Vero E6 Research Articles

Diketopiperazine/piperidine alkaloid as a potential broad-spectrum coronaviral entry inhibitor identified by supercomputer-based virtual screening from a large natural product-based library.

The COVID-19 pandemic has underscored the urgent need for antiviral agents capable of targeting a broad range of coronaviruses, including emerging variants of SARS-CoV-2. While vaccines have been pivotal, the search for drugs that can prevent viral entry into host cells remains crucial, especially against evolving viral forms and other coronaviruses. In this study, we investigated natural products as a source of antiviral agents, focusing on their potential to block the spike protein's receptor-binding domain (RBD). Utilizing a library of over 210,000 natural product-based compounds from the ZINC database, we employed a Snakemake workflow to screen for inhibitors against RBDs of SARS-CoV-2, its variants, SARS-CoV, and MERS-CoV. Among top N-heterocyclic candidates from virtual screening we found that one compound, i.e., ((2 R,8S)-6-(1-benzylpiperidin-4-yl)-2-naphthalen-1-yl-3,6,17-triazatetracyclo[8.7.0.03,8.011,16]heptadeca-1(10),11,13,15 tetraene-4,7-dione), inhibited SARS-CoV-2 pseudovirus and live virus entry in HEK-ACE2 and Vero E6 host cells at low micromolar IC50 values. Cell viability assays showed that this compound exerted low cytotoxicity towards HEK-ACE2 while it was not toxic against Vero E6 and MRC5 cell lines. Microscale thermophoresis revealed that this compound strongly bound to the RBDs of SARS-CoV-2, SARS-CoV-2 XBB, SARS-CoV, MERS-CoV, and HCoV-HKU1, with their Kd values increasing as sequence similarity decreased. Molecular docking studies indicated this active compound binds to the SARS-CoV-2 spike protein RBD and interacts with hotspot amino acid residues required for the RBD-ACE2 interaction and cellular infection. These findings show that this diketopiperazine/piperidine-type alkaloid can be considered for further development as a potential pan-coronavirus entry inhibitor.

Design, synthesis, and biological evaluation of novel 2'-deoxy-2'-spirooxetane-7-deazapurine nucleoside analogs as anti-SARS-CoV-2 agents.

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused an unprecedented global public health crisis and continues to pose grave threats to human health. The efficacy of current vaccines and therapeutics is likely limited for future emerging strains due to the highly mutative nature of the virus, underscoring an urgent need for the development of new, potent antiviral agents. In this study, we report the design and synthesis of a series of novel 2'-deoxy-2'-spirooxetane-7-deazapurine nucleoside analogs as potential inhibitors of SARS-CoV-2 replication. Some of these compounds demonstrate potent antiviral activity, offering a potential new weapon for therapeutic intervention against the ever-evolving SARS-CoV-2 virus. Among the tested compounds, nucleoside analog 11q exhibited the most potent antiviral activity against SARS-CoV-2 in Vero E6 cells, with IC50 values of 0.14 μM for the wild-type strain and 0.36 μM for the BA.5 strain. Notably, compound 11q exhibits up to nine times greater inhibitory activity against wild-type SARS-CoV-2 compared to Remdesivir and also possesses a superior selectivity index. These findings suggest that compound 11q is a highly promising lead candidate for future drug development aimed at combating SARS-CoV-2.

Lipid-encapsulated gold nanoparticles: an advanced strategy for attenuating the inflammatory response in SARS-CoV-2 infection

