The public health impact of Paxlovid COVID-19 treatment in the United States (preprint)

The antiviral drug Paxlovid has been shown to rapidly reduce viral load. Coupled with vaccination, timely administration of safe and effective antivirals could provide a path towards managing COVID-19 without restrictive non-pharmaceutical measures. Here, we estimate the population-level impacts of expanding treatment with Paxlovid in the US using a multi-scale mathematical model of SARS-CoV-2 transmission that incorporates the within-host viral load dynamics of the Omicron variant. We find that, under a low transmission scenario (Re~1.2) treating 20% of symptomatic cases with Paxlovid would be life and cost saving, leading to an estimated 0.26 (95% CrI:0.03, 0.59) million hospitalizations averted, 30.61 (95% CrI:1.69, 71.15) thousand deaths averted, and US$52.16 (95% CrI:2.62, 122.63) billion reduction in the US. Rapid and broad use of the antiviral Paxlovid could substantially reduce COVID-19 morbidity and mortality, while averting socioeconomic hardship.

Hepatitis C Virus Drugs Simeprevir and Grazoprevir Synergize with Remdesivir to Suppress SARS-CoV-2 Replication in Cell Culture (preprint)

Effective control of COVID-19 requires antivirals directed against SARS-CoV-2 virus. Here we assess ten available HCV protease inhibitor drugs as potential SARS-CoV-2 antivirals. There is a striking structural similarity of the substrate binding clefts of SARS- CoV-2 Mpro and HCV NS3/4A proteases, and virtual docking experiments show that all ten HCV drugs can potentially bind into the Mpro binding cleft. Seven of these HCV drugs inhibit SARS-CoV-2 Mpro protease activity, while four dock well into the PLpro substrate binding cleft and inhibit PLpro protease activity. These same seven HCV drugs inhibit SARS-CoV-2 virus replication in Vero and/or human cells, demonstrating that HCV drugs that inhibit Mpro, or both Mpro and PLpro, suppress virus replication. Two HCV drugs, simeprevir and grazoprevir synergize with the viral polymerase inhibitor remdesivir to inhibit virus replication, thereby increasing remdesivir inhibitory activity as much as 10-fold. HighlightsO_LISeveral HCV protease inhibitors are predicted to inhibit SARS-CoV-2 Mpro and PLpro. C_LIO_LISeven HCV drugs inhibit Mpro enzyme activity, four HCV drugs inhibit PLpro. C_LIO_LISeven HCV drugs inhibit SARS-CoV-2 replication in Vero and/or human cells. C_LIO_LIHCV drugs simeprevir and grazoprevir synergize with remdesivir to inhibit SARS- CoV-2. C_LI eTOC blurbBafna, White and colleagues report that several available hepatitis C virus drugs inhibit the SARS-CoV-2 Mpro and/or PLpro proteases and SARS-CoV-2 replication in cell culture. Two drugs, simeprevir and grazoprevir, synergize with the viral polymerase inhibitor remdesivir to inhibit virus replication, increasing remdesivir antiviral activity as much as 10-fold. O_FIG O_LINKSMALLFIG WIDTH=185 HEIGHT=200 SRC="FIGDIR/small/422511v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@1c12181org.highwire.dtl.DTLVardef@7ed993org.highwire.dtl.DTLVardef@1fe56aaorg.highwire.dtl.DTLVardef@ebc34e_HPS_FORMAT_FIGEXP M_FIG C_FIG

