EXPRESSION PROFILE OF TLR7 GENE IN LYMPHOID TISSUES OF THE NIGERIAN INDIGENOUS AND ISA BROWN COMMERCIAL LAYER CHICKENS

Abstract

This work was designed to evaluate the expression profile of toll-like receptor 7 (TLR7)gene in the liver and thymus tissues from the Nigerian indigenous chickens and ISA Brown commercial layer chicken. The study population comprises naked neck, normal and frizzled-feathered chickens in rain forest and Guinea Savannah regions respectively; Fulani ecotype chicken from Guinea Savannah region, and ISA brown (exotic) commercial layer chicken. Tissues from the thymus and the liver were
aseptically collected from two (2) clinically healthy chickens from each of the eight (8) groups and were immediately transferred into separate 1.5 ml Eppendorf tubes containing 1 ml of RNALater solution. Total RNA was isolated using ISOLATE II RNA Mini kit (BIOLINE, USA). Complementary DNA (cDNA) was synthesized using SensiFASTTMcDNA synthesis kit (BIOLINE, USA), following manufacturer‟s instructions. The expression of chTLR7 RNA was determined by qPCR assay; β-actin was used as the reference gene. Constitutive expressions of TLR7 in the liver and thymus were significantly different (P<0.01) among the eight chicken groups; the Nigerian indigenous chickens expressed more TLR7 gene than ISA brown commercial layer chicken. Rain forest naked neck chicken had significantly (P<0.01) the highest TLR7 expression of 2.07±0.07 fold. However, expression of TLR7 gene in the liver of rain forest frizzle-feathered and normal chicken, Guinea Savannah naked neck, frizzle-feathered and normal chicken, and Fulani ecotype chicken were similar (P>0.05). Gene expression analysis of TLR7 mRNA suggests that the Nigerian indigenous chicken genotypes could have similar antiviral response, but comparatively more antiviral immune response
than ISA brown (exotic) commercial layer chicken.