BackgroundNanodrugs play a crucial role in biomedical applications by enhancing drug delivery. To address safety and toxicity concerns associated with nanoparticles, lipid-nanocarrier-based drug delivery systems have emerged as a promising approach for developing next-generation smart nanomedicines. Ginseng has traditionally been used for various therapeutic purposes, including antiviral activity. This study aimed to prepare a biocompatible and therapeutically potent Korean ginseng nanoemulsion (KGS-NE) using ginseng seed oil (GSO), optimize its encapsulation and drug delivery efficiency, and evaluate its antiviral activity.ResultsVarious techniques were utilized to confirm the KGS-NE formation. Energy-dispersive X-ray spectroscopy identified gold nanoparticles with the highest Au peak at 2.1 keV. Selected area diffraction patterns revealed crystallographic structures. FT-IR spectrometry detected functional groups, with peaks at 2922.09 cm−1 (alkene C–H stretching), 1740.24 cm−1 (aldehyde C=O stretching), and 1098.07 cm−1 (C–O stretching in secondary alcohol). Storage stability studies showed that KGS-NE maintained its size and stability for 6 months at 4 °C. The KGS-NE exhibited a dose-dependent suppression of HCoV-OC43 viral replication in Vero E6 cells. RNA sequencing analysis unveiled differentially expressed genes (DEGs) specifically involved in the ABC transporters signaling pathway. KGS-NE oral administration facilitated the recovery of mice induced with the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein, as confirmed by inflammatory markers expression in lung tissue. In the Syrian hamster infected with the SARS-CoV-2 model, the lungs dissected showed enlarged morphology and induced inflammatory cytokines. This effect was mitigated with KGS-NE oral administration, as observed through H&E and qRT-PCR analysis. Biochemical analysis at various oral administration concentrations demonstrated that KGS-NE had no adverse effects on the kidney and liver.ConclusionsOur findings strongly suggest that oral administering KGS-NE in mice and Syrian hamster models has the potential to effectively mitigate lung inflammation against coronavirus. This indicates a promising new strategy for developing the antiviral nano-agent against SARS-CoV-2.Graphical

Characteristics of the monkeypox virus isolate obtained from the first patient in Russia and its sensitivity to 7-[N-(4-trifluoromethylbenzoyl)-hydrazinocarbonyl]-tricyclo-[3.2.2.0^2,4]non-8-en-6-carboxylic acid

Introduction. Since early May 2022, more than 90,000 cases of monkeypox virus infection have been reported in more than 70 countries around the World. This is the largest outbreak of monkeypox ever recorded outside of Africa. The aim of the study is to confirm the first case of monkeypox in Russia, to isolate and sequence a new strain of monkeypox virus (MPXV), and to assess its sensitivity to the 7-[N-(4-trifluoromethylbenzoyl)-hydrazinocarbonyl]-tricyclo-[3.2.2.0^2,4]non-8-en-6-carboxylic acid (NIOCH-14) antipox drug. Materials and methods. The biological materials obtained from the affected area of the skin (contents of vesicles), a nasopharyngeal smear, sputum and venous blood from a patient with suspected monkeypox were used. The disease was confirmed by PCR followed by determination of the nucleotide sequence of viral DNA by sequencing. Isolation of the new MPXV strain from clinical samples was carried out in Vero E6 cells. The antiviral effectiveness of NIOCH-14 against the new MPXV strain was assessed using an adapted spectrophotometric method. Results. A diagnostic study of the biological samples of a patient who returned from a tourist trip to European countries with complaints of skin rashes all over the body revealed MPXV DNA. A new strain of MPXV was isolated from vesicles in Vero E6 cells, and the genomic sequence MPXV-pustule S45 was assembled using high-throughput parallel sequencing (NGS). Discussion. The effectiveness of the finished dosage form of NIOCH-14 against the new strain of MPXV based on the results of determining the 50% virus inhibitory concentration (IC50) was 0.02 μg/mL, and the selectivity index (SI) was 15,000. Conclusion. In this study, the pathogen of monkeypox was detected and identified using real-time PCR, NGS and electron microscopy, and the first imported case of this disease in Russia was confirmed. It has been proven that the drug NIOCH-14 exhibits high antiviral activity in vitro against the new MPXV strain.

Behind the scenes of cellular organization: Quantifying spatial phenotypes of puncta structures with statistical models including random fields.

The cellular interior is a spatially complex environment shaped by non-trivial stochastic and biophysical processes. Within this complexity, spatial organizational principles-also called spatial phenotypes-often emerge with functional implications. However, identifying and quantifying these phenotypes in the stochastic intracellular environment is challenging. To overcome this challenge for puncta, we discuss the use of inference of point-process models that link the density of points to other imaged structures and a random field that captures hidden processes. We apply these methods to simulated data and multiplexed immunofluorescence images of Vero E6 cells. Our analysis suggests that peroxisomes are likely to be found near the perinuclear region, overlapping with the ER, and located within a distance of 1 μm to mitochondria. Moreover, the random field captures a hidden variation of the mean density in the order of 15 μm. This length scale could provide critical information for further developing mechanistic hypotheses and models. By using spatial statistical models including random fields, we add a valuable perspective to cell biology.

