GNF-2 Inhibits Dengue Virus by Targeting Abl Kinases and the Viral E Protein

Abstract

Summary Dengue virus infects over 300 million people annually, yet there is no widely protective vaccine or drugs against the virus. Efforts to develop antivirals against classical targets such as the viral protease and polymerase have not yielded drugs that have advanced to the clinic. Here we show that the allosteric Abl kinase inhibitor GNF-2 interferes with dengue virus replication via activity mediated by cellular Abl kinases but additionally blocks viral entry via an Abl-independent mechanism. To characterize this newly discovered antiviral activity, we developed disubstituted pyrimidines that block dengue virus entry with structure-activity relationships distinct from those driving kinase inhibition. We demonstrate that biotin- and fluorophore-conjugated derivatives of GNF-2 interact with the dengue glycoprotein, E, in the prefusion conformation that exists on the virion surface and that this interaction inhibits viral entry. This study establishes GNF-2 as an antiviral compound with polypharmacological activity and provides ‘lead’ compounds for further optimization efforts.

Repurposing of Kinase Inhibitors as Broad-Spectrum Antiviral Drugs

“…C-Abl is implicated in the budding or release of poxviruses (Reeves et al, 2011) and EBOV (Garcia et al, 2012), the entry of coxsackievirus (Coyne and Bergelson, 2006) and polyomavirus (Swimm et al, 2010), and in DENV infection (Clark et al, 2016). Imatinib and/or nilotinib, approved anticancer c-Abl inhibitors lacking anti-SFK activity, inhibited replication of EBOV (Garcia et al, 2012), DENV (Clark et al, 2016), MERS-CoV and/or SARS-CoV (Dyall et al, 2014) in cultured cells. While dasatinib also inhibited MERS-CoV and SARS-CoV, it remained uncertain which molecular target(s) (Abl only or Abl plus Src) mediated its activity against these viruses (Dyall et al, 2014).…”

“…Similarly, the anti-DENV effect of dasatinib was attributed to the inhibition of SFKs, particularly Fyn Yang, 2007) (de Wispelaere et al, 2013). Nevertheless, the finding that c-Abl, another dasatinib target, is essential for DENV infection (Clark et al, 2016) suggests that c-Abl inhibition likely represents yet another mechanism through which dasatinib mediates its antiviral activity. These examples underscore the importance of validating not only the antiviral targets but also the molecular targets underlying the antiviral effect of such inhibitors.…”

Highlights of the 30th International Conference on Antiviral Research

“…To answer that question, Priscilla's group began by using a cellbased phenotypic screen of DENV-infected cells to identify active compounds, detecting E expression by immunofluorescence and automated microscopy, followed by time-of-addition experiments to discriminate between inhibitors of virus entry and those blocking later steps in replication (Chu and Yang, 2007;Clark et al, 2016). Screening identified three series of small molecules -2,4diaminopyrimidines, 4,6-disubstituted pyrimidines, and cyanohydrazonesthat interfere with entry.…”

“…Screening identified three series of small molecules -2,4diaminopyrimidines, 4,6-disubstituted pyrimidines, and cyanohydrazonesthat interfere with entry. By linking the compounds to biotin or fluorophores, her group has shown that the inhibitors interact with the soluble pre-fusion E dimer, but not the postfusion trimer (Clark et al, 2016) (Fig. 4), and that they block pHtriggered, E-mediated fusion of virions with liposomes (unpublished).…”

“…NS5B polymerase of HCV genotypes 1e4, with a high barrier to resistance; had a good safety profile; and showed additive to synergistic activity in vitro in combination with ribavirin or interferon (Clark et al, 2005).…”