Herpes Simplex Virus Type 1 Replication Research Articles

Harmol used for the treatment of herpes simplex virus induced keratitis.

Herpes simplex virus type 1 (HSV-1) infection of the eyes results in herpes simplex keratitis (HSK), which has led to vision loss and even blindness in patients. However, the rate of drug resistance in HSV is on the rise; therefore, new antiviral agents with sufficient safety profiles must be developed. At present, we assessed the anti-HSV-1 activity of 502 natural compounds and their ability to reduce the HSV-1-induced cytopathic effect. We chose harmol for further studies because it exhibited the highest antiviral activity. We found that harmol inhibited both HSV-1F and HSV-1/153 (a clinical drug-resistant strain) replication, with an EC50 of 9.34 µM and 5.84 µM, respectively. Moreover, harmol reduced HSV-1 replication in corneal tissues and viral progeny production in tears, and also alleviated early corneal surface lesions related to HSK. For example, harmol treatment preserved corneal thickness and nerve density in HSK mice. Interestingly, harmol also showed a promising antiviral effect on HSV-1/153 induced HSK in mouse model. Furthermore, harmol combined with acyclovir (ACV) treatment showed a greater antiviral effect than either one alone in vitro. Therefore, harmol may be a promising therapeutic agent for managing HSK.

Enterocin DD14 can inhibit the infection of eukaryotic cells with enveloped viruses.

Bacteriocins are ribosomally synthesized bacterial peptides endowed with antibacterial, antiprotozoal, anticancer and antiviral activities. In the present study, we evaluated the antiviral activities of two bacteriocins, enterocin DD14 (EntDD14) and lacticaseicin 30, against herpes simplex virus type 1 (HSV-1), human coronavirus 229E (HCoV-229E) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Vero, Huh7 and Vero E6 cells, respectively. In addition, the interactions of these bacteriocins with the envelope glycoprotein D of HSV-1 and the receptor binding domains of HCoV-229E and SARS-CoV-2 have been computationally evaluated using protein-protein docking and molecular dynamics simulations. HSV-1 replication in Vero cells was inhibited by EntDD14 and, to a lesser extent, by lacticaseicin 30 added to cells after virus inoculation. EntDD14 and lacticaseicin 30 had no apparent antiviral activity against HCoV-229E; however, EntDD14 was able to inhibit SARS-CoV-2 in Vero E6 cells. Further studies are needed to elucidate the antiviral mechanism of these bacteriocins.

Cytosolic DNA sensors activation of human astrocytes inhibits herpes simplex virus through IRF1 induction.

While astrocytes participate in the CNS innate immunity against herpes simplex virus type 1 (HSV-1) infection, they are the major target for the virus. Therefore, it is of importance to understand the interplay between the astrocyte-mediated immunity and HSV-1 infection. Both primary human astrocytes and the astrocyte line (U373) were used in this study. RT-qPCR and Western blot assay were used to measure IFNs, the antiviral IFN-stimulated genes (ISGs), IFN regulatory factors (IRFs) and HSV-1 DNA. IRF1 knockout or knockdown was performed with CRISPR/Cas9 and siRNA transfection techniques. Poly(dA:dT) could inhibit HSV-1 replication and induce IFN-β/IFN-λs production in human astrocytes. Poly(dA:dT) treatment of astrocytes also induced the expression of the antiviral ISGs (Viperin, ISG56 and MxA). Among IRFs members examined, poly(dA:dT) selectively unregulated IRF1 and IRF9, particularly IRF1 in human astrocytes. The inductive effects of poly(dA:dT) on IFNs and ISGs were diminished in the IRF1 knockout cells. In addition, IRF1 knockout attenuated poly(dA:dT)-mediated HSV-1 inhibition in the cells. The DNA sensors activation induces astrocyte intracellular innate immunity against HSV-1. Therefore, targeting the DNA sensors has potential for immune activation-based HSV-1 therapy.

