title: Low-affinity cytotoxic T-lymphocytes require IFN-gamma to clear an acute viral infection.
abstract: The majority of the response of cytotoxic T-lymphocytes (CTL) to lymphocytic choriomeningitis virus (LCMV) in H-2d mice is directed toward one epitope located on the nucleoprotein (NP, aa 118-126), and usually no primary responses to other epitopes are detectable. Previous studies have shown that thymic expression of lymphocytic choriomeningitis virus-nucleoprotein (LCMV-NP) in H-2d transgenic mice (Thy-NP mice) leads to deletion of high-affinity anti-LCMV-NP CTL by negative selection. Selection is incomplete, so that low-affinity NP-specific CTL pass through the thymus and are detectable in the periphery. To analyze the importance of interferon-gamma (IFN-gamma) in the ability of low-affinity antiviral CTL to clear an acute viral infection, double transgenic mice were generated that are IFN-gamma deficient and express the NP of LCMV in the thymus (Thy-NP x IFN-gamma -/- mice). When infected with LCMV, these bigenic mice were unable to clear the infection despite generating low-affinity primary antiviral CTL, and they became persistently infected. In contrast, IFN-gamma competent Thy-NP mice cleared LCMV within 7-8 days and IFN-gamma deficient mice that did not express NP in their thymus generated high-affinity CTL that terminated an acute LCMV infection within 10-12 days post-viral challenge. Persistently infected IFN-gamma deficient mice selectively depleted LCMV-specific CTL and displayed reduced levels of antigen-presenting cells in the spleen, and 60% of these mice died at 2-3 months postinfection. Thus, IFN-gamma is required for clearing an acute viral infection in the absence of a high-affinity CTL response. In the absence of IFN-gamma persistent viral infection results despite the presence of low-affinity CTL.
authors.affiliation: Department of Neuropharmacology, Scripps Research Institute, La Jolla, California 92037, USA. matthias@scripps.edu
authors.forename: M G
authors.initials: MG
authors.lastname: Von Herrath
authors.forename: B
authors.initials: B
authors.lastname: Coon
authors.forename: M B
authors.initials: MB
authors.lastname: Oldstone
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D002452:Cell Count; D002522:Chlorocebus aethiops; D006224:Cricetinae; D004195:Disease Models, Animal; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology*; D008216:Lymphocytic Choriomeningitis / Q000276:immunology*; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology* / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D019251:Nucleocapsid / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014709:Vero Cells; D017735:Virus Latency
chemical_list: D007371:Interferon-gamma