L’identification d’antiviraux à large spectre est un des défis majeurs de la rechercheactuelle en virologie. Une des stratégies les plus prometteuses consiste à cibler une interactionvirus/hôte conservée. Ainsi, avec la technique d’AlphaScreen® et le modèle d’interactionprotéine VI de l’Adénovirus (AdV)/Nedd4-2, nous avons réalisé un criblage biochimique àhaut débit contre l’interaction virus/hôte [LP]PxY/Nedd4, commune à différentes familles devirus. Nous avons trouvé des candidats inhibiteurs issus d’une banque de composés approuvéspar les agences de santé. Nous les avons testés, caractérisés et validé leur effet antiviral surdeux familles de virus totalement différentes. Ainsi, les composés C9 (Sulconazole) et C4(Flunarizine) que nous avons identifiés diminuent la réplication de l’AdV, un virus à ADNenveloppé et du virus de Marburg, un virus à ARN, non enveloppé de la famille desFiloviridae. Ces résultats ont permis de valider l’interaction [LP]PxY/Nedd4 comme unecible idéale d’un antiviral à large spectre et de proposer un repositionnement de ces moléculesC9 et C4 comme antiviraux potentiels. Nous avons également synthétisé de nouvellesmolécules analogues du composé C9 et démontré qu’elles étaient tout aussi efficaces que lecomposé lui-même sur la réplication de l’AdV. Ces résultats nous ont permis de présenter laclasse des dérivés imidazolés comme structure de base pour l’élaboration de nouveauxantiviraux, potentiellement à large spectre. / Broad-spectrum antiviral identification is considered as one of the major aims of theactual virology research and one strategy consists in targeting virus/host interaction. Using theAlphaScreen® technology and the adenoviral model protein VI/Nedd4-2, we performed highthroughputbiochemical screening targeting the [LP]PxY/Nedd4 interaction, a commoninteraction of different virus families. We identified candidate inhibitors from a librarycompound approved by health agencies. We tested, characterized and validated the antiviraleffect of those compounds on two very different virus families. Indeed, compounds C9(Sulconazole) and C4 (Flunarizine) decrease replication of the adenovirus, a DNA nonenvelopedvirus and the replication of the Marburg virus, an RNA enveloped virus from theFilovirus family. Taken together, those results permit us to validate the [LP]PxY/Nedd4interaction as good target for a broad spectrum antiviral and to propose the “repositioning” ofcompounds C4 and C9 as antivirals. Moreover, we have synthesized new analogues from C9showing similar effect on AdV replication compared to the original molecule (C9). Inconclusion, our work on developing new broad-spectrum antivirals highlights the possibilityto use imidazole derivatives as a new class of antiviral compounds.

Cancer immunotherapy is an encompassing term referring to therapeutic strategies that aim to boost the immune system to fight cancer. These strategies include administering immune cells that have been altered to have greater anti-tumor activity or using biologics and small molecules that target immune components to also promote tumor clearance. Natural Killer (NK) cells are cells of the innate immune system that recognize and kill abnormal cells such as cancer cells and play an important role in the anti-tumor response. Because of their crucial role in tumor immunity, NK cells are prime targets for immunotherapies. Repurposing small molecule drugs is an attractive strategy to identify new immunotherapies from already approved drugs. Here, we screened 1,200 approved drugs from the Prestwick Chemical Library to identify drugs that increase NK cell cytotoxicity. We used a high-throughput luciferase-release cytotoxicity assay to measure the killing of the myeloid leukemia cell line, K562 cells expressing nano luciferase (NL) by NK92 cells, a human NK cell line. From the drug candidates identified from the screening assay, the antibiotic colistin sulfate increased cytotoxicity of the NK92 cell line and unstimulated human NK cells towards K562-NL cells. This increase in NK cytotoxicity was short-lived as pre-treating NK92 cells with colistin for 1 hour or 24 hours did not increase cytotoxicity. Also, we show pre-treating K562-NL target cells with colistin does not sensitize them to NK-mediated killing. Further studies are needed to uncover the mechanism of action of colistin, thus contributing to knowledge of fundamental NK cell biology regarding NK cell cytotoxicity which will aid in identifying additional small molecule drugs that enhance NK cell activity.