Efficacy of Thai medicinal plant extracts against herpes simplex virus type 1 infection in vitro and in vivo

Twenty Thai medicinal plant extracts were evaluated for anti-herpes simplex virus type 1 (HSV-1) activity. Eleven of them inhibited plaque formation of HSV-1 more than 50% at 100 μg/ml in a plaque reduction assay. Aglaia odorata, Moringa oleifera, and Ventilago denticulata among the 11 were also effective against thymidine kinase-deficient HSV-1 and phosphonoacetate-resistant HSV-1 strains. These therapeutic efficacies were characterized using a cutaneous HSV-1 infection in mice. The extract of M. oleifera at a dose of 750 mg/kg per day significantly delayed the development of skin lesions, prolonged the mean survival times and reduced the mortality of HSV-1 infected mice as compared with 2% DMSO in distilled water (P<0.05). The extracts of A. odorata and V. denticulata were also significantly effective in limiting the development of skin lesions (P<0.05). There were no significant difference between acyclovir and these three plant extracts in the delay of the development of skin lesions and no significant difference between acyclovir and M. oleifera in mean survival times. Toxicity of these plant extracts were not observed in treated mice. Thus, these three plant extracts may be possible candidates of anti-HSV-1 agents.     

Laboratory assessment and diagnosis of congenital viral infections: Rubella, cytomegalovirus (CMV), varicella-zoster virus (VZV), herpes simplex virus (HSV), parvovirus B19 and human immunodeficiency virus (HIV)

Viral infections during pregnancy may cause fetal or neonatal damage. Clinical intervention, which is required for certain viral infections, relies on laboratory tests performed during pregnancy and at the neonatal stage. This review describes traditional and advanced laboratory approaches and testing methods used for assessment of the six most significant viral infections during pregnancy: rubella virus (RV), cytomegalovirus (CMV), varicella-zoster virus (VZV), herpes simplex virus (HSV), parvovirus B19 and human immunodeficiency virus (HIV). Interpretation of the laboratory tests results according to studies published in recent years is discussed.     

Efficacy of (E)-5-(2-bromovinyl)-2'-deoxyuridine against different herpes simplex virus strains in cell culture and against experimental herpes encephalitis in mice

(E)-5-(2-Bromovinyl-2'-deoxyuridine (BrVUdR) showed strong antiviral activity against different laboratory strains and clinical isolates of herpes simplex virus type 1 (HSV-1) on primary rabbit testes (PRT) cells with a 50% inhibition of plaque formation (ID50) at 0.01-0.02 microM. One laboratory strain (HSV-1-S), however, was completely refractory even at concentrations as high as 100 microM. In contrast, the ID50S for all herpes simplex virus type 2 (HSV-2) strains were about 10(2) - 10(3) times higher (8-25 microM) than for the HSV-1 strains. No toxicity in mice treated with 140 mg BrVUdR/kg/day for 14 days was observed, and successful treatments of herpes encephalitis in mice induced experimentally by intracerebral infection with one laboratory strain (HSV-1-Kupka) and one clinical isolate (HSV-1-64) were achieved. Treatment of encephalitis in mice induced by the strain HSV-1-S insensitive to BrVUdR in cell culture failed to be effective. Similar antibody titers against HSV-1 were found in surviving mice of the control and of the BrVUdR-treated groups.     

单纯疱疹病毒-2型抗原gG-2在大肠埃希菌中的表达及纯化

目的用基因工程方法表达单纯疱疹病毒-2型(HSV-2型)血清型特异性抗原,代替传统的病毒检测抗原。方法采取PCR和蛋白质原核细胞表达方法。结果成功地克隆出了HSV-2型特异性基因,采用该抗原包被试剂盒,能检测出生殖器疱疹感染者血清中的IgM抗体。结论HSV-2型特异性抗原基因的成功表达,为HSV-2型感染者的特异性诊断和HSV-2型疫苗的研究打下基础。     

Virostatic potential of micro-nano filopodia-like ZnO structures against herpes simplex virus-1

Herpes simplex virus type-1 (HSV-1) entry into target cell is initiated by the ionic interactions between positively charged viral envelop glycoproteins and a negatively charged cell surface heparan sulfate (HS). This first step involves the induction of HS-rich filopodia-like structures on the cell surface that facilitate viral transport during cell entry. Targeting this initial first step in HSV-1 pathogenesis, we generated different zinc oxide (ZnO) micro-nano structures (MNSs) that were capped with multiple nanoscopic spikes mimicking cell induced filopodia. These MNSs were predicted to target the virus to compete for its binding to cellular HS through their partially negatively charged oxygen vacancies on their nanoscopic spikes, to affect viral entry and subsequent spread. Our results demonstrate that the partially negatively charged ZnO-MNSs efficiently trap the virions via a novel virostatic mechanism rendering them unable to enter into human corneal fibroblasts - a natural target cell for HSV-1 infection. The anti-HSV-1 activity of ZnO MNSs was drastically enhanced after creating additional oxygen vacancies under UV-light illumination. Our results provide a novel insight into the significance of ZnO MNSs as the potent HSV-1 inhibitor and rationalize their development as a novel topical agent for the prevention of HSV-1 infection.     

