Clinical effects and in vitro studies of trifluorothymidine combined with interferon-alpha for treatment of drug-resistant and -sensitive herpes simplex virus infections.

Three AIDS patients with severe cutaneous herpes simplex virus (HSV) infection refractory to therapy with acyclovir and foscarnet (2 patients) were treated with a topical preparation of trifluorothymidine (TFT) and interferon-alpha. Complete healing of lesions occurred in 1 patient; a second had significant regression of the infected area. In the third, the lesion was stabilized twice after application of the preparation and reduced in size after a subsequent treatment. In vitro studies confirmed that isolates from these patients were acyclovir- or acyclovir/foscarnet-resistant. In addition, they revealed strong synergy between TFT and interferon-alpha for these isolates and for strains with wild-type drug sensitivity profiles. Topical TFT/interferon-alpha may be of benefit in the therapy of mucocutaneous HSV infections, especially when they are resistant to treatment with systemic antiviral agents.     

Recurrent genital herpes and suppressive oral acyclovir therapy. Relation between clinical outcome and in-vitro drug sensitivity

To evaluate the association between in-vitro resistance of herpes simplex virus type 2 to acyclovir and breakthrough recurrences of herpes despite chronic suppressive therapy, we determined the in-vitro sensitivity of herpes simplex virus isolated before, during, and after therapy. One hundred eighty-three virus isolates from 107 patients were tested. Before therapy, the median amount of drug required to inhibit 50% of the virus in tissue culture (ID50) was 0.91 microgram/mL. The median ID50 after therapy was 0.99. Six isolates from patients with culture-positive breakthrough recurrences were evaluated. The median ID50 was 0.90 microgram/mL (range, 0.39 to 1.55). The development of breakthrough recurrences could not be correlated with infection with strains of herpes simplex virus type 2 that were resistant to acyclovir in vitro. Acyclovir-resistant strains are not commonly recovered from patients during acyclovir therapy, nor does there seem to be a high frequency of resistance after 4 months of chronic suppressive therapy.     

Antimicrobial activity of a new intact skin antisepsis formulation

Different antiseptic formulations have shown limitations when applied to disinfecting intact skin, notably short-term tolerability and/or efficacy. The purpose of this study was optimizing a new antiseptic formulation specifically targeted at intact skin disinfection and evaluating its in vitro microbicidal activity and in vivo efficacy. METHODS: The biocidal properties of the antiseptic solution containing 0.5% chloramine-T diluted in 50% isopropyl alcohol (Cloral; Eurospital SpA Trieste, Italy) were measured in vitro versus gram-positive-, gram-negative-, and acid-alcohol-resistant germs and fungi with standard suspension tests in the presence of fetal bovine serum. Virus-inhibiting activity was evaluated in vitro against human cytomegalovirus, herpes simplex virus, poliovirus, hepatitis B virus, and hepatitis C virus. Tests used different methods for the different biologic and in vitro replication capacity of these human viruses. Lastly, Cloral tolerability and skin colonization retardation efficacy after disinfection were studied in vivo. RESULTS: The antiseptic under review showed fast and sustained antimicrobial activity. The efficacy of Cloral against clinically important bacterial and viral pathogens and fungi was highlighted under the experimental conditions described in this article. Finally, microbial regrowth lag and no side effects were documented in vivo after disinfection of 11 volunteers. CONCLUSIONS: A stable chloramine-T solution in isopropyl alcohol may be suggested for intact skin antisepsis.     

Evaluation of four antiviral agents in the treatment of herpes simplex encephalitis in a rat model.

Three hundred four animals were used for the systematic evaluation of the in vivo efficacy of 5-iodo-2'-deoxyuridine (IUDR), cytosire arabinoside, 9-beta-arabinofuranosyladenine, and isoprinosine in the therapy of herpes simplex encephalitis in an adult rat model. Type 1 herpes simplex virus was inoculated intracerabrally, and drug was administered by the intraperitoneal route. All experiments included tests for toxicity and viral controls, Eight sets of experiments were used for evaluation of ttherapy with IUDR; the inoculum ranged from 64 to 2,000 TCID50, dose of drug from 0.1 mg/g to 1.0 mg/g per day, and duration of therapy from one to five days. There was no significant improvement in the number of animals surviving or in the survival time when the viral controls were compared with mice in treated groups. A slight trend toward increased survival time and decreased titer of virus in the brains of animals treated with IUDR was noted in the group that received the largest dose. Three or four sets of experiments were used to evaluate each of the other three antiviral drugs. Results were similar to those reported for IUDR. These results indicate a need for further studies, including investigations of the pharmacology and toxicity of these antiviral agents, to establish more clearly the dosages of drug that are therapeutic, those that are toxic, and ratios of these dosages.     

