Furthermore, a mixed infection with PCV-2a and PCV-2b occurred in the liver and lungs of 1 pig. Comparison of whole genome sequences representing known viruses and the newly discovered Alberta viruses revealed mutations distributed over the entire genome of PCV-2; however, sequences encoding for immunodominant epitopes of PCV-2 appear to be unaffected by these mutations.
L. McIntyre, M. Chaiyakul, E.G. Clark, F. Marshall, M. Czub. Genomic analysis of porcine circovirus type-2 isolates in Alberta pigs demonstrating clinical porcine circovirus associated disease (PCVAD). Canadian Journal of Veterinary Research. April 2010.