Block Virus Entry Research Articles

Functional Infectious Nanoparticle Detector: Finding Viruses by Detecting Their Host Entry Functions Using Organic Bioelectronic Devices.

Emerging viruses will continue to be a threat to human health and wellbeing into the foreseeable future. The COVID-19 pandemic revealed the necessity for rapid viral sensing and inhibitor screening in mitigating viral spread and impact. Here, we present a platform that uses a label-free electronic readout as well as a dual capability of optical (fluorescence) readout to sense the ability of a virus to bind and fuse with a host cell membrane, thereby sensing viral entry. This approach introduces a hitherto unseen level of specificity by distinguishing fusion-competent viruses from fusion-incompetent viruses. The ability to discern between competent and incompetent viruses means that this device could also be used for applications beyond detection, such as screening antiviral compounds for their ability to block virus entry mechanisms. Using optical means, we first demonstrate the ability to recapitulate the entry processes of influenza virus using a biomembrane containing the viral receptor that has been functionalized on a transparent organic bioelectronic device. Next, we detect virus membrane fusion, using the same, label-free devices. Using both reconstituted and native cell membranes as materials to functionalize organic bioelectronic devices, configured as electrodes and transistors, we measure changes in membrane properties when virus fusion is triggered by a pH drop, inducing hemagglutinin to undergo a conformational change that leads to membrane fusion.

Combination of natural antivirals and potent immune invigorators: A natural remedy to combat COVID-19.

The flare‐up in severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) that emerged in December 2019 in Wuhan, China, and spread expeditiously worldwide has become a health challenge globally. The rapid transmission, absence of anti‐SARS‐CoV‐2 drugs, and inexistence of vaccine are further exacerbating the situation. Several drugs, including chloroquine, remdesivir, and favipiravir, are presently undergoing clinical investigation to further scrutinize their effectiveness and validity in the management of COVID‐19. Natural products (NPs) in general, and plants constituents specifically, are unique sources for various effective and novel drugs. Immunostimulants, including vitamins, iron, zinc, chrysin, caffeic acid, and gallic acid, act as potent weapons against COVID‐19 by reinvigorating the defensive mechanisms of the immune system. Immunity boosters prevent COVID‐19 by stimulating the proliferation of T‐cells, B‐cells, and neutrophils, neutralizing the free radicals, inhibiting the immunosuppressive agents, and promoting cytokine production. Presently, antiviral therapy includes several lead compounds, such as baicalin, glycyrrhizin, theaflavin, and herbacetin, all of which seem to act against SARS‐CoV‐2 via particular targets, such as blocking virus entry, attachment to host cell receptor, inhibiting viral replication, and assembly and release.

Anti-SARS-CoV-2 Natural Products as Potentially Therapeutic Agents.

Severe acute respiratory syndrome–related coronavirus-2 (SARS-CoV-2), a β-coronavirus, is the cause of the recently emerged pandemic and worldwide outbreak of respiratory disease. Researchers exchange information on COVID-19 to enable collaborative searches. Although there is as yet no effective antiviral agent, like tamiflu against influenza, to block SARS-CoV-2 infection to its host cells, various candidates to mitigate or treat the disease are currently being investigated. Several drugs are being screened for the ability to block virus entry on cell surfaces and/or block intracellular replication in host cells. Vaccine development is being pursued, invoking a better elucidation of the life cycle of the virus. SARS-CoV-2 recognizes O-acetylated neuraminic acids and also several membrane proteins, such as ACE2, as the result of evolutionary switches of O-Ac SA recognition specificities. To provide information related to the current development of possible anti–SARS-COV-2 viral agents, the current review deals with the known inhibitory compounds with low molecular weight. The molecules are mainly derived from natural products of plant sources by screening or chemical synthesis via molecular simulations. Artificial intelligence–based computational simulation for drug designation and large-scale inhibitor screening have recently been performed. Structure–activity relationship of the anti–SARS-CoV-2 natural compounds is discussed.

