Evolution and genomic profile ofserovar Gallinarum biovar Pullorum isolates from Brazil.

Abstract

subspeciesserovar Gallinarum biovar Pullorum (Pullorum) is a pathogenic bacterium that causes Pullorum disease (PD). PD is an acute systemic disease that affects young chickens, causing white diarrhea and high mortality. Although many sanitary programs have been carried out to eradicatePullorum, PD outbreaks have been reported in different types of birds (layers, broilers, breeders) worldwide. This study aimed to evaluate the evolution and genetic characteristics ofPullorum isolated from PD in Brazil. Phylogenetic analysis ofPullorum genomes sequenced in this study and available genomic databases demonstrated that all isolates from Brazil are from sequence type 92 (ST92) and cluster into two lineages (III and IV). ColpVC, IncFIC(FII), and IncFII(S) were plasmid replicons frequently found in the Brazilian lineages. Two resistance genes (', conferring resistance to aminoglycoside, disinfecting agents, and antiseptics () and tetracycline () were detected frequently. Altogether, these results are important to understand the circulation ofPullorum and, consequently, to develop strategies to reduce losses due to PD.