Topical cidofovir is more effective than is parenteral therapy for treatment of progressive vaccinia in immunocompromised mice

BACKGROUND: Severe complications may arise as a result of virus dissemination after smallpox (live vaccinia virus) vaccination, particularly in immunocompromised individuals. We developed a new mouse model for studying the effects of antiviral agents on progressive vaccinia virus infections. METHODS: Hairless mice were treated with cyclophosphamide (100 mg/kg/day) every 4 days starting 1 day before vaccinia virus exposure to wounded skin. Primary lesions progressed in severity, satellite lesions developed, and the infection eventually killed the mice. RESULTS: Topical treatment with 1%-cidofovir cream (twice daily for 7 days) was much more effective in reducing the severity of primary lesions and the number of satellite lesions than was parenteral cidofovir treatment (100 mg/kg/day, given every 3 days). Both forms of treatment delayed death. Topical drug treatment markedly reduced virus titers in the skin and snout, whereas parenteral treatment did not, suggesting that the latter treatment resulted in lower drug exposure to skin. Topical treatment starting 9 days after infection delayed death by 10 days, compared with treatment with placebo. Combining topical and parenteral cidofovir treatments provided the greatest reduction in lesion severity and prolongation of life. CONCLUSIONS: Topical cidofovir treatment was superior to parenteral treatment. This new animal model may be useful in evaluation of the efficacy of treatment regimens against complications from smallpox vaccination.     

Genital herpes: pathogenesis and chemotherapy in the guinea pig model

Genital herpes is different from other common venereal diseases in that there is no cure. As yet the natural history of genital herpes is not well understood. There are many unanswered questions regarding the biology of the disease; the virulence of the virus strains, individual host responses, and means for prevention and control all require further investigation. The study of genital herpes has been greatly aided in recent years by the development of animal models. The clinical and pathologic features of acute and recurrent genital disease of guinea pigs inoculated with low doses of herpes simplex virus are similar to those seen in human infection. Therefore, questions not readily studied in human infection--such as latent infection in the nervous system, the natural history, prevention, and treatment of neonatal herpes, the effects of immunosuppression on herpes infection, and the efficacy and toxicity of antiviral drugs and vaccines--are amenable to study in the guinea pig model. The applications of this animal model and its relevance to human disease are herein reviewed.     

Humoral and cellular immune responses to an envelope-associated antigen of herpes simplex virus.

The humoral and cellular immune responses of rabbits and guinea pigs to the envelope-associated antigen of herpes simplex virus type I were studied. Neutralizing antibody (at high titer) and lymphocytes reactive to herpes simplex virus were detected in both guinea pigs and rabbits after immunization with the antigen. In a standard assay of cellular immunity to herpes simplex virus, the antigen stimulated blast transformation of herpes simplex virus-reactive splenic lymphocytes in vitro. Furthermore, immunization of rabbits with the envelope-associated antigen protected the animals from a lethal dose of live herpes simplex virus. Thus an antigen of herpes simplex virus can be prepared which contains neither infectious nor noninfectious viral particles and which stimulates immunity to the virus in laboratory animals.     

Pathogenesis of XJ and Romero strains of Junin virus in two strains of guinea pigs

Argentine hemorrhagic fever (AHF), a systemic infectious disease caused by infection with Junin virus, affects several organs, and patients can show hematologic, cardiovascular, renal, or neurologic symptoms. We compared the virulence of two Junin virus strains in inbred and outbred guinea pigs with the aim of characterizing this animal model better for future vaccine/antiviral efficacy studies. Our data indicate that this passage of the XJ strain is attenuated in guinea pigs. In contrast, the Romero strain is highly virulent in Strain 13 as well as in Hartley guinea pigs, resulting in systemic infection, thrombocytopenia, elevated aspartate aminotransferase levels, and ultimately, uniformly lethal disease. We detected viral antigen in formalin-fixed, paraffin-embedded tissues. Thus, both guinea pig strains are useful animal models for lethal Junin virus (Romero strain) infection and potentially can be used for preclinical trials in vaccine or antiviral drug development.     

Acylovir in oral and ganglionic herpes simplex virus infections.