Comparison of the immunologic response to herpes simplex virus type 1 entry glycoproteins induced in humans after primary infection of oral or genital sites

<h3>Objectives</h3> We sought to determine potential differences in the humoral immune response to herpes simplex virus type 1 (HSV-1) in patients after primary infection in either oral or genital sites. <h3>Methods</h3> Serum samples from 20 patients with primary HSV-1 infection (10 oral, 10 genital) were compared. A neutralization assay categorized samples by their ability to inhibit virus entry into cells. An enzyme-linked immunosorbent assay determined the quantity of antibodies against each of the major HSV-1 glycoproteins (gD, gB, gC, gH/gL). Surface plasmon resonance imaging (SPRi) was used to estimate the quality of the response by determining the epitope specificity of antibodies against the receptor-binding glycoprotein gD. Information from these assays was combined to develop a comprehensive profile of immunologic response to HSV-1 infection. <h3>Results</h3> All 10 oral site serum samples contained significant levels of virus-specific antibodies to block virus entry and demonstrated excellent immune response to the major virion glycoproteins. In contrast, only 4 of the 10 genital site serum samples were able to block virus entry. The 6 genital site sera that failed to block entry had markedly reduced antiglycoprotein antibody levels, indicating a poor overall HSV-1 immunologic response. The quantity of antiglycoprotein antibodies in the 4 genital (protective) sera mirrored that induced by oral infection. Subsequently, SPRi was used to determine whether the qualitative response was equivalent between the oral and genital site sera. All 10 oral site sera targeted gD epitopes at levels significantly higher and more varied than those generated for the 4 protective genital site samples. Interestingly, the gD epitope profiles of the 6 nonprotective genital site samples were directed at a single non-neutralizing antigenic site on gD that is involved in cell-to-cell spread. <h3>Conclusions</h3> Based on a comprehensive profile of immunologic response to HSV-1 infection for individuals infected at either oral or genital sites, results of this study suggest that the site of primary infection is important in driving the overall humoral immune-protective response. Findings of this study will have direct implications for the future development of a glycoprotein-epitope–based HSV-1 vaccine.

Epigallocatechin-3-gallate exhibits antiviral effects against the duck Tembusu virus via blocking virus entry and upregulating type I interferons

The duck Tembusu virus (DTMUV) is a novel mosquito-borne Flavivirus which caused huge economic losses for poultry industries in Southeast Asia and China. Currently, no effective antiviral drugs against this virus have been reported. (-)-Epigallocatechin-3-gallate (EGCG), a polyphenol present in abundance in green tea, has recently been demonstrated to have an antiviral activity for many viruses; however, whether EGCG can inhibit DTMUV infection remains unknown. Here, we tried to explore the anti-DTMUV effects and mechanisms of EGCG both in vitro and in vivo. Several EGCG treatment regimens were used to study the comprehensive antiviral activity of EGCG in DTMUV-infected baby hamster kidney cell line (BHK-21). The DTMUV titers of mock- and EGCG-treated infected cell cultures were determined using the tissue culture infective dose assay and the DTMUV mRNA copy number as determined using quantitative Real Time PCR. Moreover, the therapeutic efficacy of EGCG against DTMUV was assessed in DTMUV-infected ducklings. Our results suggested that EGCG significantly reduced the viral infection in BHK-21 cells in a dose-dependent manner, as reflected by the reduction of virus titers, virus copy number, and the expressions of viral E protein. We also observed that EGCG exhibited direct virucidal abilities against DTMUV. Notably, a significant reduction in virus binding ability was also observed, indicating that EGCG possesses excellent inhibitory effects on the viral adsorption step. In addition, DTMUV replication was also suppressed in BHK-21 cells treated with EGCG after viral entry, likely because of upregulation of the levels of interferon alfa and interferon beta. Finally, we also proved that EGCG exhibited anti-DTMUV efficacy in a duckling infection model because the survival rate was significantly improved. This is the first study to demonstrate the protective effect of EGCG against DTMUV, suggesting its potential use as an antiviral drug for DTMUV infection.

