Evaluation of Ebola Virus Inhibitors for Drug Repurposing

A systematic screen of FDA-approved drugs was performed to identify compounds with in vitro antiviral activities against Ebola virus (EBOV). Compounds active (>50% viral inhibition and <30% cellular toxicity) at a single concentration were tested in dose-response assays to quantitate the antiviral activities in replication and viral entry assays as well as cytotoxicity in the Vero cell line used to conduct these assays. On the basis of the approved human dosing, toxicity/tolerability, and pharmacokinetic data, seven of these in vitro hits from different pharmacological classes (chloroquine (CQ), amiodarone, prochlorperazine, benztropine, azithromycin, chlortetracycline, and clomiphene) were evaluated for their in vivo efficacy at a single dose and were administered via either intraperitoneal (ip) or oral route. Initially, azithromycin (100 mg/kg, twice daily, ip), CQ (90 mg/kg, twice daily, ip), and amiodarone (60 mg/kg, twice daily, ip) demonstrated significant increases in survival in the mouse model. After repeat evaluation, only CQ was found to reproducibly give significant efficacy in the mouse model with this dosing regimen. Azithromycin and CQ were also tested in a guinea pig model of EBOV infection over a range of doses, but none of the doses increased survival, and drug-related toxicity was observed at lower doses than in the mouse. These results show the benefits and specific challenges associated with drug repurposing and highlight the need for careful evaluation of approved drugs as rapidly deployable countermeasures against future pandemics.

Resveratrol Inhibits HCoV-229E and SARS-CoV-2 Coronavirus Replication In Vitro

A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in China at the end of 2019 causing a large global outbreak. As treatments are of the utmost importance, drug repurposing embodies a rich and rapid drug discovery landscape, where candidate drug compounds could be identified and optimized. To this end, we tested seven compounds for their ability to reduce replication of human coronavirus (HCoV)-229E, another member of the coronavirus family. Among these seven drugs tested, four of them, namely rapamycin, disulfiram, loperamide and valproic acid, were highly cytotoxic and did not warrant further testing. In contrast, we observed a reduction of the viral titer by 80% with resveratrol (50% effective concentration (EC50) = 4.6 µM) and lopinavir/ritonavir (EC50 = 8.8 µM) and by 60% with chloroquine (EC50 = 5 µM) with very limited cytotoxicity. Among these three drugs, resveratrol was less cytotoxic (cytotoxic concentration 50 (CC50) = 210 µM) than lopinavir/ritonavir (CC50 = 102 µM) and chloroquine (CC50 = 67 µM). Thus, among the seven drugs tested against HCoV-229E, resveratrol demonstrated the optimal antiviral response with low cytotoxicity with a selectivity index (SI) of 45.65. Similarly, among the three drugs with an anti-HCoV-229E activity, namely lopinavir/ritonavir, chloroquine and resveratrol, only the latter showed a reduction of the viral titer on SARS-CoV-2 with reduced cytotoxicity. This opens the door to further evaluation to fight Covid-19.

Small-Molecule CD4-Mimics: Structure-Based Optimization of HIV-1 Entry Inhibition

The optimization, based on computational, thermodynamic, and crystallographic data, of a series of small-molecule ligands of the Phe43 cavity of the envelope glycoprotein gp120 of human immunodeficiency virus (HIV) has been achieved. Importantly, biological evaluation revealed that the small-molecule CD4 mimics (4-7) inhibit HIV-1 entry into target cells with both significantly higher potency and neutralization breadth than previous congeners, while maintaining high selectivity for the target virus. Their binding mode was characterized via thermodynamic and crystallographic studies.

Structure-Based Design and Synthesis of an HIV-1 Entry Inhibitor Exploiting X-Ray and Thermodynamic Characterization

The design, synthesis, thermodynamic and crystallographic characterization of a potent, broad spectrum, second-generation HIV-1 entry inhibitor that engages conserved carbonyl hydrogen bonds within gp120 has been achieved. The optimized antagonist exhibits a sub-micromolar binding affinity (110 nM) and inhibits viral entry of clade B and C viruses (IC₅₀ geometric mean titer of 1.7 and 14.0 μM, respectively), without promoting CD4-independent viral entry. thermodynamic signatures indicate a binding preference for the (R,R)-over the (S,S)-enantiomer. The crystal structure of the small molecule-gp120 complex reveals the displacement of crystallographic water and the formation of a hydrogen bond with a backbone carbonyl of the bridging sheet. Thus, structure-based design and synthesis targeting the highly conserved and structurally characterized CD4:gp120 interface is an effective tactic to enhance the neutralization potency of small molecule HIV-1 entry inhibitors.

