Herpes simplex virus zosteriform lesions with adoptive transfer of immune cells: a murine model which mimics human recurrent disease

COMPARATIVE EFFICACY OF ANTIVIRAL AGENTS FOR PREVENTION AND MANAGEMENT OF HERPES LABIALIS: A SYSTEMATIC REVIEW AND NETWORK META-ANALYSIS

OBJECTIVE

To compare the relative efficacy and safety of antiviral agents used in the prevention and management of herpes labialis through a network meta-analysis of clinical trials.

METHODS

A systematic search was performed in Ovid Medline PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus and Clinicaltrials.gov for randomized controlled trials (RCTs) reporting a comparison of antiviral agents in the management and prevention of herpes labialis in healthy/immunocompetent adults. The data extracted from the selected RCTs were assessed and a network meta-analysis (NMA) was performed. The interventions were ranked according to the surface under the cumulative ranking (SUCRA).

RESULTS

A total of 52 articles were included for qualitative synthesis and for the quantitative part, 26 articles were analyzed for the primary treatment outcome and 7 studies were analyzed for the primary prevention outcome. The combination therapy of oral valacyclovir and topical clobetasol was the best ranked with a mean reduction in healing time of -3.50 (95% CI -5.22 to -1.78) followed by vidarabine monophosphate of -3.22 (95% CI -4.59 to -1.85). No significant inconsistencies, heterogeneity, and publication bias were reported for TTH outcome analysis. For primary prevention outcomes, only 7 RCTs fulfilled the inclusion criteria, and none of the interventions was shown to be superior to each other. The absence of adverse events was reported by 16 studies, whereas other studies reported mild side effects only.

CONCLUSION

NMA highlighted that several agents were effective in the management of herpes labialis among which the combination of oral valacyclovir with topical clobetasol therapy was the most effective in reducing the time to heal. However, further studies are required to determine which intervention is the most effective in preventing the recurrence of herpes labialis.

ME-609: A Treatment for Recurrent Herpes Simplex Virus Infections

Studies in conventional murine models of HSV infection use immunologically naive animals. These models thus mimic primary infections rather than recurrent infections in humans. We have, therefore, used a newly developed mouse model that more closely mimics recurrent HSV infection in humans. In this model, the mice are infected, and zosteriform HSV-1 infection develops in the presence of a primed immune response using adoptive transfer of immunity (ATI) as we have described previously. Using the ATI mouse model, it has been shown that a more beneficial therapy for recurrent mucocutaneous HSV infection could be achieved by controlling both the viral replication and the inflammatory response to the virus. Topical treatment was initiated in this model at the time of first occurrence of symptoms and was given three times daily for 4 days. Topical treatment with ME-609 (which contains 5% acyclovir and 1% hydrocortisone) in the ATI mouse model was substantially more efficacious than 5% Zovirax® cream, 1% hydrocortisone or no treatment, respectively. The beneficial properties of ME-609 were also found to be superior to those of Zovirax cream when tested in the standard guinea pig model, representing a primary HSV infection. ME-609 represents a novel treatment principle of recurrent HSV infections and the present paper summarizes the preclinical and early clinical experience of ME-609.

Single amino acid substitutions in the HSV-1 helicase protein that confer resistance to the helicase-primase inhibitor BAY 57-1293 are associated with increased or decreased virus growth characteristics in tissue culture

Two mutants (BAYr1 and BAYr2) that are 100-fold and >3000-fold resistant, respectively, to the helicase-primase inhibitor (HPI) BAY 57-1293 were derived from a plaque-pure parental strain, HSV-1 SC16 cl-2. BAYr1 has two substitutions in the HSV-1 helicase (UL5) protein (A4 to V; K356 to Q) and BAYr2 has one (G352 to R). It was shown reproducibly that BAYr1 grows to higher titres in tissue culture while BAYr2 grows more slowly than wild-type. Marker transfer experiments confirmed that K356Q and G352R are the drug-resistance mutations and that they are directly associated with differences in virus growth in tissue culture. When BAYr1 was tested in a murine infection model, this virus was shown to be fully pathogenic. We present evidence that single mutations close to a predicted functional domain of an essential HSV-1 replication enzyme (helicase) are associated with drug resistance and virus growth characteristics.

Double-blind, randomized, placebo-controlled study of topical 5% acyclovir-1% hydrocortisone cream (ME-609) for treatment of UV radiation-induced herpes labialis

Immunopathology is recognized as an important component of infectious disease manifestations, and corticosteroids have been used as an adjunct to antimicrobial therapy for a variety of conditions. Antiviral therapy of herpes labialis has been shown to result in only a small reduction in the time to healing and the duration of pain. To determine if topical application of a combination product containing 5% acyclovir and 1% hydrocortisone (ME-609) could provide benefit to herpes labialis patients, 380 immunocompetent adults with a history of herpes labialis were exposed to experimental UV radiation (UVR) to induce a recurrence. On day 2, just before the appearance of the majority of lesions ("delayed" lesions), subjects were randomized to receive active medication or vehicle control six times per day for 5 days. Overall, 120 of 380 patients developed delayed classical lesions, of whom 50 of 190 (26%) had been treated with ME-609 and 70 of 190 (37%) had received placebo (a reduction of 29% [P = 0.02]). Healing time, measured as the time to normal skin, was reduced by treatment with ME-609 (9.0 days for treated patients versus 10.1 days for the controls [P = 0.04]). There was a trend toward a reduction in the maximum lesion size in the ME-609 recipients compared to that in the controls (43 versus 60 mm(2), respectively [P = 0.07]). The treatment had no effect on lesion pain, but ME-609 treatment reduced the number of patients with moderate or severe tenderness. Compared to treatment with a placebo, treatment with the combination antiviral-immunomodulatory cream provided benefit to patients with experimental UVR-induced herpes labialis, reducing classical lesion incidence, healing time, lesion size, and lesion tenderness. ME-609 is a novel product that merits further evaluation as a treatment for cold sores.