Targeting TMPRSS2 and Cathepsin B/L together may be synergistic against SARS-CoV-2 infection.

The entry of SARS-CoV-2 into target cells requires the activation of its surface spike protein, S, by host proteases. The host serine protease TMPRSS2 and cysteine proteases Cathepsin B/L can activate S, making two independent entry pathways accessible to SARS-CoV-2. Blocking the proteases prevents SARS-CoV-2 entry in vitro. This blockade may be achieved in vivo through ‘repurposing’ drugs, a potential treatment option for COVID-19 that is now in clinical trials. Here, we found, surprisingly, that drugs targeting the two pathways, although independent, could display strong synergy in blocking virus entry. We predicted this synergy first using a mathematical model of SARS-CoV-2 entry and dynamics in vitro. The model considered the two pathways explicitly, let the entry efficiency through a pathway depend on the corresponding protease expression level, which varied across cells, and let inhibitors compromise the efficiency in a dose-dependent manner. The synergy predicted was novel and arose from effects of the drugs at both the single cell and the cell population levels. Validating our predictions, available in vitro data on SARS-CoV-2 and SARS-CoV entry displayed this synergy. Further, analysing the data using our model, we estimated the relative usage of the two pathways and found it to vary widely across cell lines, suggesting that targeting both pathways in vivo may be important and synergistic given the broad tissue tropism of SARS-CoV-2. Our findings provide insights into SARS-CoV-2 entry into target cells and may help improve the deployability of drug combinations targeting host proteases required for the entry.

Antivirals Against SARS-CoV2: Relevance to the Treatment of Alzheimer’s Disease

A recent study in vitro has shown that a sulphated polysaccharide, a type of fucoidan, has potent antiviral activity against SARS-Cov2. If the antiviral action were successful also for COVID-19 patients, it would be enormously valuable against not only acute disease but also long-term mental effects, which might include Alzheimer's disease (AD). In a trial of AD patients, the apparent success of treatment with a polysaccharide, GV971, was suggested to result from antiviral action against herpes simplex virus type 1 (HSV1) in brain, a pathogen strongly implicated in AD, and that sulphation of GV971, making it fucoidan-like, might increase its putative antiviral action. These data indicate that treatment of AD patients might be very effective using valacyclovir, a conventional antiviral, which inhibits viral replication, together with a fucoidan, which blocks virus entry into cells.

Furin Inhibitors Block SARS-CoV-2 Spike Protein Cleavage to Suppress Virus Production and Cytopathic Effects

Development of specific antiviral agents is an urgent unmet need for SARS-coronavirus 2 (SARS-CoV-2) infection. This study focuses on host proteases that proteolytically activate the SARS-CoV-2 spike protein, critical for its fusion after binding to angiotensin-converting enzyme 2 (ACE2), as antiviral targets. We first validate cleavage at a putative furin substrate motif at SARS-CoV-2 spikes by expressing it in VeroE6 cells and find prominent syncytium formation. Cleavage and the syncytium are abolished by treatment with the furin inhibitors decanoyl-RVKR-chloromethylketone (CMK) and naphthofluorescein, but not by the transmembrane protease serine 2 (TMPRSS2) inhibitor camostat. CMK and naphthofluorescein show antiviral effects on SARS-CoV-2-infected cells by decreasing virus production and cytopathic effects. Further analysis reveals that, similar to camostat, CMK blocks virus entry, but it further suppresses cleavage of spikes and the syncytium. Naphthofluorescein acts primarily by suppressing viral RNA transcription. Therefore, furin inhibitors may be promising antiviral agents for prevention and treatment of SARS-CoV-2 infection.

