title: Alpha/beta interferon protects adult mice from fatal Sindbis virus infection and is an important determinant of cell and tissue tropism.
abstract: Infection of adult 129 Sv/Ev mice with consensus Sindbis virus strain TR339 is subclinical due to an inherent restriction in early virus replication and viremic dissemination. By comparing the pathogenesis of TR339 in 129 Sv/Ev mice and alpha/beta interferon receptor null (IFN-alpha/betaR(-/-)) mice, we have assessed the contribution of IFN-alpha/beta in restricting virus replication and spread and in determining cell and tissue tropism. In adult 129 Sv/Ev mice, subcutaneous inoculation with 100 PFU of TR339 led to extremely low-level virus replication and viremia, with clearance under way by 96 h postinoculation (p.i.). In striking contrast, adult IFN-alpha/betaR(-/-) mice inoculated subcutaneously with 100 PFU of TR339 succumbed to the infection within 84 h. By 24 h p.i. a high-titer serum viremia had seeded infectious virus systemically, coincident with the systemic induction of the proinflammatory cytokines interleukin-12 (IL-12) p40, IFN-gamma, tumor necrosis factor alpha, and IL-6. Replicating virus was located in macrophage-dendritic cell (DC)-like cells at 24 h p.i. in the draining lymph node and in the splenic marginal zone. By 72 h p.i. virus replication was widespread in macrophage-DC-like cells in the spleen, liver, lung, thymus, and kidney and in fibroblast-connective tissue and periosteum, with sporadic neuroinvasion. IFN-alpha/beta-mediated restriction of TR339 infection was mimicked in vitro in peritoneal exudate cells from 129 Sv/Ev versus IFN-alpha/betaR(-/-) mice. Thus, IFN-alpha/beta protects the normal adult host from viral infection by rapidly conferring an antiviral state on otherwise permissive cell types, both locally and systemically. Ablation of the IFN-alpha/beta system alters the apparent cell and tissue tropism of the virus and renders macrophage-DC-lineage cells permissive to infection.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA. kryman@med.unc.edu
authors.forename: K D
authors.initials: KD
authors.lastname: Ryman
authors.forename: W B
authors.initials: WB
authors.lastname: Klimstra
authors.forename: K B
authors.initials: KB
authors.lastname: Nguyen
authors.forename: C A
authors.initials: CA
authors.lastname: Biron
authors.forename: R E
authors.initials: RE
authors.lastname: Johnston
mesh_terms: D018354:Alphavirus Infections / Q000517:prevention & control*; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D016207:Cytokines / Q000096:biosynthesis; D006023:Glycoproteins / Q000235:genetics; D007370:Interferon Type I / Q000627:therapeutic use*; D008264:Macrophages / Q000821:virology; D051379:Mice; D012845:Sindbis Virus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D018523:Tropism; D014774:Virulence; D014779:Virus Replication
chemical_list: D016207:Cytokines; D006023:Glycoproteins; D007370:Interferon Type I