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Antiviral Response (antiviral + response)

Distribution by Scientific Domains

Medical Sciences	86%
Life Sciences	13%

Selected Abstracts

Influenza A virus abrogates IFN-, response in respiratory epithelial cells by disruption of the Jak/Stat pathway

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2008
Kohsaku Uetani
Abstract The innate immunity to viral infections induces a potent antiviral response mediated by interferons (IFN). Although IFN-, is detected during the acute stages of illness in the upper respiratory tract secretions and in the serum of influenza A virus-infected individuals, control of influenza A virus is not dependent upon IFN-, as evidenced by studies using anti-IFN-, Ab and IFN-,,/, mice. Thus, we hypothesized that IFN-, is not critical in host survival because influenza A virus has mechanisms to evade the antiviral activity of IFN-,. To test this, A549 cells, an epithelial cell line derived from lung adenocarcinoma, were infected with influenza virus strain A/Aichi/2/68 (H3N2) (Aichi) and/or stimulated with IFN-, to detect IFN-,-stimulated MHC class II expression. Influenza A virus infection inhibited IFN-,-induced up-regulation of HLA-DR, mRNA and the IFN-, induction of class II transactivator (CIITA), an obligate mediator of MHC class II expression. Nuclear translocation of Stat1, upon IFN-, stimulation was significantly inhibited in influenza A virus-infected cells and this was associated with a decrease in Tyr701 and Ser727 phosphorylation of Stat1,. Thus, influenza A virus subverts antiviral host defense mediated by IFN-, through effects on the intracellular signaling pathways. [source]

Hepatitis C virus escape from the interferon regulatory factor 3 pathway by a passive and active evasion strategy,

HEPATOLOGY, Issue 5 2007
Marco Binder
Hepatitis C virus (HCV) has been known to replicate with extremely varying efficiencies in different host cells, even within different populations of a single human hepatoma cell line, termed Huh-7. Several reports have implicated the retinoic-acid inducible gene I (RIG-I)/ interferon regulatory factor 3 (IRF-3) pathway of the innate antiviral response with differences in host cell permissiveness to HCV. To investigate the general impact of the IRF-3 response onto HCV replication in cell culture, we generated an ample array of stable Huh-7 cell lines with altered IRF-3 responsiveness. Neither blocking IRF-3 activation in various host cells by expression of dominant negative RIG-I or HCV NS3/4A protease nor reconstitution of RIG-I signaling in Huh7.5, a cell clone known to be defective in this pathway, had any impact on HCV replication. Only by overexpressing constitutively active RIG-I or the signaling adaptor Cardif (also known as interferon-beta promoter stimulator 1, mitochondrial anti-viral signaling protein, or virus-induced signaling adaptor), both leading to a stimulation of the IRF-3 pathway in the absence of inducers, was HCV replication significantly inhibited. We therefore assessed the extent of RIG-I, dependent IRF-3 activation by different species of RNA, including full-length HCV genomes and HCV RNA duplexes, and observed strong induction only in response to double-stranded RNAs. Conclusion: Based on these findings, we propose a refined model of innate immune escape by HCV involving limited initial induction and stringent subsequent control of the IRF-3 response. (HEPATOLOGY 2007.) [source]

Lack of response to exogenous interferon-, in the liver of chimpanzees chronically infected with hepatitis C virus,,

HEPATOLOGY, Issue 4 2007
Robert E. Lanford
The mechanism of the interferon-alpha (IFN,),induced antiviral response is not completely understood. We recently examined the transcriptional response to IFN, in uninfected chimpanzees. The transcriptional response to IFN, in the liver and peripheral blood mononuclear cells (PBMCs) was rapidly induced but was also rapidly down-regulated, with most interferon-alpha,stimulated genes (ISGs) returning to the baseline within 24 hours. We have extended these observations to include chimpanzees chronically infected with hepatitis C virus (HCV). Remarkably, using total genome microarray analysis, we observed almost no induction of ISG transcripts in the livers of chronically infected animals following IFN, dosing, whereas the response in PBMCs was similar to that in uninfected animals. In agreement with this finding, no decrease in the viral load occurred with up to 12 weeks of pegylated IFN, therapy. The block in the response to exogenous IFN, appeared to be HCV-specific because the response in a hepatitis B virus,infected animal was similar to that of uninfected animals. The lack of a response to exogenous IFN, may be due to an already maximally induced ISG response because chronically HCV-infected chimpanzees already have a highly up-regulated hepatic ISG response. Alternatively, negative regulation may block the response to exogenous IFN,, yet it does not prevent the continued response to endogenous ISG stimuli. The IFN, response in chronically HCV-infected chimpanzees may be mechanistically similar to the null response in the human population. Conclusion: In chimpanzees infected with HCV, the highly elevated hepatic ISG expression may prevent the further induction of ISGs and antiviral efficacy following an IFN, treatment. (HEPATOLOGY 2007.) [source]