Smart polymeric eye gear: A possible preventive measure against ocular transmission of COVID-19

The angiotensin-converting enzyme 2(ACE-2) receptors with approx. 0.8% congestion in conjunctival surface, leads to increase susceptibility of Covid-19 transmission through ocular surface. It has been observed that prophylactic measures such as goggle or face shield are unable to offer complete protection against ocular transmission of SRS-CoV-2. Hence, it is hypothesized that topical ocular prophylaxis using biocompatible polymers with reported in-vitro and in-vivo evidence of ACE inhibition and antiviral activity appears to be a promising strategy for preventing ocular transmission of Covid-19 to healthcare workers. They are capable of binding to ACE-2 receptors which may provide highly potential trails to block virus entry to host cells. Further biopolymers imparting antiviral activities greatly improve their protective performance. They not only provide prolong protection but also are safe for long-term use. This article discusses the description of structural and functional attributes of ACE-2 to identify appropriate polymer with better binding affinity. Furthermore, potential polymers with appropriate concentration are suggested for evaluation through a hypothesis to consider them for Covid-19 implication.

A molecular trap against COVID-19.

Structure-function studies reveal a new receptor decoy to block virus entry

Caveolae and Lipid Rafts in Endothelium: Valuable Organelles for Multiple Functions

Caveolae are flask-shaped invaginations of the plasma membrane found in numerous cell types and are particularly abundant in endothelial cells and adipocytes. The lipid composition of caveolae largely matches that of lipid rafts microdomains that are particularly enriched in cholesterol, sphingomyelin, glycosphingolipids, and saturated fatty acids. Unlike lipid rafts, whose existence remains quite elusive in living cells, caveolae can be clearly distinguished by electron microscope. Despite their similar composition and the sharing of some functions, lipid rafts appear more heterogeneous in terms of size and are more dynamic than caveolae. Following the discovery of caveolin-1, the first molecular marker as well as the unique scaffolding protein of caveolae, we have witnessed a remarkable increase in studies aimed at investigating the role of these organelles in cell functions and human disease. The goal of this review is to discuss the most recent studies related to the role of caveolae and caveolins in endothelial cells. We first recapitulate the major embryological processes leading to the formation of the vascular tree. We next discuss the contribution of caveolins and cavins to membrane biogenesis and cell response to extracellular stimuli. We also address how caveolae and caveolins control endothelial cell metabolism, a central mechanism involved in migration proliferation and angiogenesis. Finally, as regards the emergency caused by COVID-19, we propose to study the caveolar platform as a potential target to block virus entry into endothelial cells.

Equine Alphaherpesviruses Require Activation of the Small GTPases Rac1 and Cdc42 for Intracellular Transport.

Viruses utilize host cell signaling to facilitate productive infection. Equine herpesvirus type 1 (EHV-1) has been shown to activate Ca2+ release and phospholipase C upon contact with α4β1 integrins on the cell surface. Signaling molecules, including small GTPases, have been shown to be activated downstream of Ca2+ release, and modulate virus entry, membrane remodeling and intracellular transport. In this study, we show that EHV-1 activates the small GTPases Rac1 and Cdc42 during infection. The activation of Rac1 and Cdc42 is necessary for virus-induced acetylation of tubulin, effective viral transport to the nucleus, and cell-to-cell spread. We also show that inhibitors of Rac1 and Cdc42 did not block virus entry, but inhibited overall virus infection. The Rac1 and Cdc42 signaling is presumably orthogonal to Ca2+ release, since Rac1 and Cdc42 inhibitors affected the infection of both EHV-1 and EHV-4, which do not bind to integrins.

