GC376 / Anivive - LARVOL DELTA

The C117D oxidation mimic reveals the monomeric structure of SARS-CoV-2 main protease. (PubMed, Protein Sci) - "Rescue of the stable, dimeric state for C117D was achieved through formation of the covalent C117D-GC376 complex. These findings establish a high-resolution structure of monomeric full-length SARS-CoV-2 Mpro and underscore a critical role of C117 in maintaining dimerization and enzymatic function. Furthermore, the unique monomeric domain II-III interface present in the monomeric form may offer opportunities for allosteric inhibitor design targeting Mpro dimerization."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Systematic Modeling of Covalent Inhibitors of SARS-CoV-2 Main Protease and Its Mutants. (PubMed, ACS Catal) - "Among these, the aldehyde-based inhibitor H102 exhibits nanomolar inhibition of Mpro (IC50 = 8.8 nM), outperforming other reported inhibitors such as GC376 and the clinically approved nitrile-based inhibitor PF-07321332. Furthermore, we successfully predict the absolute binding free energies (ABFEs) of H102 and its analogues across wild-type and mutant Mpro variants, accurately reproducing experimental affinities and providing quantitative insight into how mutations impact inhibitor potency. Collectively, these findings not only elucidate the mechanistic basis of aldehyde-based covalent inhibition but also highlight the utility of ABFE-guided computational strategies in the rational design of potent, mutation-resilient antiviral therapeutics."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Repurposing FDA-Approved Drugs as Potential Inhibitors of Feline Infectious Peritonitis Virus 3CLpro: An Integrated In Silico and In Vitro Study with Synergistic Combination Analysis. (PubMed, ACS Pharmacol Transl Sci) - "Synergy analysis with established anti-FIP agents (GC376, remdesivir, GS-441524, and molnupiravir) using SynergyFinder 3.0 revealed strong synergistic interactions: saquinavir + GC376 (mean ZIP score: 54.59), lumacaftor + GC376 (mean ZIP: 21.44), and gliquidone + remdesivir (mean ZIP: 24.13). These rational combinations enable substantial dose reduction, offering practical strategies to improve treatment accessibility, reduce costs, and minimize adverse effects. This study establishes a framework for repurposing FDA-approved drugs in FIP therapy and supports translational evaluation of these combination regimens."

FDA event • Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • IFNB1 • IL6 • TNFA

PRISM-Gen: A physics-informed multi-fidelity framework for broad-spectrum coronavirus mpro inhibitor discovery. (PubMed, Comput Biol Chem) - "Applied to 4136 generated candidates, the pipeline identifies 36 broad-spectrum-consistent inhibitor candidates whose top-ranked members exhibit predicted worst-case binding energies comparable to those of the non-covalent reference inhibitor ensitrelvir under identical docking conditions, while sharing no Bemis-Murcko scaffolds with nirmatrelvir, ensitrelvir, or GC376. Retrospective analysis demonstrates that replacing GEM's continuous moderation with a conventional hard electronic cutoff would eliminate 48.0% of candidates, including 55.6% of the final 36 molecules, disproportionately depleting scaffold diversity. These results establish that continuous, physics-informed electronic moderation integrated within a multi-fidelity generative pipeline can recover structurally novel chemotypes that binary exclusion filters would irreversibly discard - a design principle applicable to generator-agnostic molecular discovery workflows."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Cell-Based Luciferase Assay for Testing SARS-CoV-2 3CL Protease Inhibitors. (PubMed, Biosensors (Basel)) - "IC50 values obtained in this system for nirmatrelvir and GC376 correlated with live-virus assay data but differed significantly from those of a cell-free FRET assay, reflecting the impact of cellular barriers. This approach combines simplicity, a standard substrate, and high reproducibility, making it promising for high-throughput screening in basic laboratory settings and adaptable to other viral proteases."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Update on Treatment of Feline Infectious Peritonitis: European Advisory Board on Cat Diseases (ABCD) Guidelines. (PubMed, Viruses) - "In these revised guidelines, the European Advisory Board on Cat Diseases (ABCD) presents an update on the treatment of FIP, incorporating the findings of new studies including the range of available treatments (such as GS-441524, remdesivir and molnupiravir (EIDD-2801) and its active metabolite EIDD-1931), which varies globally, as well as suggestions for monitoring and prognostic indicators...Remdesivir is primarily reserved as an injectable antiviral for severely affected cats unable to tolerate oral medication; it is usually replaced by oral medication as soon as, and when, possible. Although 84-day treatment courses have historically been used, emerging evidence suggests that shorter regimens of 42 days can be equally effective."

