Search Results (60)

Background/Objectives: Highly pathogenic coronaviruses (CoVs), including SARS-CoV, MERS-CoV, and SARS-CoV-2, continue to pose a significant threat to global public health. Therefore, this situation highlights the urgent need for effective broad-spectrum antiviral agents. Curcumin, a naturally occurring polyphenol known for its antiviral and anti-inflammatory properties, faces limitations such as poor bioavailability and rapid metabolic degradation, restricting its practical therapeutic application. Methods: To address these limitations, this study introduces a novel design strategy aimed at 42 new curcumin derivatives with improved pharmacokinetic profiles, specifically targeting the conserved coronavirus enzyme papain-like protease (PLpro). A comprehensive in silico evaluation was performed, including ADMET (Absorption, Distribution, Metabolism, Elimination, and Toxicity) analysis, molecular docking, molecular dynamics (MD) simulations, and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) calculations. Results: Extensive pharmacokinetic and toxicological assessments (ADMET analyses) identified 19 derivatives exhibiting optimal drug-like characteristics according to Lipinski’s Rule of Five (Ro5). Molecular docking analyses demonstrated that these novel derivatives possess significantly enhanced binding affinities to PLpro enzymes from SARS-CoV, MERS-CoV, and SARS-CoV-2 compared to standard antiviral agents and natural curcumin. Further validation through MD simulations and MM/PBSA calculations confirmed the structural stability and robust interactions of the most promising derivatives within the SARS-CoV PLpro active site. Conclusions: The results of this study provide essential structural and functional insights, reinforcing the potential of these newly developed curcumin derivatives as potent, broad-spectrum antiviral agents effective against current and future coronavirus threats. Full article

Background/Objectives: The use of virus-like particles (VLPs) in vaccinology has expanded significantly in recent years. VLPs have the advantage of being non-infectious while effectively stimulating B cell responses through the repetitive presentation of epitope motifs on their surface. Since VLPs are often derived from human-infecting viruses, preexisting immunity may influence the immune response they elicit, warranting further investigation. Methods: We have developed a 60-mer VLP derived from human adenovirus type 3, a common pathogen. We investigated the impact of pre-existing adenovirus immunity on the immunization outcome against the linear S14P5 epitope of SARS-CoV-2, which was engineered into the particle (Ad-VLP-S14P5). To this end, antibody responses to S14P5 were evaluated following immunization with Ad-VLP-S14P5 in either naive or vector-primed mice. Results: Mice with pre-existing anti-vector immunity exhibited significantly greater anti-S14P5 antibody responses compared to vector-naive animals, demonstrating a beneficial impact of prior anti-adenovirus responses. However, the addition of an oil-in-water adjuvant for the immunizations abolished this positive impact, even leading to a deleterious effect of the pre-existing anti-vector immunity. Conclusions: The data suggest that the immune status against immunizing VLPs must be taken into consideration when designing immunization protocols. Importantly, the effects of prior immunity may vary depending on the nature of the protocol, including factors such as adjuvant use. Full article

Background: Vaccines against COVID-19 target the spike protein. There is minimal information on longitudinal COVID-19 immune profiling in recovered versus naïve and vaccinated versus non-vaccinated healthcare workers (HCWs). Methods: This is a prospective longitudinal observational cohort of pediatric HCWs (pHCWs) conducted during 2020–2022 at an academic center, exploring the impact of COVID-19 vaccination on immunoglobulin G (IgG) antibody titers over time and cross-reactivity with other coronaviruses, including SARS-CoV-1, MERS-CoV, and seasonal coronaviruses (HCoV-HKU1 and HCoV-OC43). Results: A total of 642 pHCWs initially enrolled, and 337 participants had repeat IgG titers measured post-vaccine and post-booster. Most participants were female, median age range of 31–40 years. Anti-spike was higher in all vaccinated individuals versus non-vaccinated (p < 0.0001) and naïve versus infected (p < 0.0001). A single dose of vaccine was sufficient to attain maximum titers in recovered participants versus naïve who received both doses of vaccine. Anti-spike titers dropped significantly at 9 months after the primary series, whereas sustained anti-spike titers were observed at 9 months post-booster. Conclusions: All vaccinated pHCWs developed antibodies to spike. COVID-19 infection and/or vaccination yielded antibodies that cross-reacted to SARS-CoV-1, MERS-CoV, HCoV-HKU1, and HCoV-OC43. Anti-spike titers were more durable post-booster compared to the primary series. Longitudinal immune profiling of COVID-19 responses provides vital data to shape public health policies, optimize vaccine strategies, and strengthen pandemic preparedness. Full article