Ethyl caffeate as a novel targeted inhibitor of 3CLpro with antiviral activity against porcine epidemic diarrhea virus.

Porcine epidemic diarrhea virus (PEDV) can cause severe diarrhea death in newborn piglets, resulting in significant economic losses for the pig industry. Therefore, the advancement of safe and effective anti-PEDV drugs for the treatment of PEDV is of paramount importance. In this study, molecular docking was used to screen natural drugs that can target PEDV 3C like protease (3CLpro). As well, the anti-PEDV effects of the screened drugs were evaluated in vitro and in vivo. Molecular docking and molecular dynamics (MD) simulation results showed that ethyl caffeate (EC) could efficiently bind to the active cavity of PEDV 3CLpro. Biolayer interferometry (BLI) and fluorescence resonance energy transfer (FRET) analyses demonstrated that EC directly interacts with PEDV 3CLpro (KD=1650μM) and inhibits the activity of 3CLpro (IC50=33.87μM). EC has been shown to significantly inhibit the replication of PEDV in Vero E6 cells. The half maximal inhibitory concentration (CC50) and half-effective concentration (EC50) were determined to be 283.1μM and 8.641μM, respectively, yielding a selectivity index as high as 32.7. Furthermore, EC was evaluated using a piglet infection model for PEDV. It demonstrated the ability to inhibit PEDV infection in vivo and improve the survival rate of piglets (3/5, 60%). Compared to the control group, oral administration of EC significantly reduced intestinal pathological damage and viral load. Our study indicated that EC, targeting PEDV 3CLpro, is a safe and effective anti-PEDV drug with promising clinical application prospects.

The Ability of Combined Flavonol and Trihydroxyorganic Acid to Suppress SARS-CoV-2 Reproduction.

The global burden of COVID-19 continues to rise, and despite significant progress in vaccine development, there remains a critical need for effective treatments for the severe inflammation and acute lung injury associated with SARS-CoV-2 infection. In this study, we explored the antiviral properties of a plant-derived complex consisting of flavonol and hydroxyorganic acid compounds. Our research focused on the ability of the flavonol and hydroxyorganic acid complex to suppress the activity of several key proteins involved in the replication and maturation of SARS-CoV-2. These proteins include ACE2 protein, HRV 3C Protease, and Mpro (Main Protease). It was shown that the plant-based complex effectively inhibited the activity of these viral proteins. In addition to its effects on viral proteins, the flavonol and hydroxyorganic acid complex were shown to suppress viral replication in Vero E6 cells. At a dose of 22 μg/mL, the drug demonstrated maximum antiviral activity, significantly reducing the replication of SARS-CoV-2 in vitro. In preliminary studies, the complex showed both prophylactic and therapeutic potential, suggesting that it may be useful for preventing infection, as well as reducing the severity of disease once an individual has been infected with SARS-CoV-2. Based on the compelling results of this study, we propose the flavonol and hydroxyorganic acid complex as a potential therapeutic compound for SARS-CoV-2. Its ability to inhibit key viral proteins, suppress viral replication and exhibit protective and therapeutic effects positions it as a valuable candidate for further research and clinical evaluation. As the global fight against SARS-CoV-2 continues, plant-based therapies like this complex could complement existing treatments and provide new options for managing and treating the disease.

Development of 111In-Labeled Monoclonal Antibodies Targeting SFTSV Structural Proteins for Molecular Imaging of SFTS Infectious Diseases by SPECT.

No effective vaccines or treatments are currently available for severe fever with thrombocytopenia syndrome (SFTS), a fatal tick-borne infectious disease caused by the SFTS virus (SFTSV). This study evaluated the potential of 111In-labeled anti-SFTSV antibodies targeting SFTSV structural proteins as single-photon emission computed tomography (SPECT) imaging agents for the selective visualization of SFTSV-infected sites. This study used nuclear medicine imaging to elucidate the pathology of SFTS and assess its therapeutic efficacy. Immunostaining experiments confirmed that the anti-SFTSV antibody (N-mAb), which targets the N protein, specifically accumulated in SFTSV-infected Vero E6 cells. 111In-labeled N-mAb was successfully prepared using a diethylenetriaminepentaacetic acid (DTPA) chelator, resulting in [111In]In-DTPA-N-mAb with high radiochemical purity exceeding 95% and a radiochemical yield of 55%. Cell-binding assays using SFTSV-infected Vero E6 cells demonstrated that [111In]In-DTPA-N-mAb binding was detectable even without membrane permeabilization, with the binding intensity correlating with infection levels. In vivo studies using SFTSV-infected A129 mice showed high spleen accumulation of [111In]In-DTPA-N-mAb (87.5% ID/g), consistent with SFTSV tropism, compared to 12.3% ID/g in mock-infected mice. SPECT/CT imaging clearly revealed high radioactivity in these regions. Although nonspecific accumulation was noted in the liver and spleen, this issue may be mitigated through antibody modifications such as fragmentation or PEGylation. Overall, [111In]In-DTPA-N-mAb is a promising imaging agent for non-invasive visualization of SFTSV-infected sites and may aid in elucidating SFTS pathology and assessing therapeutic efficacy.

