Development of Antivirals against Filovirus Replication

SUMMARY (Project 3: Kawaoka) As part of the Rapidly Emerging Antiviral Drug Development Initiative-AViDD Center (READDI-AC) program, the goal of Project 3: Filoviruses is to identify and develop promising hit and lead compounds with robust anti- filovirus activity, while also advancing the field of filovirus drug development through the identification of new chemical entities and druggable targets. In Aim 1 ('Identification of compound hits and conserved filovirus druggable target sites'), a multipronged approach will be used to identify hit compounds by using different screening assays including targeted nucleoside libraries, a DNA-encoded library screen, enzyme-based screens, and promising compounds from other Projects. We will also identify and validate druggable target sites in the functional domains of the filovirus polymerase (L) protein by using AlphaFold and fragment mapping, which may be applicable to the discovery of additional broadly active anti-filovirus small molecule compounds by Discovery Core B. After hit compounds are prioritized by Adman Core A and MedChem Core D, in Aim 2 ('Optimization of hit compounds against filoviruses') 2-4 hit series will be identified for Hit-to-Probe optimization by MedChem Core D. This core will synthesize compound analogs for antiviral evaluation, improve upon their activity via structural-activity relationship studies, and determine their drug absorption, distribution, metabolism, excretion and pharmacokinetic (PK) properties. In addition to hit compounds identified in Aim 1, we will bring into this program, two hit nucleoside analogs against filoviruses through a collaboration with Dr. Seley-Radtke, a co-investigator. The antiviral activity of the compounds and synthesized analogs will be evaluated for antiviral breadth in enzyme-based assays by Enzymology Core C and in cell-based assays using a novel Ebola reporter- virus system and authentic filoviruses by Project 3. Two lead compounds will advance into Aim 3 ('Lead development to establish in vivo efficacy'), where the studies will be carried out to generate a pre-clinical package. With input from MedChem Core D, formulation and in vivo PK studies to gain a better understanding of the PK properties of the compounds for their advancement to in vivo antiviral efficacy studies will be carried out by contracted research organizations. Antiviral efficacy studies will be carried out by Project 3, first in rodent models of filovirus infection, followed by confirmatory studies in a ferret model. Ultimately, we expect to deliver targets, hits, leads, and chemical probes for public crowd-sharing, and pre-IND enabling data for one compound with antiviral activity against at least three important Ebola viruses, and possibly Marburg virus, to the stage of early in vivo optimization with the goal of attracting an industry partner(s) to eventually move the drug to clinical trials.