Polymerase chain reaction assay based on ratA gene allows differentiation between Salmonella enterica subsp. enterica serovar Gallinarum biovars Gallinarum and Pullorum

Abstract

Salmonella Pullorum and Salmonella Gallinarum are classified as biovars of Salmonella enterica subsp. enterica serovar Gallinarum. These salmonellae are the causative agents of Pullorum disease and fowl typhoid, respectively, and are widely distributed throughout the world. Although many developed countries have eradicated these diseases from commercial poultry, they are still the cause of significant economic loss in developing countries. When serovar Gallinarum is isolated, it is difficult to immediately differentiate between biovars because they are antigenically identical by serotyping. However, they cause distinct diseases with different epidemiology, and therefore it is important to differentiate them. This may be done biochemically but takes 2 to 3 days. In the present study, S. Pullorum and S. Gallinarum whole genomes were compared, and 1 genomic region of difference, which is part of the ratA gene, was chosen as a molecular marker for a polymerase chain reaction assay to differentiate rapidly between these organisms. In all, 26 strains of S. Gallinarum and 17 S. Pullorum strains were tested and successfully differentiated by the assay.

Molecular identification of Salmonella enterica subsp. enterica serovar Gallinarum biovars Gallinarum and Pullorum by a duplex PCR assay

“…3 However, as reported previously, the ratA CDS may be found in other Salmonella genomes. 3 Thus, misinterpretation might arise if the tested DNA does not come from Salmonella isolates of serovar Gallinarum. In this study, we have overcome this impairment by introducing a second pair of primers into the PCR reaction.…”

“…Previously, we developed a polymerase chain reaction (PCR) assay, based on a polymorphism in the ratA coding sequence (CDS) able to differentiate biovars Gallinarum and Pullorum. 3 However, as reported previously, the ratA CDS may be found in other Salmonella genomes. 3 Thus, misinterpretation might arise if the tested DNA does not come from Salmonella isolates of serovar Gallinarum.…”

A Sensitive, Highly Specific Novel Isothermal Amplification Method Based on Single-Nucleotide Polymorphism for the Rapid Detection of Salmonella Pullorum

“…Hence, the polymorphisms at positions 237 represent a potential robust molecular target for the specific detection of S. Pullorum (Luk et al, 1993;Shah et al, 2005;Ren et al, 2017). Furthermore, this target is present in all S. Pullorum strains, unlike the gene ipaj (Xu et al, 2018) which only exists in a plasmid not carried by all the strains, or the ratA gene which is not specific enough to be found in other Salmonella serotypes genomes, our method will not overlook any strains or cause false detection (Batista et al, 2013(Batista et al, , 2016. Through the choice of this ideal detection target and the original design reaction scheme, our method has great inclusivity due to the fact that all 55 strains of S. Pullorum were successfully detected while 31 strains of other different Salmonella serovars and 9 strains of non-Salmonella pathogens did not cause interference, even when there was only one base difference in the target gene, like those for S. Gallinarum and S. Enteritidis.…”

Phenotypic and genotypic characterization of locally isolated Salmonella strains used in preparation of Salmonella antigens in Egypt

“…In bacterial genomes, pseudogenes are continually created from ongoing mutational processes and are subject to degradation and removal by further accumulation of mutations. Their retention time seems to be extremely short and, even in very closely related bacteria, they tend to be deleted at a relatively rapid rate [26]. All these findings decreased the sensitivity and reliability of this duplex PCR.…”