Method for conjugating a peptide immunogen by a reactive group of an amino acid residue of the peptide immunogen with a protein / polypeptide transporter having one or more functional groups, the method comprising the steps of: (a) derivatizing one or more of the functional groups of the protein / polypeptide transporter for generating a derivatized transporter with reactive sites, in which the transporter is selected from the group consisting of CRM197, ORF1224 of Streptococcus pyogenes, ORF1664 of Streptococcus pyogenes, ORF2452 of Streptococcus pyogenes and ORF T858 of Chlamydia pneum； (b) reacting the derivatized protein / polypeptide transporter of step (a) with a reactive group of an amino acid of the peptide immunogen under reaction conditions such that the peptide immunogen is conjugated to the protein / polypeptide transporter derivatized by the functional groups； and (c) further reacting the conjugate with N-acetylcysteamine to inactivate unreacted reactive free functional groups in the derivatized protein / polypeptide transporter, thus preserving the functionality of the transporter, so as to retain its ability to induce the desired immune responses against the peptide immunogen that would not otherwise be produced without a transporter, in which the conjugate has the formula: ** Formula ** in which C is the protein / polypeptide transporter, Xd is a functional group derivatized from the protein / polypeptide transporter , P is the peptide immunogen, R is a protective molecule, n is an integer greater than 0, but less than or equal to 85, and p is an integer greater than 0, but less than or equal to 85.Método para conjugar un inmunógeno peptídico mediante un grupo reactivo de un resto aminoacídico del inmunógeno peptídico con un transportador proteico/polipeptídico que tiene uno o más grupos funcionales, comprendiendo el método las etapas de: (a) derivatizar uno o más de los grupos funcionales del transportador proteico/polipeptídico para generar un tran
