ABSTRACT
1. The aim of the present study was to determine if the 9R-strain of the Salmonella Gallinarum live vaccine was responsible for having fowl typhoid outbreaks in chicken flocks from both chicken and turkey breeders as well as to verify the antimicrobial resistance of the isolates from the outbreaks. 2. The triplex polymerase chain reaction, standard antimicrobial test, beta-lactamase genes identification and Ion Torrent PMG whole-genome sequence were used in the field isolates and in the vaccine strain of S. Gallinarum. 3. The 60 tested isolates were not from vaccine origin and manifested high resistance to drugs from macrolide and quinolone groups. Whole-genome sequencing (WGS) and single nucleotide polymorphism analysis on selected isolates for core genes from Salmonella enterica confirmed the wild origin of these isolates and showed two possible sources of S. Gallinarum in the studied outbreaks. 4. S. Gallinarum isolated from fowl typhoid outbreaks in the studied period were not caused by the use of the SG9R live vaccine. The source of strains sequenced was diverse.
Subject(s)
Chickens , Drug Resistance, Bacterial , Genome, Bacterial , Poultry Diseases/epidemiology , Salmonella Infections, Animal/epidemiology , Salmonella enterica/physiology , Turkeys , Animals , Brazil/epidemiology , Phylogeny , Polymorphism, Single Nucleotide , Poultry Diseases/microbiology , Salmonella Infections, Animal/microbiology , Salmonella Vaccines/analysis , Salmonella enterica/classification , Salmonella enterica/genetics , Sequence Alignment/veterinary , Vaccines, Attenuated/analysis , Whole Genome Sequencing/veterinaryABSTRACT
Salmonella flagellin, expressed as flagella in live attenuated vaccine strains, elicits distinct systemic (IgG) and secreted (IgA) antibodyresponses in mice following delivery via mucosal (nasal/oral) or parenteral (intraperitoneal (i.p.)) immunization routes. Reduced flagellinspecificantibodies were detected either systemically or locally following delivery of flagellated derivatives of aroA Salmonella entericaserovar Dublin SL1438 via the nasal route, the most effective mucosal site for activation of immune responses in mice. In contrast, flagellinrepresents the most potent Salmonella antigen for the generation of specific serum antibody (IgG) responses following i.p. inoculations. Thedistinct immunogenic properties of Salmonella flagellin could not be ascribed to deficient colonization, reduced invasive ability or loss of theflagellin expression by the flagellated vaccine strains.
