Human herpesvirus type-8 (HHV-8) in haematopoietic neoplasia

Human herpesvirus type-8 (HHV-8) is a lymphotropic herpesvirus originally identified in Kaposi's sarcoma. Among lymphoproliferative disorders, HHV-8 infection is restricted to body-cavity-based lymphoma (BCBL) and multicentric Castleman's disease (MCD). BCBL are B-cell lymphomas growing in liquid phase in the body cavities and most frequently associated with AIDS. BCBL express indeterminate phenotypes, in all cases are associated with HHV-8 infection, and frequently carry Epstein-Barr virus genomes in the absence of c-MYC rearrangements or other genetic lesions characteristic of B-cell lymphomas. The clinical outcome of BCBL is poor with a median survival of only few months. MCD is an atypical lymphoproliferative disorder which displays marked vascular hyperplasia and is commonly associated with Kaposi's sarcoma. HHV-8 infection occurs in 100% of AIDS-related MCD and in approximately 40% of AIDS-unrelated cases. Overall, the consistency of HHV-8 infection in BCBL and MCD, its selectivity throughout the spectrum of lymphoproliferative disorders and the high copy number of HHV-8 DNA sequences in infected cells suggest that the virus plays a pathogenetic role in these disorders.