Monitoring of human herpesvirus-6 and -7 genomes in saliva samples of healthy adults by competitive quantitative PCR

Abstract

Human herpesviruses-6 and -7 (HHV-6 and HHV-7) are thought to be transmitted during early infancy through saliva. However, the kinetics of the virus shedding in saliva of healthy adults, from whom children are assumed to acquire the viruses, is mostly unknown. This study was conducted to determine how many copies of the genome are secreted in saliva of healthy adults and to clarify the relationship between viral DNA load and virus isolation of HHV-6 and HHV-7. Competitive PCR was performed using primer sets in the U42 gene of each viral genome. In saliva samples from 29 healthy adults, HHV-6 and HHV-7 DNA was detected in 41.4% and 89.7%, respectively. The average copy number of the HHV-7 genome in the positive samples was higher than that of the HHV-6 genome. Follow-up studies of six seropositive individuals for 3 months showed that the amount of HHV-7 DNA was constant in each individual and that "high producers" and "low producers" could be distinguished. By contrast, the amount of HHV-6 DNA varied drastically over time in each individual. Although HHV-6 was never isolated from the saliva of any of the six individuals during the follow-up period, HHV-7 was isolated from each individual several times. The amount of HHV-7 DNA tended to be higher at the times when the virus was isolated than at the times when the virus was not isolated. These data demonstrate a striking contrast between HHV-6 and HHV-7 in the kinetics of genome and virus shedding.

Effect of Prophylactic Valacyclovir on the Presence of Human Herpesvirus DNA in Saliva of Healthy Individuals after Dental Treatment

“…Therefore, in these regards, our data are novel. Our median copy number yields for positive samples are similar to values reported by several investigators (8,15,17,27,42,66) but lower than that reported by Walling et al (80) for EBV (1,110,000 in 0.5 g of DNA). Differences could be attributed to selection bias from their use of smaller numbers of patients, regional population differences, or the facts that we examined HSV-seropositive individuals, samples were freeze-thawed, and DNA was analyzed from the cellular fraction of saliva.…”

Real-Time PCR for Quantification of Human Herpesvirus 6 DNA from Lymph Nodes and Saliva

“…The virus was found in 76.5% of this normal population, which is similar to previously published prevalence values (9,15). Viral loads for positive samples ranged between 2,240 and 347,328 copies per ml for fresh extracts.…”

Latent infection of human herpesvirus 7 in CD4+ T lymphocytes

“…The quantities of the viral DNA in saliva also vary among individuals [Kidd et al, 1996;Fujiwara et al, 2000]. A longitudinal viral isolation study [Ihira et al, 2003] suggested that persistent HHV-7 infection of the salivary glands and CD4 þ T cells might be regulated by host factors.…”