The local and trigeminal ganglionic therapeutic efficacy of two topical and systemic antiviral drugs was studied in mouse lips inoculated with herpes simplex virus type 1 after thermal injury. Application of topical 3% acylovir (acycloguanosine) ointment three times daily for four days completely blocked the replication of virus in the lips, and the healing process was greatly accelerated compared with that in placebo-treated infected controls. However, neither the healing process nor the viral replication was influenced by similar therapy with 3% vidarabine ointment. When given systemically for four days, starting one day after inoculation, acyclovir (40-60 mg/kg per day) and vidarabine (50 mg/kg per day) significantly reduced the clinical manifestations on the lips and viral titers of cultures obtained from the lips. Establishment of viral latency in the trigeminal ganglion was significnatly inhibited by systemic acyclovir (60 mg/kg per day), whereas systemic vidarabine (50 mg/kg per day) was ineffective. These data suggest that acyclovir may be one of the most promising antiviral agents for the management of oral herpes viral infections and trigeminal ganglionic latency of virus as demonstrated in the mouse model.     

Efficacy of immunized milk for preventing viral infection

This paper investigated the efficacy of passive protection provided by milk (immunized milk) against enterovirus infection in mice experimentally infected with enterovirus. Milk with a high antibody titer against six enterovirus serotypes was prepared from hyperimmunized goat. In vivo and in vitro experiments were performed and the results showed that immunized milk has an antiviral activity against enterovirus infection. Further observation was performed using Coxsackie B 3 virus (CVB 3). When immunized milk was orally applied to mice prior to oral inoculation with CVB 3, preventive effects against viral infection such as reduction of histopathological changes in the heart and reduced detection of the virus genome in the organs were seen. The antiviral effect was also indicated by the increase of CD4+T cells proportion in the i-IEL. The proportion of virus specific CD4+T cells was increased in mice treated with immunized milk, whereas no such increase was detected in control mice. These results suggest that oral application of immunized milk is not only capable of preventing viral infection but also induces specific immunological responses. These phenomena may play an important role in host defense mechanisms.     

Beta interferon produced by keratinocytes in human cutaneous infection with herpes simplex virus

beta Interferon (IFN) was demonstrated by specific, sequential antibody-neutralization assays of vesicle fluids from patients with recurrent skin lesions due to herpes simplex virus. To determine the origin of this antiviral activity, we cultured keratinocytes from normal facial skin and infected them with three strains of herpes simplex virus. Keratinocyte cultures then developed characteristic cytopathic changes, and antiviral activity was found in culture supernatant media. All such activity from these supernatants was neutralized with specific antiserum to IFN-beta but not with antiserum to IFN-alpha. No IFN-gamma was detectable by radioimmunoassay. Immunoperoxidase staining with antiserum to IFN-beta in five biopsy specimens from culture-proven, recurrent herpes simplex lesions showed positive staining of epidermal keratinocytes but not of dermal or infiltrating cells. Thus, the primary sources of IFN-beta in recurrent herpes lesion vesicles are the virus-infected keratinocytes.     

Early intervention with high-dose acyclovir treatment during primary herpes simplex virus infection reduces latency and subsequent reactivation in the nervous system in vivo

There remains a lack of agreement on the effect of antiviral therapy on herpes simplex virus (HSV) latency and subsequent reactivation. To gain insight into this important issue, a single-cell polymerase chain reaction assay was used to quantify the effects of high-dose acyclovir on latent infection in a mouse model. Treatment with 50 mg/kg of acyclovir every 8 h reduced the number of latently infected neurons by >90% when treatment was begun before 24 h after infection and by 80% and 70% when begun at 48 or 72 h after infection, respectively. The biologic significance of these reductions was evaluated by using a well-established in vivo reactivation model. The number of animals in which virus reactivated was reduced significantly, even when acyclovir therapy was delayed until 72 h after infection, a time when animals had developed lesions. These findings indicate that potent antiviral therapy during early primary HSV infection can reduce the magnitude of the latent infection, such that a significant decrease in reactivation is observed.     

Multiple herpes simplex virus infections with various resistance patterns in a matched unrelated donor transplant recipient.

A 45-year-old matched unrelated BMT recipient had sequential mucocutaneous herpes simplex virus (HSV) type 2 infections. Five months after BMT, a penile lesion occurred and was cured using acyclovir, as expected from in vitro susceptibility results. The same lesion recurred 1 month later but worsened with acyclovir. The HSV isolate was resistant to acyclovir (IC(50) = 105 microM), and a nucleotide (G) was added to the thymidine kinase gene leading to a premature stop codon. The lesion improved markedly with foscarnet. During this treatment a second HSV infection occurred on the buttocks 2 weeks after the first one and healed completely with acyclovir. This course correlated with in vitro results of the buttock HSV isolate which was foscarnet-resistant (IC(50) = 300 microg/ml) and acyclovir-sensitive. Surprisingly, no mutation gene of the foscarnet-resistant isolate was detected in the DNA polymerase gene. This case shows that an HSV acyclovir-resistant infection may be followed by an acyclovir-sensitive one. Determination of antiviral susceptibility is needed to monitor the treatment of various HSV infections in immunocompromised BMT recipients.     

