Inhibition of herpes simplex virus 1 (HSV-1) and poliovirus (PV-1) by bacteriocins from lactococcus lactis subsp. lactis and enterococcus durans strains isolated from goat milk

Bacteriocins have unusual inhibitory activity, including antiviral properties, and this can be exploited to give alternative applications. Semi–purified bacteriocins of six lactic acid bacteria (LAB) strains isolated from goat milk (two Lactococcus lactis: GLc03 and GLc05, and four Enterococcus durans: GEn09, GEn12, GEn14 and GEn17) were tested for cytotoxicity in Vero cells (50% Cytotoxicity Concentration: CC₅₀), and for their antiviral activities against herpes simplex virus 1 (HVS-1) and poliovirus (PV-1). Semi-purified bacteriocins presented low cytotoxicity, with CC₅₀ varying from 256.2?µg/mL (GLc05) to 1084.5?µg/mL (GEn14). CC₁₀ was determined for all isolates (GLc03: 36.9?µg/mL; GLc05: 51.2?µg/mL; GEn09: 88.1?µg/mL; GEn12: 99.9?µg/mL; GEn14: 275?µg/mL; and GEn17: 62.2?µg/mL) and considered for antiviral activity assays. Antiviral activity before virus adsorption was recorded against PV-1 for GLc05 (4.9%), GEn09 (3.4%), GEn12 (24.7%) and GEn17 (23.5%), and against HSV-1 for GEn12 (27.9%), GEn14 (58.7%) and GEn17 (39.2%). Antiviral activity after virus adsorption was identified against PV-1 for GLc05 (32.7%), GEn09 (91.0%), GEn12 (93.7%) and GEn17 (57.2%), and against HSV-1 for GEn17 (71.6%). The results obtained indicate the potential of some bacteriocins, particularly those produced by E. durans strains investigated in the present study, in viral inhibition and their application as new antiviral agents.     

Identification and characterization of a benzothiophene inhibitor of herpes simplex virus type 1 replication which acts at the immediate early stage of infection.

Analysis of a large compound library in a high throughput virus infection assay screen identified the benzothiophene PD146626 as a potent and specific inhibitor of herpes simplex virus type 1 (HSV-1) replication. PD146626 possessed an EC(50) and EC(90) against HSV-1 of 0.1 and 1 microM, respectively, and mediated no detectable cytotoxicity in cells at concentrations up to 1 microM. Western blot analyses and time of addition experiments demonstrated that in the presence of PD146626 HSV-1 underwent a specific block in viral gene expression at the immediate early stage. However, several observations indicated that a cellular function rather than a viral immediate early transactivator protein represented the molecular target for PD146626, including the lack of resistance of VP16 and ICP0 mutant viruses to the compound, the inability to select resistant strains of HSV-1 following exhaustive serial passaging of virus in the presence of the compound, and the sensitivity of human cytomegalovirus, which lacks VP16 and ICP0 homologs, to the compound. Moreover, kinetic studies suggested an unusual pattern of responsiveness of the host cell to PD146626, in that the compound could induce an extended antiviral state in cells after only a brief exposure. Together these results suggest that PD146626 targets a novel cellular function that is critical for the expression of HSV-1 immediate early genes but not host cell genes.     

Studies on the antiviral activity of 5′-amino-2′,5′-dideoxy-5-iodouridine (AIU) against herpes viruses in vivo and in vitro

5′-Amino-2′,5′-dideoxy-5-iodouridine (AIU) is known to have antiviral activity against herpes simplex virus type 1 (HSV-1) in cell cultures but is less potent than the parent compound 5-iodo-2′-deoxyuridine (IDU). Studies on its activity in vivo are limited. AIU showed antiviral effects in BHK cells against wild-type HSV-1 but not a thymidine kinase-negative (TK^?) mutant, indicating the importance of phosphorylation of the compound by HSV-1-induced thymidine kinase for antiviral effects. When cells were coinfected with the TK^? mutant and a wild-type TK⁺ strain, both strains were inhibited by AIU, suggesting that the failure to phosphorylate AIU accounts for the resistance of the TK^? strain alone. AIU failed to limit death after systemic HSV-1 infection of mice when the drug was administered parenterally or orally, although IDU in similar treatment regimens was effective. Tested for efficacy in a local HSV-1 skin infection of mice, topical AIU in a petrolatum ointment or dimethyl sulphoxide (DMSO) did not reduce titres of virus in the skin or modify the clinical course of infection, whereas topical application of IDU in DMSO caused a significant reduction in the titres of virus in the skin and reduced both the occurrence and the severity of lesions. When administered subcutaneously or orally AIU had a slight antiviral effect against HSV-1 infection in the skin of mice. Moreover, intraperitoneally (i.p.) administered AIU limited HSV-1 replication in peritoneal cells of i.p. infected mice, indicating that AIU is inherently antiviral in vivo. The poor antiviral activity of AIU in vivo compared with IDU is attributed to its lower antiviral potency as judged by its activity in cell cultures and its inability to enter neural tissue.     

