Antiviral activity of Spirulina maxima against herpes simplex virus type 2

Spirulina has been used in a variety of practical applications in biotechnology and medical sciences. This paper presents the antiviral activity found in a hot water extract (HWE) of a commercial preparation of Spirulina maxima, studied by a microplate inhibition assay, using several viruses. The HWE inhibited the infection for: herpes simplex virus type 2 (HSV-2), pseudorabies virus (PRV), human cytomegalovirus (HCMV), and HSV-1, and the 50% effective inhibition doses (ED(50)) were 0.069, 0.103, 0.142, and 0.333 mg/ml for each virus, respectively. For adenovirus the inhibition was less than 20%, and no inhibition was found for measles virus, subacute sclerosing panencephalitis virus (SSPE), vesicular stomatitis virus (VSV), poliovirus 1 and rotavirus SA-11, at concentrations of 2 mg/ml of the HWE. The highest antiviral activity was for HSV-2, with a selectivity index of 128. The antiviral activity was not due to a virucidal effect. Herpesvirus infection was inhibited at the initial events (adsorption and penetration) of the viral cycle. To initiate the isolation and identification of the compound that exhibits the antiviral activity of S. maxima, some extracts made by using several solvents with different polarity were evaluated by microplate inhibition assay using HSV-2. The highest antiviral activity was detected in the methanol-water 3:1, which suggests that the antiviral activity is probably due to highly polar compounds.     

展枝马尾藻硫酸多糖对呼吸道合胞病毒的抗病毒活性及其机理研究

目的研究从褐藻展枝马尾藻Sargassumpatens中分离到的一种硫酸多糖SP2的抗病毒活性及抗病毒作用机理。方法通过细胞致病效应实验、MTT测定和空斑形成抑制实验对该多糖的抗病毒活性、细胞毒性和可能的抗病毒机理进行测定。结果通过空斑形成抑制实验测定结果显示,该多糖对呼吸道合胞病毒有好的抗病毒活性,其EC50值为1.1但没有抗流感病毒A和B、副流感病毒的活性。多糖的CC50高达3000μg.mL-1。其对呼吸道合胞病毒的抗病毒选择性指数被估计大于2727。用SP2预处理宿主细胞,不显示任何对病毒感染的保护作用。SP2对呼吸道合胞病毒有一定的杀病毒活性,其EC50值超过100μg.mL-1。时间加入实验证明,只有在37℃呼吸道合胞病毒吸附时期加入SP2才能完全抑制病毒的复制。结论SP2可能是一种有潜力的抗呼吸道合胞病毒感染的多糖。其对呼吸道合胞病毒的抗病毒作用机制与抑制病毒的吸附有关。     

Antiviral activities of gossypol and its derivatives against herpes simplex virus type II

Gossypol, a disequiterpene obtained from cottonseed oil, and a series of peri-acylated gossylic nitriles were compared for their antiviral activities against HSV-II and for their toxicities to the host Vero cells. All of the peri-acylated gossylic nitriles exhibited lower cytotoxicities to the host cell than did the parent compound gossypol. Both gossypol and the series of derivatives exhibited antiviral activities against HSV-II when the virus was treated with drug at concentrations as low as 5 X 10(-7) M. Two of the derivatives, gossylic nitrile-1,1'-diacetate and gossylic nitrile-1,1'-divalerate, were capable of inhibiting viral multiplication in Vero cells that were infected with virus before administration of the drug. The results of this study indicate that modification of the aldehyde functional groups on gossypol lowers the toxicity of this drug but does not abolish its antiviral properties. Derivatives of gossypol may be useful antiviral agents.     

Antiviral activity of Bifidobacterium adolescentis SPM 0214 against herpes simplex virus type 1

Herpes Simplex Virus type 1 (HSV-1) antibodies are found in up to 90 percent of the general population. About 30% of patients who have been exposed to HSV-1 develop recurrent infections, and this degree is continually increasing. In addition, resistance to all major anti-herpetic drugs such as acyclovir (ACV) has been increasingly reported. These observations underscore the importance of discovering new therapeutic tools for the treatment of HSV-1 infections. Bifidobacterium spp. has been studied in various fields including antibacterial and anticancer effect, but the antiviral activity was studied very little. The aim of this study was to test the antiviral activity of Bifidobacterium spp. against HSV-1. The Bifidobacterium adolescentis SPM 0214 used in this study through the screening of 23 Bifidobacterium spp. by plaque assay was assessed the cell viability assay in Vero cells. We also measured the plaque reduction assay and yield reduction assay after B. adolescentis SPM 0214 treatment at concentrations ranging between 10 and 10⁴ ??g/mL. The B. adolescentis SPM 0214 was not toxic to Vero cells, and the inhibition of plaque and yield formation was obviously increased compared to those of the control (no additive). Therefore, these results indicate that antiviral activity of B. adolescentis SPM 0214 against HSV-1.     

