Novel human herpesviruses and related diseases.

Three new human herpesviruses have been discovered recently: human herpesvi rus 6 (HHV-6), human herpesvirus 7 (HHV-7), human herpesvirus 8 (HHV-8). HH V-6 and HHV-7 were identified after their isolation from blood lymphocyte c ultures; HHV-8 was first detected by means of a specific molecular biology approach in the search for the etiologic agent of Kaposi's sarcoma. The thr ee viruses infect lymphocytes, T-cells in the case of HHV-6 and HHV-7, B-ce lls in the case of HHV-8 They also infect endothelial and epithelial cells. Human infection with HHV-6 and HHV-7 is ubiquitous and widespread while th e frequency of HHV-8 infection is increasing from Northern Europe to the ce nter of Africa. Polymerase chain reaction is the most common detection meth od for these three viruses in human samples. HHV-6 is the causative agent o f exanthem subitum and opportunistic infections. The pathogenicity of HHV-7 seems to be weak. HHV-8 is strongly associated with three lymphoproliferat ive diseases: Kaposi's sarcoma, Castleman's disease and primary effusion ly mphomas. (C) 2000 Editions scientifiques et medicales Elsevier SAS.