The antiviral activity of arbidol hydrochloride against herpes simplex virus type II (HSV-2) in a mouse model of vaginitis

ObjectiveHSV-2 infection has increased significantly in recent years, which is closely associated with cervical cancer and HIV infection. The lack of success in vaccine development and the emergence of drug resistance to commonly used drugs emphasize the urgent need for alternative antivirals against HSV-2 infection. Arbidol (ARB) has been demonstrated to be a broad spectrum antiviral drug that exhibits immunomodulatory properties that affect the HSV-2 life cycle. This study investigated the efficacy and mechanism of ARB against HSV-2 in vivo and in vitro to further explore the clinical application of ARB.MethodsThe efficacy of ARB on HSV-2 infection in vitro was examined by CPE and MTT assays. A vaginitis model was established to monitor changes in histopathology and inflammatory cytokine (IL-2, IL-4, TNF-α and TGF-β) expression by H&E staining and ELISA, respectively, and the efficacy of ARB was evaluated accordingly. Furthermore, flow cytometry was used to determine the ratio of CD4⁺/CD8⁺ T cells in the peripheral blood of the vaginitis animals. Considering the balance of efficacy and pharmacokinetics, ARB ointment was strictly prepared to observe formulation efficacy differences compared to the oral dosing form.ResultsThe results showed that, in vitro, the TC₅₀ and IC₅₀ of ARB were 32.32 μg/mL and 4.77 μg/mL (SI = 6.82), respectively, indicating that ARB presents effective activity against HSV-2 in a dose-dependent manner. The results of the time-course assay suggested that 25 μg/mL ARB affected the late stage of HSV-2 replication. However, ARB did not inhibit viral attachment or cell penetration. The in vivo results showed that ARB ointment can improve the survival rate, prolong the survival time and reduce the reproductive tract injury in mice infected with HSV-2, regulate cytokine expression; and balance the CD4⁺ and CD8⁺ T lymphocyte ratio in the peripheral blood to participate in the regulation of immune response.ConclusionARB showed anti-HSV-2 activity in vitro in a dose-dependent manner and played a role in inhibiting the late replication cycle of the virus. The vaginitis model was successfully established, according to immunomodulation outcomes, responded better to ARB in ointment form than in oral form.     

Oligomeric proanthocyanidins from Rumex acetosa L. inhibit the attachment of herpes simplex virus type-1

The polyphenole-enriched acetone-water extract R2 from the aerial parts of Rumex acetosa L. containing high amounts of oligomeric and polymeric proanthocyanidins and flavonoids was tested for antiviral activity. R2 exhibited strong antiviral activity against herpes simplex virus type-1 (HSV-1) while the replication of adenovirus 3 was not affected. By plaque reduction test and MTT assay on Vero cells, the HSV-1-specific inhibitory concentration (IC(50)) and cytotoxic concentration (CC(50)) were determined. R2 exibited an IC(50) of 0.8 μg/mL and a selectivity index (SI) (ratio of IC(50) to CC(50)) of approximately 100 when added to the virus inoculum for 1h at 37°C prior to infection. The antiviral activity was due to the presence of flavan-3-ols and oligomeric proanthocyanidins in the extract. Structure-activity analyses indicated that flavan-3-ols and proanthocyanidins with galloylation at position O-3 are highly potent compounds (SI>40), while ungalloylated compounds did not exhibit antiviral effects (SI<1). R2 and a major proanthocyanidin from R2, epicatechin-3-O-gallate-(4β→8)-epicatechin-3-O-gallate abolished virus entry into the host cell by blocking attachment to the cell surface. When added after attachment at a concentration of ≥ 12.5 μg/mL, R2 inhibited also penetration of HSV-1 into the host cell. R2 and epicatechin-3-O-gallate-(4β→8)-epicatechin-3-O-gallate were shown to directly interact with viral particles leading to the oligomerisation of envelope proteins as demonstrated for the essential viral glycoprotein gD. Using raft cultures with three-dimensional organotypic human skin equivalents it was shown that treatment of cultures with R2 after infection with HSV-1 resulted in a reduced viral spread.     

