Antiviral Molecules Research Articles

Single-Point Mutations within the Coxsackie B Virus Receptor-Binding Site Promote Resistance against Soluble Virus Receptor Traps.

Coxsackie B viruses (CVB) cause a wide spectrum of diseases, ranging from mild respiratory syndromes and hand, foot, and mouth disease to life-threatening conditions, such as pancreatitis, myocarditis, and encephalitis. Previously, we and others found that the soluble virus receptor trap sCAR-Fc strongly attenuates CVB3 infection in mice. In this study, we investigated whether treatment with sCAR-Fc results in development of resistance by CVB3. Two CVB3 strains (CVB3-H3 and CVB3 Nancy) were passaged in HeLa cells in the presence of sCAR-Fc. The CVB3-H3 strain did not develop resistance, whereas two populations of CVB3 Nancy mutants emerged, one with complete (CVB3M) and one with partial (CVB3K) resistance. DNA sequence alignment of the resistant virus variant CVB3M with CVB3 Nancy revealed an amino acid exchange from Asn(N) to Ser(S) at position 139 of the CVB3 capsid protein VP2 (N2139S), an amino acid predicted to be involved in the virus's interaction with its cognate receptor CAR. Insertion of the N2139S mutation into CVB3-H3 by site-directed mutagenesis promoted resistance of the engineered CVB3-H3N2139S to sCAR-Fc. Interestingly, development of resistance by CVB3-H3N2139S and the exemplarily investigated CVB3M-clone 2 (CVB3M2) against soluble CAR did not compromise the use of cellular CAR for viral infection. Infection of HeLa cells showed that sCAR-Fc resistance, however, negatively affected both virus stability and viral replication compared to that of the parental strains. These data demonstrate that during sCAR-Fc exposure, CVB3 can develop resistance against sCAR-Fc by single-amino-acid exchanges within the virus-receptor binding site, which, however, come at the expense of viral fitness.IMPORTANCE The emergence of resistant viruses is one of the most frequent obstacles preventing successful therapy of viral infections, representing a significant threat to human health. We investigated the emergence of resistant viruses during treatment with sCAR-Fc, a well-studied, highly effective antiviral molecule against CVB infections. Our data show the molecular aspects of resistant CVB3 mutants that arise during repetitive sCAR-Fc usage. However, drug resistance comes at the price of lower viral fitness. These results extend our knowledge of the development of resistance by coxsackieviruses and indicate potential limitations of antiviral therapy using soluble receptor molecules.

Molecular structure elucidation, charge transfer interactions, electronic properties, vibrational spectral investigation and molecular docking of the antiviral active molecule (E)-4-[1-(2-carbamothioylhydrazinylidene)ethyl]-phenyl benzoate dimer - aided by density functional theory

The molecular structure of the novel thiosemicarbazide (E)-4-[1-(2-carbamothioylhydrazinylidene) ethyl] - phenyl benzoate has been synthesized and subjected to Raman and Fourier transform infrared spectral studies. Optimized parameters of (E)-4-[1-(2-carbamothioylhydrazinylidene) ethyl] - phenyl benzoate monomer and dimer have been compared with X-ray diffraction data. The existence of hydrogen bonded intramolecular interactions, intermolecular interactions and the hyperconjugative energy leading to the stabilization of the system have been revealed by natural bond orbital analysis. Charge transfer interactions from highest occupied molecular orbital to lowest unoccupied molecular orbital and the observed low energy gap predict the molecule to be more reactive. Molecular electrostatic potential image shows the potential binding site is around the sulfur atom. The spectra have been analyzed and the assignments of the normal modes of vibrations have been carried out with the help of normal coordinate analysis following the scaled quantum chemical force field methodology. The observed spectral shift substantiates the spectral evidence of the intermolecular hydrogen bonding. Molecular docking scores reveal good binding affinity and the inhibition activity of the molecule against dengue viral protein 4c11.

