Purpose To assess the frequency of shedding of herpes simplex virus type 1 (HSV-1) DNA in tears and saliva of asymptomatic individuals.
Methods Fifty subjects without signs of ocular herpetic disease participated. Serum samples from all subjects were tested for HSV IgG antibodies by ELISA and for HSV-1 by neutralization assay. HSV-1 DNA copy number and frequency of shedding were determined by real-time PCR analysis of tear and saliva samples collected twice daily for 30 consecutive days.
Results Thirty-seven of the 50 subjects (74%) were positive for HSV IgG by ELISA. The percentages of positive eye and mouth swabs were approximately equivalent, 33.5% (941/2806) and 37.5% (1020/2723), respectively. However, the percentage of samples with high HSV-1 genome copy numbers was greater in saliva than in tears, which may have been a result of the sample volume collected. Shedding frequency in tears was nearly the same for males (347/1003; 34.6%) and females (594/1705; 34.8%); in saliva, males had a higher frequency of shedding (457/1009; 45.3% vs. 563/1703; 33.1%, male vs. female, respectively). Overall, 49 of 50 (98%) subjects shed HSV-1 DNA at least once during the course of the 30-day study.
Conclusion The percentage of asymptomatic subjects who intermittently shed HSV-1 DNA in tears or saliva was higher than the percentage of subjects with positive ELISA or neutralization antibodies to HSV. Since most HSV transmission occurs during asymptomatic shedding, further knowledge of the prevalence of HSV-1 DNA in tears and saliva is warranted in order to control its spread. Shedding is simple to study, and its suppression might be an efficient way to evaluate new antivirals in humans.