Journal • Review • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Development of a Complementation Assay to Monitor Pan-Coronavirus 3C-like Protease Activity. (PubMed, Viruses) - "Using the broad-spectrum 3CLpro inhibitor GC376, we observed increased reporter activity, indicating the assay's efficacy for identifying inhibitors across multiple coronaviruses. The adaptation and improvement of the assay can facilitate the development of inhibitors against 3CLpro from multiple or novel coronaviruses."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases • SPECC1

Electrophilic warhead engagement and structure-activity relationship of Benzothiazole-based putative covalent inhibitors targeting SARS-CoV-2 Main protease. (PubMed, Bioorg Chem) - "Lead optimization afforded highly potent derivatives, notably compound 35 (IC50 = 0.026 μM), exhibiting superior potency compared to GC376 and an exceptionally high selectivity index (10,653.8), indicating a favorable potency and safety profile...MD simulations confirmed that compound 35 stabilized the protein structure with enhanced compactness, stable interactions, and reduced conformational fluctuations compared to the apo protein. Collectively, these findings highlight benzothiazole-based scaffolds as promising SARS-CoV-2 Mpro inhibitors."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Conquering viral drug resistance: Structural and mechanistic paradigms for antiresistance drug design. (PubMed, Pharm Sci Adv) - "For SARS-CoV-2, GC376's flexible benzyl group overcomes nirmatrelvir resistance. HIV-1's non-nucleoside reverse transcriptase inhibitors (NNRTIs) 5i3 adapts to resistant mutants via a quinazoline scaffold, while MPXV's tecovirimat acts as a "molecular glue" stabilizing F13 dimers...Key strategies include dynamic flexibility, multivalent interactions, and oligomerization control, integrated with AI-driven design and real-time surveillance. This perspective bridges structural insights with translational applications, offering a roadmap for next-generation, mutation-resilient antivirals."

Journal • Review • Hepatitis B • Human Immunodeficiency Virus • Infectious Disease • Inflammation • Influenza • Novel Coronavirus Disease • Respiratory Diseases • Targeted Protein Degradation

Structural Analysis of Inhibitor Binding to the Feline Enteric Coronavirus (FECV) Main Protease. (PubMed, Viruses) - "This study presents crystal structures of four clinically relevant inhibitors-GC376, PF-00835231, nirmatrelvir, and ibuzatrelvir-bound to Mpro from the feline coronavirus strain FECV-UU23. We therefore propose to incorporate sterically constrained, functionally tailored heterocyclic moieties at the P3 site of known inhibitors which can optimally engage Q187, P188, and S189 residues of the S4 loop. The findings presented enhance understanding of inhibitor specificity and reinforce the promise of these inhibitor scaffolds for developing antivirals against feline coronavirus strains, with possible applications in broad-spectrum coronavirus therapy."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Development of a Cell-Based Recombinant Green Fluorescent Protein Assay System for Generalized Discovery of Viral Protease Inhibitors. (PubMed, ACS Pharmacol Transl Sci) - "For proof of concept, we validated this method using two well-characterized SARS-CoV-2 3CLpro inhibitors, GC376 and ensitrelvir, to demonstrate its applicability for inhibitor screening. Our results indicate that the DIFF-rGFP assay is a safe, efficient, and reliable platform for identifying viral protease inhibitors with potential applications in accelerating antiviral drug discovery."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Glycosylated 18β-glycyrrhetinic acid derivatives as promising inhibitors of the SARS-CoV-2 main protease. (PubMed, RSC Adv) - "Biolayer interferometry revealed favorable binding affinities and reversible interactions with Mpro, while molecular docking demonstrated their stable binding conformations resembling that of GC376. These glycosides also showed improved predicted oral bioavailability and physicochemical profiles. Our findings support the potential of glycosylated 18β-GA derivatives as cost-effective and scalable antiviral candidates targeting SARS-CoV-2 Mpro."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Development of GFP-expressing infectious clones for PRRSV using TAR cloning for antiviral drug screening. (PubMed, Npj Viruses) - "Screening SARS-CoV-2 antivirals showed potent inhibition by the multitarget drug ribavirin, the polymerase inhibitors remdesivir and its metabolite GS-441524. Molnupiravir, targeting the polymerase by a different mechanism, showed reduced efficacy against PRRSV, while the protease inhibitor GC376 was ineffective...In contrast, structural divergence in proteases correlated with GC376's inefficacy. These findings underscore the utility of the TAR cloning for arterivirus engineering, with potential applications in vector vaccine development."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