Oligoadenylate Synthetases 1 Enhances DNA Sensor Cgas Translation to Mediate Antiviral Activity

Oligoadenylate synthetases (OAS) are a family of interferon (IFN)-stimulated genes known to inhibit viral replication through the enzymatic synthesis of 2'-5' oligoadenylates and activation of Ribonuclease L. However, this canonical mechanism does not explain the antiviral properties of enzymatically inactive OAS proteins. Here we describe an enzyme activity-independent function of OAS1 that restricts West Nile virus (WNV) growth. The human OAS1 P46 isoform, generated by alternative splicing of the G allele of rs10774671 SNP, upregulates translation of specific host mRNA including the DNA-sensor cGAS. Increased cGAS expression by OAS1 P46 augments the type I IFN response and inhibits WNV infection. A mouse Oas1 gene, Oas1b, also inhibits WNV growth through a similar mechanism. Specific residues in the RNA binding domains of P46 and Oas1b that regulate association of cGAS mRNA with OAS1, also control the antiviral activity. Our findings explain how some enzymatically inactive OAS1 proteins function as antiviral molecules.

Mechanism and inhibition of the papain-like protease, PLpro, of SARS-CoV-2.

The SARS‐CoV‐2 coronavirus encodes an essential papain‐like protease domain as part of its non‐structural protein (nsp)‐3, namely SARS2 PLpro, that cleaves the viral polyprotein, but also removes ubiquitin‐like ISG15 protein modifications as well as, with lower activity, Lys48‐linked polyubiquitin. Structures of PLpro bound to ubiquitin and ISG15 reveal that the S1 ubiquitin‐binding site is responsible for high ISG15 activity, while the S2 binding site provides Lys48 chain specificity and cleavage efficiency. To identify PLpro inhibitors in a repurposing approach, screening of 3,727 unique approved drugs and clinical compounds against SARS2 PLpro identified no compounds that inhibited PLpro consistently or that could be validated in counterscreens. More promisingly, non‐covalent small molecule SARS PLpro inhibitors also target SARS2 PLpro, prevent self‐processing of nsp3 in cells and display high potency and excellent antiviral activity in a SARS‐CoV‐2 infection model.

Therapeutic Strategies in the Development of Anti-viral Drugs and Vaccines Against SARS-CoV-2 Infection.

The whole world is currently facing a pandemic of an infectious disease known as novel coronavirus disease-2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) . This outbreak emerged unexpectedly and imposed a potential threat to humans, associated with the social and economic burden on the individual and federal governments. COVID-19, which initially started in Wuhan City of China and then spread to the whole world, has been declared a Public Health Emergency of International Concern. The continuous increase in the number of confirmed cases leads to high mortality across the world. Growing evidence indicates that the mortality rate is very predominant in elderly people and those with preexisting health conditions. However, the potential pathogenesis of SARS-CoV-2 infection in humans is still unknown. The dysregulated/exuberant immune response may have substantially contributed to the SARS-CoV-2-mediated pathology. Nevertheless, there is no clinically approved drug/vaccine currently available that can restrict its pathogenesis. However, several drugs are currently shown to provide some therapeutic benefits for COVID-19 patients, including antiviral drugs that might have a significant role in restricting the current pandemic of COVID-19. In this article, we highlighted the pharmacological treatment strategies for COVID-19 and purposed the therapeutic targets for the development of vaccines or anti-viral drug molecules against SARS-CoV-2 infection in humans.

High-Level Production of Recombinant Snowdrop Lectin in Sugarcane and Energy Cane.

