title: Disruption of MHC class II-restricted antigen presentation by vaccinia virus.
abstract: Vaccinia virus (VV), currently used in humans as a live vaccine for smallpox, can interfere with host immunity via several discrete mechanisms. In this study, the effect of VV on MHC class II-mediated Ag presentation was investigated. Following VV infection, the ability of professional and nonprofessional APC to present Ag and peptides to CD4+ T cells was impaired. Viral inhibition of class II Ag presentation could be detected within 1 h, with diminished T cell responses dependent upon the duration of APC infection and virus titer. Exposure of APC to replication-deficient virus also diminished class II Ag presentation. Virus infection of APC perturbed Ag presentation by newly synthesized and recycling class II molecules, with disruptions in both exogenous and cytoplasmic Ag presentation. Virus-driven expression of an endogenous Ag, failed to restore T cell responsiveness specific for this Ag in the context of MHC class II molecules. Yet, both class II protein steady-state and cell surface expression were not altered by VV. Biochemical and functional analysis revealed that VV infection directly interfered with ligand binding to class II molecules. Together, these observations suggest that disruption of MHC class II-mediated Ag presentation may be one of multiple strategies VV has evolved to escape host immune surveillance.
authors.affiliation: Department of Microbiology and Immunology, Center for Immunobiology, and Walther Oncology Center, Indiana University School of Medicine, and Walther Cancer Institute, Indianapolis, IN 46202, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.forename: Delu
authors.initials: D
authors.lastname: Zhou
authors.forename: Christina S K
authors.initials: CS
authors.lastname: Yee
authors.forename: Cheong-Hee
authors.initials: CH
authors.lastname: Chang
authors.forename: Randy R
authors.initials: RR
authors.lastname: Brutkiewicz
authors.forename: Janice S
authors.initials: JS
authors.lastname: Blum
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000821:virology; D001402:B-Lymphocytes / Q000276:immunology / Q000821:virology; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002460:Cell Line; D002522:Chlorocebus aethiops; D018076:DNA, Complementary / Q000235:genetics; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D006801:Humans; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D014616:Vaccinia virus / Q000235:genetics / Q000276:immunology*
chemical_list: D018076:DNA, Complementary; D000949:Histocompatibility Antigens Class II; D011994:Recombinant Proteins; D005968:Glutamate Decarboxylase