Suppression of recurrent genital herpes simplex virus infection with recombinant alpha 2 interferon

Superior antiviral activity of IFNβ in genital HSV-1 infection

Type I interferons (IFNs) present the first line of defense against viral infections, providing antiviral, immunomodulatory and antiproliferative effects. The type I IFN family contains 12 IFNα subtypes and IFNβ, and although they share the same receptor, they are classified as non-redundant, capable to induce a variety of different IFN-stimulated genes. However, the biological impact of individual subtypes remains controversial. Recent data propose a subtype-specificity of type I IFNs revealing unique effector functions for different viruses and thus expanding the implications for IFNα-based antiviral immunotherapies. Despite extensive research, drug-resistant infections with herpes simplex virus type 1 (HSV-1), which is the common agent of recurrent orogenital lesions, are still lacking a protective or curing therapeutic. However, due to the risk of generalized infections in immunocompromised hosts as well as the increasing incidence of resistance to conventional antiherpetic agents, HSV infections raise major health concerns. Based on their pleiotropic effector functions, the application of type I IFNs represents a promising approach to inhibit HSV-1 replication, to improve host immunity and to further elucidate their qualitative differences. Here, selective IFNα subtypes and IFNβ were evaluated for their therapeutic potential in genital HSV-1 infections. Respective in vivo studies in mice revealed subtype-specific differences in the reduction of local viral loads. IFNβ had the strongest antiviral efficacy against genital HSV-1 infection in mice, whereas IFNα1, IFNα4, and IFNα11 had no impact on viral loads. Based on flow cytometric analyses of underlying immune responses at local and peripheral sites, these differences could be further assigned to specific modulations of the antiviral immunity early during HSV-1 infection. IFNβ led to enhanced systemic cytokine secretion and elevated cytotoxic responses, which negatively correlated with viral loads in the vaginal tract. These data provide further insights into the diversity of type I IFN effector functions and their impact on the immunological control of HSV-1 infections.

Herpes simplex virus and human papillomavirus genital infections: new and investigational therapeutic options

Human papillomavirus and Herpes simplex virus are the most common genital viral infections encountered in clinical practice worldwide. We reviewed the literature focusing on new and experimental treatment modalities for both conditions, based on to the evidence-based data available. The modalities evaluated include topical agents such as immune response modifiers (imiquimod, resiquimod, and interferon), antivirals (penciclovir, cidofovir, and foscarnet), sinecatechins, microbiocidals (SPL7013 gel, and PRO 2000 gel), along with experimental (oligodeoxynucleotides), immunoprophylactic, and immunotherapeutic vaccines.

Off-label uses of biologics in dermatology: Interferon and intravenous immunoglobulin (Part 1 of 2)

The introduction of a number of biologic therapies into the market has revolutionized the practice of dermatology. These therapies include interferons, intravenous immunoglobulin, infliximab, adalimumab, etanercept, efalizumab, alefacept, and rituximab. Most dermatologists are familiar with the Food and Drug Administration-approved indications of these medications. However, numerous off-label uses have evolved. As part 1 of a 2-part series, this article will review the literature regarding the off-label uses of the interferons and intravenous immunoglobulin in dermatology.

Evaluation of imiquimod 5% cream to modify the natural history of herpes labialis: a pilot study

BACKGROUND

Imiquimod is currently approved for the treatment of genital warts and has been shown to decrease recurrences of genital herpes in the guinea pig model of genital herpes. Therefore, we evaluated the safety and potential of topical imiquimod to decrease the rate of recurrence in humans with a history of recurrent herpes labialis.

METHODS

Forty-seven subjects with recurrent herpes labialis applied imiquimod 5% (n=30) or vehicle cream (n=17) to recurrent lesion(s) on days 1, 3, and 5 of the study (day 1 of observation occurred within 48 h after recurrence of lesion). Subjects were seen at the study centers between each dose and 3 days after application of the final dose or until resolution of the lesion.

RESULTS

After application to recurrent lesions, local erythema, edema, scabbing and/or flaking, pain, burning, and maximal lesion size were significantly greater in the imiquimod group than in the vehicle group. The study was terminated early because of severe local adverse events that occurred in 5 recipients of imiquimod. The median time until the next recurrence was, however, increased from 50 days in the vehicle group to 91 days in the imiquimod group (P=.018).

CONCLUSIONS

Application of imiquimod 5% cream to herpes labialis lesions was associated with a delay in the time to the first recurrence after treatment, but severe local inflammation occurred in some individuals.