Antiviral activity of a carrageenan from Gigartina skottsbergii against intraperitoneal murine herpes simplex virus infection

The partially cyclized mu/nu-carrageenan 1C3, isolated from the red seaweed Gigartina skottsbergii, was previously shown to be a potent inhibitor of the in vitro replication of Herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). Here the protective effect of 1C3 in a murine model of intraperitoneal ( i. p.) HSV-1 infection was evaluated. OF1 mice were i. p. infected with 5 x 10 (5) PFU of HSV-1 KOS strain, and the effects of different treatments with 1C3 were studied. When 30 mg/kg of body weight of 1C3 was administered by the i. p. route immediately after HSV-1 infection, 87.5 % survival of the animals was achieved (p < 0.005), associated with a delay in the mean day of death in 1C3-treated non-surviving mice. Animal survival was not improved when multiple doses of 1C3 were also given in the period 1 - 48 h post-infection, and no protection was afforded when treatment was started after 24 h of infection. When virus and compound were injected by different routes, i. p. and intravenous ( i. v.), respectively, a still significant protection was achieved (40 % survival, p < 0.05). No toxicity of 1C3 for the animals was recorded. The pharmacokinetic properties were analyzed after injection of 1C3 into the tail vein by monitoring of [ (3)H]-1C3 in plasma and organs and by a bioassay of the anti-HSV-1 activity remaining in serum after non-radioactive 1C3 inoculation. A very rapid disappearance of the compound from the blood was observed since only 5.9 - 0.9 % of the radioactivity of the initially administered [ (3)H]-1C3 appeared in the plasma between 5-300 minutes after administration. A transient peak of radioactivity was detected in the kidney 15 minutes after inoculation. The bioassay confirms the presence of the compound circulating in a biologically active form up to 1 hour after injection.     

Antiviral activity of antimicrobial cationic peptides against Junin virus and herpes simplex virus

The in vitro antiviral activity of antimicrobial cationic peptides: cecropin A, melittin, magainin I and II and indolicidin against the arenavirus Junin virus (JV), and herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) was evaluated. Cecropin A effectively inhibited JV multiplication and failed to affect HSV replication whereas melittin impeded the multiplication of JV and HSV, but was highly toxic for the host cell. Magainins I and II exhibited inhibitory action toward HSV-1 and HSV-2 but were inactive against JV. Only indolicidin showed a direct inactivation effect on cell-free virus stocks. Besides its inhibitory effect on JV replication cecropin A also was active against the arenaviruses Tacaribe and Pichinde, mainly affecting late events of arenavirus multiplication cycle by preventing viral morphogenesis and egress from infected cells.     

Virucidal activity of polysaccharide extracts from four algal species against herpes simplex virus

Herpes simplex virus types 1 and 2 (HSV-1, HSV-2) infections are common, but can cause serious infections in neonates and the immunocompromised. Drugs currently used to treat cutaneous or genital HSV infections are effective in limiting disease, but the emergence of drug resistant viruses in immunocompromised individuals can be problematic. While the prophylactic oral treatment with antiviral drugs can reduce virus shedding and transmission, there is a need for topical microbicides that have the potential to limit sexual transmission of the virus. Previous reports demonstrated the antiviral activity of complex sulfated polysaccharides extracted from various species of marine algae and suggested that they interfered with the attachment of virions to host cells. Here, we evaluated the antiviral activity of extracts from Undaria pinnatifida, Splachnidium rugosum, Gigartina atropurpurea, and Plocamium cartilagineum against HSV-1 and HSV-2. These extracts exhibited good activity when added during the first hour of viral infection, but were ineffective if added later. Plaque reduction assays, when the extracts were added prior to viral inoculation, yielded EC₅₀ values that ranged from 2.5–3.6 μg/ml for HSV-1 and 0.7–6.6 μg/ml for HSV-2. None of the extracts exhibited significant toxicity in a neutral red uptake assay (IC₅₀ >100 μg/ml). Subsequent assays showed that the compounds had potent virucidal activity and were active at very low concentrations. We conclude that these extracts are nontoxic and effective virucidal agents that warrant further investigation to examine their potential role in the prevention of HSV infections of humans.     

