Genetic polymorphisms and expression patterns of TLR4 gene in commercial broiler breeds

Abstract

Genetic polymorphisms and expression pattern of TLR4 gene were studied in 300 one-day-old chicks of three breeds (Cobb, Avian and Ross) using PCR-RFLP and real time PCR. Blood samples were collected from chicks of each breed for DNA extraction. Spleens from randomly selected ten female chicks from each breed were collected for RNA extraction. PCR-TaqI digestion of 596-bp of a fragment of exon 1 of TLR4 gene revealed two fragments (460 and 136-bp) for the genotype BB in all breeds and three fragments (596, 460 and 136-bp) for the genotype in Ross and Avian breeds. The incidence of TLR4 genotypes and the frequencies of alleles indicated that B allele was more frequent than A allele in the population of all breeds. Gene expression pattern of TLR4 revealed a significant up-regulation in Avian breed than Cobb and Ross as shown by the lower value of ΔCT. It could be concluded that genetic TLR4/TaqI locus polymorphism could be used as a marker assisted selection (MAS) for immune traits in commercial breeds of broilers. Also, changes in the expression patterns of TLR4 gene could be a biomarker to follow up immune status of chicks to predict the most susceptible risk time for disease incidence and to build up an effective management regimen.