Viral evasion

The path that leads from full sized protein to epitopes at the cell surface is complex, consisting of the generation of small peptides, translocation of the peptides to the endoplasmic reticulum by a transporter complex, loading of the peptides onto MHC class-I molecules and relocation of the MHC class-I-peptide complex to the cell surface (Rock and Goldberg, 1999). Since many of these steps are known to be prime targets for viral evasion strategies, the next step was to identify at what point the GAr interferes with the presentation of EBNAl. 

Detailed in vitro analysis unmasked a unique mode of action for the GAr. While many viral evasion strategies target the MHC class-I complex (Collins and Baltimore, 1999 Wieitz et al., 1997), the GAr appeared to... 

Viral Evasion of Natural Killer Cells During Human Cytomegalovirus Infection... 

Viral Evasion of NaUirai Killer C ells During Human Cylomegalovirus Infection... 

Farrell HE, Davis-Poynter NJ (1998) From sabotage to camouflage viral evasion of cytotoxic T lymphocyte and natural killer cell-mediated immunity. Sem Cell Develop Biol 9 369-378 Farrell HE, Vally H, Lynch DM, Fleming P, Shellam GR, Scalzo AA, Davis-Poynter NJ (1997) Inhibition of natural killer cells by a cytomegalovirus MHC class I homologue in vivo. Nature 386 510-514... 

Feuh, K., et ah. Immune evasion by a novel family of viral PHD/LAP-finger proteins of gamma-2 herpesviruses and poxviruses. Virus Res, 2002, 88(1-2), 55-69. 

Bartee, E., et ah, Downregulation of major histocompatibility complex class I by human ubiquitin ligases related to viral immune evasion proteins. J Virol, 2004, 78(3), 1109-20. 

Ploegh HL (1998) Viral strategies of immune evasion. Science 280 248-253. 

Alcami, A. and Koszinowski, U.H. 2000. Viral mechanisms of immune evasion. Trends Microbiol. 8, 410-418. 

As previously mentioned, interferons are cytokines produced by cells to protect them from viral infection, and anti-interferon strategies are a part of the immune evasion repertoire of most viruses. These mechanisms include the production of soluble versions of interferon receptors, which act as decoys. These decoys bind and inactivate interferons before they reach their destination - normal, membrane-bound receptors.22... 

A. Alcami and U. H. Koszinowski, Viral mechanisms of immune evasion, Trends in Microbiology, 8, 2000, 410-18 D. Tortorella et al., Viral subversion of the immune system, Annual Review of Immunology, 18, 2000, 861-926. 

The enzyme catalyzes the cleavage of terminal sialic acid from adjacent sugar residues. Neuraminidase and hemagglutinin are the two glycoproteins attach to the influenza viral membrane. They make up the antigenic surface of the virus, and changes in these proteins form the basis for evasion of immune recognition from previous infections. Data extracted from Davies et ai (1990). Individual references are a) Sheriff et al. (1987) b) Padlan et al. (1989) c) Amit et al. (1986) d) Tulip et oL (1989). 

Weber KS. Selective recruitment of Th2-type cells and evasion from a cytotoxic immune response mediated by viral macrophage inhibitory protein-II. Eur J Immunol 2001 31(8) 2458-66. 

The use of viral chemokine/receptor mimics and inhibitors identified in particular virus families such as herpesviruses, poxviruses and HIV indicates their importance in pathogensis of these viruses, either for evasion of the immune response as with poxviruses and herpesviruses or addtionally the use of recptors for viral entry as with HIV and poxviruses. Further studies will almost certainly identify a greater range of viruses producing such mimics. 

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