Interferon induction in turkeys by oral administration of the imidazoquinolinamine S-28828 and modulation of the pathogenesis of Escherichia coli

A synthetic imidazoquinolinamine, S-28828, has been shown to be an effective antiviral and antitumor agent in mammals. This immune modifier induces a number of cytokines such as interferons, tumor necrosis factor-alpha, interleukins and granulocyte-macrophage colony-stimulating factors in mammals. We showed that when turkeys were given S-28828 orally, high serum titers of IFN were induced in a dose-dependent manner. Turkeys, once stimulated by S-28828, became refractory to IFN production by repeated stimulation. S-28828 induced spleen, bone marrow and peripheral leukocytes to produce IFN in vitro. Splenic adherent cells were the main producers of IFN after in vitro stimulation. S-28828-induced IFN was identified as type I IFN that was pH-resistant but heat-labile. We examined the effect of a high dose (100 mg kg(-1) body weight) of S-28828 on the pathogenesis of E. coli in turkeys. Treatment with S-28828 increased mortality in infected birds and impaired E. coli clearance from the liver. The enhancement of the pathogenicity of E. coli by S-28828 may have been due to the massive release of cytokines inducing a shock-like syndrome in infected turkeys.

Effect of topical interferon-beta on recurrence rates in genital herpes: a double-blind, placebo-controlled, randomized study

The aim of this randomized, double-blind placebo-controlled trial was to evaluate the effect of IFN-beta cream applied at the time of recurrent eruptions of genital herpes during 6 months on the overall rate of recurrence. Therapy was initiated at the clinic for the first treated recurrence, and thereafter by the patient for early treatment of eventual subsequent eruptions. Each recurrence was ascertained at the clinic in all 35 evaluable patients. The mean recurrence rate was significantly lower in the group using IFN-beta cream than in the placebo group (p = 0.03). Complete responders without recurrence for the duration of the trial were 36.4% of all patients and 46% among women versus 15.4 and 16.6% in the placebo groups, respectively. A total of 77.3% of all patients were defined as complete or partial responders, their average recurrences/year decreasing from 11 to 2.2 (p < 0.0001). The topical episodic IFN-beta treatment was well tolerated by patients and without side effects. It is concluded that IFN-beta cream application reduces the overall rate of recurrence of genital herpes.

Systemic antiviral drugs used in ophthalmology

Over the past two decades, the recognition of viral enzymes and proteins that can serve as molecular targets of drugs has revolutionized the treatment of viral infections. Beginning with acyclovir, a number of systemically administered agents which are both relatively safe and effective for the treatment of herpetic infections and human immunodeficiency virus (HIV) infections have become widely available. Because of increased numbers of herpes virus infections, as well as the rising epidemic of HIV infections, the ophthalmologist is, more likely than ever before to be involved in the treatment of severe and frequent ocular infections caused by herpes viruses. In addition, the acute retinal necrosis (ARN) syndrome has been demonstrated to be caused by herpes viruses and a once rare retinal infection caused by cytomegalovirus is common in patients with the acquired immunodeficiency syndrome (AIDS). In this article, four systemic antiviral drugs (Vidarabine, Acyclovir, Ganciclovir, and Foscarnet) that have demonstrated usefulness in the treatment of ophthalmic disease are reviewed in detail with regard to their mechanisms, applications, effectiveness, and side effects.

Antiviral therapy: current concepts and practices

Drugs capable of inhibiting viruses in vitro were described in the 1950s, but real progress was not made until the 1970s, when agents capable of inhibiting virus-specific enzymes were first identified. The last decade has seen rapid progress in both our understanding of antiviral therapy and the number of antiviral agents on the market. Amantadine and ribavirin are available for treatment of viral respiratory infections. Vidarabine, acyclovir, ganciclovir, and foscarnet are used for systemic treatment of herpesvirus infections, while ophthalmic preparations of idoxuridine, trifluorothymidine, and vidarabine are available for herpes keratitis. For treatment of human immunodeficiency virus infections, zidovudine and didanosine are used. Immunomodulators, such as interferons and colony-stimulating factors, and immunoglobulins are being used increasingly for viral illnesses. While resistance to antiviral drugs has been seen, especially among AIDS patients, it has not become widespread and is being intensely studied. Increasingly, combinations of agents are being used: to achieve synergistic inhibition of viruses, to delay or prevent resistance, and to decrease dosages of toxic drugs. New approaches, such as liposomes carrying antiviral drugs and computer-aided drug design, are exciting and promising prospects for the future.