Sugarcane and energy cane (Saccharum spp. hybrids) are ideal for plant-based production of recombinant proteins because their high resource-use efficiency, rapid growth and efficient photosynthesis enable extensive biomass production and protein accumulation at a cost-effective scale. Here, we aimed to develop these species as efficient platforms to produce recombinant Galanthus nivalis L. (snowdrop) agglutinin (GNA), a monocot-bulb mannose-specific lectin with potent antiviral, antifungal and antitumor activities. Initially, GNA levels of 0.04% and 0.3% total soluble protein (TSP) (0.3 and 3.8 mg kg–1 tissue) were recovered from the culms and leaves, respectively, of sugarcane lines expressing recombinant GNA under the control of the constitutive maize ubiquitin 1 (Ubi) promoter. Co-expression of recombinant GNA from stacked multiple promoters (pUbi and culm-regulated promoters from sugarcane dirigent5-1 and Sugarcane bacilliform virus) on separate expression vectors increased GNA yields up to 42.3-fold (1.8% TSP or 12.7 mg kg–1 tissue) and 7.7-fold (2.3% TSP or 29.3 mg kg–1 tissue) in sugarcane and energy cane lines, respectively. Moreover, inducing promoter activity in the leaves of GNA transgenic lines with stress-regulated hormones increased GNA accumulation to 2.7% TSP (37.2 mg kg–1 tissue). Purification by mannose-agarose affinity chromatography yielded a functional sugarcane recombinant GNA with binding substrate specificity similar to that of native snowdrop-bulb GNA, as shown by enzyme-linked lectin and mannose-binding inhibition assays. The size and molecular weight of recombinant GNA were identical to those of native GNA, as determined by size-exclusion chromatography and MALDI-TOF mass spectrometry. This work demonstrates the feasibility of producing recombinant GNA at high levels in Saccharum species, with the long-term goal of using it as a broad-spectrum antiviral carrier molecule for hemopurifiers and in related therapeutic applications.

In silico molecular investigations of pyridine N-Oxide compounds as potential inhibitors of SARS-CoV-2: 3D QSAR, molecular docking modeling, and ADMET screening

The new coronavirus SARS-CoV-2 virus is causing a severe pneumonia in human, provoking the serious outbreak epidemic CoV-2. Since its appearance in Wuhan, China on December 2019, CoV-2 becomes the biggest challenge the world is facing today, including the discovery of antiviral drug for SARS-CoV-2. In this study, the potential inhibitory of a class of human SARS inhibitors, namely pyridine N-oxide derivatives, against CoV-2 was addressed by quantitative structure-activity relationship 3 D-QSAR. The reliable CoMSIA developed model of 110 pyridine N-oxide based-antiviral compounds, showed Q2= 0.54 and The molecular surflex-docking was applied to identify the crystal structure of CoV-2 main protease 3CLpro (PDB: 6LU7) and two potentially and largely used antiviral molecules, namely chloroquine, hydroxychloroquine. The obtained free energy affinity and ADMET properties indicate that among the series of model antiviral compounds examined, the new antiviral compound A5 could be an excellent antiviral drug inhibitor against COVID-19. The inhibition activity of pyridine N-oxyde compounds against CoV-2 was compared with the activity of two common antiviral drug, namely chloroquine (CQ) and hydroxychloroquine (HCQ). DFT method was also used to define the sites of reactivity of pyridine N-oxyde derivatives as well as CQ and HCQ. Communicated by Ramaswamy H. Sarma

Quantum chemical insight into molecular structure, NBO analysis of the hydrogen-bonded interactions, spectroscopic (FT-IR, FT-Raman), drug likeness and molecular docking of the novel anti COVID-19 molecule 2-[(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(4-fluorophenyl)acetamide - dimer.

