Development Of Antiviral Drugs Research Articles

Acetylation of the NS3 helicase by KAT5γ is essential for flavivirus replication

Direct targeting of essential viral enzymes such as proteases, polymerases, and helicases has long been the major focus of antiviral drug design. Although successful for some viral enzymes, targeting viral helicases is notoriously difficult to achieve, demanding alternative strategies. Here, we show that the NS3 helicase of Zika virus (ZIKV) undergoes acetylation in its RNA-binding tunnel. Regulation of the acetylated state of K389 in ZIKV NS3 modulates RNA binding and unwinding and is required for efficient viral replication. NS3 acetylation is mediated by a specific isoform of the host acetyltransferase KAT5 (KAT5γ), which translocates from the nucleus to viral replication complexes upon infection. NS3 acetylation by KAT5γ and its proviral role are also conserved in West Nile virus (WNV), dengue virus (DENV), and yellow fever virus (YFV). Our study provides molecular insight into how a cellular acetyltransferase regulates viral helicase functions, unveiling a previously unknown target for antiviral drug development.

Membrane activity of viral proteins.

COVID-19 infection, caused by the SARS-CoV-2 coronavirus, has led to the largest pandemic since the Spanish flu in 1918. In view of this, the development of vaccines and antiviral drugs that can stop the spread of this infection has become an acute issue. Currently, in the search for antiviral drugs against COVID-19, much attention is paid to the study of the structure of the receptor-binding domain of the surface protein S. However, the emergence of new SARS-CoV-2 coronavirus strains indicates its high variability, which reduces the effectiveness of vaccines and antiviral drugs. At the same time, the envelope protein E of this virus is membrane active and shows a rather high conservatism. Despite the critical importance of this protein in the coronavirus life cycle, the physicochemical mechanisms of its interaction with cell membranes still remain unclear. So, we investigated the membrane activity of protein E of the SARS-CoV-2 coronavirus on models of giant unilamellar vesicles and lipid nanotubes. As a result, it was found that the protein forms pores in the lipid bilayer, i.e., performs the main function of viroporin. In addition, protein E is able to deform lipid membranes and form double-membrane vesicles depending on the concentration.

Potential pharmacokinetic interactions with concurrent use of herbal medicines and a ritonavir-boosted COVID-19 protease inhibitor in low and middle-income countries.

The COVID-19 pandemic sparked the development of novel anti-viral drugs that have shown to be effective in reducing both fatality and hospitalization rates in patients with elevated risk for COVID-19 related morbidity or mortality. Currently, nirmatrelvir/ritonavir (Paxlovid™) fixed-dose combination is recommended by the World Health Organization for treatment of COVID-19. The ritonavir component is an inhibitor of cytochrome P450 (CYP) 3A, which is used in this combination to achieve needed therapeutic concentrations of nirmatrelvir. Because of the critical pharmacokinetic effect of this mechanism of action for Paxlovid™, co-administration with needed medications that inhibit or induce CYP3A is contraindicated, reflecting concern for interactions with the potential to alter the efficacy or safety of co-administered drugs that are also metabolized by CYP3A. Some herbal medicines are known to interact with drug metabolizing enzymes and transporters, including but not limited to inhibition or induction of CYP3A and P-glycoprotein. As access to these COVID-19 medications has increased in low- and middle-income countries (LMICs), understanding the potential for herb-drug interactions within these regions is important. Many studies have evaluated the utility of herbal medicines for COVID-19 treatments, yet information on potential herb-drug interactions involving Paxlovid™, specifically with herbal medicines commonly used in LMICs, is lacking. This review presents data on regionally-relevant herbal medicine use (particularly those promoted as treatments for COVID-19) and mechanism of action data on herbal medicines to highlight the potential for herbal medicine interaction Herb-drug interaction mediated by ritonavir-boosted antiviral protease inhibitors This work highlights potential areas for future experimental studies and data collection, identifies herbal medicines for inclusion in future listings of regionally diverse potential HDIs and underscores areas for LMIC-focused provider-patient communication. This overview is presented to support governments and health protection entities as they prepare for an increase of availability and use of Paxlovid™.

