[Kaposi's disease and HHV8: a new model of virus-induced tumorigenesis]

Kaposi's sarcoma (KS) is a skin disease characterised by spindle cells proliferation and neovascularisation which, in 1994, was associated with a new Gammaherpesvirinae, named human herpesvirus 8 (HHV8). The HHV8 genome, containing more than 140 kilobases, includes genes encoding structural proteins and enzymes, and some homologues to cellular genes which could have been captured in host cells during viral evolution. Several HHV8 proteins interfere with the host cellular cycle either by inhibiting apoptosis or by positive regulation of the cell cycle (viral cyclin or v-cyclin, v-bcl-2, v-FLIP). HHV8 also contains potential oncogenes (v-IRF and v-GPCR, which promote angiogenesis, in particular the secretion of VEGF) as well as homologues of human cytokines and chemokines (v-IL6, v-MIP). HHV8 is clearly associated with KS, multicentric Castleman disease and primary effusion lymphoma. Most of the cells are infected by latent virus, resulting in persistent infection of the lesions. Only a minority of infected cells yield infectious viral particles, and their role in the development of KS and other associated diseases has not been clearly established. The molecular mechanisms and cofactors involved in the physiopathology of this infection have yet to be identified.