Activity of acetone and methanol extracts from thirty-one medicinal plant species against herpes simplex virus types 1 and 2

Context: Thirty-one medicinal plant species from Hawaii, Morocco, and the Sonoran Desert, USA have been shown in past studies to be highly inhibitory to pathogenic bacteria, fungi, and certain cancer cell lines. However, none were tested for antiviral activity.

Objective: Acetone and methanol extracts from these species were bio-assayed for antiviral activity against herpes simplex virus types 1 and 2, and for cytotoxicity to the Vero C1008 cell line.

Materials and methods: Extracts from these species were tested in vitro for antiviral activity using an immunoperoxidase mini-plaque reduction assay to detect viral structural protein synthesis. A 50% inhibitory concentration (IC₅₀) was computed. Sulforhodamine B and neutral red assays were used to qualitatively and quantitatively assess the cytotoxicity of extracts to C1008 cells, and to compute a 50% cytotoxic concentration (CC₅₀) using a dose response curve.

Results: Eight of the 31 plant species assayed showed significant antiviral activity against HSV 1 and HSV 2 viruses. The acetone extract of Kalanchoe pinnata Pers. (Crassulaceae) produced an IC₅₀ of 0.025?mg/mL and a CC₅₀ of 1.25?mg/mL yielding a therapeutic index of 50. Additionally, this extract reduced plaque numbers to zero or near zero at a concentration of 0.1?mg/mL when added 30?min before or 30?min after virus infection.

Discussion and conclusion: The mechanism of inhibition against HSV 1 and HSV 2 viruses is now being investigated, along with fractionation of the acetone extract in search of the active compound or compounds.     

Expression of herpes simplex virus type 1 recombinant thymidine kinase and its application to a rapid antiviral sensitivity assay

Antiviral-resistant herpesvirus infection has become a great concern for immunocompromised patients. Herpes simplex virus type 1 (HSV-1) infections are treated with viral thymidine kinase (vTK)-associated drugs such as acyclovir (ACV), and most ACV-resistance (ACV^r) is due to mutations in the vTK. The standard drug sensitivity test is usually carried out by the plaque reduction assay-based method, which requires over 10 days. To shorten the time required, a novel system was developed by the concept, in which 293T cells transiently expressing recombinant vTK derived from the test sample by transfection of the cells with an expression vector were infected with vTK-deficient and ACV^r HSV-1 (TAR), and then cultured in a maintenance medium with or without designated concentrations of ACV, ganciclovir (GCV) and brivudine (BVdU). The replication of TAR was strongly inhibited by ACV, GCV and BVdU in 293T cells expressing recombinant vTK of the ACV-sensitive HSV-1, whereas replication was not or slightly inhibited in cells expressing the recombinant vTK of highly resistant or intermediately resistant HSV-1, respectively. An inverse correlation was demonstrated in the 50% effective concentrations (EC₅₀s) and inhibitory effects of these compounds on the replication of TAR among ACV^s and ACV^r HSV-1 clones. These results indicate that the EC₅₀s of the vTK-associated drugs including ACV can be assumed by measuring the inhibitory effect of drugs in 293T cells expressing recombinant vTK of the target virus. The newly developed antiviral sensitivity assay system for HSV-1 makes it possible to estimate EC₅₀ for vTK-associated drugs, when whole vTK gene is available for use by gene amplification directly from lesion’s samples or from virus isolates.     

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.     

