Validation of a DIVA qPCR Duplex Assay to Differentiate Primun Salmonella T Vaccine from Salmonella enterica subsp. enterica Serovar Typhimurium Wild Strains

Salmonella enterica subsp. enterica serovar Typhimurium is an important foodborne pathogen, and poultry products are a major source of human infection. Live attenuated vaccines for poultry are an effective tool for reducing the prevalence of infection, but vaccine strains must be differentiated from wild strains to ensure effective disease surveillance and control. This study reports the validation of the SalTypm&PriSal-T qPCR Duplex kit, a DIVA qPCR assay for the differentiation of the Primun Salmonella T vaccine from wild strains using DNA extracted from isolated colonies. Analytical specificity and sensitivity, as well as diagnostic specificity and sensitivity, were evaluated with optimal results. This qPCR assay significantly reduces the time required to obtain a diagnostic result compared to reference methods based on antibiogram differentiation. Notably, this is the first qPCR test available worldwide for distinguishing this vaccine from wild strains, providing a valuable tool for improving the efficiency and accuracy of Salmonella surveillance programs in poultry production systems.