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Principal Investigator: Christopher F Basler
Organization: GEORGIA STATE UNIVERSITY
Fiscal Year: 2020
Award: $779,568
Funding agency: National Institute of Allergy and Infectious Diseases
Project Summary
Filoviruses, which include the ebolaviruses and marburgviruses, are non-segmented, negative-sense RNA
viruses (NNSVs) that cause severe human disease. These viruses are of concern as emerging pathogens and
as potential bioterrorism threats. Their importance and public health impact are reinforced by the West Africa
epidemic that began in winter of 2014 and has resulted in more than 11,000 deaths and the export of Ebola
virus disease to the U.S., the U.K. and Europe. Although the past year has seen progress toward development
of effective vaccines and treatments, current prophylactic and treatment options remain limited. Particularly
lacking are effective small molecule inhibitors. Complicating development of anti-filovirus drugs is the biosafety
level 4 (BSL4) containment needed to work with live filoviruses, which is only available at a few locations
worldwide. With substantial restrictions on the number of investigators who have access to such facilities,
antiviral testing against infectious virus in a high throughput setting is problematic. An alternate approach is to
develop assays of specific viral functions that can be assessed without generation of infectious materials. The
viral RNA-dependent RNA polymerase (RDRP) complex is a particularly promising candidate. The complex
consists of the viral nucleoprotein (NP), viral protein of 35KDa (VP35), VP30 and the large protein (L) which is
the enzymatic component of the complex and the only enzyme encoded by the virus. The RDRP complex is
required for viral mRNA expression and viral genome replication and is therefore essential for virus growth.
Inhibition of the RDRP complex would arrest virus replication. The Basler and Shaw laboratories collaborated
to optimize for 384-well high throughput screening a minigenome assay in which a functional EBOV RDRP
complex is reconstituted by transfection of plasmids that express its four components into mammalian cells.
RDRP activity is measured through the co-expression of a model viral RNA (minigenome RNA) that encodes a
reporter gene flanked by the appropriate virus-derived cis-acting regulatory sequences. This system has been
successfully transferred to collaborator Sumit Chanda at Sanford Burnham Prebys Medical Discovery Institute
where a 6,400 compound pilot screen was performed. This screen yielded hits which were carried through to
BSL4 testing by Robert Davey at Texas Biomedical Research Institute and demonstrated to inhibit Ebola virus
replication. We propose to exploit this assay and this drug discovery pipeline to identify novel small molecule
inhibitors of the Ebola virus polymerase. We will also develop additional HTS-compatible minigenome assays
based on other filoviruses associated with deadly human disease, including Bundibugyo ebolavirus and
Marburg virus, to identify and prioritize hits with pan-filovirus activity. A combination of minigenome assay and
filovirus BSL4 experiments will define mechanisms of action, and together with initial SAR studies will prioritize
hits for future development. The completion of these studies will significantly expand the number of potential
therapeutic small molecules and provide significant insight into inhibition of the filovirus RDRP complex.
Terms: <Africa><Antiviral Agents><Antiviral Drugs><Antivirals><Assay><BDBV><Bioassay><Biologic Assays><Biological Assay><Biological Terrorism><Biology><Biomedical Research><Bioterrorism><Bundibugyo ebola virus><Bundibugyo ebolavirus><Bundibugyo virus><Cell Function><Cell Process><Cell physiology><Cellular Function><Cellular Physiology><Cellular Process><Cessation of life><Clinical><Collaborations><Collection><Complex><Containment><DNA-Dependent RNA Polymerases><DNA-Directed RNA Polymerase><Death><Development><Disease Outbreaks><Dose><Drug Targeting><Drugs><EBOV><EC 2.7.7.48><Ebola Hemorrhagic Fever><Ebola Virus Disease><Ebola disease><Ebola virus><Encapsulated><Enzyme Gene><Enzymes><Epidemic><Europe><Filoviridae><Filovirus><Frankfurt-Marburg Syndrome Virus><Future><Generalized Growth><Generations><Growth><Health><High Throughput Assay><Host Factor><Host Factor Protein><Human><Impairment><Infection><Institutes><Integration Host Factors><Investigators><Laboratories><Libraries><Lipids><Location><Lytotoxicity><MAb Therapeutics><Mammalian Cell><Marburg><Marburg virus><Measures><Medical><Medication><Medicinal Chemistry><Modeling><Modern Man><Molecular Bank><NIH><National Institutes of Health><Non-Polyadenylated RNA><Nucleoproteins><Outbreaks><Pharmaceutic Chemistry><Pharmaceutic Preparations><Pharmaceutical Chemistry><Pharmaceutical Preparations><Plasmids><Polymerase><Prophylactic treatment><Prophylaxis><Proteins><Public Health><RNA><RNA Gene Products><RNA Polymerases><RNA Replicase><RNA Viruses><RNA-Dependent RNA Polymerase><RNA-Directed RNA Polymerase><Reporter Genes><Research Institute><Research Personnel><Researchers><Resistance><Ribonucleic Acid><Short interfering RNA><Site><Small Interfering RNA><Structure-Activity Relationship><Subcellular Process><System><Testing><Texas><Therapeutic><Therapeutic Monoclonal Antibodies><Tissue Growth><Transfection><United States National Institutes of Health><Vaccines><Viral><Viral Activity><Viral Diseases><Viral Function><Viral Gene Products><Viral Gene Proteins><Viral Genome><Viral Physiology><Viral Proteins><Virus><Virus Diseases><Virus Inhibitors><Virus Replication><Work><ZEBOV><Zaire Ebola virus><Zaire ebolavirus><analog><anti-viral agents><anti-viral drugs><anti-virals><assay development><base><chemical library><chemical structure function><counterscreen><cytotoxicity><depository><developmental><drug candidate><drug discovery><drug/agent><ebolavirus><effective therapy><effective treatment><experiment><experimental research><experimental study><high throughput screening><high-throughput drug screening><human disease><human model><improved><inhibitor><inhibitor/antagonist><insight><mRNA Expression><macrophage><model of human><molecular library><monoclonal antibody drugs><novel><ontogeny><pathogen><reconstitute><reconstitution><repository><resistant><response><siRNA><small molecule><small molecule inhibitor><small molecule libraries><small molecule therapeutics><structure function relationship><therapeutic mAbs><therapeutic target><viral RNA><viral infection><viral inhibitor><viral multiplication><viral replication><virus RNA><virus genome><virus infection><virus multiplication><virus protein><virus-induced disease>