Modeling partially effective HIV vaccines in vitro

Significant public health benefits could be realized with human immunodeficiency virus (HIV) vaccines that are incompletely effective. However, standard assays of experimental HIV vaccine immunogenicity may not correlate with antiviral effectiveness and cannot identify subtle effects. We developed an in vitro challenge assay (IVCA) that measures the net antiviral effect in whole peripheral blood mononuclear cells (PBMCs) to any titered HIV isolate. We then modeled partially effective postvaccination immune status 4 ways: use of PBMCs from highly exposed, uninfected individuals; depletion and partial reconstitution of autologous CD8+ cells from PBMCs from HIV-positive long-term nonprogressors; partial blocking of infection with chemokines; and variation in challenge virus dose. IVCA could detect as little as 3-fold differences in the challenge titer (30, 10, and 3 50% tissue-culture infective doses) or odds ratio of HIV infection. This robust and simple assay should be useful in determining which HIV vaccine candidates are suitable for field trials of efficacy.     

The Molecular Tweezer CLR01 Inhibits Antibody-Resistant Cell-to-Cell Spread of Human Cytomegalovirus

Human cytomegalovirus (HCMV) uses two major ways for virus dissemination: infection by cell-free virus and direct cell-to-cell spread. Neutralizing antibodies can efficiently inhibit infection by cell-free virus but mostly fail to prevent cell-to-cell transmission. Here, we show that the ‘molecular tweezer’ CLR01, a broad-spectrum antiviral agent, is not only highly active against infection with cell-free virus but most remarkably inhibits antibody-resistant direct cell-to-cell spread of HCMV. The inhibition of cell-to-cell spread by CLR01 was not limited to HCMV but was also shown for the alphaherpesviruses herpes simplex viruses 1 and 2 (HSV-1, -2). CLR01 is a rapid acting small molecule that inhibits HCMV entry at the attachment and penetration steps. Electron microscopy of extracellular virus particles indicated damage of the viral envelope by CLR01, which likely impairs the infectivity of virus particles. The rapid inactivation of viral particles by CLR01, the viral envelope as the main target, and the inhibition of virus entry at different stages are presumably the key to inhibition of cell-free virus infection and cell-to-cell spread by CLR01. Importance: While cell-free spread enables the human cytomegalovirus (HCMV) and other herpesviruses to transmit between hosts, direct cell-to-cell spread is thought to be more relevant for in vivo dissemination within infected tissues. Cell-to-cell spread is resistant to neutralizing antibodies, thus contributing to the maintenance of virus infection and virus dissemination in the presence of an intact immune system. Therefore, it would be therapeutically interesting to target this mode of spread in order to treat severe HCMV infections and to prevent dissemination of virus within the infected host. The molecular tweezer CLR01 exhibits broad-spectrum antiviral activity against a number of enveloped viruses and efficiently blocks antibody-resistant cell-to-cell spread of HCMV, thus representing a novel class of small molecules with promising antiviral activity.     

Antiviral therapy: nucleotide and nucleoside analogs

For the management of HBV infection, an increasing number of nucleotide and nucleoside analogs are active against wild-type HBV and some against HBV with YMDD and other compensatory mutations. Table 2 depicts the IC50 and susceptibilities of HBV to various antiviral agents. The dichotomy between in vitro and in vivo susceptibilities to YMDD mutants is due to a change in IC50 between wild-type and mutant virus. Thus a drug may have less activity in vitro but at doses used in vivo show activity against YMDD and other compensatory mutations. Some HBV drugs share activity against HIV, which may be useful in the co-infected patient. Other nucleoside analogs are in various stages of development, including MCC-478 and DAPD. In the future, clinicians will have a plethora of reagents to chose from, and combination therapies may be invoked.     