Renin-angiotensin-aldosterone system in new coronavirus infection 2019

The new coronavirus infection (COVID-19) is a serious threat to humanity. Although its pathogenesis has not been fully studied, angiotensin-converting enzyme 2 (ACE 2) has recently been identified as a receptor for entry into the cell of the coronavirus SARS-CoV-2, thereby contributing to the spread of infection in the body. The goal of the review was to study the significance of the renin-angiotensin-aldosterone system (RAAS) in the pathogenesis of the action of the coronavirus SARS-CoV-2, the function and regulation of ACE 2, and the effects of RAAS inhibitors in cardiovascular diseases. ACE 2 promotes the transformation of angiotensin (AT) I into AT 1–7, which have a number of beneficial effects on the state of endothelium and cardiomyocytes (vasodilation, inhibition of cell growth, inhibition of cell proliferation and inhibition of cardiomyocyte hypertrophy). SARS-CoV-2 virus, in addition to interaction with ACE 2 on the surface cells in the lungs and vascular wall, leads to dysregulation of ACE 2, which in turn leads to a shift in the balance of RAAS towards activation of ACE 1 receptors, which have the opposite effects. ACE inhibitors and angiotensin receptor blockers (ARBs) play a key role in the treatment of major cardiovascular diseases such as hypertension and chronic heart failure, and today there is no evidence that ACE inhibitors or ARBs worsen severity of cardiovascular diseases. Therefore, it is not recommended to discontinue these drugs in patients with stable cardiovascular diseases and afflicted by COVID-19. The human recombinant hrACE 2 protein may be a potential therapy for CVI by blocking virus entry and eliminating the imbalance in RAAS.

Advanced bioinformatics rapidly identifies existing therapeutics for patients with coronavirus disease-2019 (COVID-19)

BackgroundThe recent global pandemic has placed a high priority on identifying drugs to prevent or lessen clinical infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), caused by Coronavirus disease-2019 (COVID-19).MethodsWe applied two computational approaches to identify potential therapeutics. First, we sought to identify existing FDA approved drugs that could block coronaviruses from entering cells by binding to ACE2 or TMPRSS2 using a high-throughput AI-based binding affinity prediction platform. Second, we sought to identify FDA approved drugs that could attenuate the gene expression patterns induced by coronaviruses, using our Disease Cancelling Technology (DCT) platform.ResultsTop results for ACE2 binding iincluded several ACE inhibitors, a beta-lactam antibiotic, two antiviral agents (Fosamprenavir and Emricasan) and glutathione. The platform also assessed specificity for ACE2 over ACE1, important for avoiding counterregulatory effects. Further studies are needed to weigh the benefit of blocking virus entry against potential counterregulatory effects and possible protective effects of ACE2. However, the data herein suggest readily available drugs that warrant experimental evaluation to assess potential benefit. DCT was run on an animal model of SARS-CoV, and ranked compounds by their ability to induce gene expression signals that counteract disease-associated signals. Top hits included Vitamin E, ruxolitinib, and glutamine. Glutathione and its precursor glutamine were highly ranked by two independent methods, suggesting both warrant further investigation for potential benefit against SARS-CoV-2.ConclusionsWhile these findings are not yet ready for clinical translation, this report highlights the potential use of two bioinformatics technologies to rapidly discover existing therapeutic agents that warrant further investigation for established and emerging disease processes.

Repurposing of Medicinal Plants Used in Siddha Formulations As Potential Protease Inhibitors of COVID-19: An in silico Approach

Background: The Coronavirus disease (COVID-19) caused by the virus SARS-CoV-2 has become a global pandemic in a short time has infected about 1,203,959 patients and brought forth death rate about 64,788 among 206 countries as mentioned by WHO in the month of April 2020. Currently, there is no specific treatment or vaccine for fighting against this infectious disease and scientists agree that possible therapeutic may arise through drug repositioning. Herbal medicine are achieving attention because of the extensive therapeutics like potent antiviral, immunomodulatory, anti-inflammatory, and anti-oxidant properties. Materials and methods: This study was planned to screen herbs from Siddha that have the potential to increase host immune system as well as blocking virus entry in host cells. Official Siddha formulation Kabasura Kudineer, Nilavembu Kudineer, and Novel Siddha formulation – JACOM are already being in use as antiviral, immunomodulatory, anti-inflammatory, and antioxidant. 54 molecules identified and surveyed via docking study. Docking study was performed using Maestro interface (Schrodinger Suite, LLC, NY). Results: Out of these 54 Phytoconstituents, 30 Phytoconstituents were found to interact with > 2 protein structures of COVID-19. The docking results indicate that amongst the reported molecules 4 out 5 protein structure (PDB ID: 5R7Y, 5R7Z, 5R80, 5R81 and 5R82) showed promising results of binding to COVID-19 enzyme. So this formulations may be useful as a therapeutic and/or prophylactic agent for restricting viral attachment to the host cells. Discussion: The drug repurposing study provide an insight in terms of binding of active ingredients present in different plants used in formulations and targets enzymes for treatment of the COVID19.

