Project description:Type-I (e.g. IFN-alpha, IFN-beta) and type-II IFNs (IFN-gamma) have antiviral, antiproliferative, and immunomodulatory properties. Both types of IFN signal through the Jak/STAT pathway to elicit antiviral activity, yet IFN-gamma is thought to do so only through STAT1 homodimers while type-I IFNs activate both STAT1- and STAT2-containing complexes such as ISGF3. Here we show that ISGF3II - composed of phosphorylated STAT1, unphosphorylated STAT2, and IRF9 - also plays a role in IFN-gamma-mediated antiviral activity in humans. Using phosphorylated STAT1 as a marker for IFN signaling, western blot analysis of IFN-alpha2a treated human A549 cells revealed that pSTAT1 (Y701) levels peaked at 1h, decreased by 6h, and remained at low levels for up to 48h. Cells treated with IFN-gamma showed a biphasic pSTAT1 response with an early peak at 1-2h and a second peak at 15-24h. Gene expression microarray following IFN-gamma treatment for 24h indicated an induction of antiviral genes that are induced by ISGF3 and associated with a type-1 IFN response. Induction of these genes by autocrine type-I and type-III IFN signaling was ruled out using neutralizing antibodies to these IFNs in biological assays and by qRT-PCR. Despite the absence of autocrine IFNs, IFN-gamma treatment induced formation of ISGF3II. This novel transcription factor complex binds to ISRE promoter sequences, as shown by ChIP analysis of the PKR promoter. STAT2 and IRF9 knockdown in A549 cells reversed IFN-gamma-mediated ISRE induction and antiviral activity - implicating ISGF3II formation as a significant component of the cellular response and biological activity of IFN-gamma. Two treatments using three biological replicates each were performed using three million A549 cells. Each was seeded overnight in 10mL complete RPMI and treated. Three were treated with alpha-IFN and three treated with gamma-IFN for 24h. Control samples were left untreated.
Project description:Type-I (e.g. IFN-alpha, IFN-beta) and type-II IFNs (IFN-gamma) have antiviral, antiproliferative, and immunomodulatory properties. Both types of IFN signal through the Jak/STAT pathway to elicit antiviral activity, yet IFN-gamma is thought to do so only through STAT1 homodimers while type-I IFNs activate both STAT1- and STAT2-containing complexes such as ISGF3. Here we show that ISGF3II - composed of phosphorylated STAT1, unphosphorylated STAT2, and IRF9 - also plays a role in IFN-gamma-mediated antiviral activity in humans. Using phosphorylated STAT1 as a marker for IFN signaling, western blot analysis of IFN-alpha2a treated human A549 cells revealed that pSTAT1 (Y701) levels peaked at 1h, decreased by 6h, and remained at low levels for up to 48h. Cells treated with IFN-gamma showed a biphasic pSTAT1 response with an early peak at 1-2h and a second peak at 15-24h. Gene expression microarray following IFN-gamma treatment for 24h indicated an induction of antiviral genes that are induced by ISGF3 and associated with a type-1 IFN response. Induction of these genes by autocrine type-I and type-III IFN signaling was ruled out using neutralizing antibodies to these IFNs in biological assays and by qRT-PCR. Despite the absence of autocrine IFNs, IFN-gamma treatment induced formation of ISGF3II. This novel transcription factor complex binds to ISRE promoter sequences, as shown by ChIP analysis of the PKR promoter. STAT2 and IRF9 knockdown in A549 cells reversed IFN-gamma-mediated ISRE induction and antiviral activity - implicating ISGF3II formation as a significant component of the cellular response and biological activity of IFN-gamma.
Project description:Chronic hepatitis B (CHB) is a global health care challenge and a major cause of liver disease. Existing therapies do not result in a functional cure in most individuals, necessitating new antiviral strategies against Hepatitis B virus (HBV). To identify additional therapeutic avenues, we performed a focused screen of epigenetic modifiers to identify inhibitors of HBV replication. From this work we identified small molecule inhibitors of the histone lysine demethylase 5 (KDM5) with antiviral activity against HBV. To enhance the cellular permeability and liver accumulation of the most potent KDM5 inhibitor identified (GS-080) a prodrug was developed (GS-5801) that resulted in improved bioavailability and liver exposure as well as increased accumulation of the H3K4me3:H3 ratio on chromatin. GS-5801 treatment of HBV-infected primary human hepatocytes inhibited HBV replication and antigen levels. Evaluation of GS 5801 antiviral activity in a humanized mouse model of HBV infection, however, did not result in antiviral efficacy, despite achieving pharmacodynamic levels of H3K4me3:H3 predicted to be efficacious. Together these data highlight discordance between the antiviral effects of GS 5801 observed in rodent livers.