Background: Middle East Respiratory Syndrome Coronavirus (MERS-CoV) causes severe respiratory illness in humans and currently lacks an approved vaccine. The Newcastle disease virus (NDV) vector is a well-established, safe, and effective platform for vaccine development. With recent advancements in stabilizing coronavirus spike proteins to enhance their antigenicity, this study aimed to determine whether modifications to the MERS-CoV spike protein could improve its presentation on NDV particles, allowing the resulting virus to be used as an inactivated vaccine. Methods: We codon-optimized the gene encoding the ectodomain of the MERS-CoV spike protein and incorporated modifications at the S1/S2 and S2’ cleavage sites, along with a proline substitution at residues V1060-L1061. This modified spike gene was inserted into the NDV genome to create the NDV-S_MERS virus. After purification and inactivation, the vaccine’s immunogenicity was assessed in mice. Results: Mice immunized with the inactivated NDV-S_MERS vaccine developed robust anti-spike IgGs, neutralizing antibodies, and cellular immune responses. The study demonstrated that modifications to the MERS-CoV spike protein were essential for its effective presentation on NDV particles. Additionally, the spike gene insert remained stable through five egg passages, confirming the vector’s stability. Conclusions: Engineering the MERS-CoV spike protein is crucial for its successful display on NDV particles. The strong immune responses elicited by the NDV-S_MERS vaccine in mice highlight that NDV is a promising, safe, and effective platform for MERS-CoV vaccination. Full article

Background/Objectives: The Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a highly pathogenic virus causing severe respiratory illness, with limited treatment options that are mostly supportive. The success of mRNA technology in COVID-19 vaccines has opened avenues for antibody development against MERS-CoV. mRNA-based antibodies, expressed in vivo, offer rapid adaptability to viral mutations while minimizing long-term side effects. This study aimed to develop a lung-targeted lipid nanoparticle (LNP) system for mRNA-encoding neutralizing nanobodies against MERS-CoV, proposing a novel therapeutic strategy. Methods: An mRNA-encoding nanobody NbMS10 (mRNA-NbMS10) was engineered for enhanced stability and reduced immunogenicity. This mRNA was encapsulated in lung-selective LNPs using microfluidics to form the LNP-mRNA-NbMS10 system. Efficacy was assessed through in vitro assays and in vivo mouse studies, focusing on antigen-binding, neutralization, and sustained nanobody expression in lung tissues. Results: The LNP-mRNA-NbMS10 system expressed the nanobody in vitro, showing strong antigen-binding and significant MERS-CoV pseudovirus neutralization. In vivo studies confirmed selective lung mRNA delivery, with high nanobody expression sustained for up to 24 h, confirming lung specificity and prolonged antiviral activity. Conclusions: Extensive in vitro and in vivo evaluations demonstrate the LNP-mRNA-NbMS10 system’s potential as a scalable, cost-effective, and adaptable alternative to current MERS-CoV therapies. This innovative platform offers a promising solution for preventing and treating respiratory infections, and countering emerging viral threats. Full article

Nucleoside analogs (NAs) have been extensively examined as plausible antiviral agents in recent years, in particular since the outbreak of the global pandemic of COVID-19 in 2019. In this review, the structures and antiviral properties of over 450 NAs are collected according to the type of virus, namely SARS-CoV, SARS-CoV-2, MERS-CoV, HCoV-OC43, HCoV-229E, and HCoV-NL63. The activity of the NAs against HCoV-related enzymes is also presented. Selected studies dealing with the mode of action of the NAs are discussed in detail. The repurposing of known NAs appears to be the most extensively investigated scientific approach towards efficacious anti-HCoV agents. The recently reported de novo-designed NAs seem to open up additional approaches to new drug candidates. Full article

