Inhibit Herpes Simplex Research Articles

Zinc ionophores pyrithione inhibits herpes simplex virus replication through interfering with proteasome function and NF-κB activation

Pyrithione (PT), known as a zinc ionophore, is effective against several pathogens from the Streptococcus and Staphylococcus genera. The antiviral activity of PT was also reported against a number of RNA viruses. In this paper, we showed that PT could effectively inhibit herpes simplex virus types 1 and 2 (HSV-1 and HSV-2). PT inhibited HSV late gene (Glycoprotein D, gD) expression and the production of viral progeny, and this action was dependent on Zn2+. Further studies showed that PT suppressed the expression of HSV immediate early (IE) gene, the infected cell polypeptide 4 (ICP4), but had less effect on another regulatory IE protein, ICP0. It was found that PT treatment could interfere with cellular ubiquitin-proteasome system (UPS), leading to the inhibition of HSV-2-induced IκB-α degradation to inhibit NF-κB activation and enhanced promyelocytic leukemia protein (PML) stability in nucleus. However, PT did not show direct inhibition of 26S proteasome activity. Instead, it induced Zn2+ influx, which facilitated the dysregulation of UPS and the accumulation of intracellular ubiquitin-conjugates. UPS inhibition by PT caused disruption of IκB-α degradation and NF-κB activation thus leading to marked reduction of viral titer.

P1.045 Zinc Ionophores Inhibit Herpes Simplex Virus Type 1 and 2 Replication Through Dysregulation of Ubiquitin-Proteasome Pathway

BackgroundHerpes simplex virus types 1 and 2 (HSV-1 and HSV-2) are among the most prevalent human pathogens in both industrialised and developing regions. In the current study, we reported that...

Effect of black tea extract on herpes simplex virus-1 infection of cultured cells

BackgroundThe purpose of this investigation was to determine if black tea extract (BTE), consisting primarily of flavanol compounds called theaflavins, could inhibit herpes simplex virus type-1 (HSV-1) infection in cultured A549 (human epithelial) and Vero cells.MethodsThe effect of BTE both on A549 and Vero cultured cells and on HSV-1 was assessed by using phase contrast and fluorescent microscopy, and cell viability and proliferation assays. After establishing the maximum non-cytotoxic concentration of BTE, A549 and Vero cells and HSV-1 virions were treated with varying concentrations of BTE, respectively. A549 and Vero cells were infected with HSV-1 with green fluorescent protein (GFP) insert at the UL46 gene. The effect of infectivity was determined by viral DNA extraction followed by PCR, plaque assays, adsorption assays, and electrophoresis of PCR products.ResultsBTE was not cytotoxic to A549 and Vero cells, as confirmed by cell viability and proliferation assays, in which BTE treated groups paralleled the positive control group. For both cell lines, plaque assays and fluorescent microscopy indicated an inverse relationship between BTE concentration (from 0.14 μM – 1.4 mM) and HSV-1 infectivity. Specifically, PCR and electrophoresis showed a reduction in the viral genome following treatment with BTE. In addition, there was a noticeable decrease in the amount of viral plaques for BTE treated samples in the adsorption assays.ConclusionsBTE consisting primarily of theaflavins is not cytotoxic and can reduce or block the production of infectious HSV-1 virions in cultured A549 and Vero cells, thus inhibiting the infectivity of the virus by interfering in the attachment, penetration and viral DNA replication of HSV-1 particles. These findings indicate that BTE enriched with theaflavins has the potential to be developed as a safe, therapeutic antiviral agent to prevent the spread of HSV-1.