扇贝裙边糖胺聚糖体外抗I型单纯疱疹病毒实验研究

目的研究扇贝裙边糖胺聚糖(glycosaminoglycan from Scallop Skirt,SS-GAG)体外抗单纯疱疹病毒Ⅰ型(HSV-Ⅰ)的作用。方法运用单纯疱疹病毒Ⅰ型(HSV-ⅠSM44株),并以非洲绿猴肾细胞(Vero细胞)为宿主细胞,通过观察病毒感染后的细胞变性反应(cytopathic effect,CPE)和运用MTT比色法,检测不同浓度药物SS-GAG对Ⅰ型单纯疱疹病毒是否有直接的灭活作用、对HSV-Ⅰ感染复制的抑制活性以及对HSV-Ⅰ感染细胞的综合作用等,并观察药物对Vero细胞的毒性作用。结果与病毒对照组相比,SS-GAG各浓度组(100、50、25mg.L-1)能有效地保护经HSV-Ⅰ感染的Vero细胞,使细胞活性增强(P<0.01);并减弱HSV-Ⅰ导致的病变效应,抑制病毒的复制。此作用随着药物浓度的增加而增强。但是SS-GAG对HSV-Ⅰ没有直接的灭活作用;SS-GAG在50~1600mg.L-1浓度范围内对Vero细胞无明显的细胞毒性。结论SS-GAG在体外实验系统中显示出明显的保护宿主细胞抵抗HSV-Ⅰ病毒感染的活性作用。     

Toxic effects of bis(thiosemicarbazone) compounds and its palladium(II) complexes on herpes simplex virus growth

Here, we present data on the activity of benzyl bis(thiosemicarbazone); 3,5-diacyl-1,2,4-triazole bis(4-methylthiosemicarbazone) and their Pd(II) complexes against the replication of wild type and of acyclovir (ACV)-resistant, herpes simplex virus type 1 (HSV 1) and type 2 (HSV 2) strains. The data were compared to those under the action of acyclovir. The testing of cytotoxic activity suggests that these compounds may be endowed with important antiviral properties. It is interesting to note that the Pd(II)-benzyl bis(thiosemicarbazone) complex, 2, exhibits a significant activity against acyclovir-resistant viruses R-100 (HSV 1) and PU (HSV 2) with an in vitro selectivity index (SI) of 8.0 vs. 0.01 for acyclovir. This complex also negatively influenced the expression of key structural HSV 1 proteins (VP23, gH and gG/gD), thus suppressing simultaneously virus entry, transactivation of virus genome, capsid assembly, and cell-to-cell spread of infectious HSV progeny.     

Phenotypic and genotypic characterization of induced acyclovir-resistant clinical isolates of herpes simplex virus type 1

Eleven strains of acyclovir (ACV)-resistant herpes simplex virus type 1 (HSV-1) were generated from HSV-1 clinical isolates by exposure to ACV. Genotype of the thymidine kinase (TK) and DNA polymerase (pol) genes from these mutants were further analyzed. Genotypic analysis revealed four non-synonymous mutations in TK gene associated with gene polymorphism and two to three non-synonymous mutations in DNA pol gene. Seven and six strains contained at least one resistance-associated mutation at TK and DNA pol gene, respectively. Resistance-associated mutations within the TK gene consisted of 64% of non-synonymous frameshift mutations within the homopolymer region of G’s and C’s, and 36% of non-synonymous nucleotide substitutions of the conserved gene region (C336Y, R51W and R222H), nucleotide that produced stop codon (L288Stop) and two amino acid substitutions outside the conserved region (E39G & L208F). There were 10 non-synonymous amino acid substitutions located outside the conserved region with the unclear significance to confer resistance observed. Resistance-associated mutations in DNA pol gene include insertion of G at the homopolymer region of G’s (794–797) and amino acid substitutions inside (V621S) or outside (H1228D) the conserved region. In silico analysis of the mutated TK (C336Y, R51W and L208F), and DNA pol (V621S and H1228D) suggested structural changes that might alter the stability of these proteins. However, there were several mutations with unclear significance to confer ACV-resistance identified, especially mutations outside the conserved region.     

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 0.024 μg/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.     

酞丁安类似物抗单纯疱疹病毒活性的比较研究

酞丁安对HSV-1与HSV-2具有明显的抑制作用。修饰酞丁安结构,合成了14种酞丁安类似物,并对这些类似物的抗病毒活性与细胞毒性进行了研究。在14种酞丁安类似物中,有6种具有抗单纯疱疹病毒活性。但用非洲绿猴肾细胞进行空斑抑制测定,仅有一种酞丁安类似物V8540对HSV-2具有强烈的抑制作用,其抗HSV-2活性较酞丁安高10倍左右。酞丁安类似物抗HSV活性的次序为:V 8540>V 8512>V 8509>V 8502>V 8501>V 8519。其它酞丁安类似物抗单纯疱疹病毒活性很低或完全没有活性。用Vero细胞检测各种酞丁安类似物的细胞毒性,结果证明,V 8540的细胞毒性较酞丁安高。大量快速增殖的Vero细胞在V8540作用下停止了生长。     