Synthesis of multivalent sialyllactose-conjugated PAMAM dendrimers: Binding to SARS-CoV-2 spike protein and influenza hemagglutinin

Severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) and influenza viruses have spread around the world at an unprecedented rate. Despite multiple vaccines, new variants of SARS-CoV-2 and influenza have caused a remarkable level of pathogenesis. The development of effective antiviral drugs to treat SARS-CoV-2 and influenza remains a high priority. Inhibiting viral cell surface attachment represents an early and efficient means to block virus infection. Sialyl glycoconjugates, on the surface of human cell membranes, play an important role as host cell receptors for influenza A virus and 9-O-acetyl-sialylated glycoconjugates are receptors for MERS, HKU1 and bovine coronaviruses. We designed and synthesized multivalent 6′-sialyllactose-counjugated polyamidoamine dendrimers through click chemistry at room temperature concisely. These dendrimer derivatives have good solubility and stability in aqueous solutions. SPR, a real-time analysis quantitative method for of biomolecular interactions, was used to study the binding affinities of our dendrimer derivatives by utilizing only 200 micrograms of each dendrimer. Three SARS-CoV-2 S-protein receptor binding domain (wild type and two Omicron mutants) bound to multivalent 9-O-acetyl-6′-sialyllactose-counjugated and 6′-sialyllactose-counjugated dendrimers bound to a single H3N2 influenza A virus's HA protein (A/Hong Kong/1/1968), the SPR study results suggest their potential anti-viral activities.

Investigating theobromine as a potential anti-human coronaviral agent.

Coronaviruses (CoVs) have long been known to infect humans, mainly alpha-CoV and beta-CoV. The vaccines developed for SARS-CoV-2 are likely not effective against other coronavirus species, whereas the risk of the emergence of new strains that may cause the next epidemic/pandemic is high. The development of antiviral drugs that are effective across different CoVs represents a viable strategy for improving pandemic preparedness. In this study, we aim to identify pan-coronaviral agents by targeting the conserved main protease (Mpro). For drug screening, the catalytic dyad of four human CoVs (HCoVs: SARS-CoV-2, and seasonal CoV NL63, OC43, and 229E) was targeted by molecular docking. The identified leading candidate theobromine, a xanthine derivative, was further tested in cell culture models of coronavirus infection. Theobromine binds strongly with the catalytic dyad (His41 and Cys144/145) of SARS-CoV-2 and HCoV-NL63 Mpro, mildly with HCoV-OC43, but not with HCoV-229E. However, theobromine only shows dose-dependent inhibition in Calu3 cells inoculated with SARS-CoV-2, but not in cells inoculated with seasonal CoVs. Theobromine exerts antiviral activity against coronavirus infections potentially through targeting Mpro. However, the antiviral potency is distinct among different CoVs.

Programmable Proteolysis-Activated Transcription for Highly Sensitive Ratiometric Electrochemical Detection of Viral Protease.

Viral proteases play a crucial role in viral infection and are regarded as promising targets for antiviral drug development. Consequently, biosensing methods that target viral proteases have contributed to the study of virus-related diseases. This work presents a ratiometric electrochemical sensor that enables highly sensitive detection of viral proteases through the integration of target proteolysis-activated in vitro transcription and the DNA-functionalized electrochemical interface. In particular, each viral protease-mediated proteolysis triggers the transcription of multiple RNA outputs, leading to amplified ratiometric signals on the electrochemical interface. Using the NS3/4A protease of the hepatitis C virus as a model, this method achieves robust and specific NS3/4A protease sensing with sub-femtomolar sensitivity. The feasibility of this sensor was demonstrated by monitoring NS3/4A protease activities in virus-infected cell samples with varying viral loads and post-infection times. This study provides a new approach to analyzing viral proteases and holds the potential for developing direct-acting antivirals and novel therapies for viral infections.

