Broad-Spectrum Cyclopropane-Based Inhibitors of Coronavirus 3C-like Proteases: Biochemical, Structural, and Virological Studies.

The advent of SARS-CoV-2, the causative agent of COVID-19, and its worldwide impact on global health, have provided the impetus for the development of effective countermeasures that can be deployed against the virus, including vaccines, monoclonal antibodies, and direct-acting antivirals (DAAs). Despite these efforts, the current paucity of DAAs has created an urgent need for the creation of an enhanced and diversified portfolio of broadly acting agents with different mechanisms of action that can effectively abrogate viral infection. SARS-CoV-2 3C-like protease (3CL), an enzyme essential for viral replication, is a validated target for the discovery of SARS-CoV-2 therapeutics.

Potent Protease Inhibitors of Highly Pathogenic Lagoviruses: Rabbit Hemorrhagic Disease Virus and European Brown Hare Syndrome Virus.

Rabbit hemorrhagic disease (RHD) and European brown hare syndrome (EBHS) are highly contagious diseases caused by lagoviruses in the family. These infectious diseases are associated with high mortality and a serious threat to domesticated and wild rabbits and hares, including endangered species such as riparian brush rabbits (). In the United States (U.

Effects of Spike Mutations in SARS-CoV-2 Variants of Concern on Human or Animal ACE2-Mediated Virus Entry and Neutralization.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a zoonotic agent capable of infecting humans and a wide range of animal species. Over the duration of the pandemic, mutations in the SARS-CoV-2 spike (S) protein have arisen, culminating in the spread of several variants of concern (VOCs) with various degrees of altered virulence, transmissibility, and neutralizing antibody escape. In this study, we used pseudoviruses that express specific SARS-CoV-2 S protein substitutions and cell lines that express angiotensin-converting enzyme 2 (ACE2) from nine different animal species to gain insights into the effects of VOC mutations on viral entry and antibody neutralization capability.

Structure-Guided Design of Potent Spirocyclic Inhibitors of Severe Acute Respiratory Syndrome Coronavirus-2 3C-like Protease.

The worldwide impact of the ongoing COVID-19 pandemic on public health has made imperative the discovery and development of direct-acting antivirals aimed at targeting viral and/or host targets. SARS-CoV-2 3C-like protease (3CL) has emerged as a validated target for the discovery of SARS-CoV-2 therapeutics because of the pivotal role it plays in viral replication. We describe herein the structure-guided design of highly potent inhibitors of SARS-CoV-2 3CL that incorporate in their structure novel spirocyclic design elements aimed at optimizing potency by accessing new chemical space.

Structure-Guided Design of Potent Inhibitors of SARS-CoV-2 3CL Protease: Structural, Biochemical, and Cell-Based Studies.

The COVID-19 pandemic is having a major impact on public health worldwide, and there is an urgent need for the creation of an armamentarium of effective therapeutics, including vaccines, biologics, and small-molecule therapeutics, to combat SARS-CoV-2 and emerging variants. Inspection of the virus life cycle reveals multiple viral- and host-based choke points that can be exploited to combat the virus. SARS-CoV-2 3C-like protease (3CLpro), an enzyme essential for viral replication, is an attractive target for therapeutic intervention, and the design of inhibitors of the protease may lead to the emergence of effective SARS-CoV-2-specific antivirals.

Effects of Spike Mutations in SARS-CoV-2 Variants of Concern on Human or Animal ACE2-Mediated Virus Entry and Neutralization.

Unlabelled: SARS-CoV-2 is a zoonotic agent capable of infecting humans and a wide range of animal species. Over the duration of the pandemic, mutations in the SARS-CoV-2 Spike protein (S) have arisen in circulating viral populations, culminating in the spread of several variants of concern (VOC) with varying degrees of altered virulence, transmissibility, and neutralizing antibody escape. In this study, we employed lentivirus-based pseudotyped viruses that express specific SARS-CoV-2 S protein substitutions and cell lines that stably express ACE2 from nine different animal species to gain insights into the effects of VOC mutations on viral entry and antibody neutralization capability.

Postinfection treatment with a protease inhibitor increases survival of mice with a fatal SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection continues to be a serious global public health threat. The 3C-like protease (3CLpro) is a virus protease encoded by SARS-CoV-2, which is essential for virus replication. We have previously reported a series of small-molecule 3CLpro inhibitors effective for inhibiting replication of human coronaviruses including SARS-CoV-2 in cell culture and in animal models.

3C-like protease inhibitors block coronavirus replication in vitro and improve survival in MERS-CoV-infected mice.

Pathogenic coronaviruses are a major threat to global public health, as exemplified by severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and the newly emerged SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19). We describe herein the structure-guided optimization of a series of inhibitors of the coronavirus 3C-like protease (3CLpro), an enzyme essential for viral replication. The optimized compounds were effective against several human coronaviruses including MERS-CoV, SARS-CoV, and SARS-CoV-2 in an enzyme assay and in cell-based assays using Huh-7 and Vero E6 cell lines.

Interactions of viruses and the humoral innate immune response.

The innate immune response is crucial for defense against virus infections where the complement system, coagulation cascade and natural antibodies play key roles. These immune components are interconnected in an intricate network and are tightly regulated to maintain homeostasis and avoid uncontrolled immune responses. Many viruses in turn have evolved to modulate these interactions through various strategies to evade innate immune activation.

Characterization of amino acid substitutions in feline coronavirus 3C-like protease from a cat with feline infectious peritonitis treated with a protease inhibitor.

Feline infectious peritonitis (FIP) is a highly fatal disease caused by a virulent feline coronavirus in domestic and wild cats. We have previously reported the synthesis of potent coronavirus 3C-like protease (3CLpro) inhibitors and the efficacy of a protease inhibitor, GC376, in client-owned cats with FIP. In this study, we studied the effect of the amino acid changes in 3CLpro of feline coronavirus from a feline patient who received antiviral treatment for prolonged duration.

Protease inhibitors broadly effective against feline, ferret and mink coronaviruses.

Ferret and mink coronaviruses typically cause catarrhal diarrhea in ferrets and minks, respectively. In recent years, however, systemic fatal coronavirus infection has emerged in ferrets, which resembles feline infectious peritonitis (FIP) in cats. FIP is a highly fatal systemic disease caused by a virulent feline coronavirus infection in cats.