The encephalomyocarditis virus (EMCV) is a small non-enveloped single-strand RNA virus, the causative agent of not only myocarditis and encephalitis, but also neurological diseases, reproductive disorders and diabetes in many mammalian species. EMCV pathogenesis appears to be viral strain- and host-specific, and a better understanding of EMCV virulence factors is increasingly required. Indeed, EMCV is often used as a model for diabetes and viral myocarditis, and is also widely used in immunology as a double-stranded RNA stimulus in the study of Toll-like as well as cytosolic receptors. However, EMCV virulence and properties have often been neglected. Moreover, EMCV is able to infect humans albeit with a low morbidity. Progress on xenografts, such as pig heart transplantation in humans, has raised safety concerns that need to be explored. In this review we will highlight the biology of EMCV and all known and potential virulence factors.

Zika virus (ZIKV) invades and persists in the central nervous system (CNS), causing severe neurological diseases. However the virus journey, from the bloodstream to tissues through a mature endothelium, remains unclear. Here, we show that ZIKV-infected monocytes represent suitable carriers for viral dissemination to the CNS using human primary monocytes, cerebral organoids derived from embryonic stem cells, organotypic mouse cerebellar slices, a xenotypic human-zebrafish model, and human fetus brain samples. We find that ZIKV-exposed monocytes exhibit higher expression of adhesion molecules, and higher abilities to attach onto the vessel wall and transmigrate across endothelia. This phenotype is associated to enhanced monocyte-mediated ZIKV dissemination to neural cells. Together, our data show that ZIKV manipulates the monocyte adhesive properties and enhances monocyte transmigration and viral dissemination to neural cells. Monocyte transmigration may represent an important mechanism required for viral tissue invasion and persistence that could be specifically targeted for therapeutic intervention.

The encephalomyocarditis virus (EMCV), a Picornaviridae virus, has a wide host spectrum and can cause various diseases. EMCV virulence factors, however, are as yet ill defined. Here, we demonstrate that the EMCV 2A protein is essential for the pathogenesis of EMCV. Infection of mice with the B279/95 strain of EMCV resulted in acute fatal disease, while the clone C9, derived by serial in vitro passage of the B279/95 strain, was avirulent. C9 harbored a large deletion in the gene encoding the 2A protein. This deletion was incorporated into the cDNA of a pathogenic EMCV1.26 strain. The new virus, EMCV1.26⌬2A, was capable of replicating in vitro, albeit more slowly than EMCV1.26. Only mice inoculated with EMCV1.26 triggered death within a few days. Mice infected with EMCV1.26⌬2A did not exhibit clinical signs, and histopathological analyses showed no damage in the central nervous system, unlike EMCV1.26-infected mice. In vitro, EMCV1.26⌬2A presented a defect in viral particle release correlating with prolonged cell viability. Unlike EMCV1.26, which induced cytopathic cell death, EMCV1.26⌬2A induced apoptosis via caspase 3 activation. This strongly suggests that the 2A protein is required for inhibition of apoptosis during EMCV infection. All together, our data indicate that the EMCV 2A protein is important for the virus in counteracting host defenses, since ⌬2A viruses were no longer pathogenic and were unable to inhibit apoptosis in vitro.

Dengue virus (DENV) is a mosquito-borne pathogen that is the causative agent of dengue fever. Severe dengue virus infection is potentially fatal due to hemorrhaging, plasma leakage, and pulmonary shock. The four serotypes of DENV (DENV-1 to DENV-4) are defined by antigenic differences on the viral envelope protein, E, and together, they comprise a species within the Flavivirus genus of the Flaviviridae family. This family of small enveloped viruses with positive-sense RNA genomes encompasses other human pathogens, including West Nile virus (WNV), Japanese encephalitis virus (JEV), yellow fever virus (YFV), and hepatitis C virus (HCV). A recent evidence-based study suggests that approximately 300 million DENV infections occur annually (1), and no vaccine or specific antiviral drug is currently available to treat it. DENV vaccine development is a major challenge due to the antibody-dependent enhancement of infection, a phenomenon in which neutralizing antibodies against one DENV serotype can exacerbate disease upon subsequent infection with another serotype (2, 3). A parallel exploration of antiviral strategies to combat DENV infection is therefore crucial.Resistance to antiviral drugs that act against viral targets occurs rapidly due to the intrinsically high mutation rate of RNA virus polymerases. Host-targeted antivirals that can complement these more traditional antivirals may make the acquisition of resistance to antiviral drugs much less likely and may also offer broad-spectrum activity against phylogenetically related viruses. The interactions between DENV and host lipid biosynthetic, metabolic, trafficking, and signal transducing pathways represent a rich and largely unexplored class of targets for host-targeted antiviral strategies. DENV and other RNA viruses rely entirely on host lipids to supply the membranes essential for the viral replication cycle, and the interaction of viruses with lipid-related processes in the host cell is highlighted by recent studies documenting specific perturbations of these pathways by viruses (4). In addition, so-called bioactive lipids can regulate cellular processes by modulating signal transduction cascades that may impinge on viral infection. Thus, small molecules that act on host-cell lipid signaling and metabolism are attractive as potential anti-DENV compounds.To pursue the strategy of targeting host lipid metabolic and signaling pathways important for DENV infection, we screened a panel of bioactive lipids and small-molecule inhibitors of lipid metabolism for activity against DENV. We chose a library enriched for compounds with known safety and bioavailability profiles to increase our likelihood of identifying clinically useful anti-DENV compounds. We present here the identification of the bioactive lipid 4-hydroxyphenyl retinamide (4-HPR) as an inhib-

Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients' homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE 2 RD), which addresses all these impediments on a single platform. The NE 2 RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE 2 RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE 2 RD's broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the pointof-care or primary care settings and at patients' homes.iosensing platforms have enabled various applications in different fields of clinical medicine such as biomarker/drug discovery and initiation and monitoring of therapy (1-3). However, material cost, accessibility, ease of operation, lack of portability, and complexity in readout remain major challenges for developing robust diagnostic assays (SI Appendix, Table S1). Recent advances in nanotechnology and biosensing have created new avenues to address these issues (4-9). Technically, they have provided integration of high-throughput sampling with readout systems for quantitative detection of disease-specific biotargets. Therefore, they have demonstrated great potential to revolutionize medical diagnostics. However, from a clinical and technological perspective, existing platforms still face several challenges. First, lengthy assay time hinders physicians from making early clinical decisions. Second, examining clinical samples with diverse pH range, ionic content, and ionic strength requires SignificanceBiosensing technologies have significant impact on medical diagnostics but difficulties in the handling of complex biospecimens, portability, and nonlinearity in dynamic detection range present considerable technical bottlenecks in their tran...

We report here on an approach targeting the host reactive cysteinome to identify inhibitors of host factors required for the infectious cycle of Flaviviruses and other viruses. We used two parallel cellular phenotypic screens to identify a series of covalent inhibitors, exemplified by QL-XII-47, that are active against dengue virus. We show that the compounds effectively block viral protein expression and that this inhibition is associated with repression of downstream processes of the infectious cycle, and thus significantly contributes to the potent antiviral activity of these compounds. We demonstrate that QL-XII-47’s antiviral activity requires selective, covalent modification of a host target by showing that the compound's antiviral activity is recapitulated when cells are preincubated with QL-XII-47 and then washed prior to viral infection and by showing that QL-XII-47R, a non-reactive analog, lacks antiviral activity at concentrations more than 20-fold higher than QL-XII-47's IC90. QL-XII-47’s inhibition of Zika virus, West Nile virus, hepatitis C virus, and poliovirus further suggests that it acts via a target mediating inhibition of these other medically relevant viruses. These results demonstrate the utility of screens targeting the host reactive cysteinome for rapid identification of compounds with potent antiviral activity.

Virus entry into cells is a multistep process that often requires the subversion of subcellular machineries. A more complete understanding of these steps is necessary to develop new antiviral strategies. While studying the potential role of the actin network and one of its master regulators, the small GTPase Cdc42, during Junin virus (JUNV) entry, we serendipitously uncovered the small molecule ZCL278, reported to inhibit Cdc42 function as an entry inhibitor for JUNV and for vesicular stomatitis virus, lymphocytic choriomeningitis virus, and dengue virus but not for the nonenveloped poliovirus. Although ZCL278 did not interfere with JUNV attachment to the cell surface or virus particle internalization into host cells, it prevented the release of JUNV ribonucleoprotein cores into the cytosol and decreased pH-mediated viral fusion with host membranes. We also identified SVG-A astroglial cell-derived cells to be highly permissive for JUNV infection and generated new cell lines expressing fluorescently tagged Rab5c or Rab7a or lacking Cdc42 using clustered regularly interspaced short palindromic repeat (CRISPR)-caspase 9 (Cas9) gene-editing strategies. Aided by these tools, we uncovered that perturbations in the actin cytoskeleton or Cdc42 activity minimally affect JUNV entry, suggesting that the inhibitory effect of ZCL278 is not mediated by ZCL278 interfering with the activity of Cdc42. Instead, ZCL278 appears to redistribute viral particles from endosomal to lysosomal compartments. ZCL278 also inhibited JUNV replication in a mouse model, and no toxicity was detected. Together, our data suggest the unexpected antiviral activity of ZCL278 and highlight its potential for use in the development of valuable new tools to study the intracellular trafficking of pathogens. IMPORTANCEThe Junin virus is responsible for outbreaks of Argentine hemorrhagic fever in South America, where 5 million people are at risk. Limited options are currently available to treat infections by Junin virus or other viruses of the Arenaviridae, making the identification of additional tools, including small-molecule inhibitors, of great importance. How Junin virus enters cells is not yet fully understood. Here we describe new cell culture models in which the cells are susceptible to Junin virus infection and to which we applied CRISPR-Cas9 genome engineering strategies to help characterize early steps during virus entry. We also uncovered ZCL278 to be a new antiviral small molecule that potently inhibits the cellular entry of the Junin virus and other enveloped viruses. Moreover, we show that ZCL278 also functions in vivo, thereby preventing Junin virus replication in a mouse model, opening the possibility for the discovery of ZCL278 derivatives of therapeutic potential. T he Junin virus (JUNV) is an important member of the NewWorld arenavirus family (clade B) and is responsible for outbreaks of Argentine hemorrhagic fever in South America, where 5 million people are considered to be at risk (1). The reservoir of JUNV is the rodent Calomy...

Here we report the structure-activity relationship (SAR) investigations of QL-XII-47 (QL47), a compound that possesses broad-spectrum antiviral activity against dengue virus and other RNA viruses. A medicinal chemistry campaign initiated from QL47, a previously reported covalent BTK inhibitor, to derive YKL-04-085, which is devoid of any kinase activity when screened against a panel of 468 kinases and with improved pharmacokinetic properties. Both QL47 and YKL-04-085 are potent inhibitors of viral translation and exhibit cellular antiviral activity at 35-fold lower concentrations relative to inhibition of host-cell proliferation.