Potential strategies utilised by papillomavirus to evade host immunity.
The co-evolution of papillomaviruses (PV) and their mammalian hosts has produced mechanisms by which PV might avoid specific and non-specific host immune responses. Low level expression of PV proteins in infected basal epithelial cells, together with an absence of inflammation and of virus-induced cell lysis, restricts the opportunity for effective PV protein presentation to immunocytes by dendritic cells. Additionally, PV early proteins, by a range of mechanisms, may restrict the efficacy of antigen presentation by these cells. Should an immune response be induced to PV antigens, resting keratinocytes (KC) appear resistant to interferon-gamma-enhanced mechanisms of cytotoxic T-lymphocyte (CTL)-mediated lysis, and expression of PV antigens by resting KC can tolerise PV-specific CTL. Thus, KC, in the absence of inflammation, may represent an immunologically privileged site for PV infection. Together, these mechanisms play a part in allowing persistence of PV-induced proliferative skin lesions for months to years, even in immunocompetent hosts.
Centre for Immunology and Cancer Research, University of Queensland Department of Medicine, Princess Alexandra Hospital, Brisbane, Australia. ifrazer@medicine.pa.uq.edu.au
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Frazer
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Thomas
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Zhou
G R
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Leggatt
L
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Dunn
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McMillan
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Tindle
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Filgueira
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Manders
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Barnard
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Sharkey
D000818:Animals; D004847:Epithelial Cells / Q000276:immunology / Q000821:virology; D006412:Hematopoietic Stem Cells / Q000276:immunology; D006801:Humans; D016898:Interferon-alpha / Q000276:immunology; D015603:Keratinocytes / Q000276:immunology / Q000821:virology; D009856:Oncogene Proteins, Viral / Q000276:immunology; D027383:Papillomaviridae / Q000276:immunology*; D050725:Papillomavirus E7 Proteins; D030361:Papillomavirus Infections / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014412:Tumor Virus Infections / Q000276:immunology*; D014764:Viral Proteins / Q000276:immunology
D016898:Interferon-alpha; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D014764:Viral Proteins; C059731:oncogene protein E7, Human papillomavirus type 16