A Quest for Disease X: Origin, Location, and Mitigation

In February 2018, the World Health Organization (WHO) designated "Disease X" as a placeholder for a hypothetical and unidentified pathogen capable of potentially causing an epidemic in the future. The Covid-19 pandemic that unfolded recently has highlighted the emergence of a highly contagious Disease X, serving as a painful reminder of the potential risks we confront. This article aims to explore the emergence of Disease X, its possible origins, and proposes strategies to improve preparedness for such scenarios. Firstly, Disease X is probably a highly infectious zoonotic virus with RNA as its genetic material. Secondly, factors that may contribute to the emergence of the disease, including population density, ecological deterioration, and medical resources. Finally, barriers to the development of antiviral drugs and vaccines are examined, along with recommendations for social and ecological measures to enhance our preparedness for disease X.

Untargeted-based metabolomics analysis and in vitro/in silico antiviral activity of extracts from Phyllanthus brasiliensis (Aubl.) Poir.

This study describes the molecular profile and the potential antiviral activity of extracts from Phyllanthus brasiliensis, a plant widely found in the Brazilian Amazon. The research aims to shed light on the potential use of this species as a natural antiviral agent. The extracts were analysed using liquid chromatography-mass spectrometry (LC-MS) system, a potent analytical technique to discover drug candidates. In the meantime, in vitro antiviral assays were performed against Mayaro, Oropouche, Chikungunya, and Zika viruses. In addition, the antiviral activity of annotated compounds was predicted by in silico methods. Overall, 44 compounds were annotated in this study. The results revealed that P. brasiliensis has a high content of fatty acids, flavones, flavan-3-ols, and lignans. Furthermore, in vitro assays revealed potent antiviral activity against different arboviruses, especially lignan-rich extracts against Zika virus (ZIKV), as follows: methanolic extract from bark (MEB) [effective concentration for 50% of the cells (EC50 ) = 0.80 μg/mL, selectivity index (SI) = 377.59], methanolic extract from the leaf (MEL) (EC50 = 0.84 μg/mL, SI = 297.62), and hydroalcoholic extract from the leaf (HEL) (EC50 = 1.36 μg/mL, SI = 735.29). These results were supported by interesting in silico prediction, where tuberculatin (a lignan) showed a high antiviral activity score. Phyllanthus brasiliensis extracts contain metabolites that could be a new kick-off point for the discovery of candidates for antiviral drug development, with lignans becoming a promising trend for further virology research.

Identification of a receptor tyrosine kinase inhibitor CP-724714 inhibits SADS-CoV related swine diarrhea coronaviruses infection in vitro

The outbreak of the COVID-19 epidemic in 2020 has caused unprecedented panic among all mankind, pointing the major importance of effective treatment. Since the emergence of the swine acute diarrhea syndrome coronavirus (SADS-CoV) at the end of 2017, multiple reports have indicated that the bat-related SADS-CoV possesses a potential threat for cross-species transmission. Vaccines and antiviral drugs development deserve more attention. In this study, we found that the HER2 phosphorylation inhibitor (CP-724714) inhibited SADS-CoV infection in a dose-dependent manner. Further validation demonstrated that CP-724714 affected at the post-entry stage of SADS-CoV infection cycle. Also, efficient SADS-CoV infection required the activation of HER2 and its cascade Ras-Raf-Mek-Erk signaling pathway. In addition, CP-724714 has a broad-spectrum anti-swine diarrhea coronaviruses activity, and can dose-dependently combat SADS-CoV, porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV) and transmissible gastroenteritis virus (TGEV) infection in vitro with a specificity index of greater than 21.98, 9.38, 95.23 and 31.62, respectively. These results highlight the potential utility of CP-724714 or antiviral drugs targeting with HER2 and its cascade Ras-Raf-Mek-Erk signaling pathway as host-targeted SADS-CoV and other related coronaviruses therapeutics.