Novel antiviral active molecule 2- [(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(4-fluoro- phenyl)acetamide has been synthesised and characterized by FT-IR and FT-Raman spectra. The equilibrium geometry, natural bond orbital calculations and vibrational assignments have been carried out using density functional B3LYP method with the 6-311G++(d,p) basis set. The complete vibrational assignments for all the vibrational modes have been supported by normal coordinate analysis, force constants and potential energy distributions. A detailed analysis of the intermolecular interactions has been performed based on the Hirshfeld surfaces. Drug likeness has been carried out based on Lipinski's rule and the absorption, distribution, metabolism, excretion and toxicity of the title molecule has been calculated. Antiviral potency of 2- [(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(4-fluoro-phenyl) acetamide has been investigated by docking against SARS-CoV-2 protein. The optimized geometry shows near-planarity between the phenyl ring and the pyrimidine ring. Differences in the geometries due to the substitution of the most electronegative fluorine atom and intermolecular contacts due to amino pyrimidine were analyzed. NBO analysis reveals the formation of two strong stable hydrogen bonded N–H···N intermolecular interactions and weak intramolecular interactions C–H···O and N–H···O. The Hirshfeld surfaces and consequently the 2D-fingerprint confirm the nature of intermolecular interactions and their quantitative contributions towards the crystal packing. The red shift in N–H stretching frequency exposed from IR substantiate the formation of N–H···N intermolecular hydrogen bond. Drug likeness and absorption, distribution, metabolism, excretion and toxicity properties analysis gives an idea about the pharmacokinetic properties of the title molecule. The binding energy −8.7 kcal/mol of the nonbonding interaction present a clear view that 2- [(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(4-fluoro- phenyl) acetamide can irreversibly interact with SARS-CoV-2 protease.

Drugs against SARS-CoV-2: What do we know about their mode of action?

SummaryThe health emergency caused by the recent Covid‐19 pandemic highlights the need to identify effective treatments against the virus causing this disease (SARS‐CoV‐2). The first clinical trials have been testing repurposed drugs that show promising anti‐SARS‐CoV‐2 effects in cultured cells. Although more than 2400 clinical trials are already under way, the actual number of tested compounds is still limited to approximately 20, alone or in combination. In addition, knowledge on their mode of action (MoA) is currently insufficient. Their first results reveal some inconsistencies and contradictory results and suggest that cohort size and quality of the control arm are two key issues for obtaining rigorous and conclusive results. Moreover, the observed discrepancies might also result from differences in the clinical inclusion criteria, including the possibility of early treatment that may be essential for therapy efficacy in patients with Covid‐19. Importantly, efforts should also be made to test new compounds with a documented MoA against SARS‐CoV‐2 in clinical trials. Successful treatment will probably be based on multitherapies with antiviral compounds that target different steps of the virus life cycle. Moreover, a multidisciplinary approach that combines artificial intelligence, compound docking, and robust in vitro and in vivo assays will accelerate the development of new antiviral molecules. Finally, large retrospective studies on hospitalized patients are needed to evaluate the different treatments with robust statistical tools and to identify the best treatment for each Covid‐19 stage. This review describes different candidate antiviral strategies for Covid‐19, by focusing on their mechanism of action.

COVID-19 Therapeutic Options Under Investigation.

Since its emergence in China in December 2019, COVID-19 has quickly spread around the globe causing a pandemic. Vaccination or the development of herd immunity seems the only way to slow down the spread of the virus; however, both are not achievable in the near future. Therefore, effective treatments to mitigate the burden of this pandemic and reduce mortality rates are urgently needed. Preclinical and clinical studies of potential antiviral and immunomodulatory compounds and molecules to identify safe and efficacious therapeutics for COVID-19 are ongoing. Two compounds, remdesivir, and dexamethasone have been so far shown to reduce COVID-19–associated death. Here, we provide a review of the potential therapeutic agents being considered for the treatment and management of COVID-19 patients.

Evidence for an involvement of the ubiquitin-like modifier ISG15 in MHC class I antigen presentation.

