Synergistic topical therapy by acyclovir and A1110U for herpes simplex virus induced zosteriform rash in mice

Effective Prophylactic Therapy for Exposure to Monkey B Virus (Macacine alphaherpesvirus 1)

Zoonotic monkey B virus (Macacine alphaherpesvirus 1; BV) infections are extremely serious and usually fatal. Drugs currently used for treatment were developed for the treatment of herpes simplex virus but are less effective against BV. Effective suppression of viral replication in the skin could prevent the virus from invading the nervous system. To test this hypothesis, the efficacy of topical administration of several drugs against lethal BV infection was evaluated in female BALB/c mice that were infected by scarification. Drugs were then applied to the site of inoculation. As 3% preparations, most drugs were only minimally effective or ineffective. In contrast, ganciclovir and cidofovir were very effective. The ED₅₀ for cidofovir was 0.007%, compared with 1.1% for ganciclovir. At 0.5%, cidofovir protected against both death and neurologic signs, whereas 5% ganciclovir only protected against death but not neurologic involvement. All genotypes of BV were equally susceptible to cidofovir and ganciclovir. For maximal effectiveness, treatment with both cidofovir and ganciclovir had to be initiated within 8 h of infection. Cidofovir was completely protective when administered only on the day of infection, whereas a minimum of 5 d of treatment was required for maximal ganciclovir efficacy. These studies showed that topical cidofovir treatment started soon after BV exposure was very effective in preventing BV from invading the nervous system, whereas ganciclovir treatment was only partially effective. In addition, cidofovir was protective against a ganciclovir-resistant BV mutant, whereas ganciclovir was not. These studies showed that topical cidofovir treatment started soon after BV exposure is more effective than ganciclovir in preventing BV from invading the CNS.

Activity of Penciclovir in Combination with Azido-Thymidine, Ganciclovir, Acyclovir, Foscarnet and Human Interferons against Herpes Simplex Virus Replication in Cell Culture

Combinations of penciclovir (PCV) with other antiviral agents (acyclovir, ACV; ganciclovir, GCV; foscarnet, PFA; azido-thymidine, AZT) or with human interferons (HulFN-α,β,γ) were tested for inhibitory activity against herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) in cell culture. The antiviral interactions observed between combinations of PCV with ACV or GCV were purely additive. Combinations of PCV with HulFNs demonstrated highly synergistic anti-herpesvirus activity; some synergy was also detected between PCV and PFA against HSV-1. High concentrations of AZT inhibited the antiviral activity of PCV; this antagonism was competitive. In more detailed studies it was demonstrated that high concentrations of AZT also inhibited the antiviral activity of ACV, and that ACV was more sensitive to this antagonism than PCV. It was concluded that the antagonism was unlikely to have clinical significance.

Herpes murine model as a biological assay to test dialyzable leukocyte extracts activity

Human dialyzable leukocyte extracts (DLEs) are heterogeneous mixtures of low-molecular-weight peptides that are released on disruption of peripheral blood leukocytes from healthy donors. DLEs improve clinical responses in infections, allergies, cancer, and immunodeficiencies. Transferon is a human DLE that has been registered as a hemoderivate by Mexican health authorities and commercialized nationally. To develop an animal model that could be used routinely as a quality control assay for Transferon, we standardized and validated a murine model of cutaneous HSV-1 infection. Using this model, we evaluated the activity of 27 Transferon batches. All batches improved the survival of HSV-1-infected mice, wherein average survival rose from 20.9% in control mice to 59.6% in Transferon-treated mice. The activity of Transferon correlated with increased serum levels of IFN-γ and reduced IL-6 and TNF-α concentrations. Our results demonstrate that (i) this mouse model of cutaneous herpes can be used to examine the activity of DLEs, such as Transferon; (ii) the assay can be used as a routine test for batch release; (iii) Transferon is produced with high homogeneity between batches; (iv) Transferon does not have direct virucidal, cytoprotective, or antireplicative effects; and (v) the protective effect of Transferon in vivo correlates with changes in serum cytokines.