Antiviral Activity of Ecklonia cava Extracts and Dieckol Against Zika Virus.

Ecklonia cava and its major compound dieckol, both natural marine products, possess antioxidant, anti-inflammatory, and metabolic-regulating effects. Zika virus (ZIKV), an arbovirus from the Flaviviridae family, is transmitted by mosquitoes and causes serious illnesses in humans. This study aimed to evaluate the anti-ZIKV potential of Ecklonia cava and dieckol. The antiviral activity of Ecklonia cava extract (ECE), prepared with 80% ethanol, was assessed in ZIKV-infected Vero E6 cells through MTT assay, plaque assay, and quantitative polymerase chain reaction (qPCR), demonstrating no cytotoxicity and a significant reduction in viral titers and ZIKV mRNA levels. In addition, ECE decreased the expression of tumor necrosis factor-α and interferon-induced protein with tetratricopeptide repeats in the ZIKV-infected cells. Dieckol, the primary active compound in ECE, exhibited potent anti-ZIKV activity, with a half maximal inhibitory concentration (IC50), value of 4.8 µM. In silico molecular docking analysis revealed that dieckol forms stable complexes with key ZIKV proteins, including the envelope, NS2B/NS3, and RNA-dependent RNA polymerase (RdRp) protein, exhibiting high binding energies of -438.09 kcal/mol, -1040.51 kcal/mol, and -1043.40 kcal/mol, respectively. Overall, our findings suggest that ECE and dieckol are promising candidates for the development of anti-ZIKV agents.

Effect of Fluorine Atoms and Piperazine Rings on Biotoxicity of Norfloxacin Analogues: Combined Experimental and Theoretical Study.

To clarify the effect of the fluorine atom and piperazine ring on norfloxacin (NOR), NOR degradation products (NOR-DPs, P1-P8) were generated via UV combined with hydrogen peroxide (UV/H2O2) technology. NOR degradation did not significantly affect cytotoxicity of NOR against BV2, A549, HepG2, and Vero E6 cells. Compared with that of NOR, mutagenicity and median lethal concentration of P1-P8 in fathead minnow were increased, and bioaccumulation factor and oral median lethal dose of P1-P8 in rats were decreased. Molecular docking was used to evaluate the inhibitory effect of DNA gyrase A (gyrA) on NOR-DPs to determine the molecular-level mechanism and establish the structure-activity relationship. Results indicated that the most common amino acid residues were Ile13, Ser27, Val28, Gly31, Asp36, Arg46, Arg47, Asp157, and Gly340; hydrogen bonds and hydrophobic interactions played key roles in the inhibitory effect. Binding area (BA) decreased from 350.80 Å2 (NOR) to 346.21 Å2 (P1), and the absolute value of binding energy (|BE|) changed from 2.53 kcal/mol (NOR) to 2.54 kcal/mol (P1), indicating that the fluorine atom mainly affects BA. The piperazine ring clearly influenced BA and |BE|. "Yang ChuanXi Rules" were used to explain effects of molecular weight (MW), BA, |BE|, and sum of η1 + η2 (η1: normalization of BA, η2: normalization of |BE|) and predict biotoxicity of NOR-DPs based on half-maximum inhibitory concentration (IC50), half-minimal inhibitory concentration (MIC50), and half-minimal bactericidal concentration (MBC50) values.

In Vitro Screening of an In-House Library of Structurally Distinct Chemotypes Towards the Identification of Novel SARS-CoV-2 Inhibitors.

