[Human herpesvirus 6 (HHV-6)]

Human herpesvirus 6 (HHV-6) was first isolated in 1986, and it was proposed that this virus causes exanthem subitum (ES) by the following evidence; HHV-6 can be isolated from ES patients at high frequency, and the antibody titer to HHV-6 in patients increased significantly during the convalescent phase of ES. This virus transmits horizontally mainly form mother to child during infancy. HHV-6 DNA can be detected in the cerebrospinal fluid (CSF) of ES patients having neurological symptoms, and also in CSF of patients with frequent febrile convulsions after ES, suggesting high affinity to nervous system. Furthermore, HHV-6 infects latently in macrophage-like cells after the primary infection.