CK2 inhibitors increase the sensitivity of HSV-1 to interferon-β

Herpes simplex virus type 1 (HSV-1) requires the activities of cellular kinases for efficient replication. The host kinase, CK2, has been shown or is predicted to modify several HSV-1 proteins and has been proposed to affect one or more steps in the viral life cycle. Furthermore, potential cellular and viral substrates of CK2 are involved in antiviral pathways and viral counter-defenses, respectively, suggesting that CK2 regulates these processes. Consequently, we tested whether pharmacological inhibitors of CK2 impaired HSV-1 replication, either alone or in combination with the cellular antiviral factor, interferon-β (IFN-β). Our results indicate that the use of CK2 inhibitors results in a minor reduction in HSV-1 replication but enhanced the inhibitory effect of IFN-β on replication. This effect was dependent on the HSV-1 E3 ubiquitin ligase, infected cell protein 0 (ICP0), which impairs several host antiviral responses, including that produced by IFN-β. Inhibitors of CK2 did not, however, impede the ability of ICP0 to induce the degradation of two cellular targets: the promyelocytic leukemia protein (PML) and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). Notably, this effect was only apparent for HSV-1, as the CK2 inhibitors did not enhance the antiviral effect of IFN-β on either vesicular stomatitis virus or adenovirus type 5. Thus, our data suggest that the activity of CK2 is required for an early function during viral infection that assists the growth of HSV-1 in IFN-β-treated cells.     

Thymine arabinoside (Ara-T) topical and iontophoretic application for herpes simplex virus type 1 and type 2 skin infections in hairless mice

The antiviral agent thymine arabinoside (9-beta-D-arabinofuranosyl thymine, Ara-T) was applied topically and by anodal (+) iontophoresis in a NaCl solution to Herpes simplex virus type 1 (HSV-1), and Herpes simplex virus type 2 (HSV-2) skin infections in hairless mice. The chemotherapeutic efficacy of Ara-T was evaluated employing the parameters of mean lesion score, number of mice with signs of neurological involvement (paralysis), mortality and mean survival time. Anodal (+) iontophoresis of 0.4% Ara-T in a 0.1 M NaCl solution significantly suppressed HSV-1 skin infection, but the infection was not altered by topical application of 3% Ara-T. HSV-2 infection was refractory to both topical and iontophoretic application of Ara-T. This is the first report of the in vivo efficacy of Ara-T for HSV-1 skin infections.     

Virucidal activity of a beta-triketone-rich essential oil of Leptospermum scoparium (manuka oil) against HSV-1 and HSV-2 in cell culture

The inhibitory activity of manuka oil against Herpes simplex virus type 1 (HSV-1) and Herpes simplex virus type 2 (HSV-2) was tested in vitro on RC-37 cells (monkey kidney cells) using a plaque reduction assay. In order to determine the mode of antiviral action of the essential oil, manuka oil was added at different times to the cells or viruses during the infection cycle. Both HSV types were significantly inhibited when the viruses were pretreated with manuka oil 1 h prior to cell infection. At non-cytotoxic concentrations of the essential oil, plaque formation was significantly reduced by 99.5 % and 98.9 % for HSV-1 and HSV-2, respectively. The 50 % inhibitory concentration (IC (50)) of manuka oil for virus plaque formation was determined at 0.0001 % v/v ( = 0.96 microg/mL) and 0.00006 % v/v ( = 0.58 microg/mL) for HSV-1 and HSV-2, respectively. On the other hand, pretreatment of host cells with the essential oil before viral infection did not affect plaque formation. After virus penetration into the host cells only replication of HSV-1 particle was significantly inhibited to about 41 % by manuka oil. Flavesone and leptospermone, two characteristic ss-triketones of manuka oil, inhibited the virulence of HSV-1 in the same manner as the essential oil itself. When added at non-cytotoxic concentrations to the virus 1 h prior to cell infection, plaque formation was reduced by 99.1 % and 79.7 % for flavesone and leptospermone, respectively.     

