Research ArticleInfectious Disease

Prunin suppresses viral IRES activity and is a potential candidate for treating enterovirus A71 infection

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Science Translational Medicine  30 Oct 2019:
Vol. 11, Issue 516, eaar5759
DOI: 10.1126/scitranslmed.aar5759

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A translational antiviral

Human enterovirus A71 (HEVA71) is a major cause of hand, foot, and mouth disease, which can lead to severe neurological complications including fatality; currently, however, HEVA71 lacks effective treatment options. Gunaseelan et al. screened for compounds that targeted the HEVA71 internal ribosome entry site and thereby impeded viral, but not human, protein synthesis. They found that the flavonoid prunin effectively inhibited HEVA71 protein synthesis in vitro and decreased viral loads and mortality in a mouse model of infection. Prunin may therefore warrant further investigation as a potential treatment option against hand, foot, and mouth disease.

Abstract

Human enterovirus A71 (HEVA71) causes hand, foot, and mouth disease (HFMD) in young children and is considered a major neurotropic pathogen but lacks effective antivirals. To identify potential therapeutic agents against HFMD, we screened a 502-compound flavonoid library for compounds targeting the HEVA71 internal ribosome entry site (IRES) that facilitates translation of the HEVA71 genome and is vital for the production of HEVA71 viral particles. We validated hits using cell viability and viral plaque assays and found that prunin was the most potent inhibitor of HEVA71. Downstream assays affirmed that prunin disrupted viral protein and RNA synthesis and acted as a narrow-spectrum antiviral against enteroviruses A and B, but not enterovirus C, rhinovirus A, herpes simplex 1, or chikungunya virus. Continuous HEVA71 passaging with prunin yielded HEVA71-resistant mutants with five mutations that mapped to the viral IRES. Knockdown studies showed that the mutations allowed HEVA71 to overcome treatment-induced suppression by differentially regulating recruitment of the IRES trans-acting factors Sam68 and hnRNPK without affecting the hnRNPA1-IRES interaction required for IRES translation. Furthermore, prunin effectively reduced HEVA71-associated clinical symptoms and mortality in HEVA71-infected BALB/c mice and suppressed hepatitis C virus at higher concentrations, suggesting a similar mechanism of prunin-mediated IRES inhibition for both viruses. These studies establish prunin as a candidate for further development as a HEVA71 therapeutic agent.

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