钝顶螺旋藻多糖抗病毒作用的实验研究

目的探讨钝顶螺旋藻多糖(polysaccharide fromSpirulina platensis,PSP)抗单纯疱疹病毒及乙型肝炎病毒的作用及可能机制,为进一步开发该药提供理论依据。方法以不同剂量的PSP分别作用于HSV-1及HSV-2病毒复制周期的各个环节,以病毒半数感染量(TCID50),细胞病变效应(CPE),蚀斑形成单位(PFU),MTT法作为评价指标,判断PSP的抗病毒效果;ELISA法定量检测PSP对HepG2 2.2.15细胞HbsAg,HBeAg分泌的影响;FQ-PCR检测PSP对HBV-DNA合成的影响。结果PSP对Vero细胞及HepG2 2.2.15细胞毒性极低,对HSV-1及HSV-2均无直接灭活作用,可阻滞HSV-1及HSV-2病毒的吸附并抑制感染细胞内病毒的复制,但不影响病毒的释放。在HepG2 2.2.15细胞培养中PSP可显著抑制HB-sAg、HBeAg的分泌以及HBV-DNA的合成,并具有量效和时效关系。结论PSP抗HSV-1及HSV-2病毒作用的机制与抑制病毒吸附和感染细胞内病毒的生物合成有关,而PSP抗HBV作用的机制则与抑制HBV抗原分泌及病毒DNA复制有关。     

Enhanced efficacy of the acyclic nucleoside 9-(1,3-dihydroxy-2-propoxymethyl)guanine in combination with gamma interferon against herpes simplex virus type 2 in mice

The acyclic nucleoside 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG) and recombinant mouse interferon gamma (rMuIFN-gamma) were evaluated for their efficacy alone and in combination against a herpes simplex virus type 2 systemic infection in mice. Intraperitoneally infected animals were treated once a day with the drugs at various concentrations for 5 days starting 24 h after inoculation. DHPG was given subcutaneously and rMuIFN-gamma intraperitoneally. For DHPG, the effective dose at which 50% of the mice survived (ED50 was lowered approximately 10-fold from 3.4 to 0.25 mg/kg when given in combination with an ineffective dose of 4MuIFN-gamma (10(3) units per mouse). For rMuIFN-gamma, the ED50 was lowered greater than 10-fold from 6 x 10(3) to less than 3 x 10(2) units per mouse when given in combination with a marginally effective dose of DHPG (1 mg/kg). Construction of an isobologram and calculation of the corresponding fractional protective dose index (less than 0.12 where values less than or equal to 0.5 are considered synergistic) indicates an enhanced protective interaction by the combination of the two drugs.     

Intracellular uptake of thymidine and antiherpetic drugs for thymidine kinase-deficient mutants of herpes simplex virus type 1

The influence of the thymidine (Thd) kinase (TK) of herpes simplex virus type 1 (HSV-1) on the intracellular uptake and anabolism of nucleosides has been investigated. To compare the differences between the TK-positive (TK⁺) and TK-deficient strains, acyclovir (ACV)-resistant strains were cloned from a cell culture and classified into 2 groups, viz. the TK-partial (TK^p) and TK-negative (TK⁻). The cellular uptake of thymidine was highly dependent on the viral TK (vTK) activity. The TK⁺ strain showed the highest level of intracellular thymidine uptake, the TK^p strain a moderate level, which varied from strain to strain, and the TK⁻ and mock strains showed little uptake. The inhibition of viral replication by ACV, ganciclovir (GCV) and penciclovir (PCV) did not decrease the Thd uptake at all. On the contrary, a notable increase found to be induced by ACV. The influence of the vTK on the uptake of GCV or PCV was much greater than that of ACV. The metabolism was generally less dependent on the vTK activity than the influx. The influx and phosphorylation rates of GCV and PCV were dependent on the substrate specificity of the vTK.     

Relationship between structural properties and affinity for herpes simplex virus type 1 thymidine kinase of bromine substituted 5-heteroaromatic 2′-deoxyuridines

The crystal structures of 5-(5-furan-2-yl)-2′-deoxyuridine (II), 5-(5-bromofuran-2-yl)-2′-deoxyuridine (IV) and 5-(3-bromothien-2-yl)-2′-deoxyuridine (V) have been studied in order to explain the different affinity of the compounds for the herpes simplex virus type 1 (HSV-1) thymidine kinase. These compounds present a variable affinity according to the position of the heteroatom substituting the five-membered ring. An unfavourable substitution in the five-membered ring for interaction with the HSV-1 thymidine kinase has been identified.     

