Aesculus hippocastanum extract and the main bioactive constituent ß-escin as antivirals agents against coronaviruses, including SARS-CoV-2.

Respiratory viruses can cause life-threatening illnesses. The focus of treatment is on supportive therapies and direct antivirals. However, antivirals may cause resistance by exerting selective pressure. Modulating the host response has emerged as a viable therapeutic approach for treating respiratory infections. Additionally, considering the probable future respiratory virus outbreaks emphasizes the need for broad-spectrum therapies to be prepared for the next pandemics. One of the principal bioactive constituents found in the seed extract of Aesculus hippocastanum L. (AH) is ß-escin. The clinical therapeutic role of ß-escin and AH has been associated with their anti-inflammatory effects. Regarding their mechanism of action, we and others have shown that ß-escin and AH affect NF-κB signaling. Furthermore, we have reported the virucidal and broad-spectrum antiviral properties of ß-escin and AH against enveloped viruses such as RSV, in vitro and in vivo. In this study, we demonstrate that ß-escin and AH have antiviral and virucidal activities against SARS-CoV-2 and CCoV, revealing broad-spectrum antiviral activity against coronaviruses. Likewise, they exhibited NF-κB and cytokine modulating activities in epithelial and macrophage cell lines infected with coronaviruses in vitro. Hence, ß-escin and AH are promising broad-spectrum antiviral, immunomodulatory, and virucidal drugs against coronaviruses and respiratory viruses, including SARS-CoV-2.

Isoliquiritigenin inhibits virus replication and virus-mediated inflammation via NRF2 signaling.

BACKGROUND: The transcription factor NRF2 is a master redox switch that regulates the cellular antioxidant response. However, recent advances have revealed new roles for NRF2, including the regulation of antiviral responses to various viruses, suggesting that pharmacological NRF2-activating agents may be a promising therapeutic drug for viral diseases. Isoliquiritigenin (ISL), a chalcone isolated from liquorice (Glycyrrhizae Radix) root, is reported to be a natural NRF2 agonist and has has antiviral activities against HCV (hepatitis C virus) and IAV (influenza A virus). However, the spectrum of antiviral activity and associated mechanism of ISL against other viruses are not well defined. PURPOSE: This study investigated the antiviral activity and underlying mechanism of ISL against vesicular stomatitis virus (VSV), influenza A virus (H1N1), encephalomyocarditis virus (EMCV), herpes simplex virus type 1 (HSV-1). METHODS: We evaluated the antiviral activity of ISL against VSV, H1N1, EMCV, and HSV-1 using flow cytometry and qRT-PCR analysis. RNA sequencing and bioinformatic analysis were performed to investigate the potential antiviral mechanism of ISL. NRF2 knockout cells were used to investigate whether NRF2 is required for the antiviral activity of ISL. The anti-apoptosis and anti-inflammatory activities of ISL were further measured by counting cell death ratio and assessing proinflammatory cytokines expression in virus-infected cells, respectively. In addition, we evaluated the antiviral effect of ISL in vivo by measuring the survival rate, body weights, histological analysis, viral load, and cytokine expression in VSV-infected mouse model. RESULTS: Our data demonstrated that ISL effectively suppressed VSV, H1N1, HSV-1, and EMCV replication in vitro. The antiviral activity of ISL could be partially impaired in NRF2-deficient cells. Virus-induced cell death and proinflammatory cytokines were repressed by ISL. Finally, we showed that ISL treatment protected mice against VSV infection by reducing viral titers and suppressing the expression of inflammatory cytokines in vivo. CONCLUSION: These findings suggest that ISL has antiviral and anti-inflammatory effects in virus infections, which are associated with its ability to activate NRF2 signaling, thus indicating that ISL has the potential to serve as an NRF2 agonist in the treatment of viral diseases.

Diphyllin Shows a Broad-Spectrum Antiviral Activity against Multiple Medically Important Enveloped RNA and DNA Viruses.