Project description:RNA interference (RNAi) functions as the major host antiviral defense in insects, while less is understood about how to utilize antiviral RNAi in controlling viral infection in insects. Enoxacin belongs to the family of synthetic antibacterial compounds based on a fluoroquinolone skeleton that has been previously found to enhance RNAi in mammalian cells. In this study, we showed that enoxacin efficiently inhibited viral replication of Drosophila C virus (DCV) and Cricket paralysis virus (CrPV) in cultured Drosophila cells. Enoxacin promoted the loading of Dicer-2-processed virus-derived siRNA into the RNA-induced silencing complex, thereby enhancing antiviral RNAi response in infected cells. Moreover, enoxacin treatment elicited an RNAi-dependent in vivo protective efficacy against DCV or CrPV challenge in adult fruit flies. In addition, enoxacin also inhibited replication of flaviviruses, including Dengue virus and Zika virus, in Aedes mosquito cells in an RNAi-dependent manner. Together, our findings demonstrated that enoxacin can enhance RNAi in insects, and enhancing RNAi by enoxacin is an effective antiviral strategy against diverse viruses in insects, which may be exploited as a broad-spectrum antiviral agent to control vector transmission of arboviruses or viral diseases in insect farming.
Project description:Chronic hepatitis B (CHB) is a global health care challenge and a major cause of liver disease. Existing therapies do not result in a functional cure in most individuals, necessitating new antiviral strategies against Hepatitis B virus (HBV). To identify additional therapeutic avenues, we performed a focused screen of epigenetic modifiers to identify inhibitors of HBV replication. From this work we identified small molecule inhibitors of the histone lysine demethylase 5 (KDM5) with antiviral activity against HBV. To enhance the cellular permeability and liver accumulation of the most potent KDM5 inhibitor identified (GS-080) a prodrug was developed (GS-5801) that resulted in improved bioavailability and liver exposure as well as increased accumulation of the H3K4me3:H3 ratio on chromatin. GS-5801 treatment of HBV-infected primary human hepatocytes inhibited HBV replication and antigen levels. Evaluation of GS 5801 antiviral activity in a humanized mouse model of HBV infection, however, did not result in antiviral efficacy, despite achieving pharmacodynamic levels of H3K4me3:H3 predicted to be efficacious. Together these data highlight discordance between the antiviral effects of GS 5801 observed in HBV-infected primary human hepatocytes.
Project description:H441 cells lacking DNA MMR activity have reduced expression of antiviral and stress response genes during influenza A virus infection.
Project description:A novel assay was developed for Daudi cells in which the antiviral (AV) and antiproliferative (AP) activities of interferon (IFN) can be measured simultaneously. Using this novel assay, conditions allowing IFN AV protection but no growth inhibition were identified and selected. Daudi cells were treated under these conditions, and gene expression microarray analyses were performed. The results of the analysis identified 25 genes associated with IFN-alpha AV activity. Upregulation of 23 IFN-induced genes was confirmed by using reverse transcription-PCR. Of 25 gene products, 17 were detected by Western blotting at 24 h. Of the 25 genes, 10 have not been previously linked to AV activity of IFN-alpha. The most upregulated gene was IFIT3 (for IFN-induced protein with tetratricopeptide repeats 3). The results from antibody neutralizing experiments suggested an association of the identified genes with IFN-alpha AV activity. This association was strengthened by results from IFIT3-small interfering RNA transfection experiments showing decreased expression of IFIT3 and a reduction in the AV activity induced by IFN-alpha. Overexpression of IFIT3 resulted in a decrease of virus titer. Transcription of AV genes after the treatment of cells with higher concentrations of IFN having an AP effect on Daudi cells suggested pleiotropic functions of identified gene products. Gene expression was initially measured in four Daudi cell groups (3 x 10(6) in 10 ml of RPMI) treated for 24 h at IFN concentrations selected to allow comparison of gene activity in AV activity environments with environments in which no AV activity was observed. These treatment groups were: (i) 0.0036 ng of IFN-alpha2c/ml (n=5) (allowing AV activity only); (ii) 0.00036 ng of IFN-alpha2c/ml (n=5) (no AV observed); (iii) 0.036 ng of HY-2/ml (n=3) (allowing AV activity); and (iv) 0.0036 ng of HY-2/ml (n=3) (no AV observed). To refine the list of genes associated with AV activity, samples showing AP phenotype (achieved by treatment with IFN-alpha2c [0.36 ng/ml] (n=3) or HY-2 [36 ng/ml]) (n=3) were compared to identically treated samples manipulated to display the AV phenotype through subsequent neutralization with anti-IFNAR1 MAb 64.10 (1 ug/ml) (n=6). Further analysis of gene expression profiles after 6 h of incubation helped indicate genes associated with early roles in IFN-induced AV mechanisms (n=6).