Despite the rapid development of vaccines against COVID-19, they have important limitations, such as safety issues, the scope of their efficacy, and the induction of mucosal immunity. The present study proposes a potential component for a new generation of vaccines. The recombinant nucleocapsid (N) protein from the SARS-CoV-2 Delta variant was combined with the ODN-39M, a synthetic 39 mer unmethylated cytosine-phosphate-guanine oligodeoxynucleotide (CpG ODN), used as an adjuvant. The evaluation of its immunogenicity in Balb/C mice revealed that only administration by intranasal route induced a systemic cross-reactive, cell-mediated immunity (CMI). In turn, this combination was able to induce anti-N IgA in the lungs, which, along with the specific IgG in sera and CMI in the spleen, was cross-reactive against the nucleocapsid protein of SARS-CoV-1. Furthermore, the nasal administration of the N + ODN-39M preparation, combined with RBD Delta protein, enhanced the local and systemic immune response against RBD, with a neutralizing capacity. Results make the N + ODN-39M preparation a suitable component for a future intranasal vaccine with broader functionality against Sarbecoviruses. Full article

The COVID-19 pandemic, caused by SARS-CoV-2, addressed the lack of specific antiviral drugs against coronaviruses. In this study, bioguided fractionation performed on both ethyl acetate and aqueous sub-extracts of Juncus acutus stems led to identifying luteolin as a highly active antiviral molecule against human coronavirus HCoV-229E. The apolar sub-extract (CH₂Cl₂) containing phenanthrene derivatives did not show antiviral activity against this coronavirus. Infection tests on Huh-7 cells, expressing or not the cellular protease TMPRSS2, using luciferase reporter virus HCoV-229E-Luc showed that luteolin exhibited a dose-dependent inhibition of infection. Respective IC₅₀ values of 1.77 µM and 1.95 µM were determined. Under its glycosylated form (luteolin-7-O-glucoside), luteolin was inactive against HCoV-229E. Time of addition assay showed that utmost anti-HCoV-229E activity of luteolin was achieved when added at the post-inoculation step, indicating that luteolin acts as an inhibitor of the replication step of HCoV-229E. Unfortunately, no obvious antiviral activity for luteolin was found against SARS-CoV-2 and MERS-CoV in this study. In conclusion, luteolin isolated from Juncus acutus is a new inhibitor of alphacoronavirus HCoV-229E. Full article

COVID-19 has resulted in a pandemic that aggravated the world’s healthcare systems, economies, and education, and caused millions of global deaths. Until now, there has been no specific, reliable, and effective treatment to combat the virus and its variants. The current standard tedious PCR-based tests have limitations in terms of sensitivity, specificity, turnaround time, and false negative results. Thus, an alternative, rapid, accurate, and sensitive diagnostic tool that can detect viral particles, without the need for amplification or viral replication, is central to infectious disease surveillance. Here, we report MICaFVi (Magnetic Immuno-Capture Flow Virometry), a novel precise nano-biosensor diagnostic assay for coronavirus detection which combines the MNP-based immuno-capture of viruses for enrichment followed by flow-virometry analysis, enabling the sensitive detection of viral particles and pseudoviruses. As proof of concept, virus-mimicking spike-protein-coated silica particles (VM-SPs) were captured using anti-spike-antibody-conjugated MNPs (AS-MNPs) followed by detection using flow cytometry. Our results showed that MICaFVi can successfully detect viral MERS-CoV/SARS-CoV-2-mimicking particles as well as MERS-CoV pseudoviral particles (MERSpp) with high specificity and sensitivity, where a limit of detection (LOD) of 3.9 µg/mL (20 pmol/mL) was achieved. The proposed method has great potential for designing practical, specific, and point-of-care testing for rapid and sensitive diagnoses of coronavirus and other infectious diseases. Full article

This review is conducted against the background of nanotechnology, which provides us with a chance to effectively combat the spread of coronaviruses, and which primarily concerns polyelectrolytes and their usability for obtaining protective function against viruses and as carriers for anti-viral agents, vaccine adjuvants, and, in particular, direct anti-viral activity. This review covers nanomembranes in the form of nano-coatings or nanoparticles built of natural or synthetic polyelectrolytes––either alone or else as nanocomposites for creating an interface with viruses. There are not a wide variety of polyelectrolytes with direct activity against SARS-CoV-2, but materials that are effective in virucidal evaluations against HIV, SARS-CoV, and MERS-CoV are taken into account as potentially active against SARS-CoV-2. Developing new approaches to materials as interfaces with viruses will continue to be relevant in the future. Full article

