Project description:Interferons (IFNs) are key players in the antiviral response. IFN sensing by the cell activates transcription of IFN-stimulated genes (ISGs) able to induce an antiviral state by affecting viral replication and release. IFN also induces the expression of ISGs that function as negative regulators to limit the strength and duration of IFN response. The ISGs identified so far belong to coding genes. However, only a small proportion of the transcriptome corresponds to coding transcripts and it has been estimated that there could be as many coding as long non-coding RNAs (lncRNAs). To address whether IFN can also regulate the expression of lncRNAs, we analyzed the transcriptome of HuH7 cells treated or not with IFNα2 by expression arrays. Analysis of the arrays showed increased levels of several well-characterized coding genes that respond to IFN both at early or late times. Furthermore, we identified several IFN-stimulated or -downregulated lncRNAs (ISRs and IDRs). Further validation showed that ISR2, 8, and 12 expression mimics that of their neighboring genes GBP1, IRF1, and IL6, respectively, all related to the IFN response. These genes are induced in response to different doses of IFNα2 in different cell lines at early (ISR2 or 8) or later (ISR12) time points. IFNβ also induced the expression of these lncRNAs. ISR2 and 8 were also induced by an influenza virus unable to block the IFN response but not by other wild-type lytic viruses tested. Surprisingly, both ISR2 and 8 were significantly upregulated in cultured cells and livers from patients infected with HCV. Increased levels of ISR2 were also detected in patients chronically infected with HIV. This is relevant as genome-wide guilt-by-association studies predict that ISR2, 8, and 12 may function in viral processes, in the IFN pathway and the antiviral response. Therefore, we propose that these lncRNAs could be induced by IFN to function as positive or negative regulators of the antiviral response. HuH7 cells were treated with 10000 units/ml of IFN a2 and RNA was isolated 3 days post-treatment

Project description:Interferons (IFNs) are key players in the antiviral response. IFN sensing by the cell activates transcription of IFN-stimulated genes (ISGs) able to induce an antiviral state by affecting viral replication and release. IFN also induces the expression of ISGs that function as negative regulators to limit the strength and duration of IFN response. The ISGs identified so far belong to coding genes. However, only a small proportion of the transcriptome corresponds to coding transcripts and it has been estimated that there could be as many coding as long non-coding RNAs (lncRNAs). To address whether IFN can also regulate the expression of lncRNAs, we analyzed the transcriptome of HuH7 cells treated or not with IFNα2 by expression arrays. Analysis of the arrays showed increased levels of several well-characterized coding genes that respond to IFN both at early or late times. Furthermore, we identified several IFN-stimulated or -downregulated lncRNAs (ISRs and IDRs). Further validation showed that ISR2, 8, and 12 expression mimics that of their neighboring genes GBP1, IRF1, and IL6, respectively, all related to the IFN response. These genes are induced in response to different doses of IFNα2 in different cell lines at early (ISR2 or 8) or later (ISR12) time points. IFNβ also induced the expression of these lncRNAs. ISR2 and 8 were also induced by an influenza virus unable to block the IFN response but not by other wild-type lytic viruses tested. Surprisingly, both ISR2 and 8 were significantly upregulated in cultured cells and livers from patients infected with HCV. Increased levels of ISR2 were also detected in patients chronically infected with HIV. This is relevant as genome-wide guilt-by-association studies predict that ISR2, 8, and 12 may function in viral processes, in the IFN pathway and the antiviral response. Therefore, we propose that these lncRNAs could be induced by IFN to function as positive or negative regulators of the antiviral response.

Project description:Interferons (IFNs) are key players in the antiviral response. IFN sensing by the cell activates transcription of IFN-stimulated genes (ISGs) able to induce an antiviral state by affecting viral replication and release. IFN also induces the expression of ISGs that function as negative regulators to limit the strength and duration of IFN response. The ISGs identified so far belong to coding genes. However, only a small proportion of the transcriptome corresponds to coding transcripts and it has been estimated that there could be as many coding as long non-coding RNAs (lncRNAs). To address whether IFN can also regulate the expression of lncRNAs, we analyzed the transcriptome of HuH7 cells treated or not with IFNÎ±2 by expression arrays. Analysis of the arrays showed increased levels of several well-characterized coding genes that respond to IFN both at early or late times. Furthermore, we identified several IFN-stimulated or -downregulated lncRNAs (ISRs and IDRs). Further validation showed that ISR2, 8, and 12 expression mimics that of their neighboring genes GBP1, IRF1, and IL6, respectively, all related to the IFN response. These genes are induced in response to different doses of IFNÎ±2 in different cell lines at early (ISR2 or 8) or later (ISR12) time points. IFNÎ² also induced the expression of these lncRNAs. ISR2 and 8 were also induced by an influenza virus unable to block the IFN response but not by other wild-type lytic viruses tested. Surprisingly, both ISR2 and 8 were significantly upregulated in cultured cells and livers from patients infected with HCV. Increased levels of ISR2 were also detected in patients chronically infected with HIV. This is relevant as genome-wide guilt-by-association studies predict that ISR2, 8, and 12 may function in viral processes, in the IFN pathway and the antiviral response. Therefore, we propose that these lncRNAs could be induced by IFN to function as positive or negative regulators of the antiviral response. HuH7 cells were treated with 10000 units/ml of IFN a2 and RNA was isolated 3 days post-treatment

