Xpression between lethal and non-lethal virus infections (Fig. 3 A and C). It is also demonstrated that at 3DPI, IFN- ?is largely produced after the infection with a high titer of the virus compared to that with a low titer of the virus, and their amounts are equivalent at 5DPI (Fig. 5), suggesting that FasL expression in the virus-infected mice are controlled by Title Loaded From File type-I IFN depending on its time kinetics rather than its amount. Production of type-I IFN after influenza A virus infection is regulated by two different types of viral RNA recognizing receptor proteins, such as TLRs and RIG-I like proteins. While TLRs play their essential role for production of type-I IFN in macrophages or plasmacytoid dendritic cells (DC), RIG-I like proteins are critical for their production in conventional DC or fibroblasts [12,13]. In addition, it is proposed that in a respiratory RNA virus infection, alveolar macrophage is a main source for producing type-I IFN [23] and it is also reported that prevention of the recruitment of macrophages into the lungs protects mice against lethal PR/8 virus infection [24]. The differences in the time-kinetics of type-I IFN between the lethal and non-lethal infections might be due to the differences of mainly producing cell types such as alveolar macrophage or epithelial cells. Type-I IFN has been identified as a virus interference agent and stimulates production of several intracellular proteins preventing virus RNA synthesis [25]. More recently, several studies proposed that type-I IFN plays important roles for inhibition of virus production as well as regulation of the activation of immune cells [14] and contributes to the progression of autoimmune disease, such as systemic lupus erythematosus [26]. These findings and our data suggest that abnormal regulation on type-I IFN production should associate with several diseases, such as viral infection and autoimmune diseases. Taken together, it is demonstrated that type-I interferon induced by the viral infection should be associated with the induction of FasL protein which should playImportance of Type I IFN and FasL in Influenzaa negative effect on host protection against lethal influenza virus infection, and it is therefore suggested to explore the detail mechanism of regulation by the FasL/Fas system for the host immunological response; doing so should be beneficial to the controlling of the 15857111 severity of influenza.Supporting InformationFigure S1 gld/gld mutation on FasL gene does not affectvirus. At 0, 3 or 5 DPI, the mice were sacrificed and the percentages of the cell populations expressing the Title Loaded From File indicated cell type marker among live (7-AAD(2)) FSC/SSC gated lung cells were assessed by flowcytometry. (N = 3/each group). (B) B6 or B6-gld/gld mice were infected with 102 or 105 pfu/head of the PR/8 virus. At 5 DPI, the cells isolated from the lungs of these mice were analyzed as described in A. (N = 3/each 1317923 group). (TIFF)virus production in lung of mice lethally infected with PR/8 virus. Control B6 or B6-gld/gld mice were infected with 105 pfu/head of the PR/8 virus. At the indicated day, the mice were sacrificed and the virus titers in the isolated lungs of the mice were assessed by plaque assay as described in Materials and Methods. (TIFF) gld/gld mutation on FasL gene prevents the reduction of CD3(+) cell population in lung of mice lethally infected with PR/8 virus. (A) B6 (closed) or B6-gld/ gld (opened) mice were infected with 105 pfu/head of the PR/Figure SAcknowledg.Xpression between lethal and non-lethal virus infections (Fig. 3 A and C). It is also demonstrated that at 3DPI, IFN- ?is largely produced after the infection with a high titer of the virus compared to that with a low titer of the virus, and their amounts are equivalent at 5DPI (Fig. 5), suggesting that FasL expression in the virus-infected mice are controlled by type-I IFN depending on its time kinetics rather than its amount. Production of type-I IFN after influenza A virus infection is regulated by two different types of viral RNA recognizing receptor proteins, such as TLRs and RIG-I like proteins. While TLRs play their essential role for production of type-I IFN in macrophages or plasmacytoid dendritic cells (DC), RIG-I like proteins are critical for their production in conventional DC or fibroblasts [12,13]. In addition, it is proposed that in a respiratory RNA virus infection, alveolar macrophage is a main source for producing type-I IFN [23] and it is also reported that prevention of the recruitment of macrophages into the lungs protects mice against lethal PR/8 virus infection [24]. The differences in the time-kinetics of type-I IFN between the lethal and non-lethal infections might be due to the differences of mainly producing cell types such as alveolar macrophage or epithelial cells. Type-I IFN has been identified as a virus interference agent and stimulates production of several intracellular proteins preventing virus RNA synthesis [25]. More recently, several studies proposed that type-I IFN plays important roles for inhibition of virus production as well as regulation of the activation of immune cells [14] and contributes to the progression of autoimmune disease, such as systemic lupus erythematosus [26]. These findings and our data suggest that abnormal regulation on type-I IFN production should associate with several diseases, such as viral infection and autoimmune diseases. Taken together, it is demonstrated that type-I interferon induced by the viral infection should be associated with the induction of FasL protein which should playImportance of Type I IFN and FasL in Influenzaa negative effect on host protection against lethal influenza virus infection, and it is therefore suggested to explore the detail mechanism of regulation by the FasL/Fas system for the host immunological response; doing so should be beneficial to the controlling of the 15857111 severity of influenza.Supporting InformationFigure S1 gld/gld mutation on FasL gene does not affectvirus. At 0, 3 or 5 DPI, the mice were sacrificed and the percentages of the cell populations expressing the indicated cell type marker among live (7-AAD(2)) FSC/SSC gated lung cells were assessed by flowcytometry. (N = 3/each group). (B) B6 or B6-gld/gld mice were infected with 102 or 105 pfu/head of the PR/8 virus. At 5 DPI, the cells isolated from the lungs of these mice were analyzed as described in A. (N = 3/each 1317923 group). (TIFF)virus production in lung of mice lethally infected with PR/8 virus. Control B6 or B6-gld/gld mice were infected with 105 pfu/head of the PR/8 virus. At the indicated day, the mice were sacrificed and the virus titers in the isolated lungs of the mice were assessed by plaque assay as described in Materials and Methods. (TIFF) gld/gld mutation on FasL gene prevents the reduction of CD3(+) cell population in lung of mice lethally infected with PR/8 virus. (A) B6 (closed) or B6-gld/ gld (opened) mice were infected with 105 pfu/head of the PR/Figure SAcknowledg.
