Comparative Genomics of Actinobacillus pleuropneumoniae Serotype 8 Reveals the Importance of Prophages in the Genetic Variability of the Species

Abstract EN

Actinobacillus pleuropneumoniae is the etiologic agent of porcine pleuropneumonia.

Currently, there are 18 different serotypes; the serotype 8 is the most widely distributed in the United States, Canada, United Kingdom, and southeastern Brazil.

In this study, genomes of seven A.

pleuropneumoniae serotype 8 clinical isolates were compared to the other genomes of twelve serotypes.

The analyses of serotype 8 genomes resulted in a set of 2352 protein-coding sequences.

Of these sequences, 76.6% are present in all serotypes, 18.5% are shared with some serotypes, and 4.9% were differential.

This differential portion was characterized as a series of hypothetical and regulatory protein sequences: mobile element sequence.

Synteny analysis demonstrated possible events of gene recombination and acquisition by horizontal gene transfer (HGT) in this species.

A total of 30 sequences related to prophages were identified in the genomes.

These sequences represented 0.3 to 3.5% of the genome of the strains analyzed, and 16 of them contained complete prophages.

Similarity analysis between complete prophage sequences evidenced a possible HGT with species belonging to the family Pasteurellaceae.

Thus, mobile genetic elements, such as prophages, are important components of the differential portion of the A.

pleuropneumoniae genome and demonstrate a central role in the evolution of the species.

This study represents the first study done to understand the genome of A.

pleuropneumoniae serotype 8.