Ribonucleotide reductase inhibitors hydroxyurea, didox, and trimidox inhibit human cytomegalovirus replication in vitro and synergize with ganciclovir

Ganciclovir (GCV) is a deoxyguanosine analog that is effective in inhibiting human cytomegalovirus (HCMV) replication. In infected cells GCV is converted to GCV-triphosphate which competes with dGTP for incorporation into the growing DNA strand by the viral DNA polymerase. Incorporated GCV promotes chain termination as it is an inefficient substrate for elongation. Because viral DNA synthesis also relies on cellular ribonucleotide reductase (RR) to synthesize deoxynucleotides, RR inhibitors are predicted to inhibit HCMV replication. Moreover, as dGTP competes with GCV-triphosphate for incorporation, RR inhibitors may also synergize with GCV by reducing intracellular dGTP levels and there by promoting increased GCV-triphosphate utilization by DNA polymerase. To investigate potential of RR inhibitors as anti-HCMV agents both alone and in combination with GCV, HCMV-inhibitory activities of three RR inhibitors, hydroxyurea, didox, and trimidox, were determined. In both spread inhibition and yield reduction assays RR inhibitors had modest anti-HCMV activity with 50% inhibitory concentrations ranging from 36±1.7 to 221±52μM. However, all three showed significant synergy with GCV at concentrations below their 50% inhibitory and 50% toxic concentrations. These results suggest that combining GCV with relatively low doses of RR inhibitors could significantly potentiate the anti-HCMV activity of GCV in vivo and could improve clinical response to therapy.

In vitro and in vivo evaluations of sodium lauryl sulfate and dextran sulfate as microbicides against herpes simplex and human immunodeficiency viruses

The efficacy of sodium lauryl sulfate (SLS), a sulfated anionic chaotropic surfactant, and dextran sulfate (DS), a polysulfated carbohydrate, against herpes simplex virus (HSV) and human immunodeficiency virus (HIV) infections was evaluated in cultured cells and in different murine models of HSV infection. Results showed that both SLS and DS were potent inhibitors of the infectivities of various HSV-1 and HSV-2 strains. Pretreatment of HIV-1 (strain NL4-3) with SLS also reduced its infectivity to 1G5 cells. DS prevented the binding of HSV to cell surface receptors and therefore its entry into cells. Pretreatment of HSV-1 (strain F) with 50 microM SLS resulted in a complete loss of virus infectivity to Vero cells. However, viruses were able to enter into cells and to produce in the nuclei capsid shells devoid of a DNA core. The amount of the glycoprotein D gene produced in these cells remained unchanged compared to controls, suggesting that SLS could interfere with the maturation of the virus. At a higher SLS concentration (100 microM), HSV was highly damaged by SLS pretreatment and only a few viral particles could enter into cells to produce abnormal capsids. Although DS was a more potent inhibitor of HSV infectivity in vitro, it was unable to provide any protection in murine models of HSV infection. However, SLS conferred a complete protection of animals infected cutaneously with pretreated viruses. In addition, skin pretreatment of mice with a polymer formulation containing SLS completely prevented the development of cutaneous lesions. More interestingly, intravaginal pretreatment of mice with SLS in a buffered solution also completely protected against lethal HSV-2 infection. Taken together, our results suggest that SLS could thus represent a candidate of choice as a microbicide to prevent the sexual transmission of HIV, HSV, and possibly other pathogens that cause sexually transmitted diseases.

Efficacies of topical formulations of foscarnet and acyclovir and of 5-percent acyclovir ointment (Zovirax) in a murine model of cutaneous herpes simplex virus type 1 infection

The topical efficacies of foscarnet and acyclovir incorporated into a polyoxypropylene-polyoxyethylene polymer were evaluated and compared to that of 5% acyclovir ointment (Zovirax) by use of a murine model of cutaneous herpes simplex virus type 1 infection. All three treatments given three times daily for 4 days and initiated 24 h after infection prevented the development of the zosteriform rash in mice. The acyclovir formulation and the acyclovir ointment reduced the virus titers below detectable levels in skin samples from the majority of mice, whereas the foscarnet formulation has less of an antiviral effect. Reducing the number of treatments to a single application given 24 h postinfection resulted in a significantly higher efficacy of the formulation of acyclovir than of the acyclovir ointment. Acyclovir incorporated within the polymer was also significantly more effective than the acyclovir ointment when treatment was initiated on day 5 postinfection. The higher efficacy of the acyclovir formulation than of the acyclovir ointment is attributed to the semiviscous character of the polymer, which allows better penetration of the drug into the skin.

