Avian toll-like receptors

  title={Avian toll-like receptors},
  author={Robert M Brownlie and Brenda J. Allan},
  journal={Cell and Tissue Research},
Analysis of the genomes of two distantly related bird species, chicken and zebra finch (divergence of about 100 million years), indicate that there are ten avian toll-like receptors and that five of these, TLR2a, 2b, 3, 4, 5 and 7, are clear orthologs to TLRs found in mammals. Duplication of genes has led to TLR1La and 1Lb, TLR2a and 2b, and two TLR7s in the zebra finch. Avian TLR21 may be orthologous to TLR21 found in fish and amphibians, and avian TLR15, which is phylogenetically related to… 

Identification and functional characterization of nonmammalian Toll-like receptor 20

In vivo infection experiments indicate a role for Tlr20 in the immune response of carp to protozoan parasites (Trypanoplasma borreli), and three-dimensional modeling indicates a best fit to the crystal structure of TLR8.

Toll-Like Receptor Evolution in Birds: Gene Duplication, Pseudogenization, and Diversifying Selection

This comparative study provides a comprehensive insight into the evolution of avian TLR genetic variability and identified candidate positions in the receptors that have been likely shaped by direct molecular host–pathogen coevolutionary interactions and most probably play key functional roles in birds.

Protein evolution of Toll-like receptors 4, 5 and 7 within Galloanserae birds

The results suggest that avian and mammalian TLR may be differentially adapted to pathogen-derived ligand recognition, and evolutionary pressures on Galloanserae TLR are depicted for the first time.

Evolution of toll-like receptor gene family in amphibians.

Molecular evolution of the vertebrate TLR1 gene family - a complex history of gene duplication, gene conversion, positive selection and co-evolution

It is demonstrated that the TLR1 gene family has mostly been subject to purifying selection but has also responded to directional selection at a few sites, possibly in response to pathogen challenge.

Diversification of the expanded teleost-specific toll-like receptor family in Atlantic cod, Gadus morhua

Positive selection pressure coupled with experimental evidence of differential expression strongly support the hypothesis that teleost-specific tlr paralogues in cod are undergoing neofunctionalisation and can recognise bacterial pathogen-associated molecular patterns to compensate for the lack of other cell surface Tlrs.

Different genetic patterns in avian Toll-like receptor (TLR)5 genes

The data indicate that the positive Darwinian selection occurred in avian TLR5 genes since frequency of non-synonymous (dN) > frequency of synonymous (dS) and demonstrate that avian LS5 genes are polymorphic among avian breeds, suggesting a varied resistance among breeds of avian.

Innate sensing of viruses by pattern recognition receptors in birds

The tissue and cellular distribution of avian PRR, the recognition and activation of PRR by viruses, and the subsequent expression of innate antiviral genes such as type I IFN and proinflammatory cytokines are discussed.

Characterisation of Toll-like receptors 4, 5 and 7 and their genetic variation in the grey partridge

The orthologues of TLR4, TLR5 and TLR7 (representing both bacterial- and viral-sensing TLRs) in the grey partridge, a European Galliform game bird species, are identified and genetic variation within these genes is assessed.

Positive selection pressure within teleost toll-like receptors tlr21 and tlr22 subfamilies and their response to temperature stress and microbial components in zebrafish

It is found that zebrafish tlrs are expressed mainly in immune-related organs, such as spleen and kidney as well as in testis and temperature stress did not have an effect on the expression of tlr21 and tlr22 in the early stages of development in zebra fish larvae.



Identification and sequence analysis of chicken Toll-like receptors

The hypothesis that one of the major evolutionary strategies of the innate immune system is to recognize a few highly conserved microbial components with several conserved TLRs is supported.

The evolution of vertebrate Toll-like receptors.

The complete sequences of Takifugu Toll-like receptor (TLR) loci and gene predictions from many draft genomes enable comprehensive molecular phylogenetic analysis and shows that coincidental evolution plays a minor role in TLR evolution.

Evolution of the chicken Toll-like receptor gene family: A story of gene gain and gene loss

Comparative phylogenetic analysis of vertebrate TLR genes provides insight into their patterns and processes of gene evolution, with examples of both gene gain and gene loss.

The duck toll like receptor 7: genomic organization, expression and function.

Induction of a Novel Chicken Toll-Like Receptor following Salmonella enterica Serovar Typhimurium Infection

A role for the TLR in avian defense against bacterial infection is suggested, and it is hypothesized that TLR15 may represent an avian-specific TLR that has been either retained in chicken and lost in other taxa or gained in the chicken.

Allelic Variation in TLR4 Is Linked to Susceptibility to Salmonella enterica Serovar Typhimurium Infection in Chickens

The cloning and characterization of the avian orthologue of mammalian Toll-like receptor 4 is described, suggesting a role of TLR4 in the host response of chickens to Salmonella infection.

Chicken toll-like receptor 3 recognizes its cognate ligand when ectopically expressed in human cells.

  • H. SchwarzK. Schneider P. Staeheli
  • Biology
    Journal of interferon & cytokine research : the official journal of the International Society for Interferon and Cytokine Research
  • 2007
It is found that polyI:C, LPS, R848, S-28463, and ODN2006, which are specifically recognized by TLR3,TLR4, TLR7/8, and TLR9 in mammals, induced substantial amounts of type I interferon (IFN) and interleukin-6 (IL-6) in freshly prepared chicken splenocytes.

Identification and characterization of a functional, alternatively spliced Toll‐like receptor 7 (TLR7) and genomic disruption of TLR8 in chickens

The deletion of TLR8 in galliforms, accompanied with the differential response after exposure to TLR7 agonists, offers insight into the evolution of vertebrate TLR function.