[Retroviral inheritance in man].

The data provided by the sequencing of the human genome showed that retroviral-like elements constituted approximately 8 % of the euchromatin. The origin of these elements, their propagation leading to an organization in families, their genetic structure and the identification of the fonctional domains of the components of these elements are described. Placenta is used as a model to illustrate the physiological involvement of HERVs. Transcriptional regulatory element (LTR) functions and the putative implication of retroviral proteins in resistance to infection, immunosuppression, and cellular differentiation are clarified. The data implicating the envelope encoded by the ERVWE1 locus of the HERV-W family in the fusion process, leading to syncytiotrophoblast formation, is analysed. The putative pathological effect of HERVs is illustrated by the expression of the HERV-K superfamily in cancer. More precisely, the association between the Rec regulatory protein encoded by HERV-K(HML-2) and testicular tumorigenesis is developed. Whether HERVs are triggers or markers in other physiopathological contexts is discussed. To conclude, the dual benefit-hazard underlying the acquisition/propagation of HERVs is examined with respect to species evolution, considering the multicopy trait of HERV families and the mainly multi-factorial aspect of autoimmune diseases and cancers.