A rapid method to identify Salmonella enterica serovar Gallinarum biovar Pullorum using a specific target gene ipaJ

Avian Pathol. 2018 Jun;47(3):238-244. doi: 10.1080/03079457.2017.1412084. Epub 2018 Feb 19.

Abstract

Salmonella enterica serovar Gallinarum biovar Pullorum (S. Pullorum) is the pathogen of pullorum disease, which leads to severe economic losses in many developing countries. Traditional methods to identify S. enterica have relied on biochemical reactions and serotyping, which are time-consuming with accurate identification if properly carried out. In this study, we developed a rapid polymerase chain reaction (PCR) method targeting the specific gene ipaJ to detect S. Pullorum. Among the 650 S. Pullorum strains isolated from 1962 to 2016 all over China, 644 strains were identified to harbour ipaJ gene in the plasmid pSPI12, accounting for a detection rate of 99.08%. Six strains were ipaJ negative because pSPI12 was not found in these strains according to whole genome sequencing results. There was no cross-reaction with other Salmonella serotypes, including Salmonella enterica serovar Gallinarum biovar Gallinarum (S. Gallinarum), which show a close genetic relationship with S. Pullorum. This shows that the PCR method could distinguish S. Gallinarum from S. Pullorum in one-step PCR without complicated biochemical identification. The limit of detection of this PCR method was as low as 90 fg/μl or 102 CFU, which shows a high sensitivity. Moreover, this method was applied to identify Salmonella isolated from the chicken farm and the results were consistent with what we obtained from biochemical reactions and serotyping. Together, all the results demonstrated that this one-step PCR method is simple and feasible to efficiently identify S. Pullorum.

Keywords: PCR; Salmonella enterica serovar Gallinarum biovar Pullorum (S. Pullorum); ipaJ gene; sensitivity; specificity.

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Chickens / microbiology*
  • China
  • Plasmids / genetics
  • Polymerase Chain Reaction / veterinary
  • Poultry Diseases / diagnosis*
  • Poultry Diseases / microbiology
  • Salmonella Infections, Animal / diagnosis*
  • Salmonella Infections, Animal / microbiology
  • Salmonella enterica / classification*
  • Salmonella enterica / genetics
  • Salmonella enterica / isolation & purification
  • Sensitivity and Specificity
  • Serogroup

Substances

  • Bacterial Proteins