The present invention relates to polymerized recombinant proteins, to recombinant nucleic acids coding for the polymerized recombinant proteins, to expression cassettes comprising the recombinant nucleic acids, to host cells transformed by the expression cassettes and to a method for multimerizing a recombinant protein. The polymerized proteins of the invention may be used in pharmaceutical or immunogenic compositions. In particular, the recombinant proteins may be antigens, antibodies or scaffolds. In particular, the polymerized recombinant protein may be an influenza haemagglutinin.