Genetic and catalytic efficiency structure of an HCV protease quasispecies,

HEPATOLOGY, Issue 4 2007
Sandra Franco
The HCV nonstructural protein (NS)3/4A serine protease is not only involved in viral polyprotein processing but also efficiently blocks the retinoic-acid,inducible gen I and Toll-like receptor 3 signaling pathways and contributes to virus persistence by enabling HCV to escape the interferon antiviral response. Therefore, the NS3/4A protease has emerged as an ideal target for the control of the disease and the development of new anti-HCV agents. Here, we analyzed, at a high resolution (approximately 100 individual clones), the HCV NS3 protease gene quasispecies from three infected individuals. Nucleotide heterogeneity of 49%, 84%, and 91% were identified, respectively, which created a dense net that linked different parts of the viral population. Minority variants having mutations involved in the acquisition of resistance to current NS3/4A protease inhibitors (PIs) were also found. A vast diversity of different catalytic efficiencies could be distinguished. Importantly, 67% of the analyzed enzymes displayed a detectable protease activity. Moreover, 35% of the minority individual variants showed similar or better catalytic efficiency than the master (most abundant) enzyme. Nevertheless, and in contrast to minority variants, master enzymes always displayed a high catalytic efficiency when different viral polyprotein cleavage sites were tested. Finally, genetic and catalytic efficiency differences were observed when the 3 quasispecies were compared, suggesting that different selective forces were acting in different infected individuals. Conclusion: The rugged HCV protease quasispecies landscape should be able to react to environmental changes that may threaten its survival. (HEPATOLOGY 2007;45:899,910.) [source]

Factors associated with virological response in HIV-infected patients failing antiretroviral therapy: a prospective cohort study

HIV MEDICINE, Issue 2 2005
S Fournier
Objectives To assess the antiviral response to optimized therapy following genotypic resistance testing and to identify factors associated with virological response in HIV-1-infected patients failing antiretroviral therapy. Methods A prospective cohort study was conducted in 344 HIV-1-infected patients who underwent genotypic resistance testing because of virological failure. Virological response was defined as a plasma HIV RNA level below 200 HIV-1 RNA copies/mL or a drop of plasma viral load from baseline of more than 1 log10. A multivariate logistic regression analysis was performed to identify factors associated with virological response. Results The median age of the patients was 40 years, with a male to female ratio of 4:1. Fifty-one per cent of patients had received the three major classes of antiretrovirals and the median duration of previous antiretroviral therapy was 4.6 years. At baseline, the median plasma HIV RNA level was 4.4 log10 copies/mL and the median CD4 cell count was 274 cells/,L. At 3 months, 55% of patients (188 of 344) had a virological response, which was sustained at 6 months (53%). Predictors of virological response were exposure to two or fewer protease inhibitors [odds ratio (OR) 1.8; P=0.046], and use in optimized therapy of a new class of antiretrovirals (OR 2.9; P=0.006), of more than two new drugs (OR 3.0; P<0.0001), of abacavir (OR 1.9; P=0.03), or of lopinavir/ritonavir (OR 3.7; P=0.0002). Conclusions A high proportion of patients achieved a short-term virological response in this cohort study. Patients with the least experience of protease inhibitor treatment and in whom a new class of antiretroviral, more than two new drugs, abacavir or lopinavir/ritonavir was used in optimized therapy had the best virological outcome. [source]

Interferon-alpha regulates the dynamic balance between human activated regulatory and effector T cells: implications for antiviral and autoimmune responses