Project description:We investigated the roles of IRF-3 and IRF-7 in innate antiviral immunity against dengue virus (DENV). Double-deficient Irf-3-/-7-/- mice infected with the DENV2 strain S221 possessed 1,000-150,000 fold higher levels of viral RNA than wild-type and single-deficient mice 24 hours after infection; however, they remained resistant to lethal infection. IFN-α/β was induced similarly in wild-type and Irf-3-/- mice post DENV infection, whereas in the Irf-7-/- and Irf-3-/-7-/- mice, significantly low levels of IFN-α/β expression was observed within 24 hours post-infection. IFN-stimulated gene (ISG) induction was also delayed in Irf-3-/-7-/- mice relative to wild-type and single-deficient mice. In particular, Cxcl10 and Ifnα2 were rapidly induced independently of both IRF-3 and IRF-7 in the Irf-3-/-7-/- mice with DENV infection. Higher levels of serum IFN-γ, IL-6, CXCL10, IL-8, IL-12 p70, and TNF were also observed in Irf-3-/-7-/- mice 24 hours after infection, at which time point viral titers peaked and started to be cleared. Antibody-mediated blockade experiments revealed that IFN-γ, CXCL10, and CXCR3 function to restrict DENV replication in Irf-3-/-7-/- mice. Additionally, the ISGs Cxcl10, Ifit1, Ifit3, and Mx2 can be induced via an IRF-3- and IRF-7-independent pathway that does not involve IFN-γ signaling for protection against DENV. Collectively, these results demonstrate that IRF-3 and IRF-7 are redundant, albeit IRF-7 plays a more important role than IRF-3 in inducing the initial IFN-α/β response; only the combined actions of IRF-3 and IRF-7 are necessary for efficient control of early DENV infection; and the late, IRF-3- and IRF-7-independent pathway contributes to anti-DENV immunity. To identify the antiviral genes that are controlled by IRF-3 and IRF-7 signaling during DENV infection, we examined a panel of ISG expression in the spleens of wild-type, Irf-3-/-, Irf-7-/- and Irf-3-/-7-/- mice at 12 or 24 hours after DENV infection using a quantitative PCR array kit. The fold changes in expression of 55 genes from infected mice were normalized to that of strain-matched naïve mice.

Project description:Inflammation following SARS-CoV-2 infection is a hallmark of COVID-19 and predictive of morbidity and death. However, the inflammatory pathways contributing to host-defense vs immune-mediated pathology have not been fully elucidated. This duality is clearly seen with type-I interferons (IFN-I) which are critical mediators of innate control of viral infections, but also drive recruitment of inflammatory cells to site of infection, a key feature of severe COVID-19. Here, we modulated IFN-I signaling in rhesus macaques (Macaca mulatta) prior to and during acute SARS-CoV-2 infection (day -1 through day 2 post infection) using a mutated IFNα2 (IFN-modulator; IFNmod) which blocks binding to IFNAR2 and signaling of endogenous IFN-I. IFNmod treatment resulted in a highly significant and consistent reduction in SARS-CoV-2 viral load in BAL, lung, and hilar LN (>3-log difference) and upper airways (nasal swabs). IFNmod also potently reduced inflammatory cytokines and chemokines in BAL, expansion of inflammatory monocytes (CD14+CD16+), and lung pathogenesis. Furthermore, Siglec-1 expression, which has been shown to enhance SARS-CoV-2 infection, was rapidly downregulated in the lung and on monocytes of IFNmod-treated SARS-CoV-2 infected RMs. Notably, while RNAseq analysis showed that IFNmod induced a modest upregulation of antiviral IFN-stimulated genes (ISGs) in uninfected RMs, it resulted in a robust reduction in pathways associated with both antiviral and inflammatory ISGs in SARS-CoV-2-infected RMs. In conclusion, IFNmod treatment provides sufficient levels of type I IFN signaling that inhibit viral replication while also limiting hyperinflammation. IFN-I plays a vital role in regulating SARS-CoV-2 replication, but uncontrolled IFN signaling has a detrimental impact on inflammation and pathogenesis. A better understanding of the role of IFN-I pathways is essential for designing therapies targeting these pathways and aimed at limiting COVID-19 pathogenesis.

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Type I interferon regulates the expression of long non-coding RNAs [expression array]

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