy of vaccination (2.1.2, 3.3.3).

Other names

H5N1 hemagglutinin-specific T-cell receptorHA-specific T-cell receptorAvian influenza-specific TCRH5N1-specific TCRHemagglutinin-derived peptide-specific TCR

Activation of the adaptive immune system via TCR-MHC-peptide interaction (for CD4+ and CD8+ T cells) or direct activation by HA trimers (for γδ T cells), leading to the expansion of antigen-specific T cells, cytokine secretion, and elimination of virus-infected cells.