Compact, Polyvalent Mannose Quantum Dots as Sensitive, Ratiometric FRET Probes for Multivalent Protein-Ligand Interactions

A highly efficient cap-exchange approach for preparing compact, dense polyvalent mannose-capped quantum dots (QDs) has been developed. The resulting QDs have been successfully used to probe multivalent interactions of HIV/Ebola receptors DC-SIGN and DC-SIGNR (collectively termed as DC-SIGN/R) using a sensitive, ratiometric Förster resonance energy transfer (FRET) assay. The QD probes specifically bind DC-SIGN, but not its closely related receptor DC-SIGNR, which is further confirmed by its specific blocking of DC-SIGN engagement with the Ebola virus glycoprotein. Tuning the QD surface mannose valency reveals that DC-SIGN binds more efficiently to densely packed mannosides. A FRET-based thermodynamic study reveals that the binding is enthalpy-driven. This work establishes QD FRET as a rapid, sensitive technique for probing structure and thermodynamics of multivalent protein-ligand interactions.

The polyoma virus T antigen interferes with interferon-inducible gene expression

Murine polyoma virus (MPyV) is a small DNA virus that induces tumors in multiple tissues of infected host. In this investigation, we show that cell lines derived from wild type virus-induced breast tumors are resistant to the growth inhibitory action of interferon beta (IFN-beta). Furthermore, replication of heterologous viruses such as vesicular stomatitis virus and encephalomyocarditis virus was not inhibited by IFN-beta in these cells. This effect was due to inhibition of IFN-stimulated gene expression by viral T antigen. Activation of IFN-stimulated gene factor 3 was inhibited in cells derived from a tumor induced by wild-type MPyV but not those from a mutant that lacks the pRB binding site of the large T antigen. Similarly IFN-gamma-inducible gene expression was also inhibited in cells transformed by wild-type virus. The levels of components of IFN-stimulated gene factor 3 and signal transducing Janus tyrosine kinases were comparable between the cells transformed by the wild-type and mutant viruses. The viral large T antigen bound to Janus tyrosine kinase 1 and inactivated signaling through IFN receptors. Thus, these studies identify a mechanism of viral resistance to IFN action.

Inhibitors of L-Type Calcium Channels Show Therapeutic Potential for Treating SARS-CoV-2 Infections by Preventing Virus Entry and Spread

COVID-19 is caused by a novel coronavirus, the severe acute respiratory syndrome coronavirus (CoV)-2 (SARS-CoV-2). The virus is responsible for an ongoing pandemic and concomitant public health crisis around the world. While vaccine development is proving to be highly successful, parallel drug development approaches are also critical in the response to SARS-CoV-2 and other emerging viruses. Coronaviruses require Ca2+ ions for host cell entry, and we have previously shown that Ca2+ modulates the interaction of the viral fusion peptide with host cell membranes. In an attempt to accelerate drug repurposing, we tested a panel of L-type calcium channel blocker (CCB) drugs currently developed for other conditions to determine whether they would inhibit SARS-CoV-2 infection in cell culture. All the CCBs tested showed varying degrees of inhibition, with felodipine and nifedipine strongly limiting SARS-CoV-2 entry and infection in epithelial lung cells at concentrations where cell toxicity was minimal. Further studies with pseudotyped particles displaying the SARS-CoV-2 spike protein suggested that inhibition occurs at the level of virus entry. Overall, our data suggest that certain CCBs have the potential to treat SARS-CoV-2 infections and are worthy of further examination for possible treatment of COVID-19.