Lanatoside C inhibits herpes simplex virus 1 replication by regulating NRF2 distribution within cells

BackgroundIn the past decades, extensive research has been conducted to identify new drug targets for the treatment of Herpes simplex virus type 1 (HSV-1) infections. However, the emergence of drug-resistant HSV-1 strains remains a major challenge. This necessitates the identification of new drugs with novel mechanisms of action. Lanatoside C (LanC), a cardiac glycoside (CG) approved by the US Food and Drug Administration (FDA), has demonstrated anticancer and antiviral properties. Nevertheless, its potential as an agent against HSV-1 infections and the underlying mechanism of action are currently unknown. PurposeThis study aimed to investigate the antiviral activity of LanC against HSV-1 and elucidate its molecular mechanisms. MethodsThe in vitro antiviral activity of LanC was assessed by examining the levels of viral genes, proteins, and virus titers in HSV-1-infected ARPE-19 and Vero cells. Immunofluorescence (IF) analysis was performed to determine the intracellular distribution of NRF2. Additionally, an in vivo mouse model of HSV-1 infection was developed to evaluate the antiviral activity of LanC, using indicators such as intraepidermal nerve fibers (IENFs) loss and viral gene inhibition. ResultsOur findings demonstrate that LanC significantly inhibits HSV-1 replication both in vitro and in vivo. The antiviral effect of LanC is mediated by the perinuclear translocation of NRF2. ConclusionsLanC exhibits anti-HSV-1 effects in viral infections, which are associated with the intracellular translocation of NRF2. These findings suggest that LanC has the potential to serve as a novel NRF2 modulator in the treatment of viral diseases.

Plant Cell-Engineered Gold Nanoparticles Conjugated to Quercetin Inhibit SARS-CoV-2 and HSV-1 Entry.

Recent studies have revealed considerable promise in the antiviral properties of metal nanomaterials, specifically when biologically prepared. This study demonstrates for the first time the antiviral roles of the plant cell-engineered gold nanoparticles (pAuNPs) alone and when conjugated with quercetin (pAuNPsQ). We show here that the quercetin conjugated nanoparticles (pAuNPsQ) preferentially inhibit the cell entry of two medically important viruses-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and herpes simplex virus type-1 (HSV-1) using different mechanisms. Interestingly, in the case of SARS-CoV-2, the pre-treatment of target cells with pAuNPsQ inhibited the viral entry, but the pre-treatment of the virus with pAuNPsQ did not affect viral entry into the host cell. In contrast, pAuNPsQ demonstrated effective blocking capabilities against HSV-1 entry, either during the pre-treatment of target cells or by inducing virus neutralization. In addition, pAuNPsQ also significantly affected HSV-1 replication, evidenced by the plaque-counting assay. In this study, we also tested the chemically synthesized gold nanoparticles (cAuNPs) of identical size and shape and observed comparable effects. The versatility of plant cell-based nanomaterial fabrication and its modification with bioactive compounds opens a new frontier in therapeutics, specifically in designing novel antiviral formulations.

AMPK protects endothelial cells against HSV-1 replication via inhibition of mTORC1 and ACC1.

Herpes simplex virus type 1 (HSV-1) is a widespread contagious pathogen, mostly causing mild symptoms on the mucosal entry side. However, systemic distribution, in particular upon reactivation of the virus in immunocompromised patients, may trigger an innate immune response and induce damage of organs. In these conditions, HSV-1 may infect vascular endothelial cells, but little is known about the regulation of HSV-1 replication and possible defense mechanisms in these cells. The current study addresses the question of whether the host cell protein AMP-activated protein kinase (AMPK), an important metabolic sensor, can control HSV-1 replication in endothelial cells. We show that downregulation of the catalytic subunits AMPKα1 and/or AMPKα2 increased HSV-1 replication as monitored by TCID50 titrations, while a potent AMPK agonist, MK-8722, strongly inhibited it. MK-8722 induced a persistent phosphorylation of the AMPK downstream targets acetyl-CoA carboxylase (ACC) and the rapamycin-sensitive adaptor protein of mTOR (Raptor) and, related to this, impairment of ACC1-mediated lipid synthesis and the mechanistic target of the rapamycin complex-1 (mTORC1) pathway. Since blockade of mTOR by Torin-2 as well as downregulation of ACC1 by siRNA also decreased HSV-1 replication, MK-8722 is likely to exert its anti-viral effect via mTORC1 and ACC1 inhibition. Importantly, MK-8722 was able to reduce virus replication even when added after HSV-1. Together, our data highlight the importance of endothelial cells as host cells for HSV-1 replication upon systemic infection and identify AMPK, a metabolic host cell protein, as a potential target for antiviral strategies against HSV-1 infection and its severe consequences. IMPORTANCE Herpes simplex virus type 1 (HSV-1) is a common pathogen that causes blisters or cold sores in humans. It remains latent in infected individuals and can be reactivated multiple times. In adverse conditions, for instance, in immunocompromised patients, HSV-1 can lead to serious complications such as encephalitis, meningitis, or blindness. In these situations, infection of endothelial cells lining the surface of blood vessels may contribute to the manifestation of disease. Here, we describe the role of AMP-activated protein kinase (AMPK), a potent regulator of cellular energy metabolism, in HSV-1 replication in endothelial cells. While downregulation of AMPK potentiates HSV-1 replication, pharmacological AMPK activation inhibits it by limiting the availability of required host cell macromolecules such as proteins or fatty acids. These data highlight the role of metabolic host cell proteins as antiviral targets and reveal activation of endothelial AMPK as a potential strategy to protect from severe consequences of HSV-1 infection.

