The present invention provides a chimeric polypeptide comprising a plurality of polypeptide domains that are capable of being secreted in combination with membrane vesicles and in particular exosomes.The invention also concerns the use of polypeptides of the invention and polynucleotides coding for these polypeptides, for the production of immunogenic compositions based on exosomes or DNA, to screen protein interactions. The present invention also concerns exploiting the properties of exosomes comprising a polypeptide of the invention and immunogenic compositions of the invention in immunology.The present invention concerns the use of exosomes comprising a polypeptide of the invention as a diagnostic tool.The present invention also concerns exploiting the properties of membrane vesicles and protein compositions of the invention for the prophylaxis and/or treatment of a disease due to a functional deficit, in particular to transport a protein or a nucleic acid, in particular to compensate for or make up for an enzymatic deficit, or in particular to induce a transcriptional or translational modification in the target cells or organs.