小檗碱衍生物HB-13抗单纯疱疹病毒-2作用机制的研究

目的 探讨小檗碱衍生物HB-13抗单纯疱疹病毒-2(HSV-2)的作用机制.方法 采用细胞病变法检测HB-13是否对HSV-2有直接作用;空斑法检测HB-13是否抑制HSV-2的吸附和释放;荧光定量PCR检测HB-13是否影响HSV-2 DNA复制以及蛋白免疫印迹方法 检测HB-13是否影响HSV-2蛋白质合成.结果 HB-13在细胞外无直接杀灭HSV-2作用;对HSV-2的吸附和释放亦无影响;不抑制HSV-2 DNA复制;但HB-13浓度依赖性地抑制HSV-2蛋白质合成.结论 HB-13可抑制HSV-2蛋白质合成,其抗HSV-2作用机制与ACV等核苷类药物不同.     

Antiviral mode of action of a synthetic brassinosteroid against Junin virus replication

The antiviral mode of action of the synthetic brassinosteroid (22S,23S)-3beta-bromo-5alpha,22,23-trihydroxystigmastan-6-one (6b) against Junin virus replication in Vero cells was investigated. Time-related experiments showed that 6b mainly affects an early event of virus growth cycle. Neither adsorption nor internalization of viral particles was the target of the inhibitory action. The analysis of the effect of 6b on viral RNA synthesis demonstrated that the presence of the compound adversely affects virus RNA replication by preventing the synthesis of full length antigenomic RNA. Although 6b was most effective the earlier it was added to the cells after infection with JV, a high level of inhibition of JV yield and fusion activity of newly synthesized viral glycoproteins was still detected when the compound was present during the last hours of infection. Therefore, we cannot rule out an inhibitory action of 6b on later events of JV replicative cycle.     

Antiviral properties of isoborneol, a potent inhibitor of herpes simplex virus type 1.

Isoborneol, a monoterpene and a component of several plant essential oils, showed dual viricidal activity against herpes simplex virus 1 (HSV-1). First, it inactivated HSV-1 by almost 4 log10 values within 30 min of exposure, and second, isoborneol at a concentration of 0.06% completely inhibited viral replication, without affecting viral adsorption. Isoborneol did not exhibit significant cytotoxicity at concentrations ranging between 0.016% and 0.08% when tested against human and monkey cell lines. Isoborneol specifically inhibited glycosylation of viral polypeptides based on the following data: (1) the mature fully glycosylated forms of two viral glycoproteins gB and gD were not detected when the virus was replicated in the presence of isoborneol, (2) no major changes were observed in the glycosylation pattern of cellular polypeptides between untreated and isoborneol treated Vero cells, (3) isoborneol did not affect the glycosylation of gB produced from a copy of the gB gene resident in the cellular genome, and (4) other monoterpenes such as 1,8-cineole and borneol, a stereoisomer of isoborneol, did not inhibit HSV-1 glycosylation.     

Mechanism of the protective effect of heteropolyoxotungstate against herpes simplex virus type 2

The effects of heteropolyoxotungstate (K(7)[PTi(2)W(10)O(40)]. 6H(2)O; PM-19) on the replication of herpes simplex virus type 2 (HSV-2) were examined using a semiquantitative polymerase chain reaction of intracellular viral DNA established by us and also other methods. Vero cells were infected with HSV-2 strains: either the standard strain 169, or the acyclovir-resistant strain YS-4C-1. PM-19 was added at various stages during the replication of HSV-2. PM-19 strongly inhibited the synthesis of viral genomic DNA when it was added at the time of infection. The addition of PM-19 60-90 min after viral inoculation time-dependently decreased the antiviral activity and increased the relative yield of viral DNA, and the addition of PM-19 was completely ineffective at times later than 90 min. These results suggested that PM-19 inhibited viral penetration but did not affect the synthesis of viral DNA. Furthermore, PM-19 strongly inhibited a second round of infection.     