Cidofovir is effective against caprine herpesvirus 1 infection in goats

Caprine herpesvirus 1 (CpHV-1) is a virus able to cause genital infection leading to vulvovaginitis or balanoposthitis in adult goats. CpHV-1 shares several biological similarities with herpes simplex type 2 (HSV-2) infection in man, such as genital tropism, type and site of typical lesions and it might provide an animal model for studies on antiviral drugs for HSV-2 infection in man. In this view the efficacy of cidofovir (CDV) drug was tested in six goats intravaginally infected with BA.1 strain of CpHV-1. Three goats received an intravaginal application of 3 ml of a 1% CDV preparation at 4h post infection and then every 12 h for five consecutive days. Three goats were kept as untreated controls. The goats were daily examined for clinical evidence of the infection and viral shedding. CDV was able to protect against disease progression and inhibited the onset of the local lesions due to the CpHV-1 replication. Treated animals shed virus for a shorter period (3 days less) and at lower titres than the control animals. CpHV-1 infection in goats may represent an excellent animal model for the study of novel strategies for the treatment of primary genital HSV-2 infection in man.     

重组干扰素α-2b栓的抗疱疹病毒作用

目的探讨重组干扰素α-2b栓(IFNα-2b栓)的体外、体内抗单纯疱疹病毒Ⅰ型和Ⅱ型作用。方法应用细胞病变抑制法,观察IFNα-2b栓的体外抗病毒作用。建立HSV-2豚鼠阴道炎模型和HSV-1型豚鼠皮肤感染模型,分别用0.75、2.25、6.75 mg.kg-1的IFNα-2b栓治疗,进行豚鼠阴道分泌物的病毒毒力检测及阴道组织的病理组织学等检查,每天记录豚鼠皮肤损伤病变分值情况,观察IFNα-2b栓的体内抗病毒作用。结果体外实验,IFNα-2b栓、重组人干扰素α-2b注射液和阿昔洛韦对单纯疱疹病毒Ⅱ型的IC50分别是(0.59±0.11)、(0.56±0.08)、(21.20±1.90)mg.L-1。体内实验,各给药组中,IFNα-2b栓6.75 mg.kg-1剂量抗病毒作用最强,豚鼠阴道分泌物中病毒毒力显著低于模型组(P<0.01)。阴道组织切片病理结果也表明IFNα-2b栓对豚鼠阴道损伤具有较好的治疗作用。IFNα-2b栓能显著的减轻单纯疱疹I型病毒感染豚鼠的皮肤损伤程度(P<0.01),在相同剂量下,干扰素α-2b栓剂与干扰素α-2b注射液的抗单纯疱疹病毒活性相比较,2.25 mg.kg-1的干扰素α-2b栓剂组与其注射液组的治疗作用相当。结论 IFNα-2b栓在体外及体内均有一定的病毒抑制作用。     

Yatein from Chamaecyparis obtusa suppresses herpes simplex virus type 1 replication in HeLa cells by interruption the immediate-early gene expression

Inhibitory effects of methanolic extracts from nine Chinese herbs on herpes simplex virus type 1 (HSV-1) replication were studied. By a bioassay-guided fractionation procedure, yatein (C(22)H(23)O(7); M.W.399) was isolated from Chamaecyparis obtusa; yatein significantly suppressed HSV-1 multiplication in HeLa cells without apparent cytotoxicity. To further localize the point in the HSV-1 replication cycle where arrest occurred, a set of key regulatory events leading to the viral multiplication was examined, including viral immediate-early (alpha) and late (gamma) gene expression and DNA replication. Results indicated that levels of glycoprotein B (gB) and gC mRNA expression in HeLa cells were impeded by yatein. Data from polymerase chain reaction showed that replication of HSV-1 DNA in HeLa cells was arrested by yatein. Furthermore, yatein decreased ICP0 and ICP4 gene expression in HeLa cells. Results of an electrophoretic mobility shift assay demonstrated that yatein interrupted the formation of alpha-trans-induction factor/C1/Oct-1/GARAT multiprotein complex. The mechanisms of antiviral action of yatein seem to be mediated, by inhibiting HSV-1 alpha gene expression, including expression of the ICP0 and ICP4 genes, and by arresting HSV-1 DNA synthesis and structural protein expression in HeLa cells. These results suggest that yatein is an antiviral agent against HSV-1 replication.     