Background/Objectives: Four years after the COVID-19 pandemic, a very limited number of drugs has been marketed; thus, the search for new medications still represents a compelling need. In our previous work on antiviral, antiparasitic, and antiproliferative agents, we described several compounds (1-13 and 16-20) structurally related to clofazimine, chloroquine, and benzimidazole derivatives. Thus, we deemed it worthwhile to test them against the replication of SARS-CoV-2, together with a few other compounds (14, 15 and 21-25), which showed some analogy to miscellaneous anti-coronavirus agents. Methods: Twenty-five structurally assorted compounds were evaluated in vitro for cytotoxicity against Vero E6 and for their ability to inhibit SARS-CoV-2 replication. Results: Several compounds (2, 3, 10, 11, 13-15, 18-20) demonstrated antiviral activity (IC50 range 1.5-28 µM) and six of them exhibited an interesting selectivity index in the range 4.5-20. The chloroquine analogs 10 and 11 were more potent than the reference chloroquine itself and doubled its SI value (20 versus 11). Also, the benzimidazole ring emerged as a valuable scaffold, originating several compounds (13-15 and 18-20) endowed with anti-SARS-CoV-2 activity. Despite the modest activity, the cytisine and the arylamino enone derivatives 23 and 25, respectively, also deserve further consideration as model compounds. Conclusions: The investigated chemotypes may represent valuable hit compounds, deserving further in-depth biological studies to define their mechanisms of action. The derived information will guide the subsequent chemical optimization towards the development of more efficient anti-SARS-CoV-2 agents.

Сравнительное исследование in vitro противовирусной активности эфирных масел и дезинфицирующих средств разных групп в отношении штаммов SARS-CoV-2 с различной вирулентностью

Introduction. To study the antiviral activity of essential oils against the SARS-CoV-2 virus, essential oils of conifers and other plants with known antimicrobial and antiseptic properties were studied. Comparative studies were conducted to study the antiviral activity of disinfectants of different groups widely used in practical healthcare, such as chloramine, formalin and ethyl alcohol, with the virucidal activity of selected essential oils against two strains of the SARS-CoV-2 virus with different virulence. Objectiv. To compare the antiviral activity of essential oils against selected strains of the SARS-CoV-2 coronavirus using the suspension method and the author’s method of contactless exposure, and to compare it with the antiviral activity of vapors of known disinfectants used to disinfect virological boxed rooms. Materials and methods. A comparative study of the antiviral activity of essential oils and disinfectants was carried out using the suspension method and the author’s non-contact exposure method specially developed for this study. Non-contact exposure method: the coronavirus viral suspension was applied to the surface of the lid of sterile plastic Petri dishes. Essential oils and disinfectants were applied to the inner surface of the bottom of the Petri dishes. After exposure to vapors of essential oils or disinfectants (without direct contact) on the SARS-CoV-2 viral suspension, swabs were taken from the surface of the Petri dish lid. The residual infectious activity of the SARS-CoV-2 virus was determined by TCD50/ml using the standard titration method in Vero E6 cell culture. Results. The results obtained during the studies using these methods showed that essential oils are capable of suppressing the infectious activity of the SARS-CoV-2 coronavirus. Essential oils of coniferous plants had the greatest antiviral ability. Essential oils of juniper, pine and tea tree had a fairly high antiviral effect, while essential oils of thyme, orange and clove had a moderate effect. Conclusion. Essential oils are effective disinfectants that can suppress the infectious activity of the studied strains of the SARS-CoV-2 coronavirus. Keywords: essential oils, antiviral activity, disinfectants, formalin, SARS-CoV-2 coronavirus.

Prevalence, Isolation, and Molecular Characterizationof Severe Fever with Thrombocytopenia Syndrome Virus in Cattle from the Republic of Korea.