A MAGNETIC BEAD-BASED FLUORESCENT SUBSTRATE FOR SENSITIVE ASSAY OF SARS-CoV-2 3C-LIKE PROTEASE ACTIVITY. (PubMed, Protein Expr Purif) - "The assay showed ∼50-fold greater sensitivity compared to SDS-PAGE and the inhibitory effect of GC376 for 3CLpro was also determined, with IC50 of 0.88 μM. Since the modular substrate design allows for substitution of the N-terminal domain and cleavage motif, our development of the substrate and assay could be expanded to other high-specificity proteases."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Antiviral and Immunomodulatory Effects of α-Mangostin Against Feline Infectious Peritonitis Virus: In Vitro Assay. (PubMed, Animals (Basel)) - "Drug combination studies using the ZIP model revealed enhanced cooperative effects when AMEs and α-MG were combined with GC-376 or GS-441524, with GC-376 combinations showing particularly strong synergistic potential. These findings suggest that α-MG and AMEs are promising candidates for FIPV treatment, either as monotherapy or in combination therapy. This study provides insights into developing novel therapeutic strategies to combat FIPV infections and offers a foundation for future veterinary antiviral drug development."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • IFNB1 • IL6 • TNFA

Enzyme kinetics model for the coronavirus main protease including dimerization and ligand binding. (PubMed, Biophys J) - "The reversible covalent inhibitor GC376 strongly induces dimerization and binds to the dimer with no cooperativity. In contrast, the fluorescent peptide substrate has a minor effect on dimerization but binds to the dimer with positive cooperativity. The biphasic concentration response curve occurs because compared to substrate, the inhibitor accelerates turnover in the opposite catalytic site."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

3CLpro of SARS-CoV-2 as a new target for bufadienolides: in silico and in vitro study. (PubMed, J Comput Aided Mol Des) - "In vitro enzymatic assays also confirmed these results, demonstrating that A and C exhibited potent inhibitory activity against 3CLpro with IC50 values of 1.37 µM and 2 µM, respectively, compared to the other bufadienolides; however, they were less active than the positive control GC376 (IC50 = 0.27 µM)...In silico ADME profiling also revealed good pharmacokinetic properties, indicating that bufadienolides A-F are lead compounds for further antiviral drug development. Taken together, our results support the hypothesis that bufadienolides are SARS-CoV-2 3CLpro inhibitors and elucidate their mechanism of action, thereby laying the foundation for potential therapeutic advances against COVID-19."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Novel SARS-CoV-2 allosteric inhibitors that destabilize the Main Protease Mpro dimer. (PubMed, Int J Biol Macromol) - "Molecular modelling studies suggested that compounds 1 and 11 bind Mpro similarly to the allosteric inhibitor AT7519. Small-angle X-ray scattering studies revealed that 1 and 11 strongly shift Mpro equilibrium to the monomeric form, while the allosteric inhibitor pelitinib and the catalytic inhibitors nirmatrelvir and GC376 stabilize the dimer. Compounds 1 and 11 inhibited Mpro proteolytic activity in SARS-CoV-2 infected cells acting as allosteric inhibitors that stabilize the monomeric form. In conclusion, we validated an allosteric site in Mpro that could be exploited for the development of effective anti-SARS-CoV-2 antivirals targeting Mpro with a novel mechanism."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Strategy to overcome a nirmatrelvir resistance mechanism in the SARS-CoV-2 nsp5 protease. (PubMed, Sci Adv) - "E166V in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nsp5 protease confers strong resistance to the antiviral component of Paxlovid, nirmatrelvir (NIR), in passaging and clinical samples. Crystal structures reveal a steric clash between the rigid, bulky NIR tert-butyl group and the β-branched Val166, disrupting the covalent binding of NIR to the catalytic Cys145 and leading to high resistance in BA.1 and WA1 replicons. NIR-resistant replicons remained susceptible to GC376, which can still covalently bind Cys145 by avoiding a steric clash with Val166 through "wiggling and jiggling." Hence, strategic flexibility is a strategy that will help design second-generation antivirals against NIR-resistant viruses."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases • SPECC1