Therapeutic Potential of Biochanin A in Herpes Simplex Keratitis.

Herpes simplex keratitis (HSK) is a blinding eye disease that is initiated by the herpes simplex virus type 1 (HSV-1). Resistance to acyclovir (ACV) and the side effects of corticosteroid drugs have become concerning issues, so it is crucial to develop new antivirals for treating HSK. In this study, we report that biochanin A (BCA), a naturally occurring flavonoid compound, provides multifaceted protective effects with anti-viral, anti-inflammatory, anti-oxidative stress and anti-apoptotic activities to alleviate HSK. The results show that BCA significantly inhibited HSV-1 replication in vitro and further proved that BCA principally influenced the early stage of virus infection. We reveal that BCA downregulated the expression of pro-inflammatory factors triggered by HSV-1, including TNF-α, RANTES, IL-1β and IL-6. Furthermore, BCA treatment alleviated oxidative stress and apoptotic arising from HSV-1 infection. Lastly, we induced HSK in male C57BL/6 mice and treated them with either BCA or phosphate buffer solution (PBS) eye drops. We observed the ocular surface lesions; determined the virus load in the tear fluid, corneas as well as trigeminal ganglions (TGs); and detected the levels of inflammation and apoptosis in the corneas simultaneously. These results show that BCA inhibits HSV-1 and alleviates the corneal lesion degree. Our study illustrates that BCA is a promising therapeutic approach for application in treating HSK.

Early Events after Herpes Simplex Virus-Type 1 Entry Are Necessary for the Release of Gamma-Hydroxybutyrate upon Acute Infection.

We reported that gamma-hydroxybutyrate (GHB) is released upon Herpes Simplex Virus Type-1 (HSV-1) acute infection. However, the cellular biochemical processes involved in the production of GHB in infected cells are unclear. This study aims to shed light on the biochemical pathway and the stage within the viral life cycle responsible for the release of GHB in infected cells. UV-inactivation, acyclovir (ACV), and cycloheximide (CHX) treatments were used to inhibit HSV-1 replication at various stages. Vero cells treated with UV-inactivated HSV-1 significantly decreased GHB production. However, ACV or CHX treatments did not affect GHB production. We also showed that inhibition of glycolytic enzyme enolase by sodium fluoride (NaF) significantly reduces GHB production upon infection. This finding suggests that suppression of glycolytic activity negatively affects cellular GHB production. Our data also indicated that succinic semialdehyde dehydrogenase, an enzyme involved in the shunt of the tricarboxylic acid (TCA) cycle to generate succinic acid, was decreased upon infection, suggesting that infection may trigger the accumulation of succinic semialdehyde, causing the production of GHB. Although the precise mechanism has yet to be defined, our results suggest that early events following infection modulates the release of GHB, which is generated through the metabolic pathways of glycolysis and TCA cycle.

BMS-265246, a Cyclin-Dependent Kinase Inhibitor, Inhibits the Infection of Herpes Simplex Virus Type 1.

