Neutral sphingomyelinase-inhibiting guanidines prevent herpes simplex virus-1 replication

We synthesized a series of new guanidinium derivatives and studied the inhibitory activity on both neutral sphingomyelinase and herpes simplex virus-1 (HSV-1) replication. The lipophilic quality of the molecules was found to be correlated with the inhibitory potential of the compounds. Undecylidene-aminoguanidine was superior to derivatives with 10, 8 or 6 carbon atoms whereas propylidene-aminoguanidine was completely inactive. Decylidene-aminoguanidine was the most active derivative, with 10 carbon atoms. Various cyclic saturated isomers were inferior to the linear molecule. Aromatic cyclic residues were superior to saturated cyclic residues. The most active compound was a derivative containing 11 carbon atoms, undecylidene-aminoguanidine (C11AG), which inhibited the replication of HSV-1 by 50% at a concentration of 2.6 microM while cytotoxic adverse effects were only observed at a concentration of 31 microM. Expression of immediate early gene ICP-4 and concomitantly of HSV-1 specific DNA replication was found to be a target of C11AG. This result suggests that C11AG interferes with cellular signal transduction mechanisms that regulate expression of HSV-1 immediate early genes. C11AG was shown to inhibit neutral sphingomyelinase without affecting phospholipase A2, phosphatidylcholine-specific phospholipase C and phospholipase D.     

Phenoxazine derivatives inactivate human cytomegalovirus, herpes simplex virus-1, and herpes simplex virus-2 in vitro.

We examined whether phenoxazine derivatives, 2-amino-4,4alpha-dihydro-4alpha-7-dimethyl-3H-phenoxazine-3-one (Phx-1), 3-amino-1,4alpha-dihydro-4alpha-8-dimethyl-2H-phenoxazine-2-one (Phx-2), and 2-amino-phenoxazine-3-one (Phx-3) may have antiviral activity against herpes family viruses: human cytomegalovirus (HCMV), herpes simplex virus type 1 (HSV-1), and herpes simplex virus type 2 (HSV-2). The antiviral activity was evaluated by the selectivity index (SI), which is the ratio of 50% cytotoxic concentration (CC(50)) and 50% antiviral concentration (IC(50)). Among these phenoxazines, Phx-2 exerted strong antiviral activity to HCMV with the SI of 200, while Phx-1 and Phx-3 exerted no marked anti-HCMV activity. Phx-2 also showed moderate inhibition of HSV-1 and HSV-2, with the SI of 6.7 and 17, respectively. In the time-of-addition experiments, inhibitory effect of Phx-2 against HCMV was active even when applied to cells at 100 h after HCMV infection, while ganciclovir (GCV) showed potent inhibition when applied to cells before 42-h post-infection, but its inhibitory effects disappeared thereafter. Attachment and penetration of HCMV was not affected by the presence of Phx-2. When HCMV was pretreated with Phx-2, concentration-dependent virucidal action was observed, suggesting that Phx-2 inactivates HCMV directly. From these data, it was found that Phx-2 might have a different anti-HCMV target from GCV.     

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 therapy of herpes simplex

Herpes simplex virus (HSV) infections in immunocompromised patients are more severe and invasive than in non-immunocompromised patients. They are characterised by prolonged viral shedding and a tendency to heal more slowly. In addition, resistant viruses are exclusively isolated in immunocompromised patients, requiring other drugs with distinct mechanisms of action. The reference compound for the treatment of HSV infections is acyclovir (ACV) that selectively inhibits HSV DNA replication with low host-cell toxicity. Recently, two molecules, valaciclovir (VACV), the L-valyl ester of ACV and famciclovir (FCV), the diacetyl ester of 6-deoxy-penciclovir (PCV), another potent nucleoside analogue, were developed showing an increased oral bioavailability compared to the original compounds. Foscavir (PFA) and more recently cidofovir (CDV) are drugs that do not need the viral thymidine kinase (TK) to be activated and therefore are the appropriate candidates for the treatment of resistant viruses emerging under acyclovir or penciclovir.     

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.     

Resveratrol inhibition of herpes simplex virus replication.

