An enzyme-activated loop primer probe LAMP method based on a new SNP site in the group_17537 gene for rapid on-site detection of Salmonella Pullorum

Pullorum disease (PD) is a widespread disease that causes significant economic losses within the poultry industry of developing countries. An effective strategy for its prevention and control involves the implementation of decontamination procedures utilizing highly specific on-site detection techniques. In this study, a single-nucleotide polymorphism (SNP) site within the group_17537 gene of Salmonella enterica serovar Gallinarum biovars Pullorum (S. Pullorum) was found by using bioinformatics tools. The prevalence of this SNP among 165 strains of S. Pullorum was determined to exceed 96.3 %. The SNP exhibited a specificity rate greater than 99.9 %, with only 0.08 % detected among 2490 non-target Salmonella strains. It can be concluded that this SNP can be employed to distinguish S. Pullorum from other serotypes of Salmonella, specifically Salmonella enterica serovar Enteritidis (S. Enteritidis) and Salmonella enterica serovar Gallinarum biovars Gallinarum (S. Gallinarum). Additionally, an enzyme-activated loop primer probe LAMP (EALP-LAMP) was developed based on this SNP site for the detection of S. Pullorum. This method exhibited excellent specificity and reproducibility, achieving limit of detection of 53.5 copies/µL with plasmid DNA and 0.2 pg/µL with genomic DNA. Moreover, in clinical applications involving 190 chick embryo samples from poultry farms, 24 samples identified as S. Pullorum positive, aligning with results obtained through traditional isolation and quantitative real-time PCR (qPCR) methods. These fingdings highlight the significant potential of this method, which offers accurate, rapid, on-site and visual detection of S. Pullorum.