In this study, the prevalence of Salmonella typhimurium in Egyptian chicken farms was studied. Examination of 79 chicken farms distributed in Egypt governorates from 2017 to 2019. Salmonella was detected in broiler flocks 20 % positivity (18 out of 90). However, in layer flocks showed 70 % positivity (7 out of 10). Then Salmonella typhimurium was confirmed using Salmonella typhimurium STM4 495 gene using conventional PCR.
Lipopolysaccharides (LPSs) are the major constituent of the bacterial Gram-negative outer membrane including Salmonella. (LPSs) is an immunodominant molecule that is important for the virulence and pathogenesis of Salmonella typhimurium which called endotoxin. Extraction and purification of LPS from isolated S. typhimurium using isopropanol and sodium hydroxide mixture this overcome the presence of nucleic acids of extracted Salmonella in the final product. The purity of LPS isolated from Salmonella typhimurium was assessed by HPLC showing highly purified extracted LPS. Effect of extracted LPS of Salmonella typhimurium on poultry immunity were studied via a biological experiment using Chicks of the broiler breeds to assess the response to LPS stimulation via in vivo experiment using Different concentrations of extracted LPS (50,100,150 and 200 μg/kg) were injected subcutaneously in 21-day old SPF chicks. After 3 hours of injection samples taken to assest of the effect of LPS on RNA expression of the immune-related genes; interferon-γ (IFN-γ) and interleukin 1β (IL-1β). There was significant upregulation of IFN-γ and low downregulation of IL-1β of the immune-related genes.