Stephen L. Sacks

Progressive Esophagitis from Acyclovir-Resistant Herpes Simplex: Clinical Roles for DNA Polymerase Mutants and Viral Heterogeneity?

Clinically acquired acyclovir resistance in herpes simplex has usually been associated with a deficiency in viral thymidine kinase, which, in turn, has been linked with attenuated virulence in animal models. Diminished pathogenicity in thymidine kinase-deficient isolates has been partly responsible for controversies about the clinical significance of antiviral resistance. We report on a series of resistant virus isolates from a patient who had severe, progressive esophagitis. These isolates had various thymidine kinase activities, ranging from 2.8% to 130% when compared with the activity of the isolate obtained before treatment; the resistant isolate 615 retained enzyme activity as well as neurovirulence in an encephalitis model. Plaque purification showed a heterogeneous mixture containing at least one acyclovir-resistant, foscarnet-resistant plaque isolate (615.8) fully able to phosphorylate acyclovir. The 3.3-kbp BamHI fragment containing most of the DNA polymerase gene from isolate 615.8 was purified and used to successfully transfer both acyclovir and foscarnet resistance. Acquisition of in-vitro acyclovir resistance was associated with progression of clinical disease, as well as with maintenance of pathogenicity in an animal model and at least one mutation in viral DNA polymerase. Patients with herpes simplex infections that progress during acyclovir therapy should be observed for acquisition of resistance in the setting of antiviral chemotherapy; future studies should also consider the presence of heterogeneous virus populations in such patients.

Topical resiquimod 0.01% gel decreases herpes simplex virus type 2 genital shedding: A randomized, controlled trial

BACKGROUND Resiquimod, an investigational immune response modifier and Toll-like receptor (TLR) 7 and 8 agonist, stimulates production of cytokines that promote an antigen-specific T helper type 1 (Th1)--acquired immune response. In animal models, induction of Th1-specific responses modifies experimental herpes simplex virus (HSV) infection. METHODS We conducted a randomized, double-blind, vehicle-controlled trial to assess the efficacy of resiquimod 0.01% gel for reducing human anogenital HSV-2 mucosal reactivation. Adults with genital HSV-2 applied resiquimod or vehicle topically to herpes lesions 2 times weekly for 3 weeks and then collected daily anogenital swabs for 60 days for HSV DNA polymerase chain reaction. Recurrences during the subsequent 7 months were treated with study gel. During the final treatment-free 60 days, participants again collected daily swabs to assess shedding. RESULTS The median lesion and shedding rates were lower for resiquimod compared with vehicle recipients during the initial sampling period (10% vs. 16% [P=.03] and 10% vs. 17% [P=.08], respectively) and during the final sampling period (3% vs. 22% [P<.001] and 10% vs. 26% [P=.009], respectively). Resiquimod did not influence recurrence length. CONCLUSIONS These findings suggest that the immunological control of HSV-2 reactivation and lesion clearance may differ and that TLR7 and TLR8 agonists can reduce the frequency of mucosal HSV-2 reactivation.

Evaluations of Unformulated and Formulated Dendrimer-Based Microbicide Candidates in Mouse and Guinea Pig Models of Genital Herpes

ABSTRACT Prevention of sexually transmitted infections is a priority in developed and developing countries. One approach to prevention is the use of topical microbicides, and one promising approach is the use of dendrimers, highly branched macromolecules synthesized from a polyfunctional core. Three new dendrimer products developed to provide stable and cost-efficient microbicides were initially evaluated in vitro for anti-herpes simplex virus activity and then in vivo by using a mouse model of genital herpes. From these experiments one product, SPL7013, was chosen for further evaluation to define the dose and duration of protection. Unformulated SPL7013 provided significant protection from genital herpes disease and infection at concentrations as low as 1 mg/ml and for at least 1 h following topical (intravaginal) administration of 10 mg/ml. This compound was then formulated into three vehicles and further evaluated in mouse and guinea pig models of genital herpes infection. In the murine evaluations each of the formulations provided significant protection at concentrations of 10 and 50 mg/ml. Formulated compounds provided protection for at least 1 h at a concentration of 10 mg/ml. From these experiments formulation 2V was chosen for dose ranging experiments using the guinea pig model of genital herpes. The guinea pig evaluations suggested that doses of 30 to 50 mg/ml were required for optimal protection. From these studies a lead compound and formulation (2V of SPL7013) was chosen for ongoing evaluations in primate models of simian immunodeficiency virus and Chlamydia trachomatis infection.

