Abstract: The invention relates to immunogenic or vaccine compositions and their use in particular in the prevention or treatment of infectious or cancer disorders. More specifically, the immunogenic or vaccine compositions of the present invention comprises a ribonucleic acid (RNA) molecule comprising an open-reading frame encoding a fusion protein, wherein said fusion protein comprises or essentially consists of: (i) a first polypeptide domain comprising either a. an antigen or a fragment thereof comprising at least one epitope of said antigen, b. a peptide moiety comprising a single epitope of an antigen, or c. a plurality of peptide moieties, wherein each peptide moiety comprises an epitope of an antigen and wherein said peptide moieties are fused together, optionally via peptide linker, said first polypeptide domain being fused to (ii) a second polypeptide domain comprising a C4bp-derived oligomerization domain and a positively charged tail.