Ribavirin Induces Polyamine Depletion via Nucleotide Depletion to Limit Virus Replication

Common antivirals include nucleoside or nucleotide analogs with base prodrugs. The antiviral ribavirin, a US Food and Drug Administration (FDA)-approved nucleoside antimetabolite, halts guanine production, mutagenizes viral genomes, and activates interferon signaling. Here, we find that ribavirin induces spermidine-spermine N1-acetyltransferase (SAT1), a polyamine catabolic enzyme. Polyamines are small, positively charged molecules involved in cellular functions such as transcription and translation. Previous work showed that SAT1 activation and polyamine depletion interfere with RNA virus replication. We show ribavirin depletes polyamines via SAT1, in conjunction with its known mechanisms. SAT1 transcripts, protein, and activity are induced in a dose-dependent manner, which depletes polyamine levels and reduces viral titers. Inhibition of SAT1 activity, pharmacologically or genetically, reduces ribavirin’s effectiveness against three virus infection models. Additionally, ribavirin-mediated polyamine depletion results from nucleotide pool depletion. These data demonstrate another mechanism of ribavirin that inform its clinical effectiveness, which may provide insight for improved therapies. [Display omitted] •Ribavirin depletes polyamines via spermine-spermidine acetyltransferase (SAT1)•Inhibition of de novo guanine synthesis also induces SAT1•Ribavirin’s antiviral activity relies, in part, on SAT1’s activity Tate et al. describe another mechanism for ribavirin: polyamine depletion. They find that ribavirin and nucleotide depletion induce polyamine catabolism through spermidine-spermine acetyltransferase (SAT1). This polyamine depletion restricts virus replication, and inhibition of SAT1 reduces ribavirin’s antiviral efficacy. Thus, polyamines contribute to ribavirin’s antiviral activity.