New developments in the epidemiology, natural history and management of genital herpes

The prevalence of genital herpes is increasing in several populations worldwide. Factors that may be contributing to this increase include greater numbers of sexual partners, the high frequency of asymptomatic infections, poor use of safe sexual practices, and possibly the decreased incidence of childhood oral herpes simplex virus infection. Transmission occurs via skin-to-skin or mucous membrane contact during periods of viral shedding when lesions are present but may also occur when the patient is unaware of the lesions or when lesions are not clinically apparent. This has important implications for strategies to prevent transmission of the disease. The introduction of the antiherpes agent, acyclovir, and more recently famciclovir and valacyclovir, facilitates the management of genital herpes. Treatment of first-episode genital herpes reduces the severity and duration of symptoms, time to lesion healing, and cessation of viral shedding. Episodic treatment of recurrences as they occur may be of benefit to some patients. Daily suppressive therapy significantly reduces the frequency of recurrences and asymptomatic viral shedding. Accordingly, patients who experience frequent or severe recurrences, those particularly troubled by their disease, and those who wish to reduce the frequency of asymptomatic infection generally prefer suppressive therapy. The possibility that suppressive therapy may have an impact on transmission of the disease is currently under investigation. Antiviral treatments have important implications for public health and may help reduce the psychological and psychosocial impact of genital herpes on individual patients.

New antiherpesvirus agents : Their targets and therapeutic potential

SummaryOf the large number of agents under development for the treatment of herpes virus infections [herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV)], only ten have apparently reached clinical development.Aciclovir was approved for the treatment of HSV infections over 10 years ago, and it remains an important and reliable antiviral agent. Recent approvals in some countries of valaciclovir for VZV infection and famciclovir for both HSV and VZV infections demonstrate the rapidity of change in this field.Intravenous ganciclovir and foscarnet are approved for the treatment of CMV infection in the immunocompromised patient. Five of the antiherpetic drugs under current clinical development are nucleoside analogues or their prodrugs; another is a phosphorylated nucleoside (nucleotide). Four of the nucleoside agents — penciclovir, famciclovir, valaciclovir and lobucavir — are being developed for the management of HSV and VZV infections. Valaciclovir is also being developed for the prevention of CMV infections and famciclovir and lobucavir for the treatment of hepatitis virus infection. Oral ganciclovir, lobucavir, ISIS 2922 and cidofovir are being developed for the suppression of CMV infections in immunocompromised patients. Sorivudine has been studied in VZV infections. n-Docosanol is under development for HSV infections, and cidofovir is being developed for both HSV and CMV infections, as well as for treatment of other viral diseases.Traditionally, the adverse effects associated with anti-CMV compounds have been more difficult to manage and are acceptable clinically only because of the severity of the underlying infection and lack of safer therapeutic alternatives. In general, toxicity issues continue to be problematic in the anti-CMV arena, although newer agents have improved the situation to some extent. In contrast, the safety of anti-HSV compounds has traditionally been excellent, establishing a safety standard that must be met by newer agents entering the field.