Resveratrol, a phytoalexin, was found to inhibit herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) replication in a dose-dependent, reversible manner. The observed reduction in virus yield was not caused by the direct inactivation of HSV by resveratrol nor inhibition of virus attachment to the cell. The chemical did, however, target an early event in the virus replication cycle since it was most effective when added within 1 h of cell infection, less effective if addition was delayed until 6 h post-infection and not effective if added 9 h post-infection. Resveratrol was also found to delay the cell cycle at S-G2-M interphase, inhibit reactivation of virus from latently-infected neurons and reduce the amount of ICP-4, a major immediate early viral regulatory protein, that is produced when compared to controls. These results suggest that a critical early event in the viral replication cycle, that has a compensatory cellular counterpart, is being adversely affected.     

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 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.     

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 effect of the extract of culture medium of Lentinus edodes mycelia on the replication of herpes simplex virus type 1

An extract of culture medium of Lentinus edodes mycelia, JLS-S001, significantly blocked the release of infectious herpes simplex virus type 1 (HSV-1) from African green monkey kidney cells. The block in replication was not due to the effect of JLS-S001 on the adsorption and penetration of HSV-1 to the monkey kidney cells. This observation was supported by the fact that JLS-S001 had no significant effect on the expression of virus-specific nucleocapsid proteins in the treated cells. Furthermore, electron microscopy demonstrated the presence of nucleocapsids within the nuclei of the infected and JLS-S001-treated cells. However, the expression of glycoproteins B, C, D, E and I was reduced in the JLS-S001-treated cells. These results suggested that JLS-S001 blocked HSV-1 replication at a late stage in virus replication cycle probably in the assembly and budding of nucleocapsids and subsequent egress from the treated cells.     

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.     

Evaluation of some pyrazoloquinolines as inhibitors of herpes simplex virus type 1 replication

Three structurally related aminopyrazoloquinoline derivatives were evaluated for their antiviral activity against Herpes Simplex virus type 1. These compounds were examined for their in vitro antiviral activity by two different bioassays, namely; crystal violet staining and tetrazolium dye (MTS) measurement. The antiviral role of these compounds was confirmed by enumerating the infectious particles with plaque assay. The acute toxicity values of the biologically active compounds were determined prior to their screening as antiviral agents.     

Antiviral effects of recombinant human tumor necrosis factor-alpha in combination with natural interferon-beta in mice infected with herpes simplex virus type 1.

The protective effects of combination therapy utilizing recombinant human TNF-alpha (rTNF-alpha) and natural murine interferon-beta (IFN-beta) in mice infected with herpes simplex virus type 1 (HSV-1) was investigated. Mice treated with rTNF-alpha alone at all of the doses tested (a single i.v. administration, 2.3-2,300 micrograms/kg; multiple i.p. administrations 0.4-250 micrograms/kg) as well as mice that received IFN-beta alone at doses of 16 x 10(4) U/kg or less resulted in a 0% survival rate. Combination therapy consisting of a single administration of rTNF-alpha (230 and 23 micrograms/kg) and multiple administrations of IFN-beta (4 x 10(4) U/kg) resulted in a 40% and 60% survival rate. Multiple treatments of infected mice with rTNF-alpha (50 and 10 micrograms/kg) in combination with IFN-beta (4 x 10(4) U/kg) resulted in 50% and 70% survival rates, respectively. These results suggest that the combination therapy of rTNF and natural murine IFN-beta produce synergistic protective effects in mice infected with a lethal amount of HSV-1.     

Inhibition of herpes simplex virus replication by anthracycline compounds

The replication of type 1 and type 2 strains of herpes simplex virus (HSV) was inhibited greater than 99.9% by low concentrations (0.1-0.2 microM) of anthracycline compounds. The degree of viral inhibition was dependent upon the host cell. N,N-dimethyl daunomycin (NDMD), a non-mutagenic compound, was more potent as an inhibitor of HSV synthesis than either daunomycin (DM) or adriamycin (AD). The depression of viral yield by DM or AD was attributable, in part, to a temperature-dependent direct effect on infectious virions. Tritium-labeled DM bound tightly to HSV particles. NDMD did not directly inactivate virions in spite of superior potency in reducing viral yields. All three anthracyclines could be added late in the infectious cycle (6-8 h p.i.) and retain effectiveness. Cesium chloride density gradient analysis verified that viral DNA synthesis was blocked by addition of all three anthracyclines early in the infectious cycle. The inhibition of HSV replication was not a simple consequence of the suppression of host DNA synthesis since treatment of cells with compounds for 24 h before infection did not reduce virus yields even though host DNA synthesis was inhibited by 90%. Further, the kinetics of inhibition of cellular DNA synthesis by anthracyclines was similar in HFF or Vero cells but the degree of inhibition of virus replication was markedly different. The data suggest that anthracyclines with substitutions on the sugar moiety may be useful anti-herpes agents.     