Finding effective antiviral molecular strategies was a main concern in the scientific community when the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged at the end of 2019 as an easily transmissible and potentially deadly β-coronavirus able to cause the coronavirus disease 19 (COVID-19), which famously led to one of the most worrying pandemics in recent times. Other members of this zoonotic pathogenic family were already known before 2019, but apart from the SARS-CoV, which was responsible of severe acute respiratory syndrome (SARS) pandemic in 2002/2003, and Middle East respiratory syndrome coronavirus (MERS-CoV), whose main impact on humans is geographically restricted to Middle Eastern countries, the other human β-coronaviruses known at that time were those typically associated with common cold symptoms which had not led to the development of any specific prophylactic or therapeutic measures. Although SARS-CoV-2 and its mutations are still causing illness in our communities, COVID-19 is less deadly than before and we are returning to normality. Overall, the main lesson learnt after the past few years of pandemic is that keeping our bodies healthy and immunity defenses strong using sport, nature-inspired measures, and using functional foods are powerful weapons for preventing the more severe forms of illness caused by SARS-CoV-2 and, from a more molecular perspective, that finding drugs with mechanisms of action involving biological targets conserved within the different mutations of SARS-CoV-2—and possibly within the entire family of β-coronaviruses—gives more therapeutic opportunities in the scenario of future pandemics based on these pathogens. In this regard, the main protease (M^pro), having no human homologues, offers a lower risk of off-target reactivity and represents a suitable therapeutic target in the search for efficacious, broad-spectrum anti-β-coronavirus drugs. Herein, we discuss on the above points and also report some molecular approaches presented in the past few years to counteract the effects of β-coronaviruses, with a special focus on SARS-CoV-2 but also MERS-CoV. Full article

The present study aimed to estimate the antiviral activities of Ginkgo biloba (GB) leaves extract and eco-friendly free silver nanoparticles (Ag NPs) against the MERS-CoV (Middle East respiratory syndrome-coronavirus) and HCoV-229E (human coronavirus 229E), as well as isolation and identification of phytochemicals from GB. Different solvents and high-performance liquid chromatography (HPLC) were used to extract and identify flavonoids and phenolic compounds from GB leaves. The green, silver nanoparticle synthesis was synthesized from GB leaves aqueous extract and investigated for their possible effects as anti-coronaviruses MERS-CoV and HCoV-229E using MTT assay protocol. To verify the synthesis of Ag NPs, several techniques were employed, including X-ray diffraction (XRD), scan, transmission electron microscopy, FT-IR, and UV–visible spectroscopy. The highest contents of flavonoids and phenolic compounds were recorded for acetone, methanol, and ethanol as mixtures with water, in addition to pure water. HPLC flavonoids were detected as apegenin, luteolin, myricetin, and catechin, while HPLC phenolic compounds were pyrogallol, caffeic acid, gallic acid, and ellagic acid. In addition, our results revealed that Ag NPs were produced through the shift from yellow to dark brown. TEM examination of Ag NPs revealed spherical nanoparticles with mean sizes ranging from 5.46 to 19.40 nm and an average particle diameter of 11.81 nm. A UV–visible spectrophotometric investigation revealed an absorption peak at λ max of 441.56 nm. MTT protocol signified the use of GB leaves extract as an anti-coronavirus to be best from Ag NPs because GB extract had moderate anti-MERS-CoV with SI = 8.94, while had promising anti-HCov-229E, with an SI of 21.71. On the other hand, Ag NPs had a mild anti-MERS-CoV with SI = 4.23, and a moderate anti-HCoV-229E, with an SI of 7.51. Full article

Virus-cell interactions involve fundamental parameters that need to be considered in strategies implemented to control viral outbreaks. Among these, the surface electrostatic potential can give valuable information to deal with new epidemics. In this article, we describe the role of this key parameter in the hemagglutination of red blood cells and in the co-evolution of synaptic receptors and neurotransmitters. We then establish the functional link between lipid rafts and the electrostatic potential of viruses, with special emphasis on gangliosides, which are sialic-acid-containing, electronegatively charged plasma membrane components. We describe the common features of ganglioside binding domains, which include a wide variety of structures with little sequence homology but that possess key amino acids controlling ganglioside recognition. We analyze the role of the electrostatic potential in the transmission and intra-individual evolution of HIV-1 infections, including gatekeeper and co-receptor switch mechanisms. We show how to organize the epidemic surveillance of influenza viruses by focusing on mutations affecting the hemagglutinin surface potential. We demonstrate that the electrostatic surface potential, by modulating spike-ganglioside interactions, controls the hemagglutination properties of coronaviruses (SARS-CoV-1, MERS-CoV, and SARS-CoV-2) as well as the structural dynamics of SARS-CoV-2 evolution. We relate the broad-spectrum antiviral activity of repositioned molecules to their ability to disrupt virus-raft interactions, challenging the old concept that an antibiotic or anti-parasitic cannot also be an antiviral. We propose a new concept based on the analysis of the electrostatic surface potential to develop, in real time, therapeutic and vaccine strategies adapted to each new viral epidemic. Full article