Herpes simplex virus type 1 (HSV-1) infections are prevalent illnesses that can cause mucocutaneous ulcerative disease, keratitis, and genital herpes. In patients with compromised immune systems, the infection can lead to serious problems, such as encephalitis. Additionally, neonatal infections can cause brain problems and even death. Current first-line antiviral drugs are nucleoside analog inhibitors that target viral polymerase, and resistant strains have emerged. As a result, new drugs with distinct action modes are needed. Recent research indicates that cyclin-dependent kinases (CDKs) are prospective antiviral targets. Thus, CDK inhibitors may be effective antiviral agents against HSV-1 infection. In this study, we examined a panel of CDK inhibitors that target CDKs in the present study. BMS-265246 (BMS), a CDK 1/2 inhibitor, was found to effectively limit HSV-1 multiplication in Vero, HepG2, and Hela cells. A mechanism of action study suggested that BMS inhibits the early stages of viral replication when added early in the viral infection. The suppression of multiple steps in viral replication by BMS was revealed when HSV-1 infected cells were treated at different time periods in the viral life cycle. Our results suggest that BMS is a potent anti-HSV-1 agent and unique in that it may interfere with multiple steps in HSV-1 replication.

Herpes Simplex Virus-1 ICP27 Nuclear Export Signal Mutants Exhibit Cell Type-Dependent Deficits in Replication and ICP4 Expression.

Herpes simplex virus type-1 (HSV-1) protein ICP27 is an essential immediate early (IE) protein that promotes the expression of viral early (E) and late (L) genes via multiple mechanisms. Our understanding of this complex regulatory protein has been greatly enhanced by the characterization of HSV-1 mutants bearing engineered alterations in the ICP27 gene. However, much of this analysis has been performed in interferon-deficient Vero monkey cells. Here, we assessed the replication of a panel of ICP27 mutants in several other cell types. Our analysis shows that mutants lacking ICP27's amino (N)-terminal nuclear export signal (NES) display a striking cell type-dependent growth phenotype, i.e., they grow semi-permissively in Vero and some other cells but are tightly blocked for replication in primary human fibroblasts and multiple human cell lines. This tight growth defect correlates with a failure of these mutants to replicate viral DNA. We also report that HSV-1 NES mutants are deficient in expressing the IE protein ICP4 at early times postinfection. Analysis of viral RNA levels suggests that this phenotype is due, at least in part, to a defect in the export of ICP4 mRNA to the cytoplasm. In combination, our results (i) show that ICP27's NES is critically important for HSV-1 replication in many human cells, and (ii) suggest that ICP27 plays a heretofore unappreciated role in the expression of ICP4. IMPORTANCE HSV-1 IE proteins drive productive HSV-1 replication. The major paradigm of IE gene induction, developed over many years, involves the parallel activation of the five IE genes by the viral tegument protein VP16, which recruits the host RNA polymerase II (RNAP II) to the IE gene promoters. Here, we provide evidence that ICP27 can enhance ICP4 expression early in infection. Because ICP4 is required for transcription of viral E and L genes, this finding may be relevant to understanding how HSV-1 enters and exits the latent state in neurons.

Navoximod modulates local HSV-1 replication to reshape tumor immune microenvironment for enhanced immunotherapy via an injectable hydrogel

Oncolytic virotherapy can lead to tumor lysis and systemic anti-tumor immunity, but the therapeutic potential in humans is limited due to the impaired virus replication and the insufficient ability to overcome the immunosuppressive tumor microenvironment (TME). To solve the above problems, we identified that Indoleamine 2, 3-dioxygenase 1 (IDO1) inhibitor Navoximod promoted herpes simplex virus type 1 (HSV-1) replication and HSV-1-mediated oncolysis in tumor cells, making it a promising combination modality with HSV-1-based virotherapy. Thus, we loaded HSV-1 and Navoximod together in an injectable and biocompatible hydrogel (V-Navo@gel) for hepatocellular carcinoma (HCC) virotherapy. The hydrogel formed a local delivery reservoir to maximize the viral replication and distribution at the tumor site with a single-dose injection. Notably, V-Navo@gel improved the disease-free survival time of HCC- bearing mice and protects the mice against tumor recurrence. What’s more, V-Navo@gel also showed an effective therapeutic efficacy in the rabbit orthotopic liver cancer model. Mechanistically, we further discovered that our combination strategy entirely reprogramed the TME through single-cell RNA sequencing. All these results collectively indicated that the combination of Navoximod with HSV-1 could boost the viral replication and reshape TME for tumor eradication through the hydrogel reservoir.

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

BackgroundThe 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. PurposeThis 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). MethodsWe 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. ResultsOur 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. ConclusionThese 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.

