Low levels of diversity among genomes of Porcine circovirus type 1 (PCV1) points to differential adaptive selection between Porcine circoviruses

Several features related with the evolutionary patterns among all the PCV1 genomes available at GenBank have been analyzed in the present work (diversity, number of genotypes, recombination, saturation, selection, evolutionary rate). The reported results point to low levels of nucleotide and amino acid diversity, low number of positively selected codons and a slow evolution rate. Compared with the other species of the Circoviridae family, the diversity is the lowest reported. This can be related with the fact that PCV1 is the single non-pathogenic member of the family. Overall, differential levels of adaptive evolution between PCV1 and PCV2 may explain the different diversity levels, and the different evolutionary and selection rates observed.