Human herpesvirus 8 infections in patients with immunodeficiencies.

Summary In 1994, Chang et al described a novel herpesvirus in tissues from patients with Kaposi sarcoma, referred to as Kaposi sarcoma herpesvirus or human herpesvirus 8. They used a very sophisticated technique of molecular biology to isolate unknown DNA sequences from Kaposi sarcoma lesions, which were not present in normal tissues. It turned out that these sequences corresponded to a previously unrecognized gamma herpesvirus highly homologous to human herpesvirus 4 (Epstein-Barr virus) and to herpesvirus saimiri. Contrary to Epstein-Barr virus, human herpesvirus 8 is not ubiquitous. The seroprevalence of human herpesvirus 8 varies greatly worldwide, with 1% to 10% of people being infected in developed countries and up to 80% of infected individuals in some areas of sub-Saharan and equatorial Africa. Human herpesvirus 8 is associated with a limited spectrum of tumors, mostly observed in immunodeficient individuals with HIV infection. Beside Kaposi sarcoma and multicentric Castleman disease, human herpesvirus 8 is associated with primary effusion lymphoma, but unlike Epstein-Barr virus, human herpesvirus 8 is not involved in epithelial tumors. Different proteins of the virus can be detected in infected cells. Antibodies against the latent nuclear antigen 1 are available in routine pathology and represent a powerful tool to detect the virus in human tissues. Although Epstein-Barr virus is the most frequent causative agent of lymphomas in immunocompromised individuals, a systematic screening of such tumors with specific antibodies reveals that the implication of human herpesvirus 8 infection is probably underestimated. Recent descriptions of non-Hodgkin lymphoma in endemic areas, solid localizations of primary effusion lymphoma, and posttransplantation lymphoproliferations have expanded the spectrum of human herpesvirus 8–related lymphoproliferative disorders. In this review, we will be presenting an overview of the recent concepts regarding human herpesvirus 8 and related disorders.