A comparison of phosphonoacetic acid and phosphonoformic acid activity in genital herpes simplex virus type 1 and type 2 infections of mice

The activity of phosphonoacetic acid (PAA) and phosphonoformic acid (PFA) against four strains of herpes simplex virus type 1 (HSV-1) and four strains of HSV-2 were compared in tissue culture and in a murine model of genital herpes. In mouse embryo fibroblast cells, both drugs were three-fold more active against the HSV-1 strains than against the HSV-2 strains. In contrast, in the animal model infections, PAA appeared to be more active against the HSV-2 strains, while PFA was equally effective against both HSV types. In mice infected intravaginally with HSV-2 and treated with intravaginal 5% PAA, none of the treated mice became infected, replication of virus in the genital tract was completely inhibited, none of the infected mice died from encephalitis, and latent infection in lumbosacral ganglia of surviving animals was completely prevented. In the HSV-1 genital infection treated with PAA, 20–60% of mice became infected, replication of virus in the genital tract was strikingly reduced, none of the infected mice died, and latent infection was completely prevented. In both HSV-2 and HSV-1 genital infections, 20–70% of animals treated with 8% PFA became infected, growth of virus in the genital tract was reduced significantly but not completely suppressed, mortality was variably altered, and there was a trend towards reduction in the frequency of latent infection. These results indicate that HSV-1 strains are more sensitive to PAA and PFA in tissue culture, but the HSV-2 strains are generally more amenable to therapy in the murine model of genital herpes. Although PAA appeared to be more active than PFA in the genital infection, both drugs significantly altered the course of the infection. Since dermal toxicity associated with PAA precludes its use in humans and since PFA is already undergoing trials in patients with recurrent herpes labialis, the current results suggest that topical PFA deserves further evaluation in the treatment of mucocutaneous HSV infections, including genital herpes.     

Antiviral activity of the marine alga Symphyocladia latiuscula against herpes simplex virus (HSV-1) in vitro and its therapeutic efficacy against HSV-1 infection in mice

The antiviral activities of extracts from 5 species of marine algae collected at Haeundae (Pusan, Korea), were examined using plaque reduction assays. Although the activity of a methanol (MeOH) extract of Sargassum ringoldianum (Sargassaceae) was the most potent against several types of viruses, it was also cytotoxic. A MeOH extract of Symphyocladia latiuscula (Rhodomelaceae) and its fractions exhibited antiviral activities against acyclovir (ACV) and phosphonoacetic acid (PAA)-resistant (AP(r)) herpes simplex type 1 (HSV-1), thymidine kinase (TK(-)) deficient HSV-1 and wild type HSV-1 in vitro without cytotoxicity. The major component, 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (TDB) of a CH(2)Cl(2)-soluble fraction was active against wild type HSV-1, as well as AP(r) HSV-1 and TK(-) HSV-1 (IC(50) values of 5.48, 4.81 and 23.3 microg/ml, respectively). The therapeutic effectiveness of the MeOH extract and TDB from S. latiuscula was further examined in BALB/c mice that were cutaneously infected with HSV-1 strain 7401H. Three daily oral administrations of the MeOH extract and TDB significantly delayed the appearance of score 2 skin lesions (local vesicles) and limited the development of further score 6 (mild zosteriform) lesions in infected mice without toxicity compared with controls. In addition, TDB suppressed virus yields in the brain and skin. Therefore TDB should be a promising anti HSV agent.     

Acyclovir treatment of experimental genital herpes simplex virus infections. I. Topical therapy of type 2 and type 1 infections of mice

Intravaginal inoculation of mice with herpes simplex virus (HSV) provides a model infection of genital herpes to determine the effectiveness of potential antiviral agents. topical (intravaginal) treatment with 1% or 5% acyclovir (ACV) in an ointment of gel vehicle initiated 3, 6 or 24 h after inoculation with HSV type 2, significantly inhibited viral replication in the genital tract and usually reduced final mortality. Treatment with 5% ACV initiated 48 or 72 h after infection also reduced vaginal virus titers but did not alter final mortality. When mice were inoculated with HSV type 1 treatment with 5% ACV significantly reduced viral replication in the genital tract when begun as late as 72 h. In HSV-2 infected mice, treatment initiated 3 h but not 24 h after infection prevented the establishment of latent infection in sacral ganglie. These results suggest that topical ACV may be effective antiviral agent for primary genital herpes in humans.