Structural and kinetic analyses of holothurian sulfated glycans suggest potential treatment for SARS-CoV-2 infection

Certain sulfated glycans, including those from marine sources, can show potential effects against SARS-CoV-2. Here, a new fucosylated chondroitin sulfate (FucCS) from the sea cucumber Pentacta pygmaea (PpFucCS) (MW ∼10-60 kDa) was isolated and structurally characterized by NMR. PpFucCS is composed of {→3)-β-GalNAcX-(1→4)-β-GlcA-[(3→1)Y]-(1→}, where X = 4S (80%), 6S (10%) or nonsulfated (10%), Y = α-Fuc2,4S (40%), α-Fuc2,4S-(1→4)-α-Fuc (30%), or α-Fuc4S (30%), and S = SO3-. The anti-SARS-CoV-2 activity of PpFucCS and those of the FucCS and sulfated fucan isolated from Isostichopus badionotus (IbFucCS and IbSF) were compared with that of heparin. IC50 values demonstrated the activity of the three holothurian sulfated glycans to be ∼12 times more efficient than heparin, with no cytotoxic effects. The dissociation constant (KD) values obtained by surface plasmon resonance of the wildtype SARS-CoV-2 spike (S)-protein receptor-binding domain (RBD) and N501Y mutant RBD in interactions with the heparin-immobilized sensor chip were 94 and 1.8 × 103 nM, respectively. Competitive surface plasmon resonance inhibition analysis of PpFucCS, IbFucCS, and IbSF against heparin binding to wildtype S-protein showed IC50 values (in the nanomolar range) 6, 25, and 6 times more efficient than heparin, respectively. Data from computational simulations suggest an influence of the sulfation patterns of the Fuc units on hydrogen bonding with GlcA and that conformational change of some of the oligosaccharide structures occurs upon S-protein RBD binding. Compared with heparin, negligible anticoagulant action was observed for IbSF. Our results suggest that IbSF may represent a promising molecule for future investigations against SARS-CoV-2.

Host and Viral Proteins Modulating Ebola and Marburg Virus Egress

The filoviruses Ebolavirus and Marburgvirus are among the deadliest viral pathogens known to infect humans, causing emerging diseases with fatality rates of up to 90% during some outbreaks. The replication cycles of these viruses are comprised of numerous complex molecular processes and interactions with their human host, with one key feature being the means by which nascent virions exit host cells to spread to new cells and ultimately to a new host. This review focuses on our current knowledge of filovirus egress and the viral and host factors and processes that are involved. Within the virus, these factors consist of the major matrix protein, viral protein 40 (VP40), which is necessary and sufficient for viral particle release, and nucleocapsid and glycoprotein that interact with VP40 to promote egress. In the host cell, some proteins are hijacked by filoviruses in order to enhance virion budding capacity that include members of the family of E3 ubiquitin ligase and the endosomal sorting complexes required for transport (ESCRT) pathway, while others such as tetherin inhibit viral egress. An understanding of these molecular interactions that modulate viral particle egress provides an important opportunity to identify new targets for the development of antivirals to prevent and treat filovirus infections.

Inhibition of Human Papillomavirus Type 16 Infection Using an RNA Aptamer

Human papillomavirus type 16 (HPV16) DNA has been found in ∼50% of cervical tumors worldwide. HPV infection starts with the binding of the virus capsid to heparan sulfate (HS) receptors exposed on the surface of epithelial basal layer keratinocytes. Previously, our group isolated a high-affinity RNA aptamer (Sc5c3) specific for HPV16 L1 virus-like particles (VLPs). In this study, we report the inhibition of HPV16 infection by Sc5c3 in a pseudovirus (PsVs) model. 293TT cells were infected by HPV16 PsVs containing the yellow fluorescent protein (YFP) as reporter gene. Incubation of HPV16 PsVs with Sc5c3 before infection resulted in a dose-dependent decrease in YFP fluorescence, suggesting infection inhibition. Aptamer degradation by RNase A restored PsVs infectivity, supporting the previous observation that Sc5c3 aptamer can inhibit infection. VLP mutants with removed HS binding sites were used in binding assays to elucidate the Sc5c3 blocking mechanism; however, no binding difference was observed between wild-type and mutant VLPs, suggesting that pseudoinfection inhibition relies on mechanisms additional to electrostatic HS binding site interaction. A DNA/RNA Sc5c3 version also inhibited HPV PsVs infection, suggesting that a modified, nuclease-resistant Sc5c3 may be used to inhibit HPV16 infection in vivo.

