Longitudinal evaluation of herpes simplex virus DNA load during episodes of herpes labialis

Abstract

Background

Few studies have performed sequential evaluation of the herpes simplex virus (HSV) load using quantitative PCR during episodes of herpes labialis.

Objective

To determine HSV viral load kinetics during recurrences of herpes labialis.

Study design

Twenty-two subjects were monitored by daily swabs during recurrences of herpes labialis. A real-time PCR detecting both HSV-1 and HSV-2 was used to quantify the viral load.

Results

Median duration of HSV-1 shedding was 60 h and 48 h by PCR and culture, respectively. No HSV-2 DNA was detected in that study. Peak viral DNA load (123.6 copies/cell) occurred at 48 h with no virus detected beyond 96 h of onset of symptoms.

Conclusions

These viral load kinetics data could be used as surrogate markers of antiviral activity in future clinical trials.

Introduction

Herpes labialis is mostly caused by herpes simplex virus (HSV) type 1. More than 50% of adults possess HSV-1 antibodies and between 20% and 40% of all adults experience cold sore outbreaks (Spruance et al., 2003). The mean duration of a classical recurrence is 7–8 days although there is a large individual variability (Spruance et al., 1997). Trials of topical and oral antiviral therapy in subjects with recurrent herpes labialis showed best results when rapid, patient-initiated, therapy consisted of administration of high doses of oral antiviral agents (Spruance et al., 2003, Spruance et al., 1999). In most of these trials, the primary endpoint was the time to complete healing of lesions. In contrast to genital herpes where a large number of virological studies have been reported, there are very limited data on the duration and magnitude of viral shedding during episodes of herpes labialis (Corey et al., 2004, Spruance et al., 1997, Wald et al., 2003). The aim of this study was to evaluate viral DNA load kinetics in sequential swabs from immunocompetent subjects with recurrent herpes labialis.