Furin Inhibitors Block SARS-CoV-2 Spike Protein Cleavage to Suppress Virus Production and Cytopathic Effects

Development of specific antivirals is an urgent unmet need for SARS-coronavirus 2 (SARS-CoV-2) infections. This study focuses on host proteases that proteolytically activate the SARS-CoV-2 spike protein, critical for its fusion activity after binding to ACE2 receptor, as antiviral targets. We first validated cleavage at a putative furin substrate motif at SARS-CoV-2 spike by expressing it in VeroE6 cells and found prominent syncytium formation. Both cleavage and syncytium were abolished by treatment with the furin inhibitors decanoyl-RVKR-chloromethylketone (CMK) and naphthofluorescein but not by the TMPRSS2 inhibitor camostat. CMK and naphthofluorescein showed antiviral effects in SARS-CoV-2-infected cells by decreasing viral production and cytopathic effects. Further analysis revealed that, similar to camostat, CMK blocks virus entry, but it further suppresses the cleavage of spike and syncytium. Naphthofluorescein instead acts primarily by suppressing viral RNA transcription after viral entry. Therefore, furin inhibitors may become promising antivirals for prevention and treatment of SARS-CoV-2 infections.Funding: This study was supported by grants from the Ministry of Science and Technology, Taiwan (106-2622-B-002-002-CC2, 107-3017-F-002-002) and the “Center of Precision Medicine” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan. Conflict of Interest: The authors declare no competing interests.

The retroviral accessory proteins S2, Nef, and glycoMA use similar mechanisms for antagonizing the host restriction factor SERINC5

Serine incorporator 5 (SERINC5) is a recently identified restriction factor that blocks virus entry but is antagonized by three unrelated retroviral accessory proteins. The S2 protein from equine infectious anemia virus (EIAV) has been reported to reduce SERINC5 expression at steady-state levels likely via the endocytic pathway; however, the precise mechanism is still unclear. Here, we investigated how EIAV S2 protein down-regulates SERINC5 compared with down-regulation induced by Nef from HIV-1 and glycoMA proteins from murine leukemia virus (MLV). Using bimolecular fluorescence complementation (BiFC) assay and immunoprecipitation (IP), we detected an interaction between S2 and SERINC5. We found that this interaction relies on the S2 myristoylation site, indicating that it may occur on the plasma membrane. S2 internalized SERINC5 via receptor-mediated endocytosis and targeted it to endosomes and lysosomes, resulting in a ubiquitination-dependent decrease in SERINC5 expression at steady-state levels. Both BiFC and IP detected a glycoMA-SERINC5 interaction, but a Nef-SERINC5 interaction was detected only by BiFC. Moreover, S2 and glycoMA down-regulated SERINC5 more effectively than did Nef. We further show that unlike Nef, both S2 and glycoMA effectively down-regulate SERINC2 and also SERINC5 from Xenopus tropicalis (xSERINC5). Moreover, we detected expression of the equine SERINC5 (eSERINC5) protein and observed that its expression is much weaker than expression levels of SERINC5 from other species. Nonetheless, eSERINC5 had a strong antiviral activity that was effectively counteracted by S2. We conclude that HIV-1, EIAV, and MLV share a similar mechanism to antagonize viral restriction by host SERINC5.

