Computational and in vitro experimental analyses of the anti-COVID-19 potential of Mortaparib and MortaparibPlus

Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has become a global health emergency. Although new vaccines have been generated and being implicated, discovery and application of novel preventive and control measures are warranted. We aimed to identify compounds that may possess the potential to either block the entry of virus to host cells or attenuate its replication upon infection. Using host cell surface receptor expression (angiotensin-converting enzyme 2 (ACE2) and Transmembrane protease serine 2 (TMPRSS2)) analysis as an assay, we earlier screened several synthetic and natural compounds and identified candidates that showed ability to down-regulate their expression. Here, we report experimental and computational analyses of two small molecules, Mortaparib and MortaparibPlus that were initially identified as dual novel inhibitors of mortalin and PARP-1, for their activity against SARS-CoV-2. In silico analyses showed that MortaparibPlus, but not Mortaparib, stably binds into the catalytic pocket of TMPRSS2. In vitro analysis of control and treated cells revealed that MortaparibPlus caused down-regulation of ACE2 and TMPRSS2; Mortaparib did not show any effect. Furthermore, computational analysis on SARS-CoV-2 main protease (Mpro) that also predicted the inhibitory activity of MortaparibPlus. However, cell-based antiviral drug screening assay showed 30-60% viral inhibition in cells treated with non-toxic doses of either MortaparibPlus or Mortaparib. The data suggest that these two closely related compounds possess multimodal anti-COVID-19 activities. Whereas MortaparibPlus works through direct interactions/effects on the host cell surface receptors (ACE2 and TMPRSS2) and the virus protein (Mpro), Mortaparib involves independent mechanisms, elucidation of which warrants further studies.

Computational and in vitro experimental analyses of the Anti-COVID-19 potential of Mortaparib and MortaparibPlus

COVID-19 pandemic caused by SARS-CoV-2 virus has become a global health emergency. Although new vaccines have been generated and being implicated, discovery and application of novel preventive and control measures are warranted. We aimed to identify compound/s that may possess the potential to either block the entry of virus to host cells or attenuate its replication upon infection. Using host cell surface receptor expression (Angiotensin-converting enzyme 2 (ACE2) and Transmembrane protease serine 2 (TMPRSS2) analysis as an assay, we earlier screened several synthetic and natural compounds and identified candidates that showed ability to downregulate their expression. Here, we report experimental and computational analyses of two small molecules, Mortaparib and MortaparibPlus that were initially identified as dual novel inhibitors of mortalin and PARP-1, for their activity against SARS-CoV-2. In silico analyses showed that MortaparibPlus, but not Mortaparib, stably binds into the catalytic pocket of TMPRSS2. In vitro analysis of control and treated cells revealed that MortaparibPlus caused downregulation of ACE2 and TMPRSS2; Mortaparib did not show any effect. Furthermore, computational analysis on SARS-CoV-2 main protease (Mpro) that also predicted the inhibitory activity of MortaparibPlus.  However, cell based anti-virus drug screening assay showed 30~60% viral inhibition in cells treated with non-toxic doses of either MortaparibPlus or Mortaparib. The data suggests that these two closely related compounds possess multimodal anti-COVID 19 activities. Whereas MortaparibPlus works through direct interactions/effects on the host cell surface receptors (ACE2 and TMPRSS2) and the virus protein (Mpro), Mortaparib involves independent mechanisms, elucidation of which warrants further studies.

High-Throughput Screening Assays for Dengue Antiviral Drug Development

Dengue is an arthropod-borne viral disease that has become endemic and a global threat in over 100 countries. The increase in prevalence would require a long-term measure to control outbreaks. Sanofi Pasteur has licensed the tetravalent dengue vaccine (Dengvaxia) in certain dengue endemic countries. However, the efficacy of the vaccine is limited against certain dengue serotypes and can only be used for individuals from the age from 9 to 45 years old. Over the years, there has been intense research conducted on the development of antivirals against dengue virus (DENV) through either inhibiting the virus replication or targeting the host cell mechanism to block the virus entry. However, no approved antiviral drug against dengue is yet available. In this chapter, we describe the dengue antiviral development workflow including (i) prophylactic, (ii) virucidal, and (iii) postinfection assays that are employed in the antiviral drug screening process against DENV. Further, we demonstrate different methods that can be used to enumerate the reduction in virus foci number including foci-forming unit reduction assay (FFURA), estimation of viral RNA copy number through quantitative real-time PCR, and a high-throughput enzyme linked immunosorbent assay (ELISA)-based quantification of virus particles.

Methods in Screening Antiviral Drugs Against Enterovirus 71

Enteroviruses 71 (EV71) is a single-stranded, neurotrophic RNA virus responsible for the numerous outbreaks of hand, foot, and mouth disease (HFMD) in the Asia-Pacific regions. HFMD primarily affects children to cause range of infection, from mild symptoms to acute flaccid paralysis, and hemorrhage. Despite increased incidence of EV71 epidemics globally and research against EV71 becoming prioritized, no antiviral agent against EV71 has yet been licensed and approved worldwide. In this chapter, detailed EV71 antiviral screening techniques are described, including plaque assay which determines viral titers through the use of a semisolid overlay, carboxymethyl cellulose to allow even viral spread and infection across the host cellular monolayers as well as a crystal violet, a distinct counterstain to visualize circular regions of infectious zones-plaques. qRT-PCR is used to quantify the viral genomic RNA in the infected samples and MTS cell viability assay to quantify the cell viability after infection or toxicity of the compound on the cells. Furthermore, various antiviral inhibition assays including prophylactic, post infection, and virucidal assays are demonstrated for estimation of the antiviral activity of potential antiviral drugs against EV71. These methods can be effectively utilized in virology laboratories for effective high-throughput screening of antiviral molecules against EV71 that can assist in the future development of antiviral drugs.