Curcumin inhibits the replication of enterovirus 71 in vitro

Human enterovirus 71(EV71)is the main causative pathogen of hand,foot,and mouth disease(HFMD)in children.The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades,and no vaccine and effective antiviral medicine are available.Curcumin has been used as a traditional medicine for centuries to treat a diversity of disorders including viral infections.In this study,we demonstrated that curcumin showed potent antiviral effect again EV71.In Vero cells infected with EV71,the addition of curcumin significantly suppressed the synthesis of viral RNA,the expression of viral protein,and the overall production of viral progeny.Similar with the previous reports,curcumin reduced the production of ROS induced by viral infection.However,the antioxidant property of curcumin did not contribute to its antiviral activity,since N-acetyl-L-cysteine,the potent antioxidant failed to suppress viral replication.This study also showed that extracellular signal-regulated kinase(ERK)was activated by either viral infection or curcumin treatment,but the activated ERK did not interfere with the antiviral effect of curcumin,indicating ERK is not involved in the antiviral mechanism of curcumin.Unlike the previous reports that curcumin inhibited protein degradation through ubiquitin–proteasome system(UPS),we found that curcumin had no impact on UPS in control cells.However,curcumin did reduce the activity of proteasomes which was increased by viral infection.In addition,the accumulation of the short-lived proteins,p53 and p21,was increased by the treatment of curcumin in EV71-infected cells.We further probed the antiviral mechanism of curcumin by examining the expression of GBF1 and PI4KB,both of which are required for the formation of viral replication complex.We found that curcumin significantly reduced the level of both proteins.Moreover,the decreased expression of either GBF1 or PI4KB by the application of siRNAs was sufficient to suppress viral replication.We also demonstrated that curcumin showed anti-apoptotic activity at the early stage of viral infection.The results of this study provide solid evidence that curcumin has potent anti-EV71 activity.Whether or not the down-regulated GBF1 and PI4KB by curcumin contribute to its antiviral effect needs further studies.

Expression Profile and Function Analysis of Long Non-coding RNAs in the Infection of Coxsackievirus B3

The roles of lnc RNAs in the infection of enteroviruses have been barely demonstrated. In this study, we used coxsackievirus B3(CVB3), a typical enterovirus, as a model to investigate the expression profiles and functional roles of lnc RNAs in enterovirus infection. We profiled lnc RNAs and m RNA expression in CVB3-infected He La cells by lnc RNA-m RNA integrated microarrays. As a result, 700 differentially expressed lnc RNAs(431 up-regulated and 269 down-regulated) and665 differentially expressed m RNAs(299 up-regulated and 366 down-regulated) were identified in CVB3 infection. Then we performed lnc RNA-m RNA integrated pathway analysis to identify potential functional impacts of the differentially expressed m RNAs, in which lnc RNA-m RNA correlation network was built. According to lnc RNA-m RNA correlation, we found that XLOC-001188, an lnc RNA down-regulated in CVB3 infection, was negatively correlated with NFAT5 m RNA,an anti-CVB3 gene reported previously. This interaction was supported by q PCR detection following si RNA-mediated knockdown of XLOC-001188, which showed an increase of NFAT5 m RNA and a reduction of CVB3 genomic RNA. In addition, we observed that four most significantly altered lnc RNAs, SNHG11, RP11-145 F16.2, RP11-1023 L17.1 and RP11-1021 N1.2 share several common correlated genes critical for CVB3 infection, such as BRE and IRF2 BP1. In all, our studies reveal the alteration of lnc RNA expression in CVB3 infection and its potential influence on CVB3 replication,providing useful information for future studies of enterovirus infection.

Stress Granule Formation is One of the Early Antiviral Mechanisms for Host Cells Against Coxsackievirus B Infection

Stress granules(SGs) are intracellular granules formed when cellular translation is blocked and have been reported to be involved in a variety of viral infections. Our previous studies revealed that SGs are involved in the coxsackievirus B(CVB)infection process, but the role of SGs in CVB infection has not been fully explored. In this study, we found that CVB type 3(CVB3) could induce SG formation in the early phase of infection. Results showed that levels of CVB3 RNA and protein were significantly inhibited during the early stage of CVB3 infection by the elevated formation of SGs, while viral RNA and protein synthesis were significantly promoted when SG formation was blocked. Our findings suggest that SG formation is one of the early antiviral mechanisms for host cells against CVB infection.

TAR DNA-Binding Protein 43 is Cleaved by the Protease 3C of Enterovirus A71

Enterovirus A71(EV-A71)is one of the etiological pathogens leading to hand,foot,and mouth disease(HFMD),which can cause severe neurological complications.The neuropathogenesis of EV-A71 infection is not well understood.The mislocalization and aggregation of TAR DNA-binding protein 43(TDP-43)is the pathological hallmark of amyotrophic lateral sclerosis(ALS).However,whether TDP-43 was impacted by EV-A71 infection is unknown.This study demonstrated that TDP-43 was cleaved during EV-A71 infection.The cleavage of TDP-43 requires EV-A71 replication rather than the activated caspases due to viral infection.TDP-43 is cleaved by viral protease 3 C between the residues 331 Q and332 S,while mutated TDP-43(Q331 A)was not cleaved.In addition,mutated 3 C which lacks the protease activity failed to induce TDP-43 cleavage.We also found that TDP-43 was translocated from the nucleus to the cytoplasm,and the mislocalization of TDP-43 was induced by viral protease 2 A rather than 3 C.Taken together,we demonstrated that TDP-43 was cleaved by viral protease and translocated to the cytoplasm during EV-A71 infection,implicating the possible involvement of TDP-43 in the pathogenesis of EV-A71 infection.

Baicalein suppresses Coxsackievirus B3 replication by inhibiting caspase-1 and viral protease 2A

Myocarditis is an inflammatory disease of the cardiac muscle and one of the primary causes of dilated cardiomyopathy.Group B coxsackievirus(CVB)is one of the leading causative pathogens of viral myocarditis,which primarily affects children and young adults.Due to the lack of vaccines,the development of antiviral medicines is crucial to controlling CVB infection and the progression of myocarditis.In this study,we investigated the antiviral effect of baicalein,a flavonoid extracted from Scutellaria baicaleinsis.Our results demonstrated that baicalein treatment significantly reduced cytopathic effect and increased cell viability in CVB3-infected cells.In addition,significant reductions in viral protein 3D,viral RNA,and viral particles were observed in CVB3-infected cells treated with baicalein.We found that baicalein exerted its inhibitory effect in the early stages of CVB3 infection.Baicalein also suppressed viral replication in the myocardium and effectively alleviated myocarditis induced by CVB3 infection.Our study revealed that baicalein exerts its antiviral effect by inhibiting the activity of caspase-1 and viral protease 2A.Taken together,our findings demonstrate that baicalein has antiviral activity against CVB3 infection and may serve as a potential therapeutic option for the myocarditis caused by enterovirus infection.