Herbal Therapeutics as Potential Prophylaxis for SARS-CoV-2 Infection

Introduction: The global pandemic COVID-19 and its uncontrolled spread and lack of effective therapeutics demand to investigate the herbal resources in search of novel, safe and potent therapeutics. Herbal medicines have proven the advantage of multi-target potential and thus can be investigated for virus-host interaction protein and viral protein targets. Objectives: Manuscript aims to provide an outcome-based analysis of studies performed towards evaluation of herbal compounds as anti-COVID agents. The studies focus on the proposed mechanism of viral inhibition by herbal compounds. Methods: The details on modern drug discovery approaches for investigation of potential antiviral agents includes in silico screening, ADMET and molecular docking studies. It helps to establish the probable mechanism of viral inhibition as well as to establish pharmacophore. The reports explaining role of herbal therapeutics/phytochemicals in antiviral drug development have been thoroughly searched. Results: The study summarizes herbal therapeutics and phytochemicals based on their antiviral properties against various pathogenic viruses. Herbal compounds that have an interesting role in the development of therapeutics and herd immunity against SARS-CoV-2 are included and discussed. Conclusion: The manuscript provides a summarized description of herbal resources and phytochemicals which are under investigation or have been investigated as potential therapeutic option for SARS-COV-2 inhibition. It will be a useful resource for researchers interested in the development of herbal therapeutics for the prevention and/or treatment of COVID-19.

Structural Modifications Introduced by NS2B Cofactor Binding to the NS3 Protease of the Kyasanur Forest Disease Virus

Kyasanur Forest Disease virus (KFDV), a neglected human pathogenic virus, is a Flavivirus that causes severe hemorrhagic fever in humans. KFDV is transmitted to humans by the bite of the hard tick (Haemaphysalis spinigera), which acts as a reservoir of KFDV. The recent expansion of the endemic area of KFDV is of concern and requires the development of new preventive measures against KFDV. Currently, there is no antiviral therapy against KFDV, and the existing vaccine has limited efficacy. To develop a new antiviral therapy against KFDV, we focused on the nonstructural proteins NS2B and NS3 of KFDV, which are responsible for serine protease activity. Viral proteases have shown to be suitable therapeutic targets in the development of antiviral drugs against many diseases. However, success has been limited in flaviviruses, mainly because of the important features of the active site, which is flat and highly charged. In this context, the present study focuses on the dynamics of NS2B and NS3 to identify potential allosteric sites in the NS2B/NS3 protease of KDFV. To our knowledge, there are no reports on the dynamics of NS2B and NS3 in KFDV, and the crystal structure of the NS2B/NS3 protease of KFDV has not yet been solved. Overall, we created the structure of the NS2B/NS3 protease of KFDV using AlphaFold and performed molecular dynamics simulations with and without NS2B cofactor to investigate structural rearrangements due to cofactor binding and to identify alternative allosteric sites. The identified allosteric site is promising due to its geometric and physicochemical properties and druggability and can be used for new drug development. The applicability of the proposed allosteric binding sites was verified for the best-hit molecules from the virtual screening and MD simulations.

The Host E3-Ubiquitin Ligase TRIM28 Impedes Viral Protein GP4 Ubiquitination and Promotes PRRSV Replication.

Porcine reproductive and respiratory syndrome (PRRS), caused by the PRRS virus (PRRSV), is a highly pathogenic porcine virus that brings tremendous economic losses to the global swine industry. PRRSVs have evolved multiple elegant strategies to manipulate the host proteins and circumvent against the antiviral responses to establish infection. Therefore, the identification of virus-host interactions is critical for understanding the pathogenesis of PRRSVs. Tripartite motif protein 28 (TRIM28) is a transcriptional co-repressor involved in the regulation of viral and cellular transcriptional programs; however, its precise role in regulating PRRSV infection remains unknown. In this study, we found that the mRNA and protein levels of TRIM28 were up-regulated in PRRSV-infected porcine alveolar macrophages (PAMs) and MARC-145 cells. Ectopic TRIM28 expression dramatically increased viral yields, whereas the siRNA-mediated knockdown of TRIM28 significantly inhibited PRRSV replication. Furthermore, we used a co-immunoprecipitation (co-IP) assay to demonstrate that TRIM28 interacted with envelope glycoprotein 4 (GP4) among PRRSV viral proteins. Intriguingly, TRIM28 inhibited the degradation of PRRSV GP4 by impeding its ubiquitination. Taken together, our work provides evidence that the host E3-ubiquitin ligase TRIM28 suppresses GP4 ubiquitination and is important for efficient virus replication. Therefore, our study identifies a new host factor, TRIM28, as a potential target in the development of anti-viral drugs against PRRSV.