Diphyllin is a natural arylnaphtalide lignan extracted from tropical plants of particular importance in traditional Chinese medicine. This compound has been described as a potent inhibitor of vacuolar (H+)ATPases and hence of the endosomal acidification process that is required by numerous enveloped viruses to trigger their respective viral infection cascades after entering host cells by receptor-mediated endocytosis. Accordingly, we report here a revised, updated, and improved synthesis of diphyllin, and demonstrate its antiviral activities against a panel of enveloped viruses from Flaviviridae, Phenuiviridae, Rhabdoviridae, and Herpesviridae families. Diphyllin is not cytotoxic for Vero and BHK-21 cells up to 100 µM and exerts a sub-micromolar or low-micromolar antiviral activity against tick-borne encephalitis virus, West Nile virus, Zika virus, Rift Valley fever virus, rabies virus, and herpes-simplex virus type 1. Our study shows that diphyllin is a broad-spectrum host cell-targeting antiviral agent that blocks the replication of multiple phylogenetically unrelated enveloped RNA and DNA viruses. In support of this, we also demonstrate that diphyllin is more than just a vacuolar (H+)ATPase inhibitor but may employ other antiviral mechanisms of action to inhibit the replication cycles of those viruses that do not enter host cells by endocytosis followed by low pH-dependent membrane fusion.

Prokaryotic viruses impact functional microorganisms in nutrient removal and carbon cycle in wastewater treatment plants.

As one of the largest biotechnological applications, activated sludge (AS) systems in wastewater treatment plants (WWTPs) harbor enormous viruses, with 10-1,000-fold higher concentrations than in natural environments. However, the compositional variation and host-connections of AS viruses remain poorly explored. Here, we report a catalogue of ~50,000 prokaryotic viruses from six WWTPs, increasing the number of described viral species of AS by 23-fold, and showing the very high viral diversity which is largely unknown (98.4-99.6% of total viral contigs). Most viral genera are represented in more than one AS system with 53 identified across all. Viral infection widely spans 8 archaeal and 58 bacterial phyla, linking viruses with aerobic/anaerobic heterotrophs, and other functional microorganisms controlling nitrogen/phosphorous removal. Notably, Mycobacterium, notorious for causing AS foaming, is associated with 402 viral genera. Our findings expand the current AS virus catalogue and provide reference for the phage treatment to control undesired microorganisms in WWTPs.

Clinical aspects of the use of lactoferrin in dentistry.

BACKGROUND: Lactoferrin (Lf) is a natural iron-binding protein involved in coordinating specific and non-specific immune responses in humans. It exhibits broad spectrum antimicrobial properties against bacteria, viruses, and fungi. Owing to its high affinity for ferric (Fe+++) ions, Lf is responsible for controlling the oxidative stress in the body, and thus protects cells from oxygen injury. In addition, Lf is a natural immunomodulatory molecule that regulates the activity of the immune system. HIGHLIGHT: Lactoferrin present in saliva plays an important role in maintaining oral hygiene. It exhibits protective function on mucosal surfaces, which constitute a barrier between the host and the external environment. Thus, Lf may be considered as the first line of defense protein that is associated with oral mucosal immunity. CONCLUSION: Many studies indicate that lactoferrin supplementation is safe and beneficial for human health. The aim of this review is to discuss the effects of Lf on oral microflora, highlighting the potential significance of this protein in dental therapy and prevention of oral diseases.

DescribePROT: database of amino acid-level protein structure and function predictions.

We present DescribePROT, the database of predicted amino acid-level descriptors of structure and function of proteins. DescribePROT delivers a comprehensive collection of 13 complementary descriptors predicted using 10 popular and accurate algorithms for 83 complete proteomes that cover key model organisms. The current version includes 7.8 billion predictions for close to 600 million amino acids in 1.4 million proteins. The descriptors encompass sequence conservation, position specific scoring matrix, secondary structure, solvent accessibility, intrinsic disorder, disordered linkers, signal peptides, MoRFs and interactions with proteins, DNA and RNAs. Users can search DescribePROT by the amino acid sequence and the UniProt accession number and entry name. The pre-computed results are made available instantaneously. The predictions can be accesses via an interactive graphical interface that allows simultaneous analysis of multiple descriptors and can be also downloaded in structured formats at the protein, proteome and whole database scale. The putative annotations included by DescriPROT are useful for a broad range of studies, including: investigations of protein function, applied projects focusing on therapeutics and diseases, and in the development of predictors for other protein sequence descriptors. Future releases will expand the coverage of DescribePROT. DescribePROT can be accessed at http://biomine.cs.vcu.edu/servers/DESCRIBEPROT/.

Antiviral Properties of Flavonoids and Delivery Strategies.