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease caused by Bandavirus dabieense. Initially identified in China, this disease has spread throughout Asian countries via tick bites and animal-to-human transmission. However, reports of the prevalence of SFTS virus (SFTSV) in cattle in Korea are lacking. This study aimed to investigate SFTSV infections in grazing cattle in the Republic of Korea (ROK). Materials and Methods: In total, 845 grazing cattle serum samples were collected over 2 years (2019 and 2020) in the ROK, and viral RNA was extracted using a kit. One-step RT-nested PCR was performed to amplify the S-segment of SFTSV. Positive serum samples were used to isolate SFTSV in Vero E6 cells, and the full sequences were analyzed. A phylogenetic tree was constructed using the maximum-likelihood method with MEGA X. In addition, immunoglobulin G antibodies against SFTSV were investigated using an enzyme-linked immunosorbent assay. Results: Here, 4.0% of serum samples (34/845) were positive for SFTSV S-segments, and one virus isolate was cultured in Vero E6 cells. Phylogenetic analysis based on the partial S-segment classified 4 SFTSV isolates as the B-2 genotype, 9 as the B-3 genotype, 18 as an unclassified B genotype, and 3 as the D genotype. One cultured virus was classified as the B-2 genotype based on SFTSV L-, M-, and S-segments. Antibody detection results showed that 21.1% of serum samples (161/763) were positive for SFTSV. Conclusion: To the best of our knowledge, this is the first study performed to identify the prevalence of SFTSV in grazing cattle in the ROK. Our findings indicate the necessity for more intensive and continuous SFTSV monitoring, not only in cattle but also in other animals, to comprehend the genetic diversity of the virus and its potential eco-epidemiological impact on human health.

Development of a seroepidemiological tool for bat-borne and shrew-borne hantaviruses and its application using samples from Zambia.

Rodent-borne orthohantaviruses are the causative agents of hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Apart from the classic rodent-borne hantaviruses, numerous species of hantaviruses have been identified in shrews and bats; however, their antigenicity and pathogenicity are unknown. This study focused on developing a serological method to detect antibodies against bat- and shrew-borne hantaviruses. Five bat-borne (Brno, Dakrong, Quezon, Robina, and Xuan Song) and 6 shrew-borne (Asama, Altai, Cao Bang, Nova, Seewis, and Thottapalayam) viruses were selected based on the phylogenetic differences in their N proteins. The recombinant N (rN) proteins of these viruses were expressed as antigens in Vero E6 and 293T cell lines using the pCAGGS/MCS vector. Antisera against the Nus-tagged rN fusion proteins of these viruses (mouse anti-Brno, Dakrong, Quezon, Robina, Xuan Song, Asama, Cao Bang, and Nova, while rabbit anti-Altai, Seewis and Thottapalayam) were also generated. Antigenic cross-reactivity was examined in antisera and rN-expressing Vero E6 cells. The rN proteins of almost all the tested viruses, except for the Quezon and Robina viruses, showed independent antigenicity. For serological screening of bat samples, 5 rNs of the bat-borne viruses were expressed together in a single transfection protocol. Similarly, 6 rNs of shrew-borne viruses were expressed. Reactivities of the mixed antigen system were also examined across the singly transfected Vero cell lines to ensure that all antigens were expressed. Using these antigens, bat serum samples collected from Zambia were screened using the indirect immunofluorescence antibody test (IFAT). Selected positive samples were individually tested for the respective antigens by IFAT and western blot assays using rN-expressing 293T cell lysates. Of the 1,764 bat serum samples tested, 11.4% and 17.4% were positive for bat and shrew mixed antigens, respectively. These samples showed positive reactions to the Brno, Dakrong, Quezon, Xuan Son, Robina, Asama, Altai, Cao Bang, or Thottapalayam virus antigens. These observations suggest that the mixed-antigen screening system is useful for serological screening For Orthohantavirus infections and that bats in Zambia are likely exposed to not only bat-borne hantaviruses but also to shrew-borne hantaviruses.

AI Promoted Virtual Screening, Structure-Based Hit Optimization, and Synthesis of Novel COVID-19 S-RBD Domain Inhibitors.