Current recommendations for the treatment of genital herpes

The incidence of genital herpes continues to increase in epidemic-like fashion. Aciclovir (acyclovir) has been the original gold standard of therapy. The recent addition of famciclovir and valaciclovir as antiherpes drugs has improved convenience as well as the efficacy of treatment. Although aciclovir remains a widely prescribed and reliable drug, its administration schedule falls short of the ease of usage that the newer nucleoside analogues offer, for both episodic and suppressive therapy. Suppression of symptomatic disease and asymptomatic shedding from the genitalia have both become popular approaches, if not the primary targets of antiviral therapy. Knowing that asymptomatic disease leads to most cases of transmission strongly suggests that suppression with antiviral agents could reduce transmission risk in discordant couples. Unfortunately, the role for antivirals in reducing transmission remains to be proven in clinical trials. Neonatal herpes is now successfully treated using aciclovir. Current randomised clinical trials are examining aciclovir and valaciclovir administration, as well as safety and efficacy for post-acute suppressive therapy. Prevention of recurrences in pregnancy is also a topic under investigation, with a view to reducing the medical need for Cesarean section, or alternatively (and far less likely to be accomplished) to protect the neonate.Although resistance is largely limited to the immunocompromised and a change in resistance patterns is not expected, several drugs are available for the treatment of aciclovir-resistant strains of herpes simplex. Foscarnet is the main alternative with proven efficacy in this setting. Unfortunately, administration of foscarnet requires intravenous therapy, although a single anecdote of topical foscarnet efficacy in this setting has been published. Alternatives include cidofovir gel, which is not commercially available but can be formulated locally from the intravenous preparation. Less effective alternatives include trifluridine and interferon. Future possibilities for treatment of genital herpes include a microparticle-based controlled-release formulation of aciclovir and resiquimod (VML-600; R-848). The search for an effective therapeutic vaccine for genital herpes has not been successful to date, although a live virus glycoprotein H-deficient (DISC) vaccine is currently in clinical trials. Recent data suggest that seronegative women are protected (albeit, not fully) by a glycoprotein D recombinant vaccine with adjuvant.Despite the established safety and convenience of current treatment options, better suppressive options and topical treatment options are much needed. Studies using existing agents as potential tools to avoid Cesarean section, or transmission to neonate or partner are ongoing. Both vaccines and antivirals may eventually play a role in prevention of infection.

Evidence of dual sites of action of dendrimers: SPL-2999 inhibits both virus entry and late stages of herpes simplex virus replication.

Dendrimers are macromolecules with broad-spectrum antiviral activity and minimal toxicity effective in animal models in preventing transmission of herpes simplex virus (HSV) infection. In order to further understand the mechanism of action, and toxicity profiles of the dendrimer SPL-2999 against HSV, we investigated in vitro activities as follows: modified plaque reduction assays for SPL-2999 showed that 50% effective concentrations (EC(50)) determined by pre-treatment of cells with SPL-2999 were 0.5 microg/ml (30 nM) for HSV-2 and 1 microg/ml (60 nM) for HSV-1, respectively. SPL-2999 was not toxic to Vero cells at concentration up to the highest tested (CC(50) greater than 1000 microg/ml). SPL-2999 appears to completely inhibit both viral adsorption and penetration to Vero cells at concentrations of higher than 3 microg/ml. Additionally, virus yield reduction assay showed that SPL-2999 was effective on cells already infected with HSV with EC(90)s (effective concentration giving 90% virus yield reduction) approximately 29.2 microg/ml for HSV-1 and 6.7 microg/ml for HSV-2. When Vero cells were infected with HSV at moi (multiplicity of infection) of 0.01 pfu/cell, the infected cells could be completely protected from viral cytopathic effect (CPE) by SPL-2999 with EC(90)s (effective concentration that protects 90% of cells from virus lysis) of 15 microg/ml for HSV-1 and 10 microg/ml for HSV-2. Results from Southern blot hybridization indicated that SPL-2999 inhibited DNA synthesis in HSV infected cells. We conclude that SPL-2999 inhibits both HSV entry into susceptible cells and late stages of HSV replication. Our data indicate that SPL-2999 is a potent inhibitor of both HSV-1 and -2 with the potential for further development as either a topical microbicide or a therapeutic agent.

