Biology subjects

Fritch, E. J.

Publications and source records attributed to Fritch, E. J..

4 recordsLinked to original sources

bioRxiv2020

Repurposing the Ebola and Marburg Virus Inhibitors Tilorone, Quinacrine and Pyronaridine: In vitro Activity Against SARS-CoV-2 and Potential Mechanisms

SARS-CoV-2 is a newly identified virus that has resulted in over 1.3 M deaths globally and over 59 M cases globally to date. Small molecule inhibitors that reverse disease severity have proven difficult to discover. One of the key approaches that has been widely applied in an effort to speed up the translation of drugs is drug repurposing. A few drugs have shown in vitro activity against Ebola virus and demonstrated activity against SARS-CoV-2 in vivo. Most notably the RNA polymerase targeting remdesivir demonstrated activity in vitro and efficacy in the early stage of the disease in humans. Testing other small molecule drugs that are active against Ebola virus would seem a reasonable strategy to evaluate their potential for SARS-CoV-2. We have previously repurposed pyronaridine, tilorone and quinacrine (from malaria, influenza, and antiprotozoal uses, respectively) as inhibitors of Ebola and Marburg virus in vitro in HeLa cells and of mouse adapted Ebola virus in mouse in vivo. We have now tested these three drugs in various cell lines (VeroE6, Vero76, Caco-2, Calu-3, A549-ACE2, HUH-7 and monocytes) infected with SARS-CoV-2 as well as other viruses (including MHV and HCoV 229E). The compilation of these results indicated considerable variability in antiviral activity observed across cell lines. We found that tilorone and pyronaridine inhibited the virus replication in A549-ACE2 cells with IC50 values of 180 nM and IC50 198 nM, respectively. We have also tested them in a pseudovirus assay and used microscale thermophoresis to test the binding of these molecules to the spike protein. They bind to spike RBD protein with Kd values of 339 nM and 647 nM, respectively. Human Cmax for pyronaridine and quinacrine is greater than the IC50 hence justifying in vivo evaluation. We also provide novel insights into their mechanism which is likely lysosomotropic.

pharmacology and toxicology↗

bioRxiv2020

Comparative analysis of coronavirus genomic RNA structure reveals conservation in SARS-like coronaviruses

Coronaviruses, including SARS-CoV-2 the etiological agent of COVID-19 disease, have caused multiple epidemic and pandemic outbreaks in the past 20 years1-3. With no vaccines, and only recently developed antiviral therapeutics, we are ill equipped to handle coronavirus outbreaks4. A better understanding of the molecular mechanisms that regulate coronavirus replication and pathogenesis is needed to guide the development of new antiviral therapeutics and vaccines. RNA secondary structures play critical roles in multiple aspects of coronavirus replication, but the extent and conservation of RNA secondary structure across coronavirus genomes is unknown5. Here, we define highly structured RNA regions throughout the MERS-CoV, SARS-CoV, and SARS-CoV-2 genomes. We find that highly stable RNA structures are pervasive throughout coronavirus genomes, and are conserved between the SARS-like CoV. Our data suggests that selective pressure helps preserve RNA secondary structure in coronavirus genomes, suggesting that these structures may play important roles in virus replication and pathogenesis. Thus, disruption of conserved RNA secondary structures could be a novel strategy for the generation of attenuated SARS-CoV-2 vaccines for use against the current COVID-19 pandemic.

microbiology↗

bioRxiv2020

SARS-CoV-2 mRNA Vaccine Development Enabled by Prototype Pathogen Preparedness

A SARS-CoV-2 vaccine is needed to control the global COVID-19 public health crisis. Atomic-level structures directed the application of prefusion-stabilizing mutations that improved expression and immunogenicity of betacoronavirus spike proteins. Using this established immunogen design, the release of SARS-CoV-2 sequences triggered immediate rapid manufacturing of an mRNA vaccine expressing the prefusion-stabilized SARS-CoV-2 spike trimer (mRNA-1273). Here, we show that mRNA-1273 induces both potent neutralizing antibody and CD8 T cell responses and protects against SARS-CoV-2 infection in lungs and noses of mice without evidence of immunopathology. mRNA-1273 is currently in a Phase 2 clinical trial with a trajectory towards Phase 3 efficacy evaluation.

immunology↗

bioRxiv2019

Zika virus infection in Collaborative Cross mice

The 2015-2016 emergence of Zika virus (ZIKV) in the Americas, and recognition that ZIKV infection during pregnancy can result in birth defects, revealed a need for small animal models to study ZIKV pathogenic mechanisms and evaluate candidate vaccines and antivirals. Mice would be an attractive system for such studies, but ZIKV replicates poorly in laboratory mice because it fails to antagonize murine STAT2 and STING. To address this, most ZIKV pathogenesis studies have used mice with impaired interferon signaling (e.g. Ifnar1-/- or treatment with IFNAR1-blocking antibodies). However, using mice with severe defects in innate antiviral signaling confounds studies of viral pathogenic mechanisms. Collaborative Cross (CC) mice have proven to be a valuable system for developing new mouse pathogenesis models for viral infections that are not well modeled in conventional laboratory mouse lines. To test whether CC mice could provide an immune-competent model for ZIKV pathogenesis, we infected CC lines with ZIKV and assessed weight loss, viremia, and production of neutralizing antibodies. We tested 21 CC lines (CC001, CC002, CC003, CC004, CC005, CC006, CC011, CC012, CC013, CC019, CC024, CC028, CC040, CC041, CC042, CC046, CC051, CC059, CC061, CC068, and CC072, 13 of which have non-functional alleles of the flavivirus restriction factor Oas1b) and 3 ZIKV strains (MR766, H/PF/2013, and a mouse-adapted variant of Dakar 41525). ZIKV infection did not induce weight loss compared to mock-infected controls and accordingly only low levels of viral RNA were detected in serum. Only a subset of mice developed neutralizing antibodies to ZIKV, likely due to overall low levels of infection and viremia. Our results are consistent with other studies demonstrating poor ZIKV infection in interferon-intact mice and suggest that the tested CC lines do not include polymorphic host genes that greatly increase susceptibility to ZIKV infection.

microbiology↗