Polymorphisms of chicken Toll-like receptors 4, 15, and 21 in different breeds.

Toll-like receptors (TLR) mediate immune responses via the recognition of pathogen-associated molecular patterns, thus playing important roles in host defense. Among the chicken (Ch) TLR family, ChTLR1, 2, 4, 15, and 21 were shown to recognize bacterial components. In our earlier study, we reported polymorphisms of TLR1, 2, and 5. In the present study, we cloned TLR4, 15, and 21 genes from different chicken breeds and analyzed their sequences. We identified 9 amino acid polymorphism sites in ChTLR4 with 8 extracellular domain sites and 1 site in the cytoplasmic domain, 15 amino acid polymorphism sites in ChTLR15 with 14 extracellular domain sites and 1 site in the cytoplasmic domain, and 7 amino acid polymorphism sites in ChTLR21 with 5 extracellular domain sites and 2 sites in the cytoplasmic domain. These results demonstrate that ChTLR genes are polymorphic among different avian breeds, suggesting a varied resistance across numerous chicken breeds. This information might help improve chicken health by breeding and vaccination.

Toll-like receptor 2 type 1 and type 2 polymorphisms in different chicken breeds.

Toll-like receptors mediate immune responses via recognition of pathogen-associated molecular patterns. Polymorphisms of toll-like receptors may affect their recognition of pathogen-associated molecular patterns, leading to varied host resistance to pathogenic infections. However, little is known about the polymorphisms of chicken toll-like receptors (ChTLR) among breeds. In this study, we cloned ChTLR2 type 1 and type 2 genes from 7 chicken breeds and analyzed their sequences. It was found that there were 10 amino acid polymorphism sites in ChTLR2 type 1 and type 2, among which 6 sites were in type 1 (5 sites in the extracellular domain and 1 site in the cytoplasmic domain) and 4 sites were in type 2 (all 4 sites in the extracellular domain). These results demonstrate that ChTLR2 type 1 and type 2 genes are polymorphic among chicken breeds, suggesting a varied resistance among breeds of chicken. We found that Laiwu Black chicken breeds have distinctive polymorphic sites at I699T in the type 1 and H561R in the type 2 ChTLR2 gene. Beijing Fatty chickens have distinctive sites at Q45R in type 1 and V66L in type 2. Nongda No.3 Chickens have distinctive sites at L115P, H232Y, and T494A in type 1. Hy-Line variety brown chickens have distinctive sites at I311V in type 2. Beijing White 939 chickens have distinctive sites at E284G in type 1 and A22V in type 2. These findings may provide some clues toward understanding the resistance of lighter chickens to salmonellosis.

Polymorphisms of chicken toll-like receptor 1 type 1 and type 2 in different breeds.

Toll-like receptors (TLR) mediate immune responses via recognition of pathogen-associated molecular patterns, thus playing important roles in the host defense. Polymorphisms of TLR may affect their recognition of pathogen-associated molecular patterns, leading to varied host resistance to pathogenic infections. However, little is known regarding the polymorphisms of chicken TLR (ChTLR) among breeds. In this study, we cloned ChTLR1 type 1 and type 2 genes from 9 chicken breeds (2 commercial breeds and 7 Chinese native breeds) and analyzed their sequences. We found 27 amino acid polymorphism sites in ChTLR: 14 sites in type 1 (8 sites in the extracellular domain, 5 sites in the cytoplasmic domain, and 1 site in the transmembrane domain) and 13 sites in type 2 (11 sites in the extracellular domain, 1 site in the cytoplasmic domain, and 1 site in the transmembrane domain). These results demonstrate that ChTLR1 type 1 and type 2 genes are polymorphic among chicken breeds, suggesting a varied resistance among breeds of chicken. This information provides new consideration for future poultry breeding and breed improvement.