The IFN stimulated gene 15 (ISG15) encodes a 15-kDa ubiquitin-like protein, that is induced by type I IFNs and is conjugated to the bulk of newly synthesized polypeptides at the ribosome. ISG15 functions as an antiviral molecule possibly by being covalently conjugated to viral proteins and disturbing virus particle assembly. Here, we have investigated the effect of ISGylation on degradation and antigen presentation of viral and cellular proteins. ISGylation did not induce proteasomal degradation of bulk ISG15 target proteins neither after overexpressing ISG15 nor after induction by IFN-β. The MHC class I cell surface expression of splenocytes derived from ISG15-deficient mice or mice lacking the catalytic activity of the major de-ISGylating enzyme USP18 was unaltered as compared to WT mice. Fusion of ubiquitin or FAT10 to the long-lived nucleoprotein (NP) of lymphocytic choriomeningitis virus accelerated the proteasomal degradation of NP while fusion to ISG15 did not detectably speed up NP degradation. Nevertheless, MHC-I restricted presentation of two epitopes of NP were markedly enhanced when it was fused to ISG15 similarly to fusion with ubiquitin or FAT10. Thus, we provide evidence that ISG15 can enhance the presentation of antigens on MHC-I most likely by promoting co-translational antigen processing.

Polymers in the Medical Antiviral Front-Line.

Antiviral polymers are part of a major campaign led by the scientific community in recent years. Facing this most demanding of campaigns, two main approaches have been undertaken by scientists. First, the classic approach involves the development of relatively small molecules having antiviral properties to serve as drugs. The other approach involves searching for polymers with antiviral properties to be used as prescription medications or viral spread prevention measures. This second approach took two distinct directions. The first, using polymers as antiviral drug-delivery systems, taking advantage of their biodegradable properties. The second, using polymers with antiviral properties for on-contact virus elimination, which will be the focus of this review. Anti-viral polymers are obtained by either the addition of small antiviral molecules (such as metal ions) to obtain ion-containing polymers with antiviral properties or the use of polymers composed of an organic backbone and electrically charged moieties like polyanions, such as carboxylate containing polymers, or polycations such as quaternary ammonium containing polymers. Other approaches include moieties hybridized by sulphates, carboxylic acids, or amines and/or combining repeating units with a similar chemical structure to common antiviral drugs. Furthermore, elevated temperatures appear to increase the anti-viral effect of ions and other functional moieties.

Unique Domain for a Unique Target: Selective Inhibitors of Host Cell DDX3X to Fight Emerging Viruses.

Emerging viruses like dengue, West Nile, chikungunya, and Zika can cause widespread viral epidemics. Developing novel drugs or vaccines against specific targets for each virus is a difficult task. As obligate parasites, all viruses exploit common cellular pathways, providing the possibility to develop broad-spectrum antiviral agents targeting host factors. The human DEAD-box RNA helicase DDX3X is an essential cofactor for viral replication but dispensable for cell viability. Herein, we exploited the presence of a unique structural motif of DDX3X not shared by other cellular enzymes to develop a theoretical model to aid in the design of a novel class of highly selective inhibitors acting against such specific targets, thus limiting off-targeting effects. High-throughput virtual screening led us to identify hit compound 5, endowed with promising antienzymatic activity. To improve its aqueous solubility, 5 and its two enantiomers were synthesized and converted into their corresponding acetate salts (compounds 11, 12, and 13). In vitro mutagenesis and biochemical and cellular assays further confirmed that the developed molecules were selective for DDX3X and were able to suppress replication of West Nile and dengue viruses in infected cells in the micromolar range while showing no toxicity for uninfected cells. These results provide proof of principle for a novel strategy in developing highly selective and broad-spectrum antiviral molecules active against emerging and dangerous viral pathogens. This study paves the way for the development of larger focused libraries targeting such domain to expand SAR studies and fully characterize their mode of interaction.