IMMUNOLOGY, Issue 1 2010
Amit Golding
Summary An adequate effector response against pathogens and its subsequent inactivation after pathogen clearance are critical for the maintenance of immune homeostasis. This process involves an initial phase of T-cell effector (Teff) activation followed by the expansion of regulatory T cells (Tregs), a unique cell population that limits Teff functions. However, significant questions remain unanswered about the mechanisms that regulate the balance between these cell populations. Using an in vitro system to mimic T-cell activation in human peripheral blood mononuclear cells (PBMC), we analysed the patterns of Treg and Teff activation, with special attention to the role of type I interferon (IFN-I). Interestingly, we found that IFN-,, either exogenously added or endogenously induced, suppressed the generation of CD4+ FoxP3HI IFN-,Neg activated Tregs (aTregs) while simultaneously promoting propagation of CD4+ FoxP3Low/Neg IFN-,Pos activated Teffs (aTeffs). We also showed that IFN-,-mediated inhibition of interleukin (IL)-2 production may play an essential role in IFN-,-induced suppression of aTregs. In order to test our findings in a disease state with chronically elevated IFN-,, we investigated systemic lupus erythematosus (SLE). Plasma from patients with SLE was found to contain IFN-I activity that suppressed aTreg generation. Furthermore, anti-CD3 activated SLE PBMCs exhibited preferential expansion of aTeffs with a very limited increase in aTreg numbers. Together, these observations support a model whereby a transient production of IFN-, (such as is seen in an early antiviral response) may promote CD4 effector functions by delaying aTreg generation, but a chronic elevation of IFN-, may tip the aTeff:aTreg balance towards aTeffs and autoimmunity. [source]

Toll-like receptor 3 agonist poly(I:C)-induced antiviral response in human corneal epithelial cells

IMMUNOLOGY, Issue 1 2006
Ashok Kumar
Summary The objective of this study was to examine the expression of Toll-like receptor 3 (TLR3) by human corneal epithelial cells (HCECs) and to determine whether exposure to the TLR3 agonist polyinosinic-polycytidylic acid [poly(I:C)]induces an antiviral response in these cells. Fluorescence-activated cell sorter (FACS) analysis revealed TLR3 to be constitutively expressed and distributed intracellularly in HCECs. Stimulation of HCECs with the TLR3 agonist poly(I:C) induced the activation of nuclear factor (NF)-,B and production of the proinflammatory cytokine interleukin (IL)-6 and the chemokine IL-8. Upon exposure to poly(I:C), HCECs initiated a potent antiviral response resulting in an increase of interferon (IFN)-, mRNA expression (7-fold). Poly(I:C) stimulation also up-regulated mRNA expression of the antiviral chemokine IFN-, inducible protein 10 (IP10), myxovirus resistance gene A and 2,,5,-oligoadenylate synthetase (5-, 10- and 9-fold, respectively), and secretion of IP10. These responses were also induced by exogenously added type 1 IFNs, but could not be blocked by pretreatment of the cells with anti-TLR3 monoclonal antibody, suggesting that the receptor was not expressed on the cell surface. Furthermore, incubation of HCECs with an endosomal acidification inhibitor, chloroquine, markedly inhibited poly(I:C)-mediated IFN-, expression in HCECs. These results suggest that corneal epithelial cells are important sentinels of the corneal innate immune system against viral infection, and that stimulation of TLR3 can induce the expression of key proinflammatory cytokines and chemokines and antiviral genes that help in the defence of the cornea against viral infection. [source]

Low efficacy of entecavir therapy in adefovir-refractory hepatitis B patients with prior lamivudine resistance

JOURNAL OF VIRAL HEPATITIS, Issue 3 2010
S. W. Cho
Summary., We determined the virologic response, incidence of entecavir resistance, and evolution of lamivudine and adefovir-resistant mutants during entecavir (ETV) therapy in adefovir-refractory patients with prior lamivudine resistance. Forty adefovir-refractory chronic hepatitis B patients with prior lamivudine resistance who had received entecavir for ,6 months were included and monitored for virologic response and entecavir resistance. Ten per cent of patients achieved HBV DNA < 50 copies/mL by PCR after 24 weeks of ETV therapy, and an initial virologic response was observed in 12 of 40 patients (30%). Higher pretreatment ALT (P = 0.039) and the presence of the rtL180M mutation (P = 0.038) were associated with an initial virologic response. During a mean follow-up of 11.4 months, four patients (10%) experienced virologic breakthrough, while ETV-resistant mutants were detected in six patients (15%). YMDD and adefovir-resistant mutants were detected in 57 and 35% of patients at baseline, respectively. At 48 weeks of therapy, 96 and 4% of patients had YMDD and adefovir-resistant mutants, respectively. These data suggest an early development of ETV resistance and low antiviral response during ETV therapy in adefovir-refractory patients with prior lamivudine resistance. [source]

