Abstract: A nucleic acid including (i) a sequence of a S gene coding for a Spike protein and (ii) a sequence coding for a pilot peptide which interacts with ESCRT proteins. Also, extracellular vesicles, in particular exosomes, harboring at their external surface a Spike protein, obtainable by transfecting cells with the nucleic acid. Further, a method of immunizing a subject against a virus of the Orthocoronavirinae subfamily, in particular against SARS-CoV-2, by DNA prime-protein boost using the nucleic acid and the extracellular vesicles of the invention.