DeepCoVDR: deep transfer learning with graph transformer and cross-attention for predicting COVID-19 drug response.

The coronavirus disease 2019 (COVID-19) remains a global public health emergency. Although people, especially those with underlying health conditions, could benefit from several approved COVID-19 therapeutics, the development of effective antiviral COVID-19 drugs is still a very urgent problem. Accurate and robust drug response prediction to a new chemical compound is critical for discovering safe and effective COVID-19 therapeutics. In this study, we propose DeepCoVDR, a novel COVID-19 drug response prediction method based on deep transfer learning with graph transformer and cross-attention. First, we adopt a graph transformer and feed-forward neural network to mine the drug and cell line information. Then, we use a cross-attention module that calculates the interaction between the drug and cell line. After that, DeepCoVDR combines drug and cell line representation and their interaction features to predict drug response. To solve the problem of SARS-CoV-2 data scarcity, we apply transfer learning and use the SARS-CoV-2 dataset to fine-tune the model pretrained on the cancer dataset. The experiments of regression and classification show that DeepCoVDR outperforms baseline methods. We also evaluate DeepCoVDR on the cancer dataset, and the results indicate that our approach has high performance compared with other state-of-the-art methods. Moreover, we use DeepCoVDR to predict COVID-19 drugs from FDA-approved drugs and demonstrate the effectiveness of DeepCoVDR in identifying novel COVID-19 drugs. https://github.com/Hhhzj-7/DeepCoVDR.

Synergistic antiviral activity of Lactobacillus acidophilus and Glycyrrhiza glabra against Herpes Simplex-1 Virus (HSV-1) and Vesicular Stomatitis Virus (VSV): experimental and In Silico insights

BackgroundThe emergence of different viral infections calls for the development of new, effective, and safe antiviral drugs. Glycyrrhiza glabra is a well-known herbal remedy possessing antiviral properties.ObjectiveThe objective of our research was to evaluate the effectiveness of a newly developed combination of the probiotics Lactobacillus acidophilus and G. glabra root extract against two viral models, namely the DNA virus Herpes simplex virus-1 (HSV-1) and the RNA virus Vesicular Stomatitis Virus (VSV), with regards to their antiviral properties.MethodologyTo examine the antiviral impacts of various treatments, we employed the MTT assay and real-time PCR methodology.ResultsThe findings of our study indicate that the co-administration of L. acidophilus and G. glabra resulted in a significant improvement in the survival rate of Vero cells, while also leading to a reduction in the titers of Herpes Simplex Virus Type 1 (HSV-1) and Vesicular Stomatitis Virus (VSV) in comparison to cells that were not treated. Additionally, an investigation was conducted on glycyrrhizin, the primary constituent of G. glabra extract, utilizing molecular docking techniques. The results indicated that glycyrrhizin exhibited a greater binding energy score for HSV-1 polymerase (− 22.45 kcal/mol) and VSV nucleocapsid (− 19.77 kcal/mol) in comparison to the cocrystallized ligand (− 13.31 and − 11.44 kcal/mol, respectively).ConclusionsThe combination of L. acidophilus and G. glabra extract can be used to develop a new, natural antiviral agent that is safe and effective.

Designing a Multi-Epitope Subunit Vaccine against VP1 Major Coat Protein of JC Polyomavirus.