Pyrrolidine Dithiocarbamate Inhibits Herpes Simplex Virus 1 and 2 Replication, and Its Activity May Be Mediated through Dysregulation of the Ubiquitin-Proteasome System

Pyrrolidine dithiocarbamate (PDTC) is widely used as an antioxidant or an NF-κB inhibitor. It has been reported to inhibit the replication of human rhinoviruses, poliovirus, coxsackievirus, and influenza virus. In this paper, we report that PDTC could inhibit the replication of herpes simplex virus 1 and 2 (HSV-1 and HSV-2). PDTC suppressed the expression of HSV-1 and HSV-2 viral immediate early (IE) and late (membrane protein gD) genes and the production of viral progeny. This antiviral property was mediated by the dithiocarbamate moiety of PDTC and required the presence of Zn(2+). Although PDTC could potently block reactive oxygen species (ROS) generation, it was found that this property did not contribute to its anti-HSV activity. PDTC showed no activity in disrupting the mitogen-activated protein kinase (MAPK) pathway activation induced by viral infection that was vital for the virus's propagation. We found that PDTC modulated cellular ubiquitination and, furthermore, influenced HSV-2-induced IκB-α degradation to inhibit NF-κB activation and enhanced PML stability in the nucleus, resulting in the inhibition of viral gene expression. These results suggested that the antiviral activity of PDTC might be mediated by its dysregulation of the cellular ubiquitin-proteasome system (UPS).

Sulfated polysaccharide of Caesalpinia ferrea inhibits herpes simplex virus and poliovirus

Herpes simplex virus (HSV) is one of the most regular human pathogens, being a public health problem, and causal agent of several diseases. Poliovirus (PV) is an enteric virus and about 1% of infected individuals develop paralytic poliomyelitis due to viral invasion of the central nervous system and destruction of motor neurons. This work evaluated the activity of a sulfated polysaccharide of Caesalpinia ferrea (SPLCf) in HSV and PV replication. The antiviral effect of SPLCf at varying concentrations was tested by plaque assay under several protocols, such as time-of-addition, adsorption and penetration inhibition and virucidal. Syntheses of viral protein and nucleic acid were also monitored by the immunofluorescence assay and PCR. The SPLCf inhibited virus adsorption and steps after penetration, and inhibited the synthesis of viral protein. Virucidal effect was also shown and nucleic acid synthesis was concurrent with positive results. Our findings suggested that the substance with low toxicity represent a potential viral inhibitor.

Effect of the Potent Antiviral 1‐Cinnamoyl‐3,11‐Dihydroxymeliacarpin on Cytokine Production by Murine Macrophages Stimulated with HSV‐2

The limonoid 1-cinnamoyl-3,11-dihydroxymeliacarpin (CDM) isolated from leaf extracts of Melia azedarach L, has potent antiherpetic effect in epithelial cells. Since Meliacine, the partially purified extract source of CDM, has therapeutic effect on murine genital herpes, the potential use of CDM as microbicide against herpetic infections was studied here. To determine the cytotoxic effect of CDM, the MTT assay and acridine orange staining of living cells were performed. The antiherpetic action of CDM was measured by plaque reduction assay, and the immunomodulatory effect was determined by measuring the cytokine production using a bioassay and ELISA method. The results presented here showed that CDM inhibited Herpes Simplex Virus type 2 (HSV-2) multiplication in Vero cells but did not affect its replication in macrophages which were not permissive to HSV infection. In macrophages, levels of TNF-α, IFN-γ, NO, IL-6 and IL-10 were increased by CDM used alone or in combination with HSV-2. Besides, CDM not only synergized TNF-α production combined with IFN-γ, but also prolonged its expression in time. Results indicate that CDM inhibits HSV-2 multiplication in epithelial cells and also increases cytokine production in macrophages, both important actions to the clearance of infecting virus in the mouse vagina.

In Vivo Anti-Herpes Simplex Virus Activity of a Sulfated Derivative of Agaricus brasiliensis Mycelial Polysaccharide