Fractionation of sulfated galactan from the red alga Botryocladia occidentalis separates its anticoagulant and anti-SARS-CoV-2 properties

Sulfation pattern and molecular weight (MW) play a key role in the biological actions of sulfated glycans. Besides anticoagulant effects, certain sulfated glycans can also exhibit anti-SARS-CoV-2 properties. To develop a more selective antiviral carbohydrate, an efficient strategy to separate these two actions is required. In this work, low MW fractions derived from the red alga Botryocladia occidentalis sulfated galactan (BoSG) were generated, structurally characterized, and tested for activity against SARS-CoV-2 and blood coagulation. The lowest MW fraction was found to be primarily composed of octasaccharides of monosulfated monosaccharides. Unlike heparin or native BoSG, we found that hydrolyzed BoSG products had weak anticoagulant activities as seen by aPTT and inhibitory assays using purified cofactors. In contrast, lower MW BoSG-derivatives retained anti-SARS-CoV-2 activity using SARS-CoV-2 spike (S)-protein pseudotyped lentivirus vector in HEK-293T-hACE2 cells monitored by GFP. Surface plasmon resonance confirmed that longer chains are necessary for BoSG to interact with coagulation cofactors but is not required for interactions with certain S-protein variants. We observed distinct affinities of BoSG derivatives for the S-proteins of different SARS-CoV-2 strains, including WT, N501Y (Alpha), K417T/E484K/N501Y (Gamma), and L542R (Delta) mutants, and stronger affinity for the N501Y-containing variants. Docking of the four possible monosulfated BoSG disaccharides in interactions with the N501Y mutant S-protein predicted potential binding poses of the BoSG constructs and favorable binding in close proximity to the 501Y residue. Our results demonstrate that depolymerization and fractionation of BoSG are an effective strategy to segregate its anticoagulant property from its anti-SARS-CoV-2 action.

Prazoles Targeting Tsg101 Inhibit Release of Epstein-Barr Virus following Reactivation from Latency

Epstein-Barr virus (EBV) is a ubiquitous herpesvirus responsible for several diseases, including cancers of lymphoid and epithelial cells. EBV cancers typically exhibit viral latency; however, the production and release of EBV through its lytic phase are essential for cancer development. Antiviral agents that specifically target EBV production do not currently exist. Previously, we reported that the proton pump inhibitor tenatoprazole, which blocks the interaction of ubiquitin with the ESCRT-1 factor Tsg101, inhibits production of several enveloped viruses, including EBV. Here, we show that three structurally distinct prazoles impair mature particle formation postreactivation and identify the impact on stages of replication. The prazoles did not impair expression of lytic genes representative of the different kinetic classes but interfered with capsid maturation in the nucleus as well as virion transport from the nucleus. Replacement of endogenous Tsg101 with a mutant Tsg101 refractory to prazole-mediated inhibition rescued EBV release. These findings directly implicate Tsg101 in EBV nuclear egress and identify prazoles as potential therapeutic candidates for conditions that rely on EBV replication, such as chronic active EBV infection and posttransplant lymphoproliferative disorders. IMPORTANCE Production of virions is necessary for the ubiquitous Epstein-Barr virus (EBV) to persist in humans and can set the stage for development of EBV cancers in at-risk individuals. In our attempts to identify inhibitors of the EBV lytic phase, we previously found that a prazole proton pump inhibitor, known to block the interaction of ubiquitin with the ESCRT-1 factor Tsg101, blocks production of EBV. We now find that three structurally distinct prazoles impair maturation of EBV capsids and virion transport from the nucleus and, by interfering with Tsg101, prevent EBV release from lytically active cells. Our findings not only implicate Tsg101 in EBV production but also identify widely used prazoles as candidates to prevent development of posttransplant EBV lymphomas.

Red Blood Cell-Derived Extracellular Vesicles Display Endogenous Antiviral Effects and Enhance the Efficacy of Antiviral Oligonucleotide Therapy

The COVID-19 pandemic has resulted in a large number of fatalities and, at present, lacks a readily available curative treatment for patients. Here, we demonstrate that unmodified red blood cell-derived extracellular vesicles (RBCEVs) can inhibit SARS-CoV-2 infection in a phosphatidylserine (PS) dependent manner. Using T cell immunoglobulin mucin domain-1 (TIM-1) as an example, we demonstrate that PS receptors on cells can significantly increase the adsorption and infection of authentic and pseudotyped SARS-CoV-2 viruses. RBCEVs competitively inhibit this interaction and block TIM-1-mediated viral entry into cells. We further extend the therapeutic efficacy of this antiviral treatment by loading antisense oligonucleotides (ASOs) designed to target conserved regions of key SARS-CoV-2 genes into RBCEVs. We establish that ASO-loaded RBCEVs are efficiently taken up by cells in vitro and in vivo to suppress SARS-CoV-2 replication. Our findings indicate that this RBCEV-based SARS-CoV-2 therapeutic displays promise as a potential treatment capable of inhibiting SARS-CoV-2 entry and replication.

