Human leukocyte antigen E in human cytomegalovirus infection:friend or foe?

摘要

Human cytomegalovirus (HCMV) is a well-studied β-herpesvirus virus,which adopts a variety of strategies to evade immune surveillance.It has been reported that in HCMV-infected cells,classical major histocompatibility (MHC) class I molecules are down-regulated,but the MHC class Ib molecule human leukocyte antigen (HLA)-E is normally expressed or even overexpressed on the cell surface.HLA-E has been first described to interact with CD94/NKG2 receptors expressed mainly on the surface of natural killer (NK) cells,thus confining its role to the regulation of NK-cell function.The engagement of CD94/NKG2A with HLA-E,with a signal peptide of the HCMV glycoprotein UL40,usually induces inhibitory signals.However,HLA-E also serves as a ligand for the TCR expressed by αβCD8+ T cells.Recognition of peptides presented by HLA-E may result in CD8+ effector T-cell activation.These findings will help to understand more on both pathogenic and protective roles of HLA-E in HCMV infection.In this review,we discussed recent studies about the roles of HLA-E in HCMV infection.