Agaricus brasiliensis (syn. A. subrufescens), a basidiomycete fungus native to the Atlantic forest in Brazil, contains cell walls rich in glucomannan polysaccharides. The β-(1 → 2)-gluco-β-(1 → 3)-mannan was isolated from A. brasiliensis mycelium, chemically modified by sulfation, and named MI-S. MI-S has multiple mechanisms of action, including inhibition of herpes simplex virus (HSV) attachment, entry, and cell-to-cell spread (F. T. G. S. Cardozo, C. M. Camelini, A. Mascarello, M. J. Rossi, R. J. Nunes, C. R. Barardi, M. M. de Mendonça, and C. M. O. Simões, Antiviral Res. 92:108-114, 2011). The antiherpetic efficacy of MI-S was assessed in murine ocular, cutaneous, and genital infection models of HSV. Groups of 10 mice were infected with HSV-1 (strain KOS) or HSV-2 (strain 333). MI-S was given either topically or by oral gavage under various pre- and posttreatment regimens, and the severity of disease and viral titers in ocular and vaginal samples were determined. No toxicity was observed in the uninfected groups treated with MI-S. The topical and oral treatments with MI-S were not effective in reducing ocular disease. Topical application of MI-S on skin lesions was also not effective, but cutaneously infected mice treated orally with MI-S had significantly reduced disease scores (P < 0.05) after day 9, suggesting that healing was accelerated. Vaginal administration of MI-S 20 min before viral challenge reduced the mean disease scores on days 5 to 9 (P < 0.05), viral titers on day 1 (P < 0.05), and mortality (P < 0.0001) in comparison to the control groups (untreated and vehicle treated). These results show that MI-S may be useful as an oral agent to reduce the severity of HSV cutaneous and mucosal lesions and, more importantly, as a microbicide to block sexual transmission of HSV-2 genital infections.

Concurrent chemotherapy inhibits herpes simplex virus-1 replication and oncolysis

Herpes simplex virus-1 (HSV-1) replication in cancer cells leads to their destruction (viral oncolysis) and has been under investigation as an experimental cancer therapy in clinical trials as single agents, and as combinations with chemotherapy. Cellular responses to chemotherapy modulate viral replication, but these interactions are poorly understood. To investigate the effect of chemotherapy on HSV-1 oncolysis, viral replication in cells exposed to 5-fluorouracil (5-FU), irinotecan (CPT-11), methotrexate (MTX) or a cytokine (tumor necrosis factor-α (TNF-α)) was examined. Exposure of colon and pancreatic cancer cells to 5-FU, CPT-11 or MTX in vitro significantly antagonizes both HSV-1 replication and lytic oncolysis. Nuclear factor-κB (NF-κB) activation is required for efficient viral replication, and experimental inhibition of this response with an IκBα dominant-negative repressor significantly antagonizes HSV-1 replication. Nonetheless, cells exposed to 5-FU, CPT-11, TNF-α or HSV-1 activate NF-κB. Cells exposed to MTX do not activate NF-κB, suggesting a possible role for NF-κB inhibition in the decreased viral replication observed following exposure to MTX. The role of eukaryotic initiation factor 2α (eIF-2α) dephosphorylation was examined; HSV-1-mediated eIF-2α dephosphorylation proceeds normally in HT29 cells exposed to 5-FU, CPT-11 or MTX. This report demonstrates that cellular responses to chemotherapeutic agents provide an unfavorable environment for HSV-1-mediated oncolysis, and these observations are relevant to the design of both preclinical and clinical studies of HSV-1 oncolysis.

Synthesis and biological evaluation of nucleoside analogues than contain silatrane on the basis of the structure of acyclovir (ACV) as novel inhibitors of hepatitis B virus (HBV)

Hepatitis B virus (HBV) infection causes major public health problems worldwide. Acyclovir (ACV) is mainly used to inhibit herpes simplex virus (HSV) rather than HBV. In this study, we used the combination principle to design and synthesize nucleoside analogues that contain silatrane on the basis of the structure of ACV. We found that the compounds were effective inhibitors of HBV, both in vitro and in vivo. All of the compounds showed suppressive activity on the expression of HBV surface antigen (HBsAg) and HBV e antigen (HBeAg) in the HepG2.2.15 cell line with low cytotoxicity. One of compounds was studied in HBV transgenic mice model, and the test results showed its ability to reduce the levels of HBsAg, HBeAg and HBV DNA by ELASE and qPCR. Furthermore, significant improvement of T lymphocyte was observed after treatment, as evaluated by flow cytometry (FCM).