Coronavirus disease 2019 (COVID-19) is caused by a new, highly pathogenic severe-acute-respiratory syndrome coronavirus 2 (SARS-CoV-2) that infects human cells through its transmembrane spike (S) glycoprotein. The receptor-binding domain (RBD) of the S protein interacts with the angiotensin-converting enzyme II (ACE2) receptor of the host cells. Therefore, pharmacological targeting of this interaction might prevent infection or spread of the virus. Here, we performed a virtual screening to identify small molecules that block S-ACE2 interaction. Large compound libraries were filtered for drug-like properties, promiscuity and protein-protein interaction-targeting ability based on their ADME-Tox descriptors and also to exclude pan-assay interfering compounds. A properly designed AI-based virtual screening pipeline was applied to the remaining compounds, comprising approximately 10% of the starting data sets, searching for molecules that could bind to the RBD of the S protein. All molecules were sorted according to their screening score, grouped based on their structure and postfiltered for possible interaction patterns with the ACE2 receptor, yielding 31 hits. These hit molecules were further tested for their inhibitory effect on Spike RBD/ACE2 (19-615) interaction. Six compounds inhibited the S-ACE2 interaction in a dose-dependent manner while two of them also prevented infection of human cells from a pseudotyped virus whose entry is mediated by the S protein of SARS-CoV-2. Of the two compounds, the benzimidazole derivative CKP-22 protected Vero E6 cells from infection with SARS-CoV-2, as well. Subsequent, hit-to-lead optimization of CKP-22 was effected through the synthesis of 29 new derivatives of which compound CKP-25 suppressed the Spike RBD/ACE2 (19-615) interaction, reduced the cytopathic effect of SARS-CoV-2 in Vero E6 cells (IC50 = 3.5 μM) and reduced the viral load in cell culture supernatants. Early in vitro ADME-Tox studies showed that CKP-25 does not possess biodegradation or liver metabolism issues, while isozyme-specific CYP450 experiments revealed that CKP-25 was a weak inhibitor of the CYP450 system. Moreover, CKP-25 does not elicit mutagenic effect on Escherichia coli WP2 uvrA strain. Thus, CKP-25 is considered a lead compound against COVID-19 infection.

Synthesis, antiviral activity against wild-type SARS-CoV-2 and molecular docking studies of new aryl(1,2-dithiolo[3,4-c]quinolin-1-ylidene)amines

Unlike most attempts to find compounds with activity against SARS-CoV-2 aimed at reusing approved drugs, our goal was to find compounds with antiviral activity among the 1,2-dithioloquinoline derivatives we synthesized. These compounds exhibit pleiotropic effects, having a novel structure compared to known pharmaceuticals. In this work, we diversified the structure of 1,2-dithioloquinoline by introducing various substituents (chlorine atom, ether, amide, sulfonamide groups, pharmacophore heterocycles) into different positions of this tricyclic framework. Using docking with further quantum chemical post-processing of calculations of the created virtual library of 404 structures, more than ten compounds of the aryl(4,4-dimethyl-4,5-dihydro-1H-[1,2]dithiolo[3,4-c]quinoline-1-ylidene)amine series were discovered, synthesized and experimentally studied. The bioactive screening of newly synthesized compounds revealed that six of them demonstrate suppression of SARS-CoV-2 replication in Vero E6 cell culture in the micromolar range of EC50 values (from 0.27 to 98.48 μM). The best compound, in the structure of which fragments of tricyclic dithioloquinoline and streptocide are combined, demonstrated a highest ability to protect Vero E6 cells from SARS-CoV-2 with EC50 = 0.27 μM, as well as low cytotoxicity with a selectivity index SI > 370, exceeding all reference values compounds used in the study (remdesivir, GC376, ML188).

Characterization of the Pathogenic Features of Multiple SARS-CoV-2 Pandemic Strains in Different Mouse Models.

Elucidating the detailed features of emerging SARS-CoV-2 strains both in vitro and in vivo is indispensable for the development of effective vaccines or drugs against viral infection. We thoroughly characterized the virological and pathogenic features of eight different pandemic SARS-CoV-2 strains, from the WT strain to current circulating sublineage EG.5.1, both in vitro and in vivo. Besides detailed virological features observed in Vero E6 cells, the Omicron variants, from BA.1 to EG.5.1, exhibited enhanced infectious effects to upper respiratory tract in K18 human angiotensin-converting enzyme (ACE2) (K18 hACE2) transgenic mice. Both XBB.1.9.1 and EG.5.1 presented stronger tropism to brain, which could be the main reason for the increased lethal effects on mice. In addition, the pathogenesis comparisons among all these viruses in C57BL/6JGpt mice indicated that Omicron variant BA.1 and two new sublineages XBB.1.9.1 and EG.5.1 possessed dual tropisms to both human and mice, which were further confirmed by subsequent bioinformatic analyses and actual affinity comparison between viral RBDs and mouse or human receptor ACE2. Furthermore, the immunocompromised BKS-db mice were found to be more susceptible to Omicron strains compared to C57BL/6JGpt mice, which revealed that viral infectivity was determined by both its affinity to the host receptor and host immunocompetence. Thus, this study not only contributes to a systematic understanding of the pathogenic features of SARS-CoV-2 in mice, but also provides new insights to combat potential future surges of new SARS-CoV-2 variants.