This review summarizes the latest advancements in phytochemicals as functional antiviral agents. We focused on flavonoids, like apigenin, vitexin, quercetin, rutin and naringenin, which have shown a wide range of biological effects including antiviral activities. The molecular mechanisms of their antiviral effects mainly consist in the inhibition of viral neuraminidase, proteases and DNA/RNA polymerases, as well as in the modification of various viral proteins. Mixtures of different flavonoids or combination of flavonoids with antiviral synthetic drugs provide an enhancement of their antiviral effects. Recent strategies in drug delivery significantly contribute to overcoming the low bioavailability of flavonoids. Frequent viral infections worldwide have led to the need for new effective antiviral agents, which can be identified among the various phytochemicals. In this light, screening the antiviral activities of a cocktail of flavonoids would be advantageous in order to prevent viral infections and improve current antiviral therapies.

Trends and targets in antiviral phototherapy.

Photodynamic therapy (PDT) is a well-established treatment option in the treatment of certain cancerous and pre-cancerous lesions. Though best-known for its application in tumor therapy, historically the photodynamic effect was first demonstrated against bacteria at the beginning of the 20th century. Today, in light of spreading antibiotic resistance and the rise of new infections, this photodynamic inactivation (PDI) of microbes, such as bacteria, fungi, and viruses, is gaining considerable attention. This review focuses on the PDI of viruses as an alternative treatment in antiviral therapy, but also as a means of viral decontamination, covering mainly the literature of the last decade. The PDI of viruses shares the general action mechanism of photodynamic applications: the irradiation of a dye with light and the subsequent generation of reactive oxygen species (ROS) which are the effective phototoxic agents damaging virus targets by reacting with viral nucleic acids, lipids and proteins. Interestingly, a light-independent antiviral activity has also been found for some of these dyes. This review covers the compound classes employed in the PDI of viruses and their various areas of use. In the medical area, currently two fields stand out in which the PDI of viruses has found broader application: the purification of blood products and the treatment of human papilloma virus manifestations. However, the PDI of viruses has also found interest in such diverse areas as water and surface decontamination, and biosafety.

Interspecies cross-feeding orchestrates carbon degradation in the rumen ecosystem.

Because of their agricultural value, there is a great body of research dedicated to understanding the microorganisms responsible for rumen carbon degradation. However, we lack a holistic view of the microbial food web responsible for carbon processing in this ecosystem. Here, we sampled rumen-fistulated moose, allowing access to rumen microbial communities actively degrading woody plant biomass in real time. We resolved 1,193 viral contigs and 77 unique, near-complete microbial metagenome-assembled genomes, many of which lacked previous metabolic insights. Plant-derived metabolites were measured with NMR and carbohydrate microarrays to quantify the carbon nutrient landscape. Network analyses directly linked measured metabolites to expressed proteins from these unique metagenome-assembled genomes, revealing a genome-resolved three-tiered carbohydrate-fuelled trophic system. This provided a glimpse into microbial specialization into functional guilds defined by specific metabolites. To validate our proteomic inferences, the catalytic activity of a polysaccharide utilization locus from a highly connected metabolic hub genome was confirmed using heterologous gene expression. Viral detected proteins and linkages to microbial hosts demonstrated that phage are active controllers of rumen ecosystem function. Our findings elucidate the microbial and viral members, as well as their metabolic interdependencies, that support in situ carbon degradation in the rumen ecosystem.

Rapid Molecular Profiling of Defined Cell Types Using Viral TRAP.

Translational profiling methodologies enable the systematic characterization of cell types in complex tissues, such as the mammalian brain, where neuronal isolation is exceptionally difficult. Here, we report a versatile strategy for profiling CNS cell types in a spatiotemporally restricted fashion by engineering a Cre-dependent adeno-associated virus expressing an EGFP-tagged ribosomal protein (AAV-FLEX-EGFPL10a) to access translating mRNAs by translating ribosome affinity purification (TRAP). We demonstrate the utility of this AAV to target a variety of genetically and anatomically defined neural populations expressing Cre recombinase and illustrate the ability of this viral TRAP (vTRAP) approach to recapitulate the molecular profiles obtained by bacTRAP in corticothalamic neurons across multiple serotypes. Furthermore, spatially restricting adeno-associated virus (AAV) injections enabled the elucidation of regional differences in gene expression within this cell type. Altogether, these results establish the broad applicability of the vTRAP strategy for the molecular dissection of any CNS or peripheral cell type that can be engineered to express Cre.