DNA sensing-independent inhibition of herpes simplex virus 1 replication by DAI/ZBP1.

DNA-dependent activator of interferon regulatory factor (DAI) acts as a cytosolic B-form DNA sensor that induces type I interferons. However, DAI is not required for DNA sensing in certain cell types due to redundancy of the DNA sensing system. Here, we investigated the effect of DAI on herpes simplex virus 1 (HSV-1) infection in HepG2 hepatocellular carcinoma cells. DAI transcription was induced after gamma interferon (IFN-γ) treatment or HSV-1 infection. HSV-1 replication was enhanced by DAI knockdown, and ectopic DAI expression repressed viral replication in a manner requiring the Zβ and D3 domains, but not the Zα domain. This activity of DAI was more prominent at low multiplicity of infection (MOI) and correlated with the reduced expression of viral immediate-early genes. Consistently, DAI repressed the activation of ICP0 promoter in reporter gene assays. DAI knockdown did not affect the B-DNA-mediated IFN-β transcription and IRF3 activation, and overexpression of DAI and RIP1 did not enhance NF-κB activation by B-DNA treatment, demonstrating that DAI is not essential for the B-DNA-mediated IFN production in HepG2 cells. DAI colocalized with ICP0 in a subset of nuclear and cytoplasmic foci in infected cells and interacted with ICP0 in coimmunoprecipitation assays. The anti-HSV-1 effect of DAI was not observed in ICP0-deleted mutant virus infection at a high MOI in HepG2 cells and mouse embryonic fibroblasts. Degradation of IFI16 and PML by ICP0 was enhanced in infection of DAI-knockdown cells. Collectively, these results demonstrate that DAI can suppress HSV-1 growth independent of DNA sensing through mechanisms involving suppression of viral genomes and regulation of ICP0.

Inhibition of herpes simplex virus type 1 with the modified green tea polyphenol palmitoyl-epigallocatechin gallate

Green tea polyphenol epigallocatechin gallate (EGCG) is a strong antioxidant that has previously been shown to reduce the number of plaques in HIV-infected cultured cells. Modified EGCG, palmitoyl-EGCG (p-EGCG), is of interest as a topical antiviral agent for herpes simplex virus (HSV-1) infections. This study evaluated the effect of p-EGCG on HSV-infected Vero cells. Results of cell viability and cell proliferation assays indicate that p-EGCG is not toxic to cultured Vero cells and show that modification of the green tea polyphenol epigallocatechin gallate (EGCG) with palmitate increases the effectiveness of EGCG as an antiviral agent. Furthermore, p-EGCG is a more potent inhibitor of herpes simplex virus 1 (HSV-1) than EGCG and can be topically applied to skin, one of the primary tissues infected by HSV. Viral binding assay, plaque forming assay, PCR, real-time PCR, and fluorescence microscopy were used to demonstrate that p-EGCG concentrations of 50μM and higher block the production of infectious HSV-1 particles. p-EGCG was found to inhibit HSV-1 adsorption to Vero cells. Thus, p-EGCG may provide a novel treatment for HSV-1 infections.

Geldanamycin, a ligand of heat shock protein 90, inhibits herpes simplex virus type 2 replication both in vitro and in vivo

Previously, we discovered geldanamycin, a ligand of heat shock protein 90, effectively inhibited herpes simplex virus type 1 replication in vitro and in vivo (mouse encephalitis model). In this study, we demonstrate that geldanamycin has very strong activities against herpes simplex virus type 2 in vitro and in vivo (mouse vagina model). In mouse vagina model, administration of geldanamycin suspension to vagina after virus infection protected the infected mice from death and increased the average survival days in a dose-dependent manner. Geldanamycin also significantly reduced virus shedding from mouse vagina. All geldanamycin-treated groups were statistically significant when compared with the infected control group. The high-dose group of geldanamycin (5.72 mg kg−1) was better than acyclovir group (2.86 mg kg−1). All geldanamycin vaginal administration mock-infected groups did not show significant body weight loss. Although geldanamycin has strong antiviral activities against various DNA and RNA viruses, geldanamycin is not suitable for systemic administration because of its high toxicity. We consider that geldanamycin is a candidate of topical usage for the treatment of herpes simplex virus type infections.Supplementary informationThe online version of this article (doi:10.1038/ja.2012.67) contains supplementary material, which is available to authorized users.

