In addition, inhibitors of three other key dislocation regulators, BiP, p97/VCP and Npl4, are under preclinical development as anti-cancer drugs all of which are well tolerated in mice (Anderson et al., 2015; Cerezo et al., 2016; Skrott et al., 2017). infection. The antiviral activities of both compounds were demonstrated for all four DENV serotypes and four ZIKV strains in multiple human cell lines. This study defines grp94 as a crucial host factor for flavivirus replication and identified CDDO-me as a potent small molecule inhibitor of flavivirus infection. Inhibition of Voreloxin Hydrochloride grp94 may contribute to the antiviral activity of CDDO-me. Further investigation of grp94 inhibitors may lead to a new class of broad-spectrum anti-flaviviral medications. mosquitoes and disseminated worldwide. There are approximately 390 million cases of human DENV infections each year and the infections cause a range of symptoms from mild fever to dengue hemorrhagic fever with a mortality rate of 2C5% (Bhatt et al., 2013; Morra et al., 2018; Schaffner and Mathis, 2014; Horstick Voreloxin Hydrochloride et al., 2014). ZIKV infection, which typically is asymptomatic or only causes mild symptoms, became a global health emergency in recent years due to its unprecedented high prevalence in several regions and its association with severe neurological complications including catastrophic microcephaly in newborns and Guillain-Barre syndrome in adults (Solomon and Mallewa, 2001; Pyke et al., 2014; Tappe et al., 2014; Rothan et al., 2019). Currently there is no approved vaccine for ZIKV. The recently approved vaccine for DENV has regional and age based restrictions due to the limitation of vaccine efficacy and the potential F3 deadly side effects (Hueston et al., 2017; Castanha et al., 2017; Dejnirattisai et al., 2016; Rothan Voreloxin Hydrochloride et al., 2018). Moreover, epidemics of ZIKV infections have mostly occurred in the DENV endemic areas and there is evidence to show co-infection of these two flaviviruses, which makes vaccine development even more complicated (Shan et al., 2018; Dejnirattisai et al., 2016; Rothan et al., 2018). There are currently also no approved antiviral drugs specific for treatment or prophylaxis of either DENV or ZIKV infection. Traditionally antivirals are developed to target viral pathogens directly and specifically. However, antivirals that target host cell components that are essential for viral infection or replication represent an alternative approach (Plummer et al., 2015; Barrows et al., 2016; Boldescu et al., 2017; Scaturro et al., 2018). Host factor-targeted antivirals would address Voreloxin Hydrochloride not only two limitations associated with vaccines: 1) evasion of immunity caused by viral mutations (Schein et al., 2005) (Chiappelli et al., 2014; Maillard et al., 2014; Silveira et al., 2016; Chang et al., 2016; Sulczewski et al., 2018), and 2) DENV and ZIKV co-infection (Shan et al., 2018; Dejnirattisai et al., 2016; Rothan et al., 2018), as these flaviviruses exhibit the same lifecycle progression and require similar host factors (Gerold et al., 2017; Wang and Zhang, 2017; Puschnik et al., 2017). Thus, targeting the shared host factors would have a broad-spectrum of anti-flavivirus activity in co-infected patients (Boldescu Voreloxin Hydrochloride et al., 2017). Flaviviruses use the endoplasmic reticulum (ER) for viral proteins production and new virion assembly (Romero-Brey and Bartenschlager, 2016). Recently, genome-scale RNAi and CRISPR/Cas9 screenings have identified many host factors that are required for DENV, West Nile Virus (WNV), and ZIKV replication (Krishnan et al., 2008; Mairiang et al., 2013; Ma et al., 2015; Zhang et al., 2016; Marceau et al., 2016; Marceau et al., 2016; Boldescu et al., 2017; Scaturro et al., 2018), including proteins in the Hrd1 complex (Krishnan et al., 2008; Mairiang et al., 2013; Ma et al., 2015; Scaturro et al., 2018). The Hrd1 complex mediates a protein quality control mechanism in the ER by which misfolded proteins are dislocated from the ER lumen to the cytosol for degradation by the proteasome, a process known as ER-associated degradation.