Adiponectin changes in HCV-Genotype 4: relation to liver histology and response to treatment

JOURNAL OF VIRAL HEPATITIS, Issue 10 2009
M. Derbala
Summary., Recently, attention has been focussed on adiponectin and its changes in different types of chronic liver disease. Its relation to hepatic fibrosis and insulin resistance in post-hepatitis liver disease is not clear. The aim of this study was to clarify the adiponectin changes in genotype 4 hepatitis C virus (HCV)-infected patient in relation to liver histology and insulin resistance, and its usefulness as a predictor of hepatic fibrosis and response to treatment. Total adiponectin and its high molecular weight (HMW) form as well as insulin levels were studied in 92 chronic HCV, genotype 4 and 66 healthy control volunteers. Neither total adiponectin (r = 0.101, P = 0.220) nor HMW adiponectin (r = 0.081, P = 0.328) correlated with viral load. Total and not HMW adiponectin was significantly correlated with hepatic fibrosis and inflammation (r = 0.267, P = 0.002, r = 0.278, P < 0.001, respectively). In addition, total adiponectin (r = 0.224, P = 0.002) and HMW adiponectin (r = 0.266, P < 0.0006) significantly correlated with insulin resistance. As fibrosis did not correlate with insulin resistance (r = 0.081, P = 0.204), the correlation between total adiponectin and fibrosis was not mediated by insulin resistance. Multivariable regression analysis, (including pretreatment cases and controls) revealed that total adiponectin was significantly associated with gender, being lower among male subjects (X2 = 13.04, P = 0.0001). The multivariable regression model supported the lack of association between insulin resistance and total adiponectin levels (X2 = 1.88, P = 0.171), while non cirrhotics had significantly lower total adiponectin levels than cirrhotics (X2 = 10.90, P = 0.004) and lower level of inflammation significantly lower total adiponectin levels than more severe inflammation (X2 = 8.95, P = 0.003). Total or HMW adiponectin did not yield receiver operating characteristic (ROC) curves with area under the curve (AUC) >75%, thus the cutoff points have poor sensitivity/specificity as predictors of fibrosis. However, as a predictor of end-of-treatment response, the ROC curve of adiponectin index gave yield an AUC = 81.4%. We can conclude that total adiponectin level, in HCV genotype 4 patients, increases with progression of hepatic fibrosis regardless of insulin resistance. Its high molecular form does not have such correlation. The adiponectin changes are not related to viral load, insulin resistance or other demographic data suggesting that this change is histologically related. In spite of this, no adiponectin cutoff level had reasonable sensitivity/specificity for predicting hepatic fibrosis stage, while this may be used as a predictor for antiviral response possibly reflecting improvement in hepatic inflammation post treatment. [source]

Influence of HFE gene polymorphism on the progression and treatment of chronic hepatitis C

JOURNAL OF VIRAL HEPATITIS, Issue 2 2004
P. Lebray
Summary., We analysed liver histology findings in a large cohort of patients with chronic hepatitis C and in roughly half of them their response to interferon- , -based on iron parameters and HFE status. Histological activity and virological response to antiviral therapy (n = 146) were analysed in 273 immunocompetent and nonalcoholic patients with chronic hepatitis C, in terms of serum iron load, intrahepatic iron load (n = 110) and HFE mutations. Patients who were heterozygous for the C282Y and H63D mutations exhibited higher iron serum parameters than subjects without these mutations. The intrahepatic iron load was higher in H63D patients only. No association was observed between HFE mutations and histological activity. Increased iron parameters were associated with liver disease severity by univariate analysis only. Genotype 1 and ferritinaemia were associated with a poor response to antiviral therapy, whereas the H63D mutation emerged as a positive predictive factor for end of treatment and sustained antiviral response. Therefore, in chronic hepatitis C patients serum and intrahepatic iron levels were weakly correlated with histological activity, while HFE mutations were not. As for the response to interferon- ,, elevated ferritinaemia constituted a negative predictive factor whereas the H63D mutation was a positive one. The H63D mutation might form part of an immunogenetic profile influencing the response to interferon therapy. [source]

Mechanisms of virus-induced asthma exacerbations: state-of-the-art.