Effect and mechanism of Saururus chinensis against herpes dimplex virus

To seek effective drugs inhibiting herpes simplex virus (HSV-2) with the signal pathway required by virus replication as the target spot. HSV-2-induced Vero cytopathic effect was observed, and MTT method was adopted to detect call activity, in order to assess the antiviral capacity of freeze dried powder of aqueous extracts of Saururus chinensis (AESC). Western blot was used to check the effect of AESC on signal pathway induced by HSV-2 virus in HeLa cells. AESC obviously inhibits the pathway activation of CPE induced by HSV-2 infection and NF-kappaB required for virus replication. The inhibition ratio of AESC freeze dried powder at 0.10, 0.03, 0.01 and 0.003 g x L(-1) were (70.68 +/- 3.39)%, (61.74 +/- 2.13)%, (39.31 +/- 1.10)% and (18.54 +/- 3.44)%, respectively. The IC50 was determined at (0.023 +/- 0.004) g x L(-1). The inhibition concentration of the positive control acyclovir was 0.001 g x L(-1) (5.0 x 10(-6) mol x L(-1)). The best administration time was from 2 h before infection to 6 h after infection. Western blot also showed that AESC can notably inhibit HSV-2-induced NF-kappaB nuclear transfer. AESC can inhibit HSV-2 virus replication, which is related to the pathway activation of NF-kappaB required for virus replication.

ASP2151 for the Treatment of Genital Herpes: A Randomized, Double-Blind, Placebo- and Valacyclovir-Controlled, Dose-Finding Study

Current therapies for genital herpes have only partial efficacy. Helicase-primase inhibitors are novel, potent inhibitors of herpes simplex virus replication. This randomized trial assessed the safety and efficacy of ASP2151 for episodic therapy of recurrent genital herpes. Participants self-initiated with ASP2151 (100, 200, or 400 mg daily for 3 days), ASP2151 (1200 mg as a single dose), placebo for 3 days, or valacyclovir (500 mg twice daily for 3 days). The primary efficacy endpoint, time to lesion healing excluding aborted lesions, was analyzed using a proportional hazards model. Statistical significance was determined by P = .01. Of 695 adults enrolled, 437 experienced a recurrence and received study drug. Median time for lesion healing excluding aborted lesions was 139.8 hours with placebo, 119.6 hours with ASP2151 (100 mg; hazard ratio [HR], 1.40; P = .065), 106.2 with ASP2151 (200 mg; HR, 1.40; P = .081), 115.9 with ASP2151 (400 mg; HR, 1.25; P = .25), 102.1 with ASP2151 (1200 mg; HR, 1.72; P = .007), and 113.9 with valacyclovir (500 mg twice daily; HR, 1.42; P = .077), indicating improvement in all treatment groups except ASP2151 (400 mg). Incidence of treatment-emergent adverse events was similar across groups. Three-day or single-day courses of ASP2151 appear to be effective and safe options for treatment of episodes of recurrent genital herpes. NCT00486200.

Lactoferricin but not lactoferrin inhibit herpes simplex virus type 2 infection in mice