Recombinant alpha-2 interferon gel treatment of recurrent herpes genitalis

Topical recombinant alpha-2 interferon treatment of recurrent genital herpes was studied in a randomized, double-blind, placebo controlled clinical trial. Three hundred and eighty-seven patients were treated at eight study centers with either interferon gel or placebo four times daily for four days. Interferon therapy caused a 26% decrease in the duration of viral shedding. For male patients, there were also significant decreases in the time to crusting (17%) and duration of pain (34%) and itching (21%). For patients with recurrent genital herpes, treatment with topical interferon was found to be effective in decreasing the duration of viral shedding and, for males, pain, itching and time to crusting.

Genital herpes simplex virus infections

There has been a dramatic increase in patient visits to physicians for evaluation and treatment of genital herpes infections. This has resulted in part from an increase in genital herpes infections, particularly severe, first-episode genital herpes infections in adults without prior HSV-1 infection. Virus culture remains the most sensitive and specific method for diagnosis, and use of viral cultures is encouraged. Type-specific antibody tests have been employed in studies documenting the role of asymptomatic shedding of HSV in transmission of genital infections, the role of genital HSV in transmission of HIV, the predominance of asymptomatic and unrecognized infections in those infected with HSV-2, and the presence of past asymptomatic or unrecognized acquisition of HSV-2 in 25% of persons presenting with first-episode genital herpes. Unfortunately, commercially available serologic tests do not reliably differentiate between antibody to HSV-1 and HSV-2. Recent studies suggest that the annual risk of transmission from a sexual partner with genital herpes is about 10% in heterosexual couples. Currently, promotion of "safe sex" is the only available approach for prevention of transmission. However, ongoing research is focused on the development of an effective vaccine. Acyclovir should be used routinely in persons with first-episode genital herpes, but careful evaluation is needed in persons with recurrent genital herpes to determine whether episodic or suppressive treatment is indicated. Acyclovir should also be used routinely for episodic or suppressive treatment of HSV infections in persons with AIDS. Additional antiviral agents are needed for more effective suppressive therapy and for treatment of ACV-resistant HSV infections in the immunocompromised host.

Effects of the immunomodulating agent R837 on acute and latent herpes simplex virus type 2 infections

R837 is an immune modulator with no in vitro activity against herpes simplex virus (HSV). We evaluated topical R837 as therapy for genital HSV type 2 infection using the guinea pig model of this disease. Furthermore, we investigated the effect of R837 therapy on acute and latent neural HSV infections. Therapy initiated 12 h after viral inoculation and given twice a day significantly reduced the acute neural infection so that HSV was recovered from only 1 of 64 neural tissue specimens obtained from R837 recipients compared with 43 of 56 specimens obtained from placebo recipients (P less than 0.0001). R837 initiated 36 h after HSV inoculation and given once a day also significantly reduced the total mean lesion score of the acute disease from 14.1 +/- 4.3 to 2.6 +/- 5.3 (P less than 0.0001) and shortened the period of vaginal HSV shedding from 6.9 +/- 1.7 to 3.2 +/- 1.4 days (P less than 0.001). R837-treated animals also developed fewer HSV recurrences than did controls (2.0 +/- 1.7 versus 5.1 +/- 1.7; P less than 0.0002). Latent HSV was detected in 23 of 24 dorsal root ganglia explant cultures from placebo recipients but in only 2 of 30 cultures from R837-treated animals, and HSV in these 2 cultures was detectable only with the addition of a demethylating agent. Topical R837 exhibited in vivo anti-HSV activity, reducing both acute and latent neural infections as well as acute and recurrent genital disease.

Topical delivery of liposomally encapsulated interferon evaluated in a cutaneous herpes guinea pig model

The topical delivery of liposomally encapsulated interferon was evaluated in the cutaneous herpes simplex virus guinea pig model. Application of liposomally entrapped interferon caused a reduction of lesion scores, whereas application of interferon formulated as a solution or as an emulsion was ineffective. The method of liposomal preparation rather than the lipid composition of the bilayers appeared to be the most important factor for reducing lesion scores. Only liposomes prepared by the dehydration-rehydration method were effective. This finding implied that the dehydration and subsequent rehydration of the liposomes facilitate partitioning of the interferon into liposomal bilayers, where the drug is positioned for transfer into the lipid compartment of the stratum corneum. Liposomes do not appear to function as permeation enhancers but seem to provide the needed physicochemical environment for transfer of interferon into the skin.