Ecology of the Oral Microbiome: Beyond Bacteria.

Although great strides have been made in understanding the complex bacterial community inhabiting the human oral cavity, for a variety of (mainly technical) reasons the ecological contributions of oral fungi, viruses, phages, and the candidate phyla radiation (CPR) group of ultrasmall bacteria have remained understudied. Several recent reports have illustrated the diversity and importance of these organisms in the oral cavity, while TM7x and Candida albicans have served as crucial paradigms for CPR species and oral fungi, respectively. A comprehensive understanding of the oral microbiota and its influence on host health and disease will require a holistic view that emphasizes interactions among different residents within the oral community, as well as their interaction with the host.

Human tyrosinase produced in insect cells: a landmark for the screening of new drugs addressing its activity.

Human tyrosinase is the first enzyme of the multistep process of melanogenesis. It catalyzes the hydroxylation of L-tyrosine to L-dihydroxyphenylalanine and the following oxidation of o-diphenol to the corresponding quinone, L-dopaquinone. In spite of its biomedical relevance, its reactivity is far from being fully understood, mostly because of the lack of a suitable expression system. Indeed, until now, studies on substrates and inhibitors of tyrosinases have been performed in vitro almost exclusively using mushroom or bacterial enzymes. We report on the production of a recombinant human tyrosinase in insect cells (Sf9 line). Engineering the protein, improving cell culture conditions, and setting a suitable purification protocol optimized product yield. The obtained active enzyme was truthfully characterized with a number of substrate and inhibitor molecules. These results were compared to those gained from a parallel analysis of the bacterial (Streptomyces antibioticus) enzyme and those acquired from the literature for mushroom tyrosinase, showing that the reactivity of the human enzyme appears unique and pointing out the great bias introduced when using non-human tyrosinases to measure the inhibitory efficacy of new molecules. The described enzyme is therefore an indispensable paradigm in testing pharmaceutical or cosmetic agents addressing tyrosinase activity.

The elemental composition of virus particles: implications for marine biogeochemical cycles.

In marine environments, virus-mediated lysis of host cells leads to the release of cellular carbon and nutrients and is hypothesized to be a major driver of carbon recycling on a global scale. However, efforts to characterize the effects of viruses on nutrient cycles have overlooked the geochemical potential of the virus particles themselves, particularly with respect to their phosphorus content. In this Analysis article, we use a biophysical scaling model of intact virus particles that has been validated using sequence and structural information to quantify differences in the elemental stoichiometry of marine viruses compared with their microbial hosts. By extrapolating particle-scale estimates to the ecosystem scale, we propose that, under certain circumstances, marine virus populations could make an important contribution to the reservoir and cycling of oceanic phosphorus.

Viral mimicking ternary polyplexes: a reduction-controlled hierarchical unpacking vector for gene delivery.

Reduction-controlled hierarchical unpacking is proposed for the development of virus-mimicking gene carriers. Disulfide-bond-modified hyaluronic acid (HA) is deposited onto the surface of diselenide-conjugated oligoethylenimine/DNA polyplexes to form DNA/OEI-SeSex/HA-SS-COOH (DOS) polyplexes. The cleavage of the disulfide and diselenide bonds is triggered by the gradient GSH level at the tumor site and inside the cells. The transfection efficiency of DOS show significant enhancement over DNA/poly(ethylene imine) (DP) in vitro and in vivo.

Nonviral gene targeting at rDNA locus of human mesenchymal stem cells.

BACKGROUND: Genetic modification, such as the addition of exogenous genes to the MSC genome, is crucial to their use as cellular vehicles. Due to the risks associated with viral vectors such as insertional mutagenesis, the safer nonviral vectors have drawn a great deal of attention. METHODS: VEGF, bFGF, vitamin C, and insulin-transferrin-selenium-X were supplemented in the MSC culture medium. The cells' proliferation and survival capacity was measured by MTT, determination of the cumulative number of cells, and a colony-forming efficiency assay. The plasmid pHr2-NL was constructed and nucleofected into MSCs. The recombinants were selected using G418 and characterized using PCR and Southern blotting. RESULTS: BFGF is critical to MSC growth and it acted synergistically with vitamin C, VEGF, and ITS-X, causing the cells to expand significantly. The neomycin gene was targeted to the rDNA locus of human MSCs using a nonviral human ribosomal targeting vector. The recombinant MSCs retained multipotential differentiation capacity, typical levels of hMSC surface marker expression, and a normal karyotype, and none were tumorigenic in nude mice. CONCLUSIONS: Exogenous genes can be targeted to the rDNA locus of human MSCs while maintaining the characteristics of MSCs. This is the first nonviral gene targeting of hMSCs.

