Measurement of human herpesvirus 7 load in peripheral blood and saliva of healthy subjects by quantitative polymerase chain reaction.

Qualitative and competitive-quantitative nested polymerase chain reaction (PCR) assays were developed for human herpesvirus 7 (HHV-7). These assays amplify a DNA sequence encoding part of the HHV-7 homologue of the human herpesvirus 6 (HHV-6) U42 gene. The PCR assays were used to analyze peripheral blood DNA (pbDNA) and saliva from 24 healthy volunteers. The prevalence of HHV-7 in saliva was 96%, with a median virus load of 1.1 x 10(6) copies/mL. Longitudinal analysis revealed sustained virus load, suggesting continued active viral replication. Analysis of 1 microgram of pbDNA showed the prevalence of HHV-7 to be 83%, with a median virus load of 40 copies (267 copies/10(6) cells). Analysis of sequential pbDNA samples showed individuals to have stable levels of HHV-7 virus load. These data demonstrate persistence of HHV-7 at two distinct sites and provide baseline data allowing comparisons with HHV-7 load in immunocompromised patients.