RpIFN-λ1 alleviates the clinical symptoms of porcine epidemic diarrhea

Porcine epidemic diarrhea (PED), caused by the porcine epidemic diarrhea virus (PEDV), primarily affects the jejunum and ileum of pigs. Interferons, glycoproteins with high species specificity and potent antiviral activity, are crucial in defending against viral infections. Unlike other interferons, interferon-lambda (IFN-λ) mainly acts on mucosal epithelial cells and exhibits robust antiviral activity at mucosal surfaces. However, the high cost limits the use of naturally extracted interferons in farming. In this study, we expressed recombinant porcine interferon-lambda 1 (rpIFN-λ1) in eukaryotic cells, demonstrating effective antiviral activity against PEDV in Vero E6 and IPI-FX cells. In vivo, rpIFN-λ1 alleviated clinical symptoms and intestinal damage, enhanced antioxidant capacity, reduced inflammation, and significantly improved the survival rate of piglets following PEDV infection. Both in vitro and in vivo studies confirmed that rpIFN-λ1 upregulated interferon-stimulated genes (ISGs) via the JAK-STAT pathway, thereby exerting antiviral effects. In conclusion, rpIFN-λ1 significantly inhibited PEDV replication and alleviated clinical symptoms. The selectivity of rpIFN-λ1 for intestinal cells and its ability to reduce viral shedding suggest that this agent is a promising antiviral for enteric viruses such as PEDV. Our findings highlight rpIFN-λ1 as a cost-effective, efficient, and novel strategy for antiviral treatment of PEDV.

Losartan and enalapril maleate differently influence SARS-CoV-2-infected vero cells

Background: The COVID-19 pandemic has posed significant challenges to global healthcare systems, particularly impacting individuals with pre-existing conditions like hypertension. This study sought to assess the impact of the antihypertensive medications, losartan and enalapril maleate on SARS-CoV-2 infected cells. Vero E6 cells were infected and treated in vitro, evaluating cell viability via the MTT colorimetric assay. Additionally, the study measured relative levels of viral RNA and selected gene messenger RNAs using reverse transcriptase followed by quantitative real-time polymerase chain reaction. Results: The findings revealed that losartan substantially reduced nucleocapsid RNA levels of SARS-CoV-2 to nearly undetectable levels, while enalapril maleate did not demonstrate a significant effect. In response to viral infection, the expression of il-18, p53, p21, and p62 increased compared to uninfected-untreated cells. Notably, il-6 expression was upregulated by both infection and treatments. A comparison between infected cells treated with losartan or enalapril maleate highlighted the presence of distinct profiles in the expression of il-6, p53, p21, and p62. Conclusions: The data from our study suggest that these medications could interfere with certain effects triggered by SARS-CoV-2 infection in Vero E6 cells. However, their influence appears to vary both quantitatively and qualitatively in the modulation of metabolic and signal transduction pathways.

Antitumor effect of the Newcastle disease virus strain NDV/Altai/pigeon/777/2010 on a model of solid Lewis carcinoma

Aim. To evaluate the efficacy of intratumoral administrations of the Newcastle disease virus strain NDV/Altai/pigeon/777/2010, to compare progression of the tumor nodes after virotherapy and to analyse pathomorphological changes in the tumor tissue in vitro and in vivo. Single intratumoral injections of the mesogenic strain of Newcastle disease virus NDV/Altai/pigeon/777/2010, isolated from a rock dove in Siberia, were done into outbred mice of the C57Bl/6 line into solid nodes of Lewis lung carcinoma that were grafted subcutaneously. Then the dynamics of tumor growth and pathomorphological changes in the tumor tissue were assessed and analyzed.It was shown that single intratumoral injections into immunocompetent C57Bl/6 mice with the mesogenic strain of Newcastle disease virus NDV/Altai/pigeon/777/2010 led to an increase in peculiar pathomorphological changes in the tumor tissue of subcutaneously grafted Lewis lung carcinoma and to a decrease in tumor growth compared to the control group of mice in vivo. A direct cytotoxic effect of the NDV strain on the Vero E6 cell line in vitro was noted.The results of this study indicate that the NDV strain NDV/Altai/pigeon/777/2010 has antitumor properties. This may enable clinical trials to prove its effectiveness as an antitumor drug.