Global expression and functional analysis of human piRNAs during HSV-1 infection

Piwi-interacting RNAs (piRNAs) are a class of non-coding RNAs that play a key role in spermatogenesis. However, little is known about their expression characterization and role in somatic cells infected with herpes simplex virus type 1 (HSV-1). In this study, we systematically investigated the cellular piRNA expression profiles of HSV-1-infected human lung fibroblasts. Compared with the control group, 69 differentially expressed piRNAs were identified in the infection group, among which 52 were up-regulated and 17 were down-regulated. The changes in the expression of 8 piRNAs were further verified by RT-qPCR with a similar expression trend. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the target genes of piRNAs were mainly involved in antiviral immunity and various human disease-related signaling pathways. Furthermore, we tested the effects of four up-regulated piRNAs on viral replication by transfecting piRNA mimics. The results showed that the virus titers of the group transfected with piRNA-hsa-28,382 (alias piR-36,233) mimic decreased significantly, and that of the group transfected piRNA-hsa-28,190 (alias piR-36,041) mimic significantly increased. Overall, our results revealed the expression characteristics of piRNAs in HSV-1-infected cells. We also screened two piRNAs that potentially regulate HSV-1 replication. These results may promote a better understanding of the regulatory mechanism of pathophysiological changes induced by HSV-1 infection.

Role of Innate Interferon Responses at the Ocular Surface in Herpes Simplex Virus-1-Induced Herpetic Stromal Keratitis.

Herpes simplex virus type 1 (HSV-1) is a highly successful pathogen that primarily infects epithelial cells of the orofacial mucosa. After initial lytic replication, HSV-1 enters sensory neurons and undergoes lifelong latency in the trigeminal ganglion (TG). Reactivation from latency occurs throughout the host's life and is more common in people with a compromised immune system. HSV-1 causes various diseases depending on the site of lytic HSV-1 replication. These include herpes labialis, herpetic stromal keratitis (HSK), meningitis, and herpes simplex encephalitis (HSE). HSK is an immunopathological condition and is usually the consequence of HSV-1 reactivation, anterograde transport to the corneal surface, lytic replication in the epithelial cells, and activation of the host's innate and adaptive immune responses in the cornea. HSV-1 is recognized by cell surface, endosomal, and cytoplasmic pattern recognition receptors (PRRs) and activates innate immune responses that include interferons (IFNs), chemokine and cytokine production, as well as the recruitment of inflammatory cells to the site of replication. In the cornea, HSV-1 replication promotes type I (IFN-α/β) and type III (IFN-λ) IFN production. This review summarizes our current understanding of HSV-1 recognition by PRRs and innate IFN-mediated antiviral immunity during HSV-1 infection of the cornea. We also discuss the immunopathogenesis of HSK, current HSK therapeutics and challenges, proposed experimental approaches, and benefits of promoting local IFN-λ responses.

Manipulation of Oxidative Stress Responses by Non-Thermal Plasma to Treat Herpes Simplex Virus Type 1 Infection and Disease

Herpes simplex virus type 1 (HSV-1) is a contagious pathogen with a large global footprint, due to its ability to cause lifelong infection in patients. Current antiviral therapies are effective in limiting viral replication in the epithelial cells to alleviate clinical symptoms, but ineffective in eliminating latent viral reservoirs in neurons. Much of HSV-1 pathogenesis is dependent on its ability to manipulate oxidative stress responses to craft a cellular environment that favors HSV-1 replication. However, to maintain redox homeostasis and to promote antiviral immune responses, the infected cell can upregulate reactive oxygen and nitrogen species (RONS) while having a tight control on antioxidant concentrations to prevent cellular damage. Non-thermal plasma (NTP), which we propose as a potential therapy alternative directed against HSV-1 infection, is a means to deliver RONS that affect redox homeostasis in the infected cell. This review emphasizes how NTP can be an effective therapy for HSV-1 infections through the direct antiviral activity of RONS and via immunomodulatory changes in the infected cells that will stimulate anti-HSV-1 adaptive immune responses. Overall, NTP application can control HSV-1 replication and address the challenges of latency by decreasing the size of the viral reservoir in the nervous system.