Identification of gp120 Residue His105 as a Novel Target for HIV-1 Neutralization by Small-Molecule CD4-Mimics

The design and synthesis of butyl chain derivatives at the indane ring 3-position of our lead CD4-mimetic compound BNM-III-170 that inhibits human immunodeficiency virus (HIV-1) infection are reported. Optimization efforts were guided by crystallographic and computational analysis of the small-molecule ligands of the Phe43 cavity of the envelope glycoprotein gp120. Biological evaluation of 11-21 revealed that members of this series of CD4-mimetic compounds are able to inhibit HIV-1 viral entry into target cells more potently and with greater breadth compared to BNM-III-170. Crystallographic analysis of the binding pocket of 14, 16, and 17 revealed a novel hydrogen bonding interaction between His105 and a primary hydroxyl group on the butyl side chain. Further optimization of this interaction with the His105 residue holds the promise of more potent CD4-mimetic compounds.

Inhibition of SARS-CoV-2 wild-type (Wuhan-Hu-1) and Delta (B.1.617.2) strains by marine sulfated glycans

The Coronavirus disease pandemic has steered the global therapeutic research efforts toward the discovery of potential anti-severe acute respiratory syndrome coronavirus (SARS-CoV-2) molecules. The role of the viral spike glycoprotein (S-protein) has been clearly established in SARS-CoV-2 infection through its capacity to bind to the host cell surface heparan sulfate proteoglycan (HSPG) and angiotensin-converting enzyme-2. The antiviral strategies targeting these 2 virus receptors are currently under intense investigation. However, the rapid evolution of the SARS-CoV-2 genome has resulted in numerous mutations in the S-protein posing a significant challenge for the design of S-protein-targeted inhibitors. As an example, the 2 key mutations in the S-protein receptor-binding domain (RBD), L452R, and T478K in the SARS-CoV-2 Delta variant (B.1.617.2) confer tighter binding to the host epithelial cells. Marine sulfated glycans (MSGs) demonstrate excellent inhibitory activity against SARS-CoV-2 via competitive disruption of the S-protein RBD-HSPG interactions and thus have the potential to be developed into effective prophylactic and therapeutic molecules. In this study, 7 different MSGs were evaluated for their anti-SARS-CoV-2 activity in a virus entry assay utilizing a SARS-CoV-2 pseudovirus coated with S-protein of the wild-type (Wuhan-Hu-1) or the Delta (B.1.617.2) strain. Although all tested MSGs showed strong inhibitory activity against both strains, no correlations between MSG structural features and virus inhibition could be drawn. Nevertheless, the current study provides evidence for the maintenance of inhibitory activity of MSGs against evolving SARS-CoV-2 strains.

Preliminary Data Related to the Effect of Climacostol Produced by the Freshwater Ciliate Climacostomum virens on Human Adenovirus

The new epidemiological scenario has so far focused on the environmental circulation of human viral pathogens. Owing to the side effects of chemical disinfectants, there is an increasing need for knowledge on the use of virucidal compounds, especially those of a natural origin. Climacostol is a molecule produced by a freshwater ciliate and it exhibits activity against bacterial and fungal pathogens. We thus also speculated that there might be an effect on viral viability, which has never been tested. To evaluate such activity, we chose human adenovirus (HAdV), which is representative of waterborne viruses. We conducted experiments using HAdV serotype 5, whose titer was determined by infecting HeLa cell cultures. HAdV5 was shown to be sensitive to climacostol at a concentration of 0.0002 mg/mL, with an approximate 3 Log₁₀ reduction when the initial titer of HAdV5 was approximately 10⁴ and 10³ TCID₅₀/mL. These preliminary results could be an important starting point for further research aimed at improving the characterization of climacostol activity under different experimental conditions and against various viruses, including enveloped ones (i.e., the coronavirus). The production of climacostol by a protist living in fresh water also suggests a possible application in the activated sludge of wastewater treatment plants.