Interplay between SARS-CoV-2 and the type I interferon response.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the current COVID-19 pandemic. An unbalanced immune response, characterized by a weak production of type I interferons (IFN-Is) and an exacerbated release of proinflammatory cytokines, contributes to the severe forms of the disease. SARS-CoV-2 is genetically related to SARS-CoV and Middle East respiratory syndrome-related coronavirus (MERS-CoV), which caused outbreaks in 2003 and 2013, respectively. Although IFN treatment gave some encouraging results against SARS-CoV and MERS-CoV in animal models, its potential as a therapeutic against COVID-19 awaits validation. Here, we describe our current knowledge of the complex interplay between SARS-CoV-2 infection and the IFN system, highlighting some of the gaps that need to be filled for a better understanding of the underlying molecular mechanisms. In addition to the conserved IFN evasion strategies that are likely shared with SARS-CoV and MERS-CoV, novel counteraction mechanisms are being discovered in SARS-CoV-2–infected cells. Since the last coronavirus epidemic, we have made considerable progress in understanding the IFN-I response, including its spatiotemporal regulation and the prominent role of plasmacytoid dendritic cells (pDCs), which are the main IFN-I–producing cells. While awaiting the results of the many clinical trials that are evaluating the efficacy of IFN-I alone or in combination with antiviral molecules, we discuss the potential benefits of a well-timed IFN-I treatment and propose strategies to boost pDC-mediated IFN responses during the early stages of viral infection.

Aggregation of 25-hydroxycholesterol in a complex biomembrane. Differences with cholesterol

25-Hydroxycholesterol (25HC), one of the most important oxysterol molecules, can be used by cells to fight bacterial and viral infections but the mechanism that defines its biological effects are unknown. Using molecular dynamics, we have aimed to describe the orientation and location of 25HC in the membrane as well as the interactions it might have with lipids. We have studied two complex model membrane systems, one similar to the late endosome membrane and the other one to the plasma membrane. Our results reinforce that 25HC is inserted in the membrane in a relative stable location similar to but not identical to cholesterol. 25HC fluctuates in the membrane to a much greater degree than cholesterol, but the effect of 25HC on the phospholipid order parameters is not significantly different. One of the most notable facts about 25HC is that, unlike cholesterol, this molecule tends to aggregate, forming dimers, trimers and higher-order aggregates. These aggregates are formed spontaneously through the formation of hydrogen bonds between the two 25HC atoms, the formation of hydrogen bonds being independent of the studied system. Remarkably, no contacts or hydrogen bonds are observed between 25HC and cholesterol molecules, as well as between cholesterol molecules themselves at any time. It would be conceivable that 25HC, by forming high order aggregates without significantly altering the membrane properties, would modify the way proteins interact with the membrane and henceforth form a true innate antiviral molecule.

Identification of Estrogen Receptor Modulators as Inhibitors of Flavivirus Infection.

Flaviviruses such as Zika virus (ZIKV), dengue virus (DENV), and West Nile virus (WNV) are major global pathogens for which safe and effective antiviral therapies are not currently available. To identify antiviral small molecules with well-characterized safety and bioavailability profiles, we screened a library of 2,907 approved drugs and pharmacologically active compounds for inhibitors of ZIKV infection using a high-throughput cell-based immunofluorescence assay. Interestingly, estrogen receptor modulators raloxifene hydrochloride and quinestrol were among 15 compounds that significantly inhibited ZIKV infection in repeat screens. Subsequent validation studies revealed that these drugs effectively inhibit ZIKV, DENV, and WNV (Kunjin strain) infection at low micromolar concentrations with minimal cytotoxicity in Huh-7.5 hepatoma cells and HTR-8 placental trophoblast cells. Since these cells lack detectable expression of estrogen receptors-α and -β (ER-α and ER-β) and similar antiviral effects were observed in the context of subgenomic DENV and ZIKV replicons, these compounds appear to inhibit viral RNA replication in a manner that is independent of their known effects on estrogen receptor signaling. Taken together, quinestrol, raloxifene hydrochloride, and structurally related analogues warrant further investigation as potential therapeutics for treatment of flavivirus infections.