Kyllinga nemoralis Methanolic Roots Extract Inhibits Herpes Simplex Virus Type 1 Replication Cycle

Kyllinga nemoralis also known as, whitehead spike sedge is a perennial herb which contains antiviral, antibacterial, antioxidant and anti-bleeding properties. This study was designed to determine the biological activity of K. nemoralis methanolic roots extract on herpes simplex virus type 1 (HSV-1) replication cycle. The effect on HSV-1 replication phases was observed by performing time-of-addition and time removal assays. Meanwhile, the level of HSV-1 selected genes expression was analysed by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). In the time addition assay, K. nemoralis extract anti-HSV-1 activity was found to be most optimum when given at 2 hpi (>45% plaque reduction). The time removal assay showed that >80% plaque reduction was achieved when treatment of K. nemoralis extract was given until 24 hpi. K. nemoralis extract suppressed immediate early, early and late phases of HSV-1 replication cycle by altering the expression of UL54, UL27 and UL30 genes during the infection. This study showed that K. nemoralis methanolic roots extract has potential as anti HSV-1 by reducing the expression of HSV-1 genes at different phases of viral replication.

Undescribed phloroglucinol derivatives with antiviral activities from Dryopteris atrata (Wall. Ex Kunze) Ching

Nine undescribed phloroglucinol derivatives (dryatraols A-I) with five different backbones and three known dimeric acylphloroglucinols were isolated from the rhizome of Dryopteris atrata (Wall. Ex Kunze) Ching (Dryopteridaceae). Dryatraol A contains an unprecedented carbon skeleton—a butyrylphloroglucinol and a rulepidanol-type sesquiterpene are linked via a furan ring to form a 6/5/6/6 ring system. Dryatraols B and C are the first examples of monomeric phloroglucinols coupled with the aristolane-type sesquiterpene through the C–C bond. Dryatraol D features a rare spiro [benzofuran-2′,5″-furan] backbone. Dryatraols E-I are five undescribed adducts with a butyrylphloroglucinol or filicinic acid incorporated into the germacrene-type sesquiterpene via a pyran ring. These undescribed structures were determined by comprehensively analysing the spectroscopic data, X-ray diffraction results, and electronic circular dichroism calculations. The result of in vitro antiviral activity evaluation indicated that dryatraol C displayed the strongest antiviral effect against both respiratory syncytial virus and influenza A virus (H1N1), with IC50 values of 11.9 μM and 5.5 μM, respectively. Dryatraols F–H exhibited considerable inhibitory activity against herpes simplex virus type 1 (HSV-1), with IC50 values ranging from 2.6 to 6.3 μM. Analysis of the inhibitory mechanism using a time-of-addition assay revealed that dryatraol G may inhibit the replication of HSV-1 by interfering with the late stage of the viral life cycle.

Metabolomics Profiles Reveal New Insights of Herpes Simplex Virus Type 1 Infection.

Herpes simplex virus type 1 (HSV-1) is a ubiquitous human pathogen that can cause significant morbidity, primarily facial cold sores and herpes simplex encephalitis. Previous studies have shown that a variety of viruses can reprogram the metabolic profiles of host cells to facilitate self-replication. In order to further elucidate the metabolic interactions between the host cell and HSV-1, we used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze the metabolic profiles in human lung fibroblasts KMB17 infected with HSV-1. The results showed that 654 and 474 differential metabolites were identified in positive and negative ion modes, respectively, and 169 and 114 metabolic pathways that might be altered were screened. These altered metabolites are mainly involved in central carbon metabolism, choline metabolism, amino acid metabolism, purine and pyrimidine metabolism, cholesterol metabolism, bile secretion, and prolactin signaling pathway. Further, we confirmed that the addition of tryptophan metabolite kynurenine promotes HSV-1 replication, and the addition of 25-Hydroxycholesterol inhibits viral replication. Significantly, HSV-1 replication was obviously enhanced in the ChOKα (a choline metabolic rate-limiting enzyme) deficient mouse macrophages. These results indicated that HSV-1 induces the metabolic reprogramming of host cells to promote or resist viral replication. Taken together, these observations highlighted the significance of host cell metabolism in HSV-1 replication, which would help to clarify the pathogenesis of HSV-1 and identify new anti-HSV-1 therapeutic targets.

Antiviral Activity of Oridonin Against Herpes Simplex Virus Type 1.