An IgM antibody targeting the receptor binding site of influenza B blocks viral infection with great breadth and potency

Broadly neutralizing antibodies (bnAbs) targeting the receptor binding site (RBS) of hemagglutinin (HA) have potential for developing into powerful anti-influenza agents. Several previously reported influenza B bnAbs are nevertheless unable to neutralize a portion of influenza B virus variants. HA-specific bnAbs with hemagglutination inhibition (HI) activity may possess the ability to block virus entry directly. Polymeric IgM antibodies are expected to more effectively inhibit virus attachment and entry into target cells due to their higher avidity and/or steric hindrance. We therefore hypothesized that certain RBS-targeted IgM antibodies with strong cross-lineage HI activity might display broader and more potent antiviral activity against rapidly evolving influenza B viruses.Methods: In this study, we generated IgM and IgG bnAbs targeting the RBS of influenza B virus using the murine hybridoma technique. IgM and IgG versions of the same antibodies were then developed by isotype switching and characterized in subsequent in vitro and in vivo experiments.Results: Two IgM and two IgG bnAbs against influenza B virus HA were identified. Of these, one IgM subtype antibody, C7G6-IgM, showed strong HI and neutralization activities against all 20 representative influenza B strains tested, with higher potency and broader breadth of anti-influenza activity in vitro than the IgG subtype variant of itself, or other previously-reported influenza B bnAbs. Furthermore, C7G6-IgM conferred excellent cross-protection against distinct lineages of influenza B viruses in mice and ferrets, performing better than the anti-influenza drug oseltamivir, and showed an additive antiviral effect when administered in combination with oseltamivir. Mechanistically, C7G6-IgM potently inhibits infection with influenza B virus strains from different lineages by blocking viral entry.Conclusion: In summary, our study highlights the potential of IgM subtype antibodies in combatting pathogenic microbes. Moreover, C7G6-IgM is a promising candidate for the development of prophylactics or therapeutics against influenza B infection.

A trivalent gC2/gD2/gE2 vaccine for herpes simplex virus generates antibody responses that block immune evasion domains on gC2 better than natural infection

Vaccines for prevention and treatment of genital herpes are high public health priorities. Our approach towards vaccine development is to focus on blocking virus entry mediated by herpes simplex virus type 2 (HSV-2) glycoprotein D (gD2) and to prevent the virus from evading complement and antibody attack by blocking the immune evasion domains on HSV-2 glycoproteins C (gC2) and E (gE2), respectively. HSV-2 gC2 and gE2 are expressed on the virion envelope and infected cell surface where they are potential targets of antibodies that bind and block their immune evasion activities. We demonstrate that antibodies produced during natural infection in humans or intravaginal inoculation in guinea pigs bind to gC2 but generally fail to block the immune evasion domains on this glycoprotein. In contrast, immunization of naïve or previously HSV-2-infected guinea pigs with gC2 subunit antigen administered with CpG and alum as adjuvants produces antibodies that block domains involved in immune evasion. These results indicate that immune evasion domains on gC2 are weak antigens during infection, yet when used as vaccine immunogens with adjuvants the antigens produce antibodies that block immune evasion domains.

Neutralizing antibodies against porcine epidemic diarrhea virus block virus attachment and internalization

BackgroundPorcine epidemic diarrhea virus (PEDV) is emerging as a pathogenic coronavirus that causes a huge economic burden to the swine industry. Interaction of the viral spike (S) surface glycoprotein with the host cell receptor is recognized as the first step of infection and is the main determinant of virus tropism. The mechanisms by which neutralizing antibodies inhibit PEDV have not been defined. Isolating PEDV neutralizing antibodies are crucial to identifying the receptor-binding domains of the viral spike and elucidating the mechanism of protection against PEDV infection.MethodsB cell hybridoma technique was used to generate hybridoma cells that secrete specific antibodies. E.coli prokaryotic expression system and Bac-to-Bac expression system were used to identify the target protein of each monoclonal antibody. qPCR was performed to analyze PEDV binding to Vero E6 cells with neutralizing antibody.ResultsWe identified 10 monoclonal antibodies using hybridoma technology. Remarkably, 4 mAbs (designed 2G8, 2B11, 3D9, 1E3) neutralized virus infection potently, of which 2B11 and 1E3 targeted the conformational epitope of the PEDV S protein. qPCR results showed that both 2B11 and 2G8 blocked virus entry into Vero cells.ConclusionThe data suggested that PEDV neutralizing antibody inhibited virus infection by binding to infectious virions, which could work as a tool to find the receptor-binding domains.