The present invention comprises methods and compositions related to the production and use of amino acid sequences. In particular, PCV2 ORF2 is shown to be useful as a virus-like particle which produces amino acid sequences that retain their immunogenicity or antigenicity when the DNA encoding the PCV2 ORF2 is inserted into an expression system. DNA sequences that are foreign to PCV2 can be attached “in-frame” to the ORF2 DNA and the entire sequence, including the DNA foreign to PCV2, is expressed. It was shown that such sequences retain their antigenicity and therefore their potential utility in immunogenic compositions.