Antiviral effects of synthetic membrane-active peptides on herpes simplex virus, type 1

Magainins are cationic peptides with antimicrobial activity which were originally isolated from the skin of the African clawed frog (Xenopus laevis). Several synthetic derivatives of this class of peptides were evaluated for antiviral activity against herpes simplex virus, type 1 (HSV). Some of the peptides (MSI-102, -248, -420, -499/500 combination, -591, -594, and -1251) showed significant reduction of HSV plaque-forming units. The antiviral effect was enhanced when HSV was pretreated with the peptides prior to inoculation onto Vero monolayers, suggesting a direct effect on the virion. Most of the peptides with anti-HSV activity were lysine-rich, and the addition of octanoyl groups to the peptides appeared to enhance the antiviral effect.     

Antiviral effect of mangiferin and isomangiferin on herpes simplex virus

Using tissue culture techniques the present study assured us of the merits of mangiferin and isomangiferin in the antiviral action against HSV-1. Utilizing 4 main patterns for evaluating drug effectiveness (ie intratube drug-on-virus direct action, simultaneous addition of drug-virus-inoculum to cell bottle, virus inoculation preceding drug addition, and drug addition followed by virus inoculation), it was readily found by logarithm determination of HSV-I inhibition that isomangiferin was superior to such control drugs as acyclovir, idoxuridine, and cyclocytidine in logarithm by 0.27-0.50, and that mangiferin was lower than isomangiferin in logarithm by 0.53. The average plaque reduction rates of mangiferin and isomangiferin were 69.5% and 56.8%, respectively. All in all, the antiviral effect of mangiferin and isomangiferin was attributed presumably to their capability to inhibit virus replication within cells.     

Antiviral activity of arbidol hydrochloride against herpes simplex virus I in vitro and in vivo

Herpes simplex virus type 1 (HSV-1) causes significant human diseases ranging from skin lesions to encephalitis, especially in neonates and immunocompromised hosts. The discovery of novel anti-HSV-1 drugs with low toxicity is required for public health. Arbidol hydrochloride (ARB) is an indole derivative molecule with broad-spectrum antiviral activity. In this study, the antiviral effects of ARB against HSV-1 infection were evaluated in vitro and in vivo. The results showed that ARB presents significant inhibitory effect on HSV-1 plaque formation and generation of progeny virus, with EC50 values (50% effective concentration) of 5.39?µg/mL (10.49?µM) and 2.26?µg/mL (4.40?µM), respectively. Moreover, time-of-addition and time-of-removal assays further suggested that ARB has viral inhibitory effects when added up to 12?h post-infection (p.i.), which could be further corroborated by determining the expression of viral immediate-early (ICP4, ICP22 and ICP27), early (ICP8 and UL42) and late (gB, gD, gH, VP1/2 and VP16) genes by real-time quantitative PCR as well as the expression of viral protein ICP4 and ICP8 at 6?h and 12?h p.i. Results of the in vivo study showed that ARB could reduce guinea pig skin lesions caused by HSV-1 infection. Conclusively, this report offers new perspectives in the search for therapeutic measures in the treatment of HSV-1 infection.     

Antiviral activity of an extract of Cordia salicifolia on herpes simplex virus type 1

A partially purified extract (COL 1-6) from whole plant of Cordia salicifolia showed an inhibitory effect on herpes simplex virus type 1 (HSV-1). The activity of COL 1-6 on different steps of HSV-1 replication in HeLa cells was investigated. Under single-cycle replication conditions, COL 1-6 exerted a greater than 99.9% inhibition in virus yield when added to the cells 3 h or 1.5 h before infection, and even when added 8 h after infection the extract still caused a greater than 99% inhibition. The extract has been shown to have a direct virucidal activity. And also, analysis of early events following infection showed that COL 1-6 affected viral penetration in HeLa cells but did not interfere with adsorption to the cells.     

