[HHV 6,7 and 8. Recently discovered herpesviruses explain the etiology of well-known diseases].

Three new members of the family of human herpesviruses (HHVs) have been identified in less than a decade, HHV 67 and 8. HHV-6 and HHV-7, both infecting T-lymphocytes and phylogenetically related to cytomegalovirus, were identified as causative agents of exanthema subitum. In addition, HHV-6 has been reported to manifest central nervous system tropism and to be frequently detected in normal brain tissue, but has also been associated with febrile seizures. HHV-7 has been suggested to be involved in the development of pityriasis rosea, but has also been found to occur in normal dermal tissue. HHV-8, related to Epstein-Barr virus and infecting B-lymphocytes, was the first herpesvirus to be identified with molecular techniques. Recent research has been focused on the involvement of proteins expressed by HHV-8 in the pathogenesis of two rare tumours, Kaposi's sarcoma and body-cavity B-cell lymphomas.