The aim of this study is to screen for genetic resistance to different doses of salmonella infection and its possible association with polymorphisms in exon 1 and 2 of TLR4 in Fayoumi breed and Hy-line strain of chickens. Two experiments was done, first one for measuring the variation of TLR4 -exon 1 and exon 2 of different genotypes of chicken under study and resistance to salmonella enteritidis. This study include 100 birds of each breeds, were infected orally with LD50 (108 cfu) salmonella enteritidis at age of two weeks and was divided into two groups (susceptible and resistance). TLR4 gene was genotyped with PCR-RFLP, The genotyping results on exon 1 (596 bp) by Taq1 restriction enzyme showed that the BB genotypes is more resistance to infection in the Fayoumi breed and also the AB genotypes is more resistance to infection in the Hy-line strain. Also The genotyping result on exon 2 (793 bp) by EcoR1 restriction enzyme showed only one genotype BB in Fayoumi breed and The frequency of AB genotypes is more resistant to infection than BB genotypes in Hy-line strain. The second experiment to evaluate the variation in immune response to the different genotypes of TLR4 -exon 1 and exon 2 this study include 100 birds of each breeds were infected with (5× 107 cfu) salmonella enteritidis and according to Elisa results the chickens devided into two groups (high and low immune response). The genotyping result on exon 1 (596 bp) by Taq1 restriction enzyme showed that the AB genotypes produce high immune response in both Fayoumi breed and Hy-line strain so can be used as a genetic marker for increase the immune response in chicks under study. Also The genotyping result on exon 2 (793 bp) by EcoR1 restriction enzyme showed only one genotype BB genotypes in Fayoumi breed and Hy-line strain.
Tol-like receptor, polymorphism, genetic resistance, salmonella enteritidis chicken