We have evaluated the potential of bovine lactoferrin and lactoferricin for their ability to prevent and/or treat genital HSV-2 infection in mice. We confirm previous data showing that both lactoferrin and lactoferricin have antiviral properties in vitro and can inhibit HSV-2 infection of GMK cells in a dose-dependent manner. When tested in vivo, lactoferricin but not lactoferrin was also a potent inhibitor of HSV-2 infection. When admixed with virus prior to inoculation, lactoferricin inhibited disease development and significantly reduced the viral load in a genital model of HSV-2 infection in mice. Lactoferrin and lactoferricin were also tested for their ability to stimulate the production of chemokines. Neither of the compounds induced the production of CCL3, CCL5, CXCL1 or CXCL2 by mouse splenocytes in vitro. However, when tested in vivo, both lactoferrin and lactoferricin were able to induce local vaginal production of CCL5. Lactoferrin also induced CXCL2 production. The prophylactic and/or therapeutic effects of lactoferrin or lactoferricin were also tested. But none of the compounds were efficient in blocking HSV-2 infection when given 24h prior to HSV-2 infection. Lactoferricin however showed promising results as a therapeutic agent and delayed both disease onset by 3days as well as reducing the viral load almost 15-fold when given as a single dose 24h post-infection. These data show that lactoferricin can block genital herpes infection in mice, and perhaps also be used for post-infection treatment.

Synthesis, antiviral and cytotoxicity studies of novel N-substituted indophenazine derivatives

A series of novel N-substituted indophenazine derivatives were synthesised and screened for antiviral activity against a panel of human pathogenic viruses. New compounds were synthesised through modifying the N-hydrogen of indophenazine moiety with different substitution and formaldehyde by Mannich reaction. The structure of the synthetic compounds was characterised by means of infra red and nuclear magnetic resonance spectral data. The compound 10H-indolo-2-Amino pyridine [3,2-b] quinoxalines inhibits Herpes simplex virus-1 and vaccinia virus at a concentration of 12 μg/ml, and the cytotoxicy was found to be 100 μg/ml. 4-Aminobenzene sulfonamide-10H-indolo [3,2-b] quinoxalines inhibit vaccinia virus at a concentration of 12 μg/ml and cytotoxicy was found to be 100 μg/ml. The anti-HIV activities of the new compounds were also screened for in vitro antiviral activity against replication of HIV-1 (IIIB) and HIV-2 (ROD) in MT-4 cells using zidovudine (AZT) as standard. Pthalimide derivative inhibited the replication of HIV-2 (EC50=11.60 μg/ml and CC50=61.63 μg/ml) in MT-4 cells.

Cascade search for HSV-1 combinatorial drugs with high antiviral efficacy and low toxicity

BackgroundInfectious diseases cause many molecular assemblies and pathways within cellular signaling networks to function aberrantly. The most effective way to treat complex, diseased cellular networks is to apply multiple drugs that attack the problem from many fronts. However, determining the optimal combination of several drugs at specific dosages to reach an endpoint objective is a daunting task.MethodsIn this study, we applied an experimental feedback system control (FSC) method and rapidly identified optimal drug combinations that inhibit herpes simplex virus-1 infection, by only testing less than 0.1% of the total possible drug combinations.ResultsUsing antiviral efficacy as the criterion, FSC quickly identified a highly efficacious drug cocktail. This cocktail contained high dose ribavirin. Ribavirin, while being an effective antiviral drug, often induces toxic side effects that are not desirable in a therapeutic drug combination. To screen for less toxic drug combinations, we applied a second FSC search in cascade and used both high antiviral efficacy and low toxicity as criteria. Surprisingly, the new drug combination eliminated the need for ribavirin, but still blocked viral infection in nearly 100% of cases.ConclusionThis cascade search provides a versatile platform for rapid discovery of new drug combinations that satisfy multiple criteria.

Efficacy of ASP2151, a helicase–primase inhibitor, against thymidine kinase-deficient herpes simplex virus type 2 infection in vitro and in vivo