In vivo and in vitro antiviral activity of five Tibetan medicinal plant extracts against herpes simplex virus type 2 infection

Extracts from five Tibetan medicinal plants collected from the Tibetan Plateau were evaluated for antiviral activity against herpes simplex virus type 2 (HSV-2) in vitro and in vivo. Viral plaque reduction assays showed that extracts from four out of five plants inhibited HSV-2 infection significantly with 50% effective concentrations (EC₅₀) values ranging from 0.35?±?0.11 to 1.83?±?0.21?mg/mL. The other plant, Swertia mussotii Franch. (Gentianaceae), exhibited activity in inhibiting the viral biosynthesis. In the attachment assay, two plants, Dracocephalum heterophyllum Benth. (Lamiaceae) and Dracocephalum tanguticum Maxim. (Lamiaceae) reduced the attachment of HSV-2 to cell surface. Interestingly, all of the extracts showed virucidal activity. Analyzed by real-time PCR, three extracts showed strong inhibition of HSV DNA replication with Dracocephalum heterophyllum and Dracocephalum tanguticum at the concentration of 4?mg/mL and Lagotis brevituba Maxim. (Scrophulariaceae) at 1?mg/mL. BALB/c mice were used for determining in vivo efficacy. Mice encephalitis herpes models were established by infection with HSV-2. The extracts of Dracocephalum heterophyllum, Dracocephalum tanguticum, and Swertia mussotii at a dose of 1?g/kg per day significantly prolonged the mean survival times and reduced the mortality of HSV-2 infected mice compared with control group (P?<?0.05). Taken together, we conclude that the antiviral mechanisms of these plants involve various stages of virus replication. Extracts from three of these plants, Dracocephalum heterophyllum, Dracocephalum tanguticum, and Swertia mussotii, may be possible candidates in developing anti-HSV-2 medicine.     

The effect of HSV multiplication rate on antiviral drug efficacy in vitro.

HSV-1 multiplication rates have been shown to vary in different tissues and the rate of multiplication may correlate with susceptibility to antiviral chemotherapy. Herpetic stromal keratitis is a necrotizing condition refractive to antiviral therapy and this lack of antiviral efficacy in stromal disease may be the result of very low rates of viral replication in the corneal stromal keratocytes. In this study, we investigated the efficacy of antiviral drugs in an in vitro system in which the virus multiplication rate is slow. In this system, the reduced rate of virus multiplication is achieved by a reduction in the incubation temperature. Vero cells were infected at one of several multiplicities of infection with McKrae strain HSV-1 and incubated for 24, 48, or 72 h at 26 or 36.5 degrees C in the presence or absence of trifluridine (50 micrograms/ml) or acyclovir (20 micrograms/ml). Both drugs suppressed viral replication at 36.5 degrees C. However, under some specific sets of conditions, trifluridine was not effective in suppressing viral replication in cells incubated at 26 degrees C. At this temperature, viral replication and cell metabolism are slowed to a pace which may be similar to that which occurs in corneal stromal keratocytes in vivo. Acyclovir significantly reduced HSV-1 replication under all conditions at 26 degrees C, indicating that the antiviral activity of this compound is effective in cells whose metabolic rate is slow and in which viral replication is taking place slowly.     

Activity of two synthetic amphiphilic peptides and magainin-2 against herpes simplex virus types 1 and 2

The in vitro antiviral activity of two amphiphilic synthetic peptides, modelin-1 (mod-1) and modelin-5 (mod-5), and of the natural antibacterial peptide magainin-2 (mag-2) against herpes simplex viruses type 1 (HSV-1) and 2 (HSV-2) were evaluated. The peptides were incubated with the virus, i.e. direct inactivation, and their effects examined by means of plaque reduction assay and/or reduction in virus yield. Only mod- displayed a strong antiviral effect against HSV-1 and HSV-2, with 50% effective dose (ED₅₀) values of 4.6 and 4.1 μg/mL, respectively. Mag-2, mod-5 and a mixture of both had no significant inhibitory effect. Addition of mod-1 up to a concentration of 100μg/mL to the culture medium had no significant cytotoxic effect on host vero cells, as measured by the trypan blue-exclusion method. It showed, however, considerable hemolytic activity against human red blood cells. Experiments including acyclovir (ACV) as a reference viral inhibitor indicated that the mode of action of mod-1 is different from that of ACV. In contrast to ACV, the peptide inactivates the virus following a very short incubation before vero cell infection, suggesting some kind of direct interaction of the peptide with the viral envelope, rather than inhibition of viral DNA replication or gene expression. Our results suggest that mod-1 may be an effective topical antiviral agent against herpes viruses.     