In search of new potent treatment of herpes simplex keratitis (HSK), inhibitory effect of oridonin (Ori) on herpes simplex virus type 1 (HSV-1) was validated by experiments. For evaluating inhibitory effect of oridonin on herpes simplex virus type 1, a series of in-vivo and in-vitro studies were carried out. Mouse HSV-1 infection model was used in the in-vivo experiments. Experimental mice were classified infivedifferentgroups: Mock (mock-infected), HSV-1+ DMSO, HSV-1+ Ori, HSV-1+ ACV, combined Ori and ACV+HSV-1. Corneas of Mock, HSV-1+ DMSO, HSV-1+ Ori group were sent formRNA-sequencing after 3 days post infection (dpi). The expression of virus and host-related genes was evaluated by quantitative real-time polymerase chain reaction (qPCR). Vero cells HSV-1 infection models were used in the in-vitro experiments. The application of ACV, Oridonin alone or a combination of both could alleviate HSV-1 severity and inhibit HSV-1 virus replication in C57BL/6 mice models. qPCR showed that compared with mock group, the expression of interleukin-6 (il-6), interleukin-1α (il-1α), and Tumor-necrosis factor-alpha (tnf-α) was up-regulated in DMSO+HSV-1 group and suppressed in other three group. Moreover, the expression of nod-like receptor protein (nlrp3), caspase 1 and interleukin-1β (il-1β) were depressed in the oridonin-treated group. Oridonin significantly inhibits HSV-1 replication, HSV-1 related gene expression, and the production of progeny HSV-1 viruses in vitro. Besides, oridonin affect the replication phase but not HSV-1 entry or penetration and cannot inactivate HSV-1. Oridonin alleviates herpes simplex keratitis infection in mouse, which may be attributed to inhibition of the NLRP3-inflammasome-IL-1β pathway. Our study illustrates that Oridonin has potential promise for application in treating HSK and other diseases caused by HSV-1 infection.

Antiviral Activity of Syzygium polyanthum Extract against Herpes Simplex Virus-Type 1 (HSV-1)

Herpes simplex virus type 1 (HSV-1) is part of the alpha subfamily of human herpesviruses. Several antiviral medications can be prescribed for treating HSV-1 which is usually first line antiviral agents such as acyclovir (ACV). But there are several cases that have been reported on ACV resistance to HSV, thus, researchers tend to develop the antiviral agent from plants extract. Syzygium polyanthum is one of the plants that has been traditionally used as a drug which is rich in bioactive compounds, including essential oils, terpenoids, tannins, and flavonoids [1]. These phytochemical compounds, which have strong antioxidant action, can aid in the inhibition of viral genome replication which disables the viral lipid envelope [2].
 
 The objective of this study is to determine the cytotoxic concentration (CC50) and antiviral activity of S. polyanthum methanolic extract. Cytotoxicity was performed using the method described by [3]. The absorbance readings were analysed using microplate reader (Infinite M200 Pro). The 50% cytotoxicity concentration (CC50) was defined as the sample concentration that able to reduce 50% of cell viability compared to the untreated cells. Antiviral activity was performed by using plaque reduction assay with three different treatments [3] which are post- treatment, pre-treatment and virucidal assay.
 
 Based on Figure 1, cytotoxicity screening against Vero cells using MTT assay showed that the CC50 values for extract was 0.135 mg/mL which considered not in the range of cytotoxic compounds. Any CC50 or IC50 of a substance less than 4 µg/mL was considered an active cytotoxic effect [4].
 Based on Figure 2, post treatment assay showed the most anti-HSV-1 activity of S. polyanthum extract which the EC50 and SI value were 0.015mg/mL and 9.03, respectively. The extract showed to be slightly effective in reducing HSV-1 replication after 2-hour incubation which might be due to the inhibition in the early phase of the attachment. For pre-treatment, EC50 and SI values were 0.019 mg/mL and 7.12, which the extract showed to be moderately effective in inhibiting the attachment of HSV-1 before the replication can occur. This might occur as Vero cells bind to the extract that could interfere with the cell membrane's glycoprotein receptors which prevented HSV-1 from attaching to the cell surface [5]. The EC50 and SI value for virucidal assay was 0.018 mg/mL and 7.28 as the result showed moderately effective inhibited the viral replication. S. polyanthum has been shown to directly inactivate HSV-1 virions within 30 minutes of exposure in this study. An SI value greater than 10 (SI>10) indicates that any antimicrobial compound has the potency to become an antiviral treatment agent [6].
 In conclusion, the findings of this study demonstrate that S. polyanthum extract seems to have moderate antiviral effects and non-toxic to Vero cells.