The JC polyomavirus virus (JCPyV) affects more than 80% of the human population in their early life stage. It mainly affects immunocompromised individuals where virus replication in oligodendrocytes and astrocytes may lead to fatal progressive multifocal encephalopathy (PML). Virus protein 1 (VP1) is one of the major structural proteins of the viral capsid, responsible for keeping the virus alive in the gastrointestinal and urinary tracts. VP1 is often targeted for antiviral drug and vaccine development. Similarly, this study implied immune-informatics and molecular modeling methods to design a multi-epitope subunit vaccine targeting JCPyV. The VP1 protein epitopic sequences, which are highly conserved, were used to build the vaccine. This designed vaccine includes two adjuvants, five HTL epitopes, five CTL epitopes, and two BCL epitopes to stimulate cellular, humoral, and innate immune responses against the JCPyV. Furthermore, molecular dynamics simulation (100 ns) studies were used to examine the interaction and stability of the vaccine protein with TLR4. Trajectory analysis showed that the vaccine and TLR4 receptor form a stable complex. Overall, this study may contribute to the path of vaccine development against JCPyV.

Coreceptor AXL Facilitates African Swine Fever Virus Entry via Apoptotic Mimicry.

African swine fever (ASF) is an acute and hemorrhagic infectious disease caused by African swine fever virus (ASFV), which is listed as an animal epidemic disease that must be reported by The World Organization for Animal Health and that causes serious economic losses to China and even the whole world. Currently, the entry mechanism of ASFV is not fully understood. Especially in the early stages of virus entry, the host factors required for ASFV entry have not yet been identified and characterized. In this study, we demonstrated that ASFV externalized phosphatidylserine (PS) on the envelope functioned as viral apoptotic mimicry, which interacts with AXL, a tyrosine kinase receptor, to mediate ASFV entry into porcine alveolar macrophages (PAMs). We found that AXL was the most pronounced phosphatidylserine receptor (PSR) affecting ASFV entry in PAMs by RNA interference screening. Knockout AXL gene expression remarkably decreased ASFV internalization and replication in MA104 cells. Furthermore, the antibody against AXL extracellular domains effectively inhibited the ASFV entry. Consistent with these results, the deletion of the intracellular kinase domain of AXL and the treatment of the AXL inhibitor, R428, significantly inhibited the internalization of ASFV. Mechanistically, AXL facilitated the internalization of ASFV virions via macropinocytosis. Collectively, we provide evidence that AXL is a coreceptor for ASFV entry into PAMs, which expands our knowledge of ASFV entry and provides a theoretical basis for identifying new antiviral targets. IMPORTANCE African swine fever (ASF) is a highly contagious infectious disease caused by the ASF virus (ASFV), with a mortality rate of up to 100%. ASFV has caused huge economic losses to pig farming worldwide. Specific cellular surface receptors are considered crucial determinants of ASFV tropism. However, the host factors required for ASFV entry have not yet been identified, and the molecular mechanism of its entry remains unclear. Here, we found that ASFV utilized phosphatidylserine (PS) on the surface of virions to masquerade as apoptotic mimicry and facilitated virus entry by interacting with host factor AXL. We found that knockout of AXL remarkably decreased ASFV internalization and replication. The antibody against AXL extracellular domains and AXL inhibitor R428 significantly inhibited the internalization of ASFV via macropinocytosis. The current work deepens our understanding of ASFV entry and provides clues for the development of antiviral drugs to control ASFV infection.

MLST8 is essential for coronavirus replication and regulates its replication through the mTORC1 pathway.