ASP2151 was developed as a novel inhibitor of herpes simplex virus (HSV) and varicella-zoster virus helicase–primase. The anti-HSV activity of ASP2151 toward a clinical HSV isolate with acyclovir (ACV)-resistant/thymidine kinase (TK)-deficiency was characterized in vitro and in vivo using a plaque reduction assay and the ear pinna infection in mice. The IC50 ranged from 0.018 to 0.024μg/ml, indicating the susceptibility of TK-deficient HSV-2 was similar to that of wild-type HSV-2 strains. Anti-HSV activity of ASP2151 in vivo was evaluated in mice infected with wild-type HSV-2 and TK-deficient HSV-2. ASP2151 significantly reduced the copy numbers of wild-type HSV-2 and TK-deficient HSV-2 at the inoculation ear pinna, while valacyclovir significantly reduced the copy number of wild type HSV-2 but not that of TK-deficient HSV-2 in the inoculated ear pinna. Thus, ASP 2151 showed therapeutic efficacy in mice infected with both wild-type and TK-deficient HSV-2. In conclusion, ASP2151 is a promising novel herpes helicase–primase inhibitor that indicates the feasibility of ASP2151 for clinical application for the treatment of HSV infections, including ACV-resistant/TK-deficient HSV infection.

Potent antiviral flavone glycosides from Ficus benjamina leaves

Crude ethanol extracts from Ficus benjamina leaves strongly inhibit Herpes Simplex Virus 1 and 2 (HSV-1/2) as well as Varicella Zoster Virus (VZV) cell infection in vitro. Bioassay-guided fractionation of the crude extract demonstrated that the most efficient inhibition of HSV-1 and HSV-2 was obtained with the flavonoid fraction. The present study was aimed to further isolate, purify and identify substances with potent antiviral activity from the flavonoid fraction of F. benjamina extracts. Flavonoids were collected from the leaf ethanol extracts through repeated purification procedure and HPLC analysis. The antiviral activity of each substance was then evaluated in cell culture. Three known flavone glycosides, ( 1) quercetin 3-O-rutinoside, ( 2) kaempferol 3-O-rutinoside and ( 3) kaempferol 3-O-robinobioside, showing highest antiviral efficiency were selected and their structure was determined by spectroscopic analyses including NMR and mass spectrometry (MS). These three flavones were highly effective against HSV-1 reaching a selectivity index (SI) of 266, 100 and 666 for compound 1, 2 and 3, respectively, while the SI of their aglycons, quercetin and kaempferol amounted only in 7.1 and 3.2, respectively. Kaempferol 3-O-robinobioside showed similar SI to that of acyclovir (ACV), the standard anti-HSV drug. Although highly effective against HSV-1 and HSV-2, these flavone glycosides did not show any significant activity against VZV.

Small interfering RNA targeting for infected‐cell polypeptide 4 inhibits herpes simplex virus type 1 replication in retinal pigment epithelial cells

Background: This study sought to inhibit herpes simplex virus type 1 replication using small interfering RNA which targeting infected‐cell polypeptide 4 genes to mediate transcription of early and late viral genes in herpes simplex virus type 1 lytic (productive) infection in retina epithelial cells. Methods: After pre‐ or post‐infecting with herpes simplex virus type 1, small interfering RNAs were transfected into retina epithelial cells. The antiviral effects of small interfering RNA were evaluated by Western blot, plaque assays, indirect immunofluorescence and reverse transcription polymerase chain reaction. The viral titre was detected by the 50% tissue culture infective dose method. Results: Small interfering RNA decreased infected‐cell polypeptide 4 expression in retina epithelial cells that were infected with herpes simplex virus type 1 before or after small interfering RNA transfection. Compared with herpes simplex virus type 1 infection alone or transfection with negative control small interfering RNA, the viral titre and the retina epithelial cell cytopathic effect were significantly decreased in retina epithelial cells transfected with infected‐cell polypeptide 4‐targeting small interfering RNA (50 and 100 nM) (P < 0.05). The small interfering RNA effectively silenced herpes simplex virus type 1 infected‐cell polypeptide 4 expression on both mRNA and the protein levels (P < 0.05). The inhibition of infected‐cell polypeptide 4‐targeting small interfering RNA on infected‐cell polypeptide 4 protein expression was also verified by Western blot in herpes simplex virus type 1 infected human cornea epithelial cell, human trabecular meshwork cells and Vero cells. Conclusions: Infected‐cell polypeptide 4‐targeting small interfering RNA can inhibit herpes simplex virus type 1 replication in retina epithelial cells, providing a foundation for development of RNA interference as an antiviral therapy.