Virus-host interactomes--antiviral drug discovery.

One of the key questions in virology is how viruses, encoding relatively few genes, gain temporary or constant control over their hosts. To understand pathogenicity of a virus it is important to gain knowledge on the function of the individual viral proteins in the host cell, on their interactions with viral and cellular proteins and on the consequences of these interactions on cellular signaling pathways. A combination of transcriptomics, proteomics, high-throughput technologies and the bioinformatical analysis of the respective data help to elucidate specific cellular antiviral drug target candidates. In addition, viral and human interactome analyses indicate that different viruses target common, central human proteins for entering cellular signaling pathways and machineries which might constitute powerful broad-spectrum antiviral targets.

Phenylboronic-acid-based carbohydrate binders as antiviral therapeutics: monophenylboronic acids.

BACKGROUND: The development of carbohydrate-binding agents as novel therapeutics for the inhibition of highly glycosylated enveloped viruses has generated much attention in recent literature. Possessing a potential dual mode of action by inhibiting virus entry and exposing the virion to neutralization by the host immune system upon the deletion of envelope glycans under drug pressure, these substances might provide a new direction in antiviral treatment. Phenylboronic acids are widely known to bind the cis-diol functionality of carbohydrate structures, thereby identifying themselves as potential lead structures. To date, few details have been disclosed of the structure-activity relationship of these substances in correlation to their antiviral activity. METHODS: In this study, a compound library of a diverse range of ortho-, meta- and para- ring-substituted monophenylboronic acids and glutamine phenylboronic acid analogues was prepared, characterized and evaluated to probe antiviral activity versus a broad range of (enveloped) viruses. RESULTS: The compounds described herein lack antiviral activity. They also did not show measurable binding to HIV type-1 (HIV-1) gp120, using surface plasmon resonance technology. However, of note is the general lack of toxicity, which suggests that further investigation of the compounds as potential therapeutics is needed. CONCLUSIONS: The monophenylboronic acids tested exhibited no antiviral activity as potential carbohydrate binders versus a broad range of enveloped and non-enveloped viruses. The compounds tested did not bind HIV-1 gp120, possibly because of their small size and lack of multivalency.

Virus production and lysate recycling in different sub-basins of the northern Baltic Sea.

In the Gulf of Bothnia, northern Baltic Sea, a large freshwater inflow creates north-southerly gradients in physico-chemical and biological factors across the two sub-basins, the Bothnian Bay (BB) and the Bothnian Sea. In particular, the sub-basins differ in nutrient limitation (nitrogen vs. phosphorus; P). Since viruses are rich in P, and virus production is commonly connected with bacterial abundance and growth, we hypothesized that the role of viral lysis differs between the sub-basins. Thus, we examined virus production and the potential importance of lysate recycling in surface waters along a transect in the Gulf of Bothnia. Surprisingly, virus production and total P were negatively correlated. In the BB, virus production rates were double those elsewhere in the system, although bacterial abundance and production were the lowest. In the BB, virus-mediated cell lysates could account for 70-180% and 100-250% of the bacterial carbon and P demand, respectively, while only 4-15% and 8-21% at the other stations. Low concentrations of dissolved DNA (D-DNA) with a high proportion of encapsulated DNA (viruses) in the BB suggested rapid turnover and high uptake of free DNA. The correlation of D-DNA and total P indicates that D-DNA is a particularly important nutrient source in the P-limited BB. Our study demonstrates large and counterintuitive differences in virus-mediated recycling of carbon and nutrients in two basins of the Gulf of Bothnia, which differ in microbial community composition and nutrient limitation.

Glycan arrays: biological and medical applications.

Carbohydrates and their conjugates are involved in various biological events, including viral and bacterial infection, the immune response, differentiation and development, and the progression of tumor cell metastasis. Glycan arrays are a new technology that has enabled the high-sensitivity and rapid analysis carbohydrate-protein interaction and contribute to significant advances in glycomics. Glycan arrays use a minute amount of materials and can be used for high-throughput profiling and quantitative analysis and provide information for the development of carbohydrate-based vaccines and new drug discovery.