Human cytomegalovirus disrupts constitutive MHC class II expression.
CD8(+) and CD4(+) T lymphocytes are important in controlling human CMV (HCMV) infection, but the virus has evolved protean mechanisms to inhibit MHC-based Ag presentation and escape T lymphocyte immunosurveillance. Herein, the interaction of HCMV with the MHC class II Ag presentation pathway was investigated in cells stably transfected with class II transactivator. Flow cytometry experiments demonstrate that HCMV infection decreases cell-surface MHC class II expression. HCMV down-regulates MHC class II surface expression without a significant effect on class II RNA or steady-state protein levels. SDS-stability and confocal microscopy experiments demonstrate normal levels of steady-state peptide-loaded class II molecules in infected cells and that class II molecules reach late endosomal and HLA-DM positive peptide-loading compartments. However, MHC class II positive vesicles are retained in an abnormal perinuclear distribution. Finally, experiments with a mutant HCMV strain demonstrate that this novel mechanism of decreased MHC class II expression is not mediated by one of the known HCMV immunomodulatory genes. These defects in MHC class II expression combined with previously identified CMV strategies for decreasing MHC class I expression enables infected cells to evade T lymphocyte immunosurveillance.
Cebulla
Colleen M
CM
Department of Pathology, Ohio State University College of Medicine and Public Health, Columbus, OH 43210, USA.
Miller
Daniel M
DM
Zhang
Yingxue
Y
Rahill
Brian M
BM
Zimmerman
Peter
P
Robinson
John M
JM
Sedmak
Daniel D
DD
D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D003587:Cytomegalovirus / Q000276:immunology* / Q000472:pathogenicity; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D006684:HLA-DR Antigens / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins; D011233:Precipitin Tests; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000276:immunology / Q000378:metabolism / Q000821:virology
D000944:Antigens, Differentiation, B-Lymphocyte; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; C083728:MHC class II transactivator protein; D009687:Nuclear Proteins; D015534:Trans-Activators; C045084:invariant chain