"Unveiling the genetic symphony: Diversity and expression of chicken IFITM genes in Aseel and Kadaknath breeds".

In this investigation, single nucleotide variants (SNVs) within the chicken interferon-inducible transmembrane protein (chIFITM) genes were explored in Aseel and Kadaknath breeds. Comparative analysis with the GRCg6a reference genome revealed 9 and 16 SNVs in the chIFITM locus for Aseel and Kadaknath breeds, respectively. When referencing the Genome Reference Consortium GRCg7b, Kadaknath exhibited 10 variants, contrasting with none in Aseel. Notably, 17, 8, 2, and 5 SNVs were identified in chIFITM1, chIFITM2, chIFITM3, and chIFITM5 genes, with chIFITM1 showing the highest polymorphism in Kadaknath, featuring 10 intronic variants, including three SNVs (rs16457112, rs16457111, and rs313341707) common to both breeds. Two synonymous exonic variants (g.1817767C > A and g.1819102C > T) were also noted in chIFITM1. Although chIFITM protein sequences were generally conserved, genetic variations clustered predominantly in UTR and intronic regions. Examination of immune response dynamics in live embryos uncovered notable variations in chIFITM gene expression across diverse organs and chicken breeds. Specifically, chIFITM1 mRNA was abundant in cecal tonsils for both breeds and bursa of Aseel (7.61 folds), but it was absent in the heart and lung tissues of both breeds. Conversely, chIFITM3 consistently exhibited heightened expression, particularly in bursa of Aseel (10.23 folds). Whereas mRNA of the chIFITM2 gene was found to be abundant in the heart of Kadaknath (11.03 folds) and lung of both breeds. Furthermore, the expression pattern of chIFITM5 diverged between the two breeds, the heart of Kadaknath chickens showed highest (10.45 folds). The study discovered that breed-specific genetic variants within these genes present a potential pathway for selection and breeding to improve disease resistance in chicken. The observed genetic variation among chicken populations highlights the critical importance of these variants in reinforcing virus resistance, exhibiting applicability across a wide range of breeds.

Expression analysis of turkey (Meleagris gallopavo) toll-like receptors and molecular characterization of avian specific TLR15.

Toll-like receptors (TLRs) constitute a multi-gene family, which plays a pivotal role in sensing invading pathogens by virtue of conserved microbial patterns. TLR repertoire of chicken and zebra finch has been well studied. However TLR family of other avian species is yet to be characterized. In the present study, we identified TLR repertoire of turkey, characterized avian specific receptor TLR15 in turkey and profiled the TLRs expressions in a range of tissues of turkey poults. All ten TLR genes orthologous to chicken TLR repertoire were found in turkey. Turkey TLR genes showed 81-93 % similarity at amino acid level to their chicken counter parts. Phylogenetic analysis confirmed the orthologous relationship of turkey TLRs with chicken and zebra finch TLRs. Open reading frame of turkey TLR15 was 2,607 bp long encoding 868 amino acids similar to that of broiler chicken and showed 92.4, 91.1 and 69.5 % identity at amino acid levels with chicken, Japanese quail and zebra finch TLR15 sequences respectively. Overall TLR expression was highest for TLR4 and lowest for TLR21. TLR1A, 2A, 2B and 21 were significantly higher in liver than other tissues investigated (P < 0.01). TLR3 expression was significantly higher in bone marrow (BM) and spleen in comparison to other tissues studied (P < 0.01). Furthermore, no significant differences in the expression levels of TLR1B, 4, 5, 7 and 15 genes were detected among the tissues studied. Our findings contribute to the characterization of innate immune system of birds and show the innate preparedness of young turkey poults to a range of pathogens.

Toll-like receptors gene expression in the gastrointestinal tract of Salmonella serovar Pullorum-infected broiler chicken.