Comparison of intramuscular recombinant alpha interferon (rIFN-2A) with topical acyclovir for the treatment of first-episode herpes genitalis and prevention of recurrences

Intramuscular recombinant alpha interferon (rIFN-2A; 9 million IU given for 5 days during a 9-day treatment period) was compared with topical acyclovir in a double-blind, placebo-controlled trial for the treatment of first-episode genital herpes simplex virus (HSV) infection and for subsequent alteration of the frequency of recurrences. rIFN-2A (within 96 h of onset of the first episode) was not superior to topical acyclovir in a well-matched group of 105 patients. The early use of rIFN-2A also did not alter the frequency or severity of genital HSV recurrences within either the first or second 6 months following therapy. Separate analyses by HSV type and by type of infection (primary versus nonprimary) did not change this conclusion. Furthermore, there was significant toxicity associated with rIFN-2A therapy. rIFN-2A is not indicated for the treatment of genital HSV infections.

Modification of immunological responses and clinical disease during topical R-837 treatment of genital HSV-2 infection

R-837, a compound with no in vitro anti-HSV activity, was administered intravaginally to guinea pigs (5 mg/kg every 12 h) for five days beginning 12 h after genital HSV-2 inoculation. Drug treatment reduced vaginal viral replication (P less than 0.0001), completely protected against primary disease and reduced recurrent genital HSV disease (P less than 0.0001). Drug treatment also induced mild fever, weight loss, and decreased water intake. R-837 was a potent interferon inducer, which also induced variable enhancement of cell-mediated cytolytic activity against HSV-2 targets. Less than 36 h of vaginal HSV shedding was observed in animals with R-837 induced early enhancement of HSV-target cytolysis. Compared to placebo, R-837 decreased ELISA and ADCC antibody to HSV-2, but accelerated HSV-2 specific in vitro IL-2 production and peripheral blood mononuclear cell (PBMC) proliferation. R-837 exhibited potent anti-HSV activity in vivo apparently due to cytokine induction and enhancement of cell-mediated responses.

Antiviral agents

Potent effective antiviral drugs recently have been licensed for several viral diseases, ushering in a new era in the treatment of viral diseases. Several unique features in the process of a viral infection have been identified as target points for inhibition. The unique steps and the interfering compounds are the subject of this review.

Promising new antiviral drugs

We now have a basis for a more rational approach to rapid evaluation and development of antiviral drugs by screening for activity in vitro, testing for toxicity and efficacy in animals, and clinical testing in humans. Acyclovir is a prototype of this improved process. Interferon has a beneficial effect against CMV infection in renal transplant patients and has promising results in the treatment of papillomas and rhinovirus infections. It does not seem to be as effective against genital herpes or varicella zoster as acyclovir. Ribavirin is effective against respiratory syncytial virus infections and Lassa fever. Varicella-zoster virus is highly sensitive to bromovinyl deoxyuridine in vitro. Phosphonoformate is effective in herpes simplex in animals but of little clinical benefit topically in human recurrent A2 herpes. Zidovudine may decrease mortality rates and infectious complications in patients with acquired immunodeficiency syndrome. DHPG (9-(1,3-dihydroxy-2-propoxymethyl]guanine is useful in treatment of cytomegalovirus and infection in immunocompromised patients. The prodrug of acyclovir results in high blood levels of acyclovir and shows promise in the treatment of varicella-zoster infections. Many halogenated pyrimidine nucleoside analogs are being developed. Buciclovir is another acyclic guanosine analog effective against herpes simplex virus in vitro. 2'-nor-cyclic guanosine monophosphate has a broad antiviral spectrum of action. Interleukin-2 is being investigated. Combined therapies of two or more antiviral drugs or antiviral drugs and other treatments are being studied.

Therapy of genital herpes with topically applied interferon

Ninety-four patients with recurrences of genital herpes were randomized in a double-blind trial to receive topical therapy for 5 days with either alpha-2a interferon at 30 X 10(6) IU/ml or 10 X 10(6) IU/ml or placebo six times daily. No differences were noted between either interferon dose and placebo with respect to the duration of viral shedding, the time to crusting, or the time to healing of herpetic lesions. Aqueous solutions of alpha-2a interferon applied topically to unroofed vesicles do not appear to be clinically useful in the treatment of recurrences of genital herpes.