herpesviruses and mechanisms of immune evasion

A unique phenomenon that is being researched in herpesviruses is their ability to evade the immune system through various mechanisms. One particular method is via down-regulation of the cell-surface expression of the major histocompatibility complex class I (MHC-I) which is found on most cells in the body. MHC-I molecules associate with viral (in this case) antigens found in the cytosol and present them to CD8 T cells.

Because my honors thesis in biology is on MHC-I downregulation of one herpesvirus, I just want to share the varying mechanisms used by different herpesviruses to evade this crucial arm of the immune response.

Virus Protein Mechanism
HSV ICP47 Competes with peptide binding on TAP complex
HCMV pp65 Phosphorylates immediate early proteins to prevent processing by the proteasome
HCMV US6 Binds to TAP complex from ER-lumenal side
HCMV US11 Exports heavy chain to cytosol
HCMV US2 Degrades heavy chain
HCMV US3 Retains MHC-I in ER
EBV EBNA-1 Interferes with proteosomal proteolysis


Fruh, K., K. Ahn, and P.A. Peterson. "Inhibition of MHC class I antigen presentation by viral proteins." J Mol Med 1997: 75; 18-27.

Ploegh, Hidde L. "Viral Strategies of Immune Evasion." Science 1998: 280; 248-253.