ALLERGY, Issue 5 2007
A GA2LEN, InterAirways document
Viral infections of the respiratory tract are the most common precipitants of acute asthma exacerbations. Exacerbations are only poorly responsive to current asthma therapies and new approaches to therapy are needed. Viruses, most frequently human rhinoviruses (RV), infect the airway epithelium, generate local and systemic immune responses, as well as neural responses, inducing inflammation and airway hyperresponsiveness. Using in vitro and in vivo experimental models the role of various proinflammatory or anti-inflammatory mediators, antiviral responses and molecular pathways that lead from infection to symptoms has been partly unravelled. In particular, mechanisms of susceptibility to viral infection have been identified and the bronchial epithelium appeared to be a key player. Nevertheless, additional understanding of the integration between the diverse elements of the antiviral response, especially in the context of allergic airway inflammation, as well as the interactions between viral infections and other stimuli that affect airway inflammation and responsiveness may lead to novel strategies in treating and/or preventing asthma exacerbations. This review presents the current knowledge and highlights areas in need of further research. [source]

Type III IFNs: New layers of complexity in innate antiviral immunity

BIOFACTORS, Issue 1 2009
Nina Ank
Abstract Cytokines are small secreted molecules, which mediate cross-talk between cells involved in the immune response. Interferons (IFN)s, constitute a class of cytokines with antiviral activities, and the type I IFNs have been ascribed particularly important roles in the innate antiviral response. Type III IFNs (also known as IFN-, or interleukin 28/29) represent a class of novel cytokines with biological activities similar to the type I IFNs, but seem to have a more specialized role in antiviral defense by exerting host-protection primarily at epithelial surfaces. In this review, we describe the current knowledge on the role of type III IFNs in antiviral defense. © 2009 International Union of Biochemistry and Molecular Biology, Inc. [source]

HIV-1 impairs in vitro priming of naïve T cells and gives rise to contact-dependent suppressor T cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2010
Karlhans F. Che
Abstract Priming of T cells in lymphoid tissues of HIV-infected individuals occurs in the presence of HIV-1. DC in this milieu activate T cells and disseminate HIV-1 to newly activated T cells, the outcome of which may have serious implications in the development of optimal antiviral responses. We investigated the effects of HIV-1 on DC,naïve T-cell interactions using an allogeneic in vitro system. Our data demonstrate a dramatic decrease in the primary expansion of naïve T cells when cultured with HIV-1-exposed DC. CD4+ and CD8+ T cells showed enhanced expression of PD-1 and TRAIL, whereas CTLA-4 expression was observed on CD4+ T cells. It is worth noting that T cells primed in the presence of HIV-1 suppressed priming of other naïve T cells in a contact-dependent manner. We identified PD-1, CTLA-4, and TRAIL pathways as responsible for this suppresion, as blocking these negative molecules restored T-cell proliferation to a higher degree. In conclusion, the presence of HIV-1 during DC priming produced cells with inhibitory effects on T-cell activation and proliferation, i.e. suppressor T cells, a mechanism that could contribute to the enhancement of HIV-1 pathogenesis. [source]

Interleukin-29 uses a type 1 interferon-like program to promote antiviral responses in human hepatocytes,

HEPATOLOGY, Issue 4 2006
Sean E. Doyle
Interleukin-28A (IL-28A), IL-28B and IL-29 are a family of class II cytokines that stimulate antiviral responses through a heterodimeric receptor that is distinct from the type I interferon (IFN) receptor. To better understand how this newly described family of cytokines regulates the antiviral state, we compared various cellular responses elicited by IL-29 and IFN-,. Here we show that these cytokines stimulate similar patterns of signal transducer and activator of transcription 1 (STAT-1), -2, -3, and -5 phosphorylation and nearly identical patterns of gene expression when analyzed in two distinct cell types by microarray analysis. Interestingly, the IL-29 receptor is preferentially expressed on primary hepatocytes within normal liver and pegylated forms of IL-29 and IFN-, induced equivalent 2,5, oligoadenylate synthetase (OAS) and MX1 gene expression in this cell type. Pegylated IL-29 also produced a significant reduction in human hepatitis B and hepatitis C viral load in vitro and reduced the cytopathic effect caused by the fully replicating flavivirus, West Nile virus. In conclusion, IL-29 and IFN-, stimulate identical antiviral responses despite their utilization of different receptors. This fact, combined with significant receptor expression in hepatitis virus-infected livers, suggests that IL-29 may have therapeutic value against chronic viral hepatitis in human patients. (HEPATOLOGY 2006;44:896,906.) [source]

Mechanisms of virus-induced asthma exacerbations: state-of-the-art.

