Anisomycin inhibits Coxsackievirus B replication by promoting the lysosomal degradation of eEF1A1.

Group B Coxsackieviruses (CVB) are non-enveloped small RNA viruses in the genus Enterovirus, family Picornaviridae. CVB infection causes diverse conditions from common cold to myocarditis, encephalitis, and pancreatitis. No specific antiviral is available for the treatment of CVB infection. Anisomycin, a pyrrolidine-containing antibiotic and translation inhibitor, was reported to inhibit the replication of some picornaviruses. However, it is unknown if anisomycin can act as an antiviral against CVB infection. Here we observed that anisomycin showed potent inhibition on CVB type 3 (CVB3) infection with negligible cytotoxicity when applied at the early stage of virus infection. Mice infected with CVB3 showed markedly alleviated myocarditis with reduced viral replication. We found that CVB3 infection significantly increased the transcription of eukaryotic translation elongation factor 1 alpha 1 (eEF1A1). CVB3 replication was suppressed by EEF1A1 knockdown, while elevated by EEF1A1 overexpression. Similar to the effect of CVB3 infection, EEF1A1 transcription was increased in response to anisomycin treatment. However, eEF1A1 protein level was decreased with anisomycin treatment in a dose-dependent manner in CVB3-infected cells. Moreover, anisomycin promoted eEF1A1 degradation, which was inhibited by the treatment of chloroquine but not MG132. We demonstrated that eEF1A1 interacted with the heat shock cognate protein 70 (HSP70), and eEF1A1 degradation was inhibited by LAMP2A knockdown, implicating that eEF1A1 is degraded through chaperone-mediated autophagy. Taken together, we demonstrated that anisomycin, which inhibits CVB replication through promoting the lysosomal degradation of eEF1A1, could be a potential antiviral candidate for the treatment of CVB infection.

Antiviral Activity of trans-Hexenoic Acid against Coxsackievirus B and Enterovirus A71.

Enterovirus infections are life-threatening viral infections which occur mainly among children and are possible causes of viral outbreak. Until now, treatment and management of infections caused by members of the genus Enterovirus largely depended on supportive care, and no antiviral medications are currently approved for the treatment of most of these infections. The urgency of discovering new therapeutic options for the treatment of enterovirus infection is increasing. In the present study, we identified that trans-2-hexenoic acid (THA), a natural product from a dietary source, possesses antiviral activity against coxsackievirus B (CVB) and enterovirus A71 (EV-A71) in a dose-dependent manner. We found that THA possesses antiviral activity at 50% effective concentrations (EC50) of 2.9 µM and 3.21 µM against CVB3 and EV-A71 infections, respectively. The time of addition assay revealed that THA inhibits both CVB3 and EV-A71 replication at the entry stage of infection. Additional results from this study further suggest that THA inhibits viral replication by blocking viral entry. Given that THA has received approval as a food additive, treatment of enterovirus infections with THA might be a safe therapeutic option or could pave the way for semisynthetic manufacturing of more antiviral drugs in the future.

Circular RNA circ_0076631 promotes coxsackievirus B3 infection through modulating viral translation by sponging miR-214-3p.

Coxsackievirus B (CVB), a member of Enterovirus genus of Picornaviridae, is the leading pathogen of viral myocarditis and dilated cardiomyopathy. The pathogenesis of CVB-induced myocarditis has not been completely elucidated, and no specific antiviral measurement is available presently. Circular RNAs (circRNAs) have been reported to be able to modulate viral replication and infection through bridging over non-coding RNAs (ncRNAs) and coding messenger RNAs (mRNAs). To date, the role of circRNAs in CVB infection is largely unknown. In this study, we found that hsa_circ_0076631 (circ_0076631) significantly promoted CVB type 3 (CVB3) replication. Further study showed that the underneath mechanism was circ_0076631 indirectly interacting with CVB3 through sponging miR-214-3p, which targeted the 3D-coding region of CVB3 genome to suppress viral translation. Knocking down circ-0076631 caused a suppression of CVB3 infection; thus, circ-0076631 may be a potential target for anti-CVB therapy.

Novel Antiviral Activity of Ethyl 3-Hydroxyhexanoate Against Coxsackievirus B Infection.

Coxsackievirus group B (CVB) is a member of the genus Enterovirus in the family Picornaviridae. CVB infection has been implicated as a major etiologic agent of viral myocarditis, dilated cardiomyopathy, meningitis, and pancreatitis among children and young adults. Until date, no antiviral agent has been licensed for the treatment of Coxsackievirus infection. In an effort to identify antiviral agents against diseases caused by the CVB, we found that ethyl 3-hydroxyhexanoate (EHX), a volatile compound present in fruits and food additives, is a potent antiviral compound. In this study, we demonstrated that EHX treatment significantly inhibits CVB replication both in vivo and in vitro. Furthermore, EHX possesses antiviral activity at 50% effective concentration (EC50) of 1.2 µM and 50% cytotoxicity (CC50) of 25.6 µM, yielding a selective index (SI) value as high as 20.8. Insights into the mechanism of antiviral activity of EHX showed that it acts at the step of viral RNA replication. Since EHX has received approval as food additives, treatment of CVB-related infections with EHX might be a safe therapeutic option and may be a promising strategy for the development of semi-synthetic antiviral drugs for viral diseases.

MiR-146a down-regulates inflammatory response by targeting TLR3 and TRAF6 in Coxsackievirus B infection.

Coxsackievirus B (CVB) is the major cause of human myocarditis and dilated cardiomyopathy. Toll-like receptor 3 (TLR3) is an intracellular sensor to detect pathogen's dsRNA. TLR3, along with TRAF6, triggers an inflammatory response through NF-κB signaling pathway. In the cells infected with CVB type 3 (CVB3), the abundance of miR-146a was significantly increased. The role of miR-146a in CVB infection is unclear. In this study, TLR3 and TRAF6 were identified as the targets of miR-146a. The elevated miR-146a inhibited NF-κB translocation and subsequently down-regulated proinflammatory cytokine expression in the CVB3-infected cells. Therefore, the NF-κB pathway can be doubly blocked by miR-146a through targeting of TLR3 and TRAF6. MiR-146a may be a negative regulator on inflammatory response and an intrinsic protective factor in CVB infection.

Aberrant PD-1 ligand expression contributes to the myocardial inflammatory injury caused by Coxsackievirus B infection.

Coxsackievirus group B (CVB) is considered as one of the most common pathogens of human viral myocarditis. CVB-induced myocarditis is mainly characterized by the persistence of the virus infection and immune-mediated inflammatory injury. Costimulatory signals are crucial for the activation of adaptive immunity. Our data reveal that the CVB type 3 (CVB3) infection altered the expression profile of costimulatory molecules in host cells. CVB3 infection caused the decrease of PD-1 ligand expression, partially due to the cleavage of AU-rich element binding protein AUF1 by the viral protease 3Cpro, leading to the exacerbated inflammatory injury of the myocardium. Moreover, systemic PD-L1 treatment, which augmented the apoptosis of proliferating lymphocytes, alleviated myocardial inflammatory injury. Our findings suggest that PD1-pathway can be a potential immunologic therapeutic target for CVB-induced myocarditis.