Antiviral activity of a selective ribonucleotide reductase inhibitor against acyclovir-resistant herpes simplex virus type 1 in vivo

The present study reports the activity of BILD 1633 SE against acyclovir (ACV)-resistant herpes simplex virus (HSV) infections in athymic nude (nu/nu) mice. BILD 1633 SE is a novel peptidomimetic inhibitor of HSV ribonucleotide reductase (RR). In vitro, it is more potent than ACV against several strains of wild-type as well as ACV-resistant HSV mutants. Its in vivo activity was tested against cutaneous viral infections in athymic nude mice infected with the ACV-resistant isolates HSV type 1 (HSV-1) dlsptk and PAAr5, which contain mutations in the viral thymidine kinase gene and the polymerase gene, respectively. Following cutaneous infection of athymic nude mice, both HSV-1 dlsptk and PAAr5 induced significant, reproducible, and persistent cutaneous lesions that lasted for more than 2 weeks. A 10-day treatment regimen with ACV given topically four times a day as a 5% cream or orally at up to 5 mg/ml in drinking water was partially effective against HSV-1 PAAr5 infection with a reduction of the area under the concentration-time curve (AUC) of 34 to 48%. The effects of ACV against HSV-1 dlsptk infection were not significant when it was administered topically and were only marginal when it was given in drinking water. Treatment under identical conditions with 5% topical BILD 1633 SE significantly reduced the cutaneous lesions caused by both HSV-1 dlsptk and PAAr5 infections. The effect of BILD 1633 SE against HSV-1 PAAr5 infections was more prominent and was inoculum and dose dependent, with AUC reductions of 96 and 67% against infections with 10(6) and 10(7) PFU per inoculation site, respectively. BILD 1633 SE also significantly decreased the lesions caused by HSV-1 dlsptk infection (28 to 51% AUC reduction). Combination therapy with topical BILD 1633 SE (5%) and ACV in drinking water (5 mg/ml) produced an antiviral effect against HSV-1 dlsptk and PAAr5 infections that was more than the sum of the effects of both drugs. This is the first report that a selective HSV RR subunit association inhibitor can be effective against ACV-resistant HSV infections in vivo.

The effects of interferon-alpha and acyclovir on herpes simplex virus type-1 ribonucleotide reductase

Herpes simplex virus-type 1 (HSV-1) encodes both the small (UL40) and large (UL39) subunits of the enzyme, ribonucleotide reductase. Treatment of HSV-1-infected cells with interferon-alpha (IFN-alpha) reduced the levels of both enzyme subunits. Reduced steady state levels of the large subunit were demonstrated by immunoblot using polyclonal antibody specific for the viral enzyme. Reduction in the amount of small subunit was shown by a reduction in the electron spin resonance signal derived from the iron-containing tyrosyl free-radical present in this subunit. Treatment of cells with 100 IU/ml of IFN-alpha decreased levels of both subunits resulting in a reduction in enzyme activity as measured by conversion of CDP to dCDP. The decrease in the amount of the large subunit was not due to a reduction in the level of its mRNA. The combination of IFN-alpha and ACV treatment of human cornea stromal cells did not result in a further reduction in amounts of ribonucleotide reductase relative to that detected with IFN-alpha alone. The IFN-alpha-induced reduction in ribonucleotide reductase activity is the likely cause of decreased levels of dGTP which we have previously demonstrated in IFN-alpha-treated, infected cells.

Efficacy of traditional herbal medicines in combination with acyclovir against herpes simplex virus type 1 infection in vitro and in vivo

Traditional herbal medicines have been safely used for the treatment of various human diseases since ancient China. We selected 10 herbal extracts with therapeutic antiherpes simplex virus type 1 (HSV-1) activity. Among these, Geum japonicum Thunb., Rhus javanica L., Syzygium aromaticum (L.) Merr. et Perry, or Terminalia chebula Retzus showed a stronger anti-HSV-1 activity in combination with acyclovir than the other herbal extracts in vitro. When acyclovir and/or a herbal extract were orally administered at doses corresponding to human use, each of the 4 combinations significantly limited the development of skin lesions and/or prolonged the mean survival times of infected mice compared with both acyclovir and the herbal extract alone (P < 0.01 or 0.05). These combinations were not toxic to mice. They reduced virus yields in the brain and skin more strongly than acyclovir alone and exhibited stronger anti-HSV-1 activity in the brain than in the skin, in contrast to acyclovir treatment by itself. Combinations of acyclovir with historically used herbal medicines showed strong combined therapeutic anti-HSV-1 activity in mice, especially reduction of virus yield in the brain.

