Abstract
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Enteroviruses
(family Picornaviridae) comprise a large group of
human pathogens against which no licensed antiviral therapy exists.
Drug-repurposing screens uncovered the FDA-approved drug fluoxetine
as a replication inhibitor of enterovirus B and D species. Fluoxetine
likely targets the nonstructural viral protein 2C, but detailed mode-of-action
studies are missing because structural information on 2C of fluoxetine-sensitive
enteroviruses is lacking. We here show that broad-spectrum anti-enteroviral
activity of fluoxetine is stereospecific concomitant with binding
to recombinant 2C. (S)-Fluoxetine inhibits with a
5-fold lower 50% effective concentration (EC50) than racemic
fluoxetine. Using a homology model of 2C of the fluoxetine-sensitive
enterovirus coxsackievirus B3 (CVB3) based upon a recently elucidated
structure of a fluoxetine-insensitive enterovirus, we predicted stable
binding of (S)-fluoxetine. Structure-guided mutations
disrupted binding and rendered coxsackievirus B3 (CVB3) resistant
to fluoxetine. The study provides new insights into the anti-enteroviral
mode-of-action of fluoxetine. Importantly, using only (S)-fluoxetine would allow for lower dosing in patients, thereby likely
reducing side effects.
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