Antiviral activity of Australian tea tree oil and eucalyptus oil against herpes simplex virus in cell culture

The antiviral effect of Australian tea tree oil (TTO) and eucalyptus oil (EUO) against herpes simplex virus was examined. Cytotoxicity of TTO and EUO was evaluated in a standard neutral red dye uptake assay. Toxicity of TTO and EUO was moderate for RC-37 cells and approached 50% (TC50) at concentrations of 0.006% and 0.03%, respectively. Antiviral activity of TTO and EUO against herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a plaque reduction assay. The 50% inhibitory concentration (IC50) of TTO for herpes simplex virus plaque formation was 0.0009% and 0.0008% and the IC50 of EUO was determined at 0.009% and 0.008% for HSV-1 and HSV-2, respectively. Australian tea tree oil exhibited high levels of virucidal activity against HSV-1 and HSV-2 in viral suspension tests. At noncytotoxic concentrations of TTO plaque formation was reduced by 98.2% and 93.0% for HSV-1 and HSV-2, respectively. Noncytotoxic concentrations of EUO reduced virus titers by 57.9% for HSV-1 and 75.4% for HSV-2. Virus titers were reduced significantly with TTO, whereas EUO exhibited distinct but less antiviral activity. In order to determine the mode of antiviral action of both essential oils, either cells were pretreated before viral infection or viruses were incubated with TTO or EUO before infection, during adsorption or after penetration into the host cells. Plaque formation was clearly reduced, when herpes simplex virus was pretreated with the essential oils prior to adsorption. These results indicate that TTO and EUO affect the virus before or during adsorption, but not after penetration into the host cell. Thus TTO and EUO are capable to exert a direct antiviral effect on HSV. Although the active antiherpes components of Australian tea tree and eucalyptus oil are not yet known, their possible application as antiviral agents in recurrent herpes infection is promising.     

Production of herpes simplex virus type 1 thymidine kinase in the presence of thymidine analogues

Treatment of herpes simplex virus type 1 (HSV-1) infected Vero, BHK, BHKtk- and LMtk- cells with 5-iodo-5'-amino-2',5'-dideoxyuridine (AIdUrd) caused increased synthesis of ICP36 and an increase in HSV-1 thymidine kinase (tk) activity at late times of infection. The overproduced ICP36 was identified as the HSV-1 encoded tk protein by immunoprecipitation. Whereas the thymidine analogue 5'-amino-5'-deoxythymidine (AdThd) caused an increase in HSV-1 tk synthesis and activity in wild type Vero and BHK cells, 5-iodo-2'-deoxyuridine (IdUrd) caused a similar increase only in tk- cells (LMtk-, BHKtk-). In vivo and in vitro stabilization studies using a [35S]methionine pulse-chase experiment or heat inactivation studies with purified HSV-1 tk revealed that stabilization of tk by the analogues could not account for the extent of the observed increase. Since overproduction of tk is observed only at late times of infection, it is suggested that the presence of these thymidine analogues in either the viral DNA or the cellular nucleotide pools is responsible for the observed differential effects.     

Effect of topically applied resveratrol on cutaneous herpes simplex virus infections in hairless mice

Resveratrol (3,5,4'-trihydroxystilbene) is a natural component of certain foods, such as grapes, that has been shown to have anti-herpes simplex virus (HSV) activity in vitro. To determine if it is active in vivo, the abraded epidermis of SKH1 mice were infected with HSV-1 and topically treated with 12.5 or 25% resveratrol cream or cream only. Initial studies demonstrated that: (1). 25% resveratrol cream topically applied two, three, or five times a day effectively suppressed lesion development whereas 12.5% resveratrol cream effectively suppressed lesion formation when applied five times a day starting 1h after infection; (2). when treatment was begun 1, 6, or 12h after infection, both 12.5 and 25% resveratrol were effective at 1 and 6h after infection, but not if applied 12h after infection. Comparative studies between resveratrol cream, 10% docosanol cream (Abreva) and 5% acyclovir ointment (Zovirax) were also carried out. When treatment was begun 1h after infection and repeated every 3h five times a day for 5 days, 12.5 and 25% resveratrol significantly (P=0.0001) inhibited the development of HSV-1 induced skin lesions. Acyclovir was as effective (P=0.0001) as resveratrol. Animals that were topically treated with docosanol were not protected and developed lesions in a manner indistinguishable from cream only controls. These studies were repeated with an HSV-1 acyclovir-resistant virus. As before, 12.5 and 25% resveratrol cream effectively suppressed lesion formation. The skin of resveratrol-treated animals showed no apparent dermal toxicity such as erythema, scaling, crusting, lichenification, or excoriation. These studies demonstrate that topically applied resveratrol inhibits HSV lesion formation in the skin of mice.