Solar simulator-induced herpes simplex labialis: use in evaluating treatment with acyclovir plus 348U87

Models of UV radiation induced herpes labialis utilizing crude light sources have previously been used to examine the efficacy of antivirals. We sought to improve upon this model by using a solar simulator. Initial studies revealed that 13 of 34 (38%) subjects with a history of recurrent HSV labialis receiving three minimal erythema doses (MED's) of UV light developed herpes labialis. We next evaluated the effects of combined therapy with topical ACV and 348U87, a ribonucleotide reductase inhibitor, begun immediately after UV exposure for the prevention and treatment of herpes labialis. No significant reduction in the incidence or severity of herpes labialis was detected although the study was terminated after the interim analysis revealed no benefit, thus reducing the power to detect a difference. This lack of effect may be explained by the general poor efficacy of topical treatment for recurrent HSV infection. Further studies of ACV + 348U87 in vehicles that should increase the penetration and stability of the drugs are planned.

Gastrointestinal invasion by herpes simplex virus type 1 inoculated cutaneously into the immunosuppressed mice

The pathogenesis of infection in mice with herpes simplex virus type 1 (HSV-1) strain 7401H was studied. Mice immunosuppressed by intraperitoneal injection of cyclophosphamide were inoculated cutaneously into the flank with the virus and developed severe zosteriform skin lesions. All of them died within 2 weeks after the infection, while most of the normal mice survived the viral infection with healing of the lesions. In the gastrointestinal tract of the immunosuppressed mice, macroscopic abnormalities were frequently observed, and infectious viruses were detected on days 7 to 9. The viruses were also detectable in the dorsal root ganglia and the spinal cord of thoracolumbar area on days 5 to 7, and in the celiac plexus on day 7. However, no viruses were detected in the blood. Immunohistological examination of the gastrointestinal tract revealed that the viral antigens were localized in Auerbach's myenteric plexus. These results suggest that HSV-1 inoculated into the flank skin invaded the gastrointestinal tract via the nervous system, which gastrointestinal involvement might possibly have caused the death of the mice.

Topical treatment of infection with acyclovir-resistant mucocutaneous herpes simplex virus with the ribonucleotide reductase inhibitor 348U87 in combination with acyclovir

The thiocarbonohydrazone 348U87 inactivates herpes simplex virus ribonucleotide reductase and potentiates the activity of acyclovir against wild-type and acyclovir-resistant strains of herpes simplex virus. We treated 10 human immunodeficiency virus-infected patients with acyclovir-resistant anogenital herpes simplex virus infection with a topical preparation of 348U87 (3%) in combination with acyclovir (5%) in an open-labelled study. Transient improvement with combination therapy occurred frequently; however, target lesions reepithelialized completely in only 1 of 10 patients. Termination of study drug therapy was most often due to cessation of therapeutic effect before complete resolution of lesions. As currently formulated, topical 348U87 offers little therapeutic benefit for this indication.

Potential for combined therapy with 348U87, a ribonucleotide reductase inhibitor, and acyclovir as treatment for acyclovir-resistant herpes simplex virus infection

Inhibitors of the ribonucleotide reductase of herpes simplex viruses (HSV) potentiate the activity of acyclovir in vitro and in animal studies. In addition, the combination of the ribonucleotide reductase inhibitor 348U87 and acyclovir has synergistic therapeutic effects against infections in mice due to thymidine kinase-deficient, thymidine kinase-altered, and DNA polymerase mutants of HSV. We performed a pilot study of topical combination therapy with 348U87 (3%) and acyclovir (5%) cream for acyclovir-resistant, anogenital HSV infections in ten human immunodeficiency virus (HIV)-infected patients. Our results, with lack of complete reepitheliazation of lesions in all patients and poor virologic response, suggest that this therapy is unlikely to be useful for this indication.

Binding of 2-acetylpyridine-5-[(2-chloroanilino)thiocarbonyl] thiocarbonohydrazone (BW348U87) to human serum albumin

Dissociation constants and rate constants for the binding of 2-acetylpyridine-5-[(2-chloroanilino)thiocarbonyl]thiocar bonohydrazone (I, BW348U87), an agent that enhances the antiherpetic efficacy of acyclovir, to human serum albumin have been determined. I quenched the fluorescence of human serum albumin, whereas the absorbance of I at 370 nm increased upon binding to the protein. The absorbance change was attributed to preferential binding of anionic I (pKa 7.0). Titration data indicated multiple binding sites for I. The dissociation constant of the high-affinity site was 0.11 microM. The time course for binding of I to 100 nM human serum albumin was biphasic. The early and late phases were described by first-order rate constants that had maximal values of 100 and 11 sec-1, respectively. The rate constant for the dissociation of I from human serum albumin was estimated to be 6 sec-1. Dodecyl sulfate and octanoate displaced I from human serum albumin.I with rate constants of 4.5 and 7.3 sec-1, respectively. Since the fluorescence emission spectrum of human serum albumin and the absorption spectrum of I overlapped significantly (the spectral overlap integral, J, was 2.6 x 10(-14) M-1 cm3), the possibility of Förster dipole-dipole energy transfer was considered. However, a significant fraction of the fluorescence quenching by I resulted from a conformational change in the protein upon binding of I and was not the result of dipole-dipole energy transfer. Nonetheless, the distance between one of the binding regions for I on human serum albumin and a tryptophan residue in the protein was estimated to be 31 A by this method. The high affinity of I for albumin could be related to its low hematological toxicity.

