Hybrid picornaviruses expressing chlamydial epitopes from the major outer membrane protein of Chlamydia trachomatis in a functional form are described. The hybrid viruses grow to high titre in cell culture and when administered to mammals induce an immune response against both the picornavirus and C. trachomatis. The antisera from immunised mammals neutralised both homotypic and heterotypic serovars of C. trachomatis. The hybrid picornaviruses have utility as vaccines and as tools for the generation of immunological reagents. Methods for modifying surface exposed loops of known sequences to produce hybrid proteins are described.
