ABSTRACT
The involvement of viral infections in the genesis of cancers is currently established. However, the narrow correlation between viruses and the activation of telomerase was defined only recently. The telomerase activity is detected in more than 85 % of human cancers and would take part to immortalization processes, associated with cellular transformation. The active minimal complex of telomerase is composed of a RNA subunit comprising a template sequence which is reverse-transcribed onto telomeres by a proteic component TERT. A disregulation of telomerase activity was observed consecutively to infection by viruses from various families. This phenomenon would mainly rest on modulation of the expression and the nuclear targeting of TERT by viral proteins or further to viral genome integrations close to the TERT gene. Moreover, the Marek's Disease herpesvirus, responsible of T-lymphomas in chickens, is particular in that it encodes, within its genome, a viral telomerase RNA subunit, vTR, which induces a more greater telomerase activity than its avian cellular counterpart, cTR.