{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T10:33:38Z","timestamp":1790159618546,"version":"4.1.0"},"reference-count":38,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2020,1,9]],"date-time":"2020-01-09T00:00:00Z","timestamp":1578528000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000925","name":"National Health and Medical Research Council","doi-asserted-by":"publisher","award":["APP1157053"],"award-info":[{"award-number":["APP1157053"]}],"id":[{"id":"10.13039\/501100000925","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000925","name":"National Health and Medical Research Council","doi-asserted-by":"publisher","award":["APP1103050"],"award-info":[{"award-number":["APP1103050"]}],"id":[{"id":"10.13039\/501100000925","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000923","name":"Australian Research Council","doi-asserted-by":"publisher","award":["DE190100304"],"award-info":[{"award-number":["DE190100304"]}],"id":[{"id":"10.13039\/501100000923","id-type":"DOI","asserted-by":"publisher"}]},{"name":"BioCurate","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells"],"abstract":"<jats:p>Viral disease is one of the greatest burdens for human health worldwide, with an urgent need for efficacious antiviral strategies. While antiviral drugs are available, in many cases, they are prone to the development of drug resistance. A way to overcome drug resistance associated with common antiviral therapies is to develop antivirals targeting host cellular co-factors critical to viral replication, such as DEAD-box helicase 3 X-linked (DDX3X), which plays key roles in RNA metabolism and the antiviral response. Here, we use biochemical\/biophysical approaches and infectious assays to show for the first time that the small molecule RK-33 has broad-spectrum antiviral action by inhibiting the enzymatic activities of DDX3X. Importantly, we show that RK-33 is efficacious at low micromolar concentrations in limiting infection by human parainfluenza virus type 3 (hPIV-3), respiratory syncytial virus (RSV), dengue virus (DENV), Zika virus (ZIKV) or West Nile virus (WNV)\u2014for all of which, no Food and Drug Administration (FDA)-approved therapeutic is widely available. These findings establish for the first time that RK-33 is a broad-spectrum antiviral agent that blocks DDX3X\u2019s catalytic activities in vitro and limits viral replication in cells.<\/jats:p>","DOI":"10.3390\/cells9010170","type":"journal-article","created":{"date-parts":[[2020,1,10]],"date-time":"2020-01-10T04:06:51Z","timestamp":1578629211000},"page":"170","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":42,"title":["RK-33 Is a Broad-Spectrum Antiviral Agent That Targets DEAD-Box RNA Helicase DDX3X"],"prefix":"10.3390","volume":"9","author":[{"given":"Sundy N. Y.","family":"Yang","sequence":"first","affiliation":[{"name":"Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3518-9785","authenticated-orcid":false,"given":"Sarah C.","family":"Atkinson","sequence":"additional","affiliation":[{"name":"Infection &amp; Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michelle D.","family":"Audsley","sequence":"additional","affiliation":[{"name":"Infection &amp; Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3323-8691","authenticated-orcid":false,"given":"Steven M.","family":"Heaton","sequence":"additional","affiliation":[{"name":"Infection &amp; Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5115-4745","authenticated-orcid":false,"given":"David A.","family":"Jans","sequence":"additional","affiliation":[{"name":"Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8677-9056","authenticated-orcid":false,"given":"Natalie A.","family":"Borg","sequence":"additional","affiliation":[{"name":"Infection &amp; Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,1,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"vew014","DOI":"10.1093\/ve\/vew014","article-title":"Antiviral drug resistance as an adaptive process","volume":"2","author":"Irwin","year":"2016","journal-title":"Virus Evol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1016\/j.jmb.2007.06.050","article-title":"Crystal structure of conserved domains 1 and 2 of the human DEAD-box helicase DDX3X in complex with the mononucleotide AMP","volume":"372","author":"Hogbom","year":"2007","journal-title":"J. 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