Salmonella enterica serovar Pullorum causes substantial mortality in chicks as well as results in persistent infection and vertical transmission in layer birds. An effective innate immune response in the early stages of infection could reduce bacterial colonization and mortality in chicks and persistency of infection in later stages. Toll-like receptors (TLRs), important components of innate immune response, plays a pivotal role in early recognition of pathogen as well as in the initiation of robust and specific adaptive immune response. In the present study, we quantified the expression levels of chicken TLRs (1LA, 1LB, 2A, 2B, 3, 4, 5, 7, 15, and 21) mRNA by quantitative real-time PCR in the gastrointestinal (GI) tissues (duodenum, jejunum, ileum, and cecum) of 3-day-old broiler chicks after 24 h of oral infection with S. enterica serovar Pullorum. We found significant upregulation of TLRs (TLR2, TLR4, TLR21) mRNA expressions in GI tract tissues after S. Pullorum infection. The exceptions were for TLR3 and TLR15 with decrease in the expression levels in the jejunum after infection. TLR4 gene expression was significantly (P < 0.05) upregulated in the duodenum and ileum of infected chicks. Gene expression for some of the TLRs (TLR1LA, ILB, 2B, and TLR5) remained unchanged after infection with S. Pullorum in all the GI tissues studied. Most substantial change in gene expression was found for TLR21, being significantly (P < 0.05) upregulated in all the tissues investigated. The differential expression levels of TLRs shed light on tailored innate immune response induced by S. Pullorum during the early stages of infection in chicks.

Differential gene expression of antimicrobial peptides ß defensins in the gastrointestinal tract of Salmonella serovar Pullorum infected broiler chickens.

Salmonella enterica serovar Pullorum causes substantial mortality in chicks as well as results in persistent infection and vertical transmission in layer birds. An effective innate immune response in the early stages of infection could reduce bacterial colonization and mortality in chicks and persistency of infection in later stages. ß Defensins (AvBDs) are now considered as one of the key components of innate immunity in avian species. In the present study, we quantified the mRNA expression levels of AvBDs (1-14) by real-time PCR in the gastrointestinal (GI) tissues (duodenum, jejunum, ileum and caecum) of 3-day-old broiler chicks after 24 h of oral infection with Salmonella Pullorum. Quantitative real-time PCR analysis revealed significant (P < 0.05) upregulation of AvBD3, 4, 5, 6 and 12 and a significant (P < 0.05) down regulation in the expressions of AvBD10, 11, 13 and 14 in one or few GI tissues, while no significant changes were observed for AvBD1, 2, 7, 8 and 9 gene expressions in any of the GI tissues investigated upon infection with S. Pullorum. Most substantial change in gene expression was found for AvBD5, being significantly (P < 0.01) upregulated in most of the GI tissues investigated. The differential expression levels of ß defensins shed light on tailored innate immune response induced by S. Pullorum during the early stages of infection in chicks.

Toll-like receptor mRNA expression, iNOS gene polymorphism and serum nitric oxide levels in indigenous chickens.

Toll-like receptor (TLR) family is one of the important members of innate immune system that recognizes conserved microbial patterns and induces innate immune response. They also act as a link to adaptive immune response. Nitric oxide (NO) is a multi-functional mediator with diverse physiological and immunological roles. In the present study TLR mRNA expression in heterophils, serum nitric oxide level and iNOS (inducible Nitric Oxide Synthase) gene polymorphism were investigated in cockerels of two Indian native chicken breeds, Aseel and Kadaknath. TLR (4 and 5) mRNA expression as quantified by real time RT-PCR revealed Kadaknath males expressed significantly (P < 0.01) higher TLR4 mRNA than Aseel males. iNOS gene polymorphism analyzed by PCR-RFLP method revealed difference in allele frequency. Kadaknath males had higher allele B frequency (0.81) than Aseel males (0.56). However, there were no genotype and breed effect on serum nitric oxide level. Based on the present study we conclude that Kadaknath has comparatively higher innate immunity levels than Aseel, however further investigations are needed.

Differential expression of Toll-like receptor mRNA in White Leghorn and indigenous chicken of India.

In the present experiment, the expression profile of Toll-like receptor mRNA in indigenous and pure line chickens was studied. The expression of TLR3, TLR4, TLR5 and TLR7 were quantified in heterophils of Aseel, Kadaknath, Naked neck, Dwarf and White Leghorn lines by Quantitative Real-time PCR. White Leghorns expressed significantly (P < 0.01) higher levels of TLR3 mRNA compared to other lines. TLR4 and TLR5 mRNA were significantly highly expressed in Kadaknath line. Among the TLRs investigated TLR5 was more expressed in all lines studied. TLR7 was highly expressed in indigenous chicken Aseel and Kadaknath than other lines. Dwarf chicken expressed significantly (P < 0.01) lower levels of all TLRs investigated. On the basis of the present study we conclude that the differential expression of TLR mRNA in the heterophils of indigenous and other chicken breeds might contribute to their variable disease resistance/susceptibility.