Antiviral effect of aqueous extracts from species of the Lamiaceae family against Herpes simplex virus type 1 and type 2 in vitro

Aqueous extracts from species of the Lamiaceae family were examined for their antiviral activity against Herpes simplex virus (HSV). Extracts from lemon balm (Melissa officinalis), peppermint (Mentha x piperita), prunella (Prunella vulgaris), rosemary (Rosmarinus officinalis), sage (Salvia officinalis) and thyme (Thymus vulgaris) were screened. Their inhibitory activity against Herpes simplex virus type 1 (HSV-1), type 2 (HSV-2) and an acyclovir-resistant strain of HSV-1 (ACV (res)) was tested in vitro on RC-37 cells in a plaque reduction assay. The 50% inhibitory concentrations (IC (50)) of the extracts for HSV plaque formation were determined in dose-response studies. All test compounds showed a high antiviral activity against HSV-1, HSV-2 and ACV (res). In order to identify the mode of antiviral action, the extracts were added to the cells or viruses at different stages of infection. Both types of Herpes virus including ACV (res) were considerably neutralized after treatment with the extracts prior to infection. At maximum non-cytotoxic concentrations of the extracts, plaque formation was significantly reduced by > 90% for HSV-1 and HSV-2 and > 85% for ACV (res). In time-response studies over a period of 2 hours, a clearly time-dependent activity was demonstrated. These results indicate that the extracts affect HSV before adsorption, but have no effect on the intracellular virus replication. Therefore, the extracts exert their antiviral effect on free HSV and offer a chance to use them for topical therapeutic application against recurrent HERPES infections.     

Stage of action of naturally occurring andrographolides and their semisynthetic analogues against herpes simplex virus type 1 in vitro

Andrographolide, an ENT-labdane diterpene, has been found to have activities against many viruses. Three free hydroxyls at C-3, C-14, and C-19 are involved in the activities. No stage of action has ever been explored. In this study, the naturally occurring compounds of andrographolide, 14-deoxy-11,12-didehydroandrographolide and 14-deoxyandrographolide, and eight semisynthetic analogues, modified at the three free OHs of andrographolide, were explored for their anti-HSV-1 activities. The concentrations that produced 80?% viable cells were used to test for both pre- and postinfections by using cytopathic effect reduction assays on Vero cell cultures. Three analogues, 14-acetyl-3,19-isopropylideneandrographolide, 14-acetylandrographolide, and 3,14,19-triacetylandrographolide, significantly exhibited preinfection step activity against the virus. For postinfection activity, only 3,19-isopropylideneandrographolide showed absolute inhibition of HSV-1 replication. Meanwhile, andrographolide exhibited slight inhibitory activities of 34.48?±?6.93?% and 56.90?±?2.65?% against HSV-1 for pre- and postinfection, respectively. The results confirm that the three hydroxyl moieties play a role in the anti-HSV-1 activity of andrographolide. From the study, it can be concluded that 14-acetyl analogues are good for blocking the viral entry, and 3,19-isopropylideneandrographolide, a cyclic dioxane analogue, is good for exerting postinfection anti-HSV-1 activity.     

Mechanism and mode of action of 5-iodo-2-pyrimidinone 2'-deoxyribonucleoside, a potent anti-herpes simplex virus compound, in herpes simplex virus-infected cells.

The anti-herpes simplex virus type 2 (-HSV-2) action of 5-iodo-2-pyrimidinone deoxyribonucleoside (IPdR) was found to be exerted through inhibition of HSV DNA synthesis. The inhibition of viral DNA synthesis was not caused by inhibition of the synthesis of HSV-2-specified proteins or HSV-2 mRNA species involved with viral DNA synthesis or by depletion of deoxynucleotides. The inhibition of viral DNA synthesis may be due to damage to the DNA template in the nuclei or to an action at the DNA replication complex, because nuclei isolated from HSV-2-infected cells treated with IPdR could not support DNA synthesis in vitro. Moreover, the addition of exogenous template to the reaction enabled nuclear DNA synthesis to occur at the level of control. The major cellular metabolite of IPdR in HeLa S3 cells infected with HSV-2 was IPdR monophosphate, which was formed through virally specified kinase. Attempts to either identify or synthesize IPdR diphosphate and triphosphate were unsuccessful. The accumulation of IPdR monophosphate was dependent on the extracellular concentration of IPdR. IPdR monophosphate did not have any inhibitory effect on nuclear DNA synthesis, even at 200 microM. Thus, the action of IPdR could be due to an unidentified metabolite of IPdR or the depletion of a cellular metabolite that is essential for viral DNA synthesis.