Coronaviruses (CoVs), which pose a serious threat to human and animal health worldwide, need to hijack host factors to complete their replicative cycles. However, the current study of host factors involved in CoV replication remains unknown. Here, we identified a novel host factor, mammalian lethal with sec-13 protein 8 (mLST8), which is a common subunit of mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), and is critical for CoV replication. Inhibitor and knockout (KO) experiments revealed that mTORC1, but not mTORC2, is essential for transmissible gastroenteritis virus replication. Furthermore, mLST8 KO reduced the phosphorylation of unc-51-like kinase 1 (ULK1), a factor downstream of the mTORC1 signaling pathway, and mechanistic studies revealed that decreased phosphorylation of the mTORC1 downstream factor ULK1 promoted the activation of autophagy, which is responsible for antiviral replication in mLST8 KO cells. Then, transmission electron microscopy indicated that both mLST8 KO and autophagy activator inhibited the formation of double-membrane vesicles in early viral replication. Finally, mLST8 KO and autophagy activator treatment could also inhibit the replication of other CoVs, indicating a conserved relationship between autophagy activation and CoV replication. In summary, our work reveals that mLST8 is a novel host regulator of CoV replication, which provides new insights into the mechanism of CoV replication and can facilitate the development of broad-spectrum antiviral drugs. IMPORTANCE CoVs are highly variable, and existing CoV vaccines are still limited in their ability to address mutations in CoVs. Therefore, the need to improve our understanding of the interaction of CoVs with the host during viral replication and to find targets for drugs against CoVs is urgent. Here, we found that a novel host factor, mLST8, is critical for CoV infection. Further studies showed that mLST8 KO inhibited the mTORC1 signaling pathway, and we found that autophagy activation downstream of mTORC1 was the main cause of antiviral replication in mLST8 KO cells. Autophagy activation impaired the formation of DMVs and inhibited early viral replication. These findings deepen our understanding of the CoV replication process and provide insights into potential therapeutic applications.

Applications of the Microscale Thermophoresis Binding Assay in COVID-19 Research.

As the COVID-19 pandemic progresses, new variants of SARS-CoV-2 continue to emerge. This underscores the need to develop optimized tools to study such variants, along with new coronaviruses that may arise in the future. Such tools will also be instrumental in the development of new antiviral drugs. Here, we introduce microscale thermophoresis (MST) as a reliable and versatile tool for coronavirus research, which we demonstrate through three different applications described in this report: (1) binding of the SARS-CoV-2 spike receptor binding domain (RBD) to peptides as a strategy to prevent virus entry, (2) binding of the RBD to the viral receptor ACE2, and (3) binding of the RBD to ACE2 in complex with the amino acid transporter SLC6A20/SIT1 or its allelic variant rs61731475 (p.Ile529Val). Our results demonstrate that MST is a highly precise approach to studying protein-protein and/or protein-ligand interactions in coronavirus research, making it an ideal tool for studying viral variants and developing antiviral agents. Moreover, as shown in our results, a unique advantage of the MST assay over other available binding assays is the ability to measure interactions with membrane proteins in their near-native plasma membrane environment.

Efficient synthesis of novel 2-deoxy-C-nucleosides containing oxa and thiadiazole derivatives and their biological activity

Five membered oxa- and thiadiazole derivatives have shown significant biological activity due to their unique bioisosteric properties. Herein, we describe an efficient synthetic approach leading to several novel C-nucleosides containing an oxadiazole or thiadiazole ring system. This work provides for the first-time ability to assemble β-C-nucleosides in a facile manner offering an ideal framework for the possible development of new antiviral and antitumor drugs. All new C-nucleosides were tested for their activity against TBEV and SARS-CoV-2. Two of the synthesized compounds exerted mild anti-SARS-CoV-2 activity, as evidenced by the decrease in viral titers by <1 log10 PFU/ml compared with controls. Mechanism for the formation of 5-substituted 1,3,4-thiadiazole ring is proposed and a structure-activity relationship established with these C-nucleosides.

β-Lactams and Ureas as Cross Inhibitors of Prokaryotic Systems

β-Lactams in the last thirty years have been viewed as universal acylating agents of serine and cysteine enzymes of both prokaryotic and eukaryotic systems. More recently, their use has been propelled by the COVID-19 pandemic, thus broadening their application as inhibitors of viral enzymes. The urea-based drugs have been extensively studied as inhibitors of the aforementioned enzymes. The focus of this review is the last decade’s drug discovery strategies, as well as new strategies that show utility in the expansion of β-lactams and ureas in the development of new antimicrobial and antiviral drugs.