Treatment of COVID-19 Pneumonia: the Case for Placenta-derived Cell Therapy

Nearly 500’000 fatalities due to COVID-19 have been reported globally and the death toll is still rising. Most deaths are due to acute respiratory distress syndrome (ARDS), as a result of an excessive immune response and a cytokine storm elicited by severe SARS-CoV-2 lung infection, rather than by a direct cytopathic effect of the virus. In the most severe forms of the disease therapies should aim primarily at dampening the uncontrolled inflammatory/immune response responsible for most fatalities. Pharmacological agents - antiviral and anti-inflammatory molecules - have not been able so far to achieve compelling results for the control of severe COVID-19 pneumonia. Cells derived from the placenta and/or fetal membranes, in particular amniotic epithelial cells (AEC) and decidual stromal cells (DSC), have established, well-characterized, potent anti-inflammatory and immune-modulatory properties that make them attractive candidates for a cell-based therapy of COVID19 pneumonia. Placenta-derived cells are easy to procure from a perennial source and pose minimal ethical issues for their utilization. In view of the existing clinical evidence for the innocuousness and efficiency of systemic administration of DSCs or AECs in similar conditions, we advocate for the initiation of clinical trials using this strategy in the treatment of severe COVID-19 disease.

The Regulation of Flavivirus Infection by Hijacking Exosome-Mediated Cell-Cell Communication: New Insights on Virus-Host Interactions.

The arthropod-borne flaviviruses are important human pathogens, and a deeper understanding of the virus–host cell interaction is required to identify cellular targets that can be used as therapeutic candidates. It is well reported that the flaviviruses hijack several cellular functions, such as exosome-mediated cell communication during infection, which is modulated by the delivery of the exosomal cargo of pro- or antiviral molecules to the receiving host cells. Therefore, to study the role of exosomes during flavivirus infections is essential, not only to understand its relevance in virus–host interaction, but also to identify molecular factors that may contribute to the development of new strategies to block these viral infections. This review explores the implications of exosomes in flavivirus dissemination and transmission from the vector to human host cells, as well as their involvement in the host immune response. The hypothesis about exosomes as a transplacental infection route of ZIKV and the paradox effect or the dual role of exosomes released during flavivirus infection are also discussed here. Although several studies have been performed in order to identify and characterize cellular and viral molecules released in exosomes, it is not clear how all of these components participate in viral pathogenesis. Further studies will determine the balance between protective and harmful exosomes secreted by flavivirus infected cells, the characteristics and components that distinguish them both, and how they could be a factor that determines the infection outcome.

Molecular Docking Study of Several Antiviral Drugs to Defeat Covid-19

Corona virus is one of the significant pathogens that destructs the human respiratory functioning. Deaths and casualties caused by coronaviruses (CoVs) include the severe acute respiratory syndrome (SARS)-CoV and the Middle East respiratory syndrome (MERS)-CoV. The aim of the work was to compare several antiviral drugs and find out which is the most active drug that might be used in treatment for COVID -19. In this study Molecular Docking approach was used to determine the binding affinities of 62 antiviral molecules. The study was carried out using Molegro Virtual Docker 6.0 with PDB 2GTB procured from RCSB Protein Data Bank. Simeprevir and Telaprevir were discovered to be most potent having high MolDock and Rerank scores of -225.158, -78.4383 and -209.467, -136.155 respectively. Further studies may be conducted to design more potent analogue and defeat COVID-19.

Virtual screening based on molecular docking of possible inhibitors of Covid-19 main protease

Coronavirus (COVID-19) is an enveloped RNA virus that is diversely found in humans and that has now been declared a global pandemic by the World Health Organization. Thus, there is an urgent need to develop effective therapies and vaccines against this disease. In this context, this study aimed to evaluate in silico the molecular interactions of drugs with therapeutic indications for treatment of COVID-19 (Azithromycin, Baricitinib and Hydroxychloroquine) and drugs with similar structures (Chloroquine, Quinacrine and Ruxolitinib) in docking models from the SARS-CoV-2 main protease (M-pro) protein. The results showed that all inhibitors bound to the same enzyme site, more specifically in domain III of the SARS-CoV-2 main protease. Therefore, this study allows proposing the use of baricitinib and quinacrine, in combination with azithromycin; however, these computer simulations are just an initial step for conceiving new projects for the development of antiviral molecules.