title: IL-12p40 and IL-18 play pivotal roles in orchestrating the cell-mediated immune response to a poxvirus infection.
abstract: A strong cell-mediated immune response is critical for controlling viral infections and is regulated by a number of cytokines, including IL-12 and IL-18. Indeed, some viruses have evolved to specifically target these pathways to counter the host immune response. Orthopoxviruses, including ectromelia virus, encode immune evasion molecules that specifically target IL-18 and IFN-gamma. We hypothesized that IL-12 and IL-18 are pivotal for induction of IFN-gamma production and subsequent generation of an effective host response to ectromelia virus infection. In this study, we demonstrate that absence of both IL-12p40 and IL-18 resulted in increased susceptibility to infection that was associated with skewing of the cytokine response to Th2 and a reduction in NK and CTL responses. The decrease in CTL response correlated with a defect in CD8(+) T cell proliferation and lower numbers of virus-specific CD8(+) T cells. Lack of either IL-12p40 and/or IL-18 was also associated with reduced numbers of CD8(+) T cells at sites of infection and with an increase in the numbers of splenic T regulatory cells. Taken together, our data indicate that IL-12p40 and IL-18 act in concert and play an important antiviral role through the up-regulation of IFN-gamma production and cell-mediated immune responses.
authors: John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.
authors: Yang
authors: Y
authors: Wang
authors: Geeta
authors: G
authors: Chaudhri
authors: Ronald J
authors: RJ
authors: Jackson
authors: Gunasegaran
authors: G
authors: Karupiah
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D004481:Ectromelia virus / Q000276:immunology*; D004482:Ectromelia, Infectious / Q000235:genetics / Q000276:immunology* / Q000401:mortality; D020022:Genetic Predisposition to Disease / Q000235:genetics; D007111:Immunity, Cellular / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics; D053762:Interleukin-12 Subunit p40 / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D020382:Interleukin-18 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D007694:Killer Cells, Natural / Q000276:immunology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000473:pathology; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology
chemical_list: D053762:Interleukin-12 Subunit p40; D020382:Interleukin-18