A method of producing an immunogenic conjugate, comprising the steps of: (a) derivatizing one or more functional groups of a carrier protein to generate an activated functional group on the carrier protein, wherein the carrier protein is selected from the group consisting of CRM197, Streptococcus pyogenes ORF1224, Streptococcus pyogenes ORF1664, Streptococcus pyogenes ORF2452, and Chlamydia pneumoniae ORF T858 (b) reacting a peptide immunogen comprising an Aß fragment with the carrier protein of step (a) under conditions to form a conjugate, wherein the peptide immunogen is covalently attached to the activated functional group on the carrier protein and (c) further reacting the conjugate of step (b) with a capping reagent to inactivate any remaining activated functional group on the carrier protein to generate the immunogenic conjugate, whereby the functionality of the carrier protein is preserved such that it retains its ability to elicit the desired immune responses against the peptide immunogen that would otherwise not occur without a carrier, wherein the conjugate has the formula: wherein C is the carrier protein, Xd is a derivatized functional group of the carrier protein, P is the peptide immunogen, R is a capping molecule formed by reaction of the conjugate with the capping reagent in step (c), n is an integer greater than 0, but less than or equal to 38, and p is an integer greater than 0, but less than or equal to 38.