Gas6 (growth arrest-specific gene 6) is a widely expressed vitamin K-dependent protein that is involved in many biological processes such as homeostatic regulation, inflammation and repair/fibrotic processes. It is known that it is the main ligand of TAMs, a tyrosine kinase receptor family of three members, namely MerTK, Tyro-3 and Axl, for which it displays the highest affinity. Gas6/TAM axis activation is known to be involved in modulating inflammatory responses as well as fibrotic evolution in many different pathological conditions. Due to the rapidly evolving COVID-19 pandemic, this review will focus on Gas6/TAM axis activation in SARS-CoV-2 infection, where de-regulated inflammatory responses and fibrosis represent a relevant feature of severe disease manifestation. Furthermore, this review will highlight the most recent scientific evidence supporting an unsuspected role of Axl as a SARS-CoV-2 infection driver, and the potential therapeutic advantages of the use of existing Axl inhibitors in COVID-19 management. From a physiological point of view, the Gas6/TAM axis plays a dual role, fostering the tissue repair processes or leading to organ damage and loss of function, depending on the prevalence of its anti-inflammatory or profibrotic properties. This review makes a strong case for further research focusing on the Gas6/TAM axis as a pharmacological target to manage different disease conditions, such as chronic fibrosis or COVID-19. Full article

The coronavirus disease 2019 (COVID-19) pandemic is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, which is defined by its positive-sense single-stranded RNA (ssRNA) structure. It is in the order Nidovirales, suborder Coronaviridae, genus Betacoronavirus, and sub-genus Sarbecovirus (lineage B), together with two bat-derived strains with a 96% genomic homology with other bat coronaviruses (BatCoVand RaTG13). Thus far, two Alphacoronavirus strains, HCoV-229E and HCoV-NL63, along with five Betacoronaviruses, HCoV-HKU1, HCoV-OC43, SARS-CoV, MERS-CoV, and SARS-CoV-2, have been recognized as human coronaviruses (HCoVs). SARS-CoV-2 has resulted in more than six million deaths worldwide since late 2019. The appearance of this novel virus is defined by its high and variable transmission rate (RT) and coexisting asymptomatic and symptomatic propagation within and across animal populations, which has a longer-lasting impact. Most current therapeutic methods aim to reduce the severity of COVID-19 hospitalization and virus symptoms, preventing the infection from progressing from acute to chronic in vulnerable populations. Now, pharmacological interventions including vaccines and others exist, with research ongoing. The only ethical approach to developing herd immunity is to develop and provide vaccines and therapeutics that can potentially improve on the innate and adaptive system responses at the same time. Therefore, several vaccines have been developed to provide acquired immunity to SARS-CoV-2 induced COVID-19-disease. The initial evaluations of the COVID-19 vaccines began in around 2020, followed by clinical trials carried out during the pandemic with ongoing population adverse effect monitoring by respective regulatory agencies. Therefore, durability and immunity provided by current vaccines requires further characterization with more extensive available data, as is presented in this paper. When utilized globally, these vaccines may create an unidentified pattern of antibody responses or memory B and T cell responses that need to be further researched, some of which can now be compared within laboratory and population studies here. Several COVID-19 vaccine immunogens have been presented in clinical trials to assess their safety and efficacy, inducing cellular antibody production through cellular B and T cell interactions that protect against infection. This response is defined by virus-specific antibodies (anti-N or anti-S antibodies), with B and T cell characterization undergoing extensive research. In this article, we review four types of contemporary COVID-19 vaccines, comparing their antibody profiles and cellular aspects involved in coronavirus immunology across several population studies. Full article