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

References:

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.