Synthetic gRNA/Cas9 Ribonucleoprotein Inhibits HIV Reactivation and Replication

The current antiretroviral therapy (ART) for human immunodeficiency virus (HIV) can halt viral replication but cannot eradicate HIV infection because proviral DNA integrated into the host genome remains genetically silent in reservoir cells and is replication-competent upon interruption or cessation of ART. CRISPR/Cas9-based technology is widely used to edit target genes via mutagenesis (i.e., nucleotide insertion/deletion and/or substitution) and thus can inactivate integrated proviral DNA. However, CRISPR/Cas9 delivery systems often require viral vectors, which pose safety concerns for therapeutic applications in humans. In this study, we used synthetic guide RNA (gRNA)/Cas9-ribonucleoprotein (RNP) as a non-viral formulation to develop a novel HIV gene therapy. We designed a series of gRNAs targeting different HIV genes crucial for HIV replication and tested their antiviral efficacy and cellular cytotoxicity in lymphoid and monocytic latent HIV cell lines. Compared with the scramble gRNA control, HIV-gRNA/Cas9 RNP-treated cells exhibited efficient viral suppression with no apparent cytotoxicity, as evidenced by the significant inhibition of latent HIV DNA reactivation and RNA replication. Moreover, HIV-gRNA/Cas9 RNP inhibited p24 antigen expression, suppressed infectious viral particle production, and generated specific DNA cleavages in the targeted HIV genes that are confirmed by DNA sequencing. Because of its rapid DNA cleavage, low off-target effects, low risk of insertional mutagenesis, easy production, and readiness for use in clinical application, this study provides a proof-of-concept that synthetic gRNA/Cas9 RNP drugs can be utilized as a novel therapeutic approach for HIV eradication.

Exploring the Inhibitory Effect of AgBiS2 Nanoparticles on Influenza Viruses

Influenza viruses are respiratory pathogens that are major threats to human health. Due to the emergence of drug-resistant strains, the use of traditional anti-influenza drugs has been hindered. Therefore, the development of new antiviral drugs is critical. In this article, AgBiS₂ nanoparticles were synthesized at room temperature, using the bimetallic properties of the material itself to explore its inhibitory effect on the influenza virus. By comparing the synthesized Bi₂S₃ and Ag₂S nanoparticles, it is found that after adding the silver element, the synthesized AgBiS₂ nanoparticles have a significantly better inhibitory effect on influenza virus infection than Bi₂S₃ and Ag₂S nanoparticles. Recent studies have shown that the inhibitory effect of AgBiS₂ nanoparticles on the influenza virus mainly occurs in the stages of influenza virus-cell internalization and intracellular replication. In addition, it is found that AgBiS₂ nanoparticles also have prominent antiviral properties against α and β coronaviruses, indicating that AgBiS₂ nanoparticles have significant potential in inhibiting viral activity.

Assessment of a diverse panel of transmitted/founder HIV-1 infectious molecular clones in a luciferase based CD8 T-cell mediated viral inhibition assay

Introduction

Immunological protection against human immunodeficiency virus-1 (HIV-1) infection is likely to require both humoral and cell-mediated immune responses, the latter involving cytotoxic CD8 T-cells. Characterisation of CD8 T-cell mediated direct anti-viral activity would provide understanding of potential correlates of immune protection and identification of critical epitopes associated with HIV-1 control.

Methods

The present report describes a functional viral inhibition assay (VIA) to assess CD8 T-cell-mediated inhibition of replication of a large and diverse panel of 45 HIV-1 infectious molecular clones (IMC) engineered with a Renilla reniformis luciferase reporter gene (LucR), referred to as IMC-LucR. HIV-1 IMC replication in CD4 T-cells and CD8 T-cell mediated inhibition was characterised in both ART naive subjects living with HIV-1 covering a broad human leukocyte antigen (HLA) distribution and compared with uninfected subjects.