Combination treatment with famciclovir and a topical corticosteroid gel versus famciclovir alone for experimental ultraviolet radiation-induced herpes simplex labialis: a pilot study

To investigate the efficacy of corticosteroids for the treatment of herpes labialis, we compared famciclovir (Famvir, 500 mg 3x/day po [per os] for 5 days) and topical fluocinonide (0.05% Lidex Gel 3x/day for 5 days) with famciclovir and topical vehicle control for experimental ultraviolet radiation-induced herpetic recurrences. We irradiated 49 volunteers, and 29 (60%) of 48 developed signs or symptoms of a recurrence. They self-initiated treatment, and we were able to evaluate them. There was a trend in the combination group toward more aborted lesions, compared with those who received antiviral therapy alone (7 [41%] of 17 vs. 1 [8%] of 12; P=.09). Combination therapy significantly reduced the median maximum lesion size (48 vs. 162 mm(2); P=.02) and the number of patients who experienced lesion pain (10 [59%] of 17 vs. 12 [100%] of 12; P=.02). Adverse events were minimal. Corticosteroids in combination with an antiviral agent may be safe and beneficial for episodic treatment of herpes labialis. Larger studies are needed to confirm these findings.     

Role of antibody-dependent cellular cytotoxicity in defense against herpes simplex virus infections

Antibody-dependent cellular cytotoxicity (ADCC) to cells infected with herpes simplex virus (HSV) is a mechanism of destruction of these cells by a combination of antiviral antibody and immunoglobulin Fc receptor-positive leukocytes. It has been well defined in vitro as a rapid lytic response utilizing minute amounts of IgG antibody. In vitro studies have shown ADCC restriction of the spread of virus. In vivo studies using adoptive transfer of human or murine ADCC effector cells plus antibody and ADCC-active, nonneutralizing F(ab1)2 antibody fragments or monoclonal antibodies have demonstrated the important role of this response in animal models of HSV infection. In humans, ADCC effector function and/or antibody levels have been associated with the outcome of infection, especially in immunocompromised patients and neonates. Reconstitution of this mechanism with appropriate antibodies or cytokines in high-risk hosts, with the resultant amelioration of severe HSV infection, will validate ADCC as a critical component of antiviral defense.     

Specific inhibition of herpes virus replication by receptor-mediated entry of an antiviral peptide linked to Escherichia coli enterotoxin B subunit.

Mimetic peptides capable of selectively disrupting protein-protein interactions represent potential therapeutic agents for inhibition of viral and cellular enzymes. This approach was first suggested by the observation that the peptide YAGAVVNDL, corresponding to the carboxyl-terminal 9 amino acids of the small subunit of ribonucleotide reductase of herpes simplex virus, specifically inhibited the viral enzyme in vitro. Evaluation and use of this peptide as a potential antiviral agent has, however, been thwarted by its failure to inhibit virus replication in vivo, presumably because the peptide is too large to enter eukaryotic cells unaided. Here, we show that the nontoxic B subunit of Escherichia coli heat-labile enterotoxin can be used as a recombinant carrier for the receptor-mediated delivery of YAGAVVNDL into virally infected cells. The resultant fusion protein specifically inhibited herpes simplex virus type 1 replication and ribonucleotide reductase activity in quiescent Vero cells. Preincubation of the fusion protein with soluble GM1 ganglioside abolished this antiviral effect, indicating that receptor-mediated binding to the target cell is necessary for its activity. This provides direct evidence of the usefulness of carrier-mediated delivery to evaluate the intracellular efficacy of a putative antiviral peptide.     

Acyclovir-resistant varicella zoster virus infection after chronic oral acyclovir therapy in patients with the acquired immunodeficiency syndrome (AIDS)

Four patients with human immunodeficiency virus (HIV) infection who received chronic oral acyclovir therapy for suppression of recurrent varicella zoster or herpes simplex virus infection developed persistent disseminated hyperkeratotic papules that failed to heal with intravenous or high-dose oral acyclovir therapy. Varicella zoster virus, resistant to acyclovir in vitro, was isolated from skin lesions of all four patients. Three patients were adults in whom the acquired immunodeficiency syndrome (AIDS) had been diagnosed 12 to 20 months before isolation of acyclovir-resistant varicella zoster virus. The fourth patient was a perinatally HIV-infected child who developed primary varicella infection at age 7 years when profoundly immunosuppressed (absolute CD4+ lymphocyte count less than 50 cells/microL). Mean antiviral susceptibilities (ED50 values) of the four clinical isolates compared with the ED50 values of the reference strain Oka were 85 compared with 3.3 mumol/L for acyclovir, 1.4 compared with 0.8 mumol/L for vidarabine, and 123 compared with 117 mumol/L for foscarnet. When assayed by [125I]-dC plaque autoradiography, 90% to 100% of the viral isolate populations had altered or no measurable thymidine kinase function. Acyclovir-resistant varicella zoster virus infection may complicate long-term oral acyclovir administration in patients with AIDS and may be associated with the appearance of atypical hyperkeratotic papules.