Abstract
Cytotoxic T lymphocytes (CTLs) undoubtedly play an important role in protection against viral infections. Virus-specific CTLs recognize virus-derived peptides in the context of major histocompatibility complex (MHC) class I molecules and lyse virus-infected cells via perforin/granzyme and Fas/Fas ligand pathways. Infection of viruses, especially herpesviruses, induces down-regulation of the surface MHC molecules, resulting in viral escape from immunosurveillance system. Viruses also modulate the chemokine/chemokine receptor system through various mechanisms, including virus-encoded chemokine ligand homologs that function as agonists or antagonists, virus-encoded cell-surface chemokine receptor homologs, virus-encoded secreted chemokine-binding proteins, and down-and up-regulation of chemokines and chemokine receptors. In this review, viral subversion of the immune system focusing on MHC expression and the chemokine system is discussed. Insight into strategies used by herpesviruses to modulate MHC expression and the chemokine system might generate novel approaches for protecting and treating viral infections.