Results & discussion

CD4 and CD8 T-cell lines were established from subjects vaccinated with a candidate HIV-1 vaccine and provided standard positive controls for both assay quality control and facilitating training and technology transfer. The assay was successfully established across 3 clinical research centres in Kenya, Uganda and the United Kingdom and shown to be reproducible. This IMC-LucR VIA enables characterisation of functional CD8 T-cell responses providing a tool for rational T-cell immunogen design of HIV-1 vaccine candidates and evaluation of vaccine-induced T-cell responses in HIV-1 clinical trials.

Investigating the Significances of Thiol Functionalities in SARS-CoV-2 Using Carbon Dots for Viral Inhibition

While the World Health Organization has declared the end of the SARS-CoV-2 public health emergency, studies related to corona viruses are still under course. As of 2024, the severity of COVID-19 has diminished with current treatments and vaccinations. However, individuals can still face severe complications, highlighting the importance of ongoing research into innovative treatments for current and future coronavirus-related diseases. This study approaches the mechanism of viral entrance into the host cells and the current evidence on the use of sulfhydryl groups for the COVID-19 treatment. Certain thiol drugs, a key contributor to inflammatory processes, exhibit both viral inhibition properties and the potential to regulate cellular oxidative stress by scavenging free radicals. Herein, we developed biocompatible thiol-functionalized carbon dots (CDs) and investigated the correlation between the number of thiols and pseudo-SARS-CoV-2 inhibition, reactive oxygen species (ROS) scavenging, and anti-inflammatory response. The free-radical scavenging experiment and the ROS cellular assay indicate that thiolated CDs serve as effective reducing agents and potential regulators of cellular oxidative stress. The CDs also demonstrated good cell viability alongside significant antiviral capabilities, with inhibition levels up to 60.4%. Furthermore, the flow cytometry results suggest that in an inflammatory environment, the presence of thiolated CDs promotes an anti-inflammatory response. Overall, the results demonstrate a strong correlation between the number of thiols and the increased efficacy observed across experiments, presenting thiolated CDs as promising candidates to prevent and treat COVID-19 infection.

Cecropin AD reduces viral load and inflammatory response against H9N2 avian influenza virus in chickens

Introduction

This study focuses on evaluating the therapeutic efficacy of cecropin AD, an antimicrobial peptide, against H9N2 avian influenza virus (AIV) in chickens. Given the global impact of H9N2 AIV on poultry health, identifying effective treatments is crucial.

Methods

To assess the impact of cecropin AD, we conducted in vivo experiments involving 108 5-week-old chickens divided into control, infected, and various treatment groups based on cecropin AD dosage levels (high, medium, and low). The methodologies included hemagglutination (HA) tests for viral titers, histopathological examination and toluidine blue (TB) staining for lung pathology, real-time PCR for viral detection, and enzyme-linked immunosorbent assays for measuring serum levels of inflammatory markers.

Results

The findings revealed that cecropin AD substantially reduced lung pathology and viral load, especially at higher dosages, comparing favorably with the effects seen from conventional treatments. Moreover, cecropin AD effectively modulated mast cell activity and the levels of inflammatory markers such as IL-6, TNF-α, IFN-γ, and 5-HT, indicating its potential to diminish inflammation and viral spread.

Discussion

Cecropin AD presents a significant potential as an alternative treatment for H9N2 AIV in chickens, as evidenced by its ability to lessen lung damage, decrease viral presence, and adjust immune responses. This positions cecropin AD as a promising candidate for further exploration in the management of H9N2 AIV infections in poultry.

Modulation of the replication of positive-sense RNA viruses by the natural plant metabolite xanthohumol and its derivatives

The COVID-19 pandemic has highlighted the importance of identifying new potent antiviral agents. Nutrients as well as plant-derived substances are promising candidates because they are usually well tolerated by the human body and readily available in nature, and consequently mostly cheap to produce. A variety of antiviral effects have recently been described for the hop chalcone xanthohumol (XN), and to a lesser extent for its derivatives, making these hop compounds particularly attractive for further investigation. Noteworthy, mounting evidence indicated that XN can suppress a wide range of viruses belonging to several virus families, all of which share a common reproductive cycle. As a result, the purpose of this review is to summarize the most recent research on the antiviral properties of XN and its derivatives, with a particular emphasis on the positive-sense RNA viruses human hepatitis C virus (HCV), porcine reproductive and respiratory syndrome virus (PRRSV), and severe acute respiratory syndrome corona virus (SARS-CoV-2).