Inhibition of herpes simplex virus DNA replication by ara-tubercidin

Preliminary studies of the biochemical basis for the antiviral activity of the pyrrolo[2,3-d]pyrimidine nucleoside ara-tubercidin were conducted. Herpes simplex virus DNA synthesis was 3-fold more sensitive to inhibition by ara-tubercidin than was cellular DNA synthesis. Partially purified herpes DNA polymerases were more sensitive to inhibition by ara-tubercidin 5'-triphosphate than were cellular polymerases alpha and beta. Inhibition of viral DNA polymerase was competitive with dATP and noncompetitive with dTTP. The results suggest that the viral DNA polymerase plays a significant role in the antiviral activity of ara-tubercidin.     

Clinical and therapeutic issues for herpes simplex virus-2 and HIV co-infection

A synergy between HIV type-1 (HIV-1) and herpes simplex virus-2 (HSV-2) has been demonstrated in many epidemiological and clinical studies over the last decade. HIV-1 infection exacerbates the clinical impact and frequency of HSV-2 reactivation events; furthermore, HSV-2 infection exacerbates the risk of HIV acquisition and transmission and may accentuate HIV disease progression. In order to maximise the impact of existing and future therapeutic and preventive interventions, this article reviews the epidemiological, clinical and therapeutic considerations associated with episodic treatment and suppression of HSV-2 infection in HIV-infected individuals.Specifically, this article describes the current expanding epidemics of both HIV and HSV-2, and how high rates of asymptomatic herpes virus shedding contribute to the under-diagnosis and continued spread of both HSV-2 and HIV. Furthermore, multiple clinical trials have studied the efficacy and clinical utility of aciclovir and other nucleoside analogues for treating and suppressing HSV-2. We review these studies and summarise the guidelines for these regimens, particularly noting the accumulated experience documenting the utility of herpes treatment and suppression in altering the natural history of symptoms and documenting the low rate of HSV-2 drug resistance to nucleoside analogues observed after more that a decade of use. Finally, there are now also growing data describing the benefits of herpes suppression in the context of individuals co-infected with HIV/HSV-2, with additional clinical trials poised to further elucidate these issues in the near future.     

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.     

Behavioral effects of neonatal herpes simplex type 1 infection of mice

Neonatal infection with a mutant herpes simplex type 1 virus produced hyperactivity in mice. Activity was measured throughout a 24 hour period during adulthood, and the elevation of activity occurred during the period of the day when mice are normally inactive. In a second experiment, infected mice showed deficits in learning to inhibit behavior in a passive avoidance task, but no deficit in learning a complex spatial task. Virus was detected in the brain by 5 days of age. The peak percentage of mice infected was reached at 10 days of age and declined thereafter. Mortality due to the virus declined with age at which the mouse was infected, but rates of hyperactivity were not different when injection occurred within the first 4 days of life. The viral infection produced no deficit in body weight in suckling mice. Thus we have shown that a mild neonatal virus infection can produce specific behavioral deficits.     

Inhibition of herpes simplex virus replication by Flos verbasci infusion

The preliminary phytochemical investigations have revealed the presence of flavonoids, iridoids, phenolic acids, saponins, amino acids, free sugars, and mucilages in the lyophilized infusion obtained from flowers of Verbascum thapsiforme Schrad. (FVI). Antiviral activity of the FVI on Herpes simplex type 1 virus (HSV-1) was studied in vitro by the yield reduction test. Decrease in the virus titer amounted to about 2.5 log at the non-toxic concentrations of FVI. The inhibitory effect of FVI on HSV studied by plaque reduction test in Vero cells showed that 50% inhibition of virus plaques occurred at 190 micrograms/ml. The virucidal effect of FVI on HSV was also shown.