Viral peptide-Major Histocompatibility Complex (pMHC)

Viral peptide-Major Histocompatibility Complex (pMHC) complexes are the primary molecular targets for cellular immunity against viruses like Cytomegalovirus (CMV), Epstein-Barr Virus (EBV), and Adenovirus. These complexes form when intracellular viral proteins are processed into short peptides and loaded onto MHC Class I or II molecules for presentation on the cell surface [1, 6]. Recognition of these pMHCs by the T-cell receptors (TCRs) of CD8+ or CD4+ T cells triggers an immune response, leading to the destruction of the infected cell [1, 19]. In the context of transplantation and immunodeficiency, these complexes are targeted by adoptive T-cell therapies, such as tabelecleucel and posoleucel, which provide exogenous virus-specific T cells to restore immune control [2, 3, 4]. These therapies are highly specific, relying on the precise matching of the TCR to the viral peptide and the patient's specific HLA allele [2, 17]. Challenges in targeting these complexes include viral evasion mechanisms that downregulate MHC expression and the risk of graft-versus-host disease or off-target effects if the viral peptide resembles a host self-peptide [9, 12, 14]. The clinical success of these therapies is often monitored through viral load reduction and the expansion of antigen-specific T cells in the patient's blood [7, 11]. Overall, these pMHC complexes represent a critical interface between the host immune system and viral pathogens, serving as a precise anchor for modern cellular immunotherapies.

Other names

Viral pMHCMHC-peptide complexHLA-restricted viral antigenCMV/EBV/AdV pMHC complexViral antigen-MHC complexpMHC complex

T-cell receptor-mediated cytotoxic cell lysis