Development of a highly sensitive luciferase assay for intracellular evaluation of coronavirus Mpro activity. (PubMed, Front Microbiol) - "Additionally, the system proved suitable for evaluating and screening of antiviral compounds, including lufotrelvir, GC376, Nirmatrelvir, X77, MG-101, and the potential inhibitor Cynaroside. The ICMP system is not only an invaluable tool for the detection of live coronaviruses, but also for the discovery of antivirals against current and future pandemic coronaviruses."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Mycophenolate mofetil exerts broad-spectrum antiviral activity against coronaviruses including SARS-CoV-2. (PubMed, Virol J) - "MMF and MPA exerted broad-spectrum anti-coronavirus effects by inhibiting IMPDH activity. MMF had a synergistic antiviral effect when combined with other drugs, showing its potential clinical antiviral applications."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Multiview Deep Learning-Based Molecule Design and Structural Optimization Accelerates Inhibitor Discover. (PubMed, IEEE Trans Neural Netw Learn Syst) - "Moreover, case study results on targeted molecule generation for the SARS-CoV-2 main protease (Mpro) show that we successfully generate new small molecules with desired drug-like properties for the Mpro by integrating molecular docking into our model as a chemical priori, potentially accelerating the de novo design of COVID-19 drugs. Furthermore, we apply MEDICO to the structural optimization of three well-known Mpro inhibitors (N3, 11a, and GC376) and achieve ˜88% improvement compared with the origin inhibitors in their binding affinity to Mpro, demonstrating the application value of our model for the development of therapeutics for SARS-CoV-2 infection."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Exploring Possible Drug-Resistant Variants of SARS-CoV-2 Main Protease (Mpro) with Noncovalent Preclinical Candidate, Mpro61. (PubMed, ACS Bio Med Chem Au) - "We investigated their kinetic and structural properties, as well as resistance level to Mpro inhibitors: nirmatrelvir, GC376-a similar peptidomimetic for feline COVID infections, and our in-house-developed nonpeptidomimetic inhibitor Mpro61. The new orientation of the Ser1 suggested potential strategies for medicinal chemistry modifications of Mpro61 to enhance hydrogen-bonding interactions between these variants and Mpro61 derivatives. These studies provide critical insights into guiding the future design of additional Mpro61 derivatives that would potentially inhibit variants with the pan-drug-resistant E166V mutation."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Computational and in vitro evaluation of sumac-derived ©Rutan compounds towards Sars-CoV-2 Mpro inhibition. (PubMed, Front Pharmacol) - "Initially, for the docking protocol validation, redocking of the co-crystal ligand GC-376* to the binding pocket of Mpro was carried out...All five components effectively interact with the catalytic pocket of Mpro and form stable complexes that allow the estimation of their inhibitory activity. Assay kit analyses revealed that Rutan and its components have effective anti-SARS-CoV-2 Mpro inhibitory activity."

Journal • Preclinical • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases

Enzyme kinetics model for the coronavirus main protease including dimerization and ligand binding. (PubMed, bioRxiv) - "The reversible covalent inhibitor GC376 strongly induces dimerization and binds to the dimer with no cooperativity. In contrast, the fluorescent peptide substrate has a minor effect on dimerization but binds to the dimer with positive cooperativity. The biphasic concentration response curve occurs because compared to substrate, the inhibitor accelerates turnover in the opposite catalytic site."

Journal • Infectious Disease • Novel Coronavirus Disease • Respiratory Diseases