The present invention relates to (isolated) recombinant proteins, also referred to as improved MAT (iMAT) molecules, comprising at least one translocation module, at least one targeting module and at least one antigen module, wherein at least one cysteine residue is substituted with a different amino acid residue. Such iMAT molecules are useful specifically as vaccines, e.g. for therapy and/or prevention of allergies and/or infectious diseases and/or prevention of transmission of infectious diseases in animals, more preferably ruminants, pigs, dogs and/or cats, but excluding equines. The present invention further relates to nucleic acids encoding such iMAT molecules, corresponding vectors and primary cells or cell lines.