REVIEW ARTICLE: Maternal and Fetal Response to Fetal Persistent Infection with Bovine Viral Diarrhea Virus,

AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 4 2010
Thomas R. Hansen
Citation Hansen TR, Smirnova NP, Van Campen H, Shoemaker ML, Ptitsyn AA, Bielefeldt-Ohmann H. Maternal and fetal response to fetal persistent infection with bovine viral diarrhea virus. Am J Reprod Immunol 2010 Problem, Infection of naïve pregnant cows with non-cytopathic (ncp) bovine viral diarrhea virus (BVDV) results in transplacental infection of the fetus. Infection of the pregnant cow with ncp BVDV late in gestation (after day 150) results in transient infection (TI), as both the dam and fetus can mount an immune response to the virus. In contrast, if the fetus is infected with ncp BVDV early in gestation (before day 150), the fetal immune system is undeveloped and unable to recognize the virus as foreign. This results in induction of immune tolerance to the infecting BVDV strain and persistent infection (PI). Methods, Infection of naïve pregnant heifers with ncp BVDV2 on day 75 was hypothesized to induce differential gene expression in white blood cells of the dams and their fetuses, adversely affecting development and antiviral immune responses in PI fetuses. Results, Gene expression differed in maternal blood cells in the presence of PI versus uninfected fetuses. PI adversely affected fetal development and antiviral responses, despite protective immune responses in the dam. Conclusion, Fetal PI with BVDV alters maternal immune function, compromises fetal growth and immune responses, and results in expression of maternal blood biomarkers that can be used to identify cows carrying PI fetuses. [source]

Evasion of innate and adaptive immune responses by influenza A virus

CELLULAR MICROBIOLOGY, Issue 7 2010
Mirco Schmolke
Summary Host organisms have developed sophisticated antiviral responses in order to defeat emerging influenza A viruses (IAVs). At the same time IAVs have evolved immune evasion strategies. The immune system of mammals provides several lines of defence to neutralize invading pathogens or limit their replication. Here, we summarize the mammalian innate and adaptive immune mechanisms involved in host defence against viral infection and review strategies by which IAVs avoid, circumvent or subvert these mechanisms. We highlight well-characterized, as well as recently described features of this intriguing virus-host molecular battle. [source]

CRK adaptor protein expression is required for efficient replication of avian influenza A viruses and controls JNK-mediated apoptotic responses

CELLULAR MICROBIOLOGY, Issue 6 2010
Eike R. Hrincius
Summary The non-structural protein 1 (A/NS1) of influenza A viruses (IAV) harbours several src-homology domain (SH) binding motifs that are required for interaction with cellular proteins. The SH3 binding motif at aa212-217 [PPLPPK] of A/NS1 was shown to be essential for binding to the cellular adaptor proteins CRK and CRKL. Both regulate diverse cellular effector pathways, including activation of the MAP-kinase JNK that in turn mediates antiviral responses to IAV infection. By studying functional consequences of A/NS1,CRK interaction we show here that A/NS1 binding to CRK contributes to suppression of the antiviral-acting JNK,ATF2 pathway. However, only IAV that encode an A/NS1-protein harbouring the CRK/CRKL SH3 binding motif PPLPPK were attenuated upon downregulation of CRKI/II and CRKL, but not of CRKII alone. The PPLPPK site-harbouring candidate strains could be discriminated from other strains by a pronounced viral activation of the JNK,ATF2 signalling module that was even further boosted upon knock-down of CRKI/II. Interestingly, this enhanced JNK activation did not alter type-I IFN-expression, but rather resulted in increased levels of virus-induced cell death. Our results imply that binding capacity of A/NS1 to CRK/CRKL has evolved in virus strains that over-induce the antiviral acting JNK,ATF2 signalling module and helps to suppress the detrimental apoptosis promoting action of this pathway. [source]