Inactivators of herpes simplex virus ribonucleotide reductase: hematological profiles and in vivo potentiation of the antiviral activity of acyclovir

A1110U (BW 1110U81) is an inactivator of herpesvirus ribonucleotide reductases and a potentiator of the antiviral activity of acyclovir (ACV) (T. Spector, J. A. Harrington, R. W. Morrison, Jr., C. U. Lambe, D. J. Nelson, D. R. Averett, K. Biron, and P. A. Furman, Proc. Natl. Acad. Sci. USA 86:1051-1055, 1989) that was subsequently found to cause hematological toxicity at high oral doses in rats. Eleven structurally related inactivators of herpes simplex virus (HSV) ribonucleotide reductase were therefore tested in vivo for hematological toxicity and for potentiation of ACV. None of the novel ribonucleotide reductase inactivators was hematologically toxic to rats following oral dosing at 60 mg/kg/day for 30 days. Four of these inactivators statistically improved the antiviral topical potency of ACV on HSV type 1-infected nude mice. A promising compound, 2-acetylpyridine 5-[(2-chloroanilino)thiocarbonyl]thiocarbonohydrazone (BW 348U87), was studied more extensively in two in vivo models: dorsum-infected athymic nude mice and snout-infected hairless mice. BW 348U87 significantly potentiated the antiviral activity of ACV against all virus strains tested, i.e., wild-type (ACV-sensitive) HSV type 1 and HSV type 2 strains and three mutant (ACV-resistant) HSV type 1 strains. The latter included a virus expressing a DNA polymerase resistant to inhibition by ACV triphosphate, a virus deficient in thymidine kinase (the enzyme responsible for phosphorylating ACV), and a virus expressing an altered thymidine kinase, which catalyzes the normal phosphorylation of thymidine but not of ACV. BW 348U87 and ACV are currently being developed as a combination topical therapy for cutaneous herpes infections.

Herpes and human ribonucleotide reductases. Inhibition by 2-acetylpyridine 5-[(2-chloroanilino)-thiocarbonyl]-thiocarbonohydrazone (348U87)

The mode of inactivation of herpes simplex virus type 1 and human ribonucleotide reductases by 2-acetylpyridine 5-[(2-chloroanilino)-thiocarbonyl]-thiocarbonohydrazone++ + (348U87) was determined and compared to that described previously [Porter et al. Biochem Pharmacol 39: 639-646, 1990] for 2-acetylpyridine 5-[(dimethylamino)thiocarbonyl]-thiocarbonohydrazone (A1110U). 348U87 inactivated herpes ribonucleotide reductase faster than did A1110U. Moreover, iron-complexed 348U87 was a considerably more potent inactivator than iron-complexed A1110U. It appeared to efficiently form an initial complex with the viral enzyme prior to rapid enzyme inactivation. The combination of 348U87 and iron-complexed 348U87 inactivated with a rate constant that was slightly greater than the sum of their individual rate constants of inactivation. The corresponding combination of A1110U species inactivated with a rate constant that was much greater than the sum of the individual rate constants of inactivation. Herpes ribonucleotide reductase that had been inactivated by either species of 348U87 was reactivated by diluting the enzyme and inactivators into assay medium containing excess iron. 348U87 was also an effective inactivator of herpes simplex virus type 2 and varicella zoster virus ribonucleotide reductases. The iron-complexed forms of 348U87 and A1110U exhibited very different modes of inactivation of human ribonucleotide reductase. Iron-complexed 348U87 was a tight-binding inactivator, whereas iron-complexed A1110U was only a weak, non-inactivating, inhibitor. Furthermore, the inactivation by iron-complexed 348U87 was not stimulated by either 348U87 or A1110U, whereas the weak inhibition by iron-complexed A1110U was converted to rapid inactivation by A1110U. Excess iron prevented the inactivation by iron-complexed 348U87. Uncomplexed 348U87 was similar to uncomplexed A1110U in that it was not an inhibitor of the human enzyme.