SEROEPIDEMIOLOGY OF HUMAN HERPESVIRUS-7 IN HEALTHY-CHILDREN AND ADULTS IN JAPAN

The isolation of human herpesvirus 7 (HHV-7) from saliva and blood, an d the prevalence of antibodies to the virus in healthy individuals wer e investigated in Japan. By cocultivating samples with phytohemaggluti nin-P-stimulated cord blood mononuclear cells, HHV-7 was isolated from the saliva of 1 of 20 children and from 4 of 38 adults but not from t heir blood. The isolates were confirmed as closely related to RK strai n of HHV-7, but not to U1102 (human herpesvirus 6, HHV-6 type A) or Z2 9 (HHV-6 type B) strains by restriction cleavage patterns of the DNA. The virus antibody of 330 healthy children and adults was measured wit h an indirect immunofluorescence assay, using one of our isolates (FG7 -6). The positivity rate of antibody was 40% in the first 2 months of life, declined during the first 6 months, then gradually increased and was 45% at 1-4 years of age. It reached the highest level (60%) at 11 -13 years of age and was maintained until the end of the third decade, then decreased thereafter. Additionally, no simultaneous rise in the antibody titers was observed in 7 virologica lly confirmed exanthem su bitum patients. (C) 1993 Wiley-Liss, Inc.