Computational Analysis of Dynamic Allostery and Control in the three SARS-CoV-2 non-structural proteins (preprint)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which caused the COVID-19 pandemic, has no vaccine or antiviral drugs available to the public, at the time of writing. The virus non-structural proteins are promising drug targets because of their vital role in the viral cycle. A significant body of work has been focused on finding inhibitors which covalently and competitively bind the active site of the non-structural proteins, but little has been done to address regions other than the active site, i.e. for non-competitive inhibition. Here we extend previous work on the SARS-CoV-2 Mpro (nsp5) to three other SARS-CoV-2 proteins: host shutoff factor (nsp1), papain-like protease (nsp3, also known as PLpro) and RNA-dependent RNA-polymerase (nsp12, also known as RdRp) in complex with nsp7 and nsp8 cofactors. Using open-source software (DDPT) to construct Elastic Network Models (ENM) of the chosen proteins we analyse their fluctuation dynamics and thermodynamics, as well as using this protein family to study convergence and robustness of the ENM. Exhaustive 2-point mutational scans of the ENM and their effect on fluctuation free energies suggest several new candidate regions, distant from the active site, for control of the proteins function, which may assist the drug development based on the current small molecule binding screens. The results also provide new insights, including non-additive effects of double-mutation or inhibition, into the active biophysical research field of protein fluctuation allostery and its underpinning dynamical structure.

Targeting Scavenger Receptor Type B-1 (SR-B1) and Cholesterol Inhibits Entry of SARS-CoV-2 Pseudovirus in Cell Culture (preprint)

The novel human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan, China in late 2019 and has now caused a global pandemic. The disease caused by SARS-CoV-2 is known as COVID-19. To date, few treatments for COVID-19 have proven effective, and the current standard of care is primarily supportive. As a result, novel therapeutic strategies are in high demand. Viral entry into target cells is frequently sensitive to cell membrane lipid composition and membrane organization. Evidence suggests that cell entry of SARS-CoV-2 is most efficient when the target cell plasma membrane is replete with cholesterol; and recent data implicate cholesterol flux through the high-affinity receptor for cholesterol-rich high-density lipoprotein (HDL), called scavenger receptor type B-1 (SR-B1), as critical for SARS-CoV-2 entry. Here, we demonstrate that a cholesterol-poor synthetic biologic high-density lipoprotein (HDL NP) targets SR-B1 and inhibits cell entry of a SARS-CoV-2 spike protein pseudovirus. Human cells expressing SR-B1 are susceptible to SARS-CoV-2 infection, and viral entry can be inhibited by 50-80% using HDL NPs in an SR-B1-dependent manner. These results indicate that HDL NP targeting of SR-B1 is a powerful potential therapy to combat COVID-19 and other viral diseases.

Structural Similarity of SARS-CoV2 Mpro and HCV NS3/4A Proteases Suggests New Approaches for Identifying Existing Drugs Useful as COVID-19 Therapeutics (preprint)

Abstract: During the current COVID-19 pandemic more than 160,000 people have died worldwide as of mid-April 2020, and the global economy has been crippled. Effective control of the SARS-CoV2 virus that causes the COVID-19 pandemic requires both vaccines and antivirals. Antivirals are particularly crucial to treat infected people during the period of time that an effective vaccine is being developed and deployed. Because the development of specific antiviral drugs can take a considerable length of time, an important approach is to identify existing drugs already approved for use in humans which could be repurposed as COVID-19 therapeutics. Here we focus on antivirals directed against the SARS-CoV2 Mpro protease, which is required for virus replication. A structural similarity search showed that the Hepatitis C virus (HCV) NS3/4A protease has a striking three-dimensional structural similarity to the SARS-CoV2 Mpro protease, particularly in the arrangement of key active site residues. We used virtual docking predictions to assess the hypothesis that existing drugs already approved for human use or clinical testing that are directed at the HCV NS3/4A protease might fit well into the active-site cleft of the SARS-CoV2 protease (Mpro). AutoDock docking scores for 12 HCV protease inhibitors and 9 HIV-1 protease inhibitors were determined and compared to the docking scores for an alpha-ketoamide inhibitor of Mpro, which has recently been shown to inhibit SARS-CoV2 virus replication in cell culture. We identified eight HCV protease inhibitors that bound to the Mpro active site with higher docking scores than the alpha-ketoamide inhibitor, suggesting that these protease inhibitors may effectively bind to the Mpro active site. These results provide the rationale for us to test the identified HCV protease inhibitors as inhibitors of the SARS-CoV2 protease, and as inhibitors of SARS-CoV2 virus replication. Subsequently these repurposed drugs could be evaluated as COVID-19 therapeutics.