Clinic-Initiated, Twice-Daily Oral Famciclovir for Treatment of Recurrent Genital Herpes: A Randomized, Double-Blind, Controlled Trial

BACKGROUND Famciclovir, the oral prodrug of penciclovir, is effective for the treatment of recurrent genital herpes. This randomized, clinic-initiated, double-blind trial compared the therapeutic efficacy and safety of treatment with famciclovir at dosages of 125 mg, 250 mg, and 500 mg twice daily for 5 days with placebo in immunocompetent adults with a recurrent episode of genital herpes. METHODS Efficacy and tolerability were assessed in 308 patients with lesions present for no more than 6.5 h at the time of the first dose. Two assessments per day were performed to increase the precision of the determination of study end points. RESULTS All doses of famciclovir were significantly more effective than placebo in reducing the time to cessation of viral shedding, complete lesion healing, and loss of all lesion-associated symptoms, particularly lesion tenderness, pain, and itching. Patients receiving treatment with famciclovir were significantly less likely to experience new lesions than were patients receiving placebo. All doses of famciclovir were tolerated as well as placebo was. There was no difference in efficacy or tolerability among the different doses of famciclovir; the lowest effective dose was 125 mg twice per day. CONCLUSIONS In immunocompetent adults with recurrent genital herpes, a 5-day course of famciclovir at a dosage of 125 mg, 250 mg, or 500 mg twice per day was significantly more effective than was placebo in reducing the duration of viral shedding and symptoms and in accelerating lesion healing. These results support the use of treatment with famciclovir at a dosage of 125 mg for 5 days as an effective, well-tolerated treatment for episodes of recurrent genital herpes.

Famciclovir Suppression of Asymptomatic and Symptomatic Recurrent Anogenital Herpes Simplex Virus Shedding in Women: A Randomized, Double-Blind, Double-Dummy, Placebo-Controlled, Parallel-Group, Single-Center Trial

Genital herpes is most often transmitted while the patient is asymptomatic, presumably during episodes of viral shedding. To determine whether famciclovir is effective in reducing asymptomatic shedding, women with frequent, recurrent genital outbreaks were enrolled in a randomized, double-blind, double-dummy, placebo-controlled, parallel-group, 112-day trial of suppressive treatment with famciclovir for anogenital viral shedding. Sixty women received 125 mg of famciclovir 3 times daily, 59 received 250 mg of famciclovir 3 times daily, and 58 received placebo. Patients recorded symptoms and self-obtained cultures daily. Famciclovir reduced asymptomatic shedding, compared with placebo (P < .0001). The onset of asymptomatic shedding was also delayed (P < .0001). Famciclovir reduced symptomatic shedding in a dose-dependent manner (0.72% for 125 mg 3 times daily vs. 0.19% for 250 mg 3 times daily [P < .0001] vs. 5.53% for placebo [P < .0001]). In conclusion, suppressive treatment with famciclovir reduced both asymptomatic and symptomatic viral shedding and delayed the onset of asymptomatic shedding in women with frequently recurring genital herpes. Studies to examine the effects of suppression by famciclovir on the transmission of genital herpes are warranted.

Topical Undecylenic Acid for Herpes Simplex Labialis: A Multicenter, Placebo-Controlled Trial

A multicenter, patient-initiated, double-blind, placebo-controlled trial of 15% undecylenic acid cream was conducted with 573 patients with recurrent herpes labialis. Treatment was applied 5 or 6 times daily until crusting and then thrice daily until healing. Patients were assessed daily until 48 h after crusting and then every other day until healing. Undecylenic acid significantly reduced the incidence and duration of viral shedding and the duration and severity of itching but did not increase abortive episodes or reduce times to healing, crusting, or progression of lesion size. When treatment was initiated during the prodrome, the time to crusting was reduced (P = .02) and the area under the symptom-time curve for pain and tenderness was reduced, approaching statistical significance (P = .06). Active treatment was well tolerated but caused dysgeusia and local irritation. Undecylenic acid 15% cream reduces viral shedding in recurrent herpes labialis, but clinical benefits are minimal and largely restricted to patients initiating therapy during the prodrome.