In vivo cell-mediated immune, hemagglutination inhibition response, hematological and biochemical values in native vs. exotic chicken breeds

Polymorphism in the leucine-rich repeats of TLR7 in different breeds of chicken and in silico analysis of its effect on TLR7 structure and function

Chicken toll-like receptor 7 (chTLR7) is a viral sensing pattern recognition receptor and detects ssRNA. The ligand binding site comprises leucine-rich repeats (LRRs) located in the ectodomain of chTLR7. Hence, any polymorphism in the binding site would modify its functional interaction with the ligand, resulting in varied strength of immune response. This study first aimed to compare the single nucleotide polymorphisms (SNPs) associated with the ligand binding site of TLR7 in three indigenous chicken breeds namely Aseel, Kadaknath, Nicobari along with an exotic breed White Leghorn. Four synonymous SNPs (P123P, I171I, N339N and L421L) and four non-synonymous SNPs (I121V, S135T, F356S and S447G) were identified among various breeds. We employed in silico tools to screen the pathogenic nsSNPs and one nsSNP was identified as having potential impact on chTLR7 protein. Moreover, sequence and structure-based methods were used to determine the effect of nsSNPs on protein stability. It revealed I121V, F356S, and S447G as decreasing the stability while S135T increasing the stability of chTLR7. Additionally, docking analysis confirmed that I121V and F356S reduced the binding affinity of ligands (R-848 and polyU) to chTLR7 protein. The results suggest that the nsSNPs found in this study could alter the ligand binding of chTLR7 and modify the immune response between different breeds further contributing to disease susceptibility or resistance. Further, in vitro and in vivo studies are needed to analyze the effect of these SNPs on susceptibility or resistance against various viral diseases in poultry.

Phytochemical analysis and immunomodulatory activities in vitro and in vivo of Aframomum melegueta K Schum seed extracts

Aframomum melegueta K Schum (A. melegueta), an herbaceous plant renowned for its medicinal seeds, was investigated for its potential immunomodulatory effects in vitro and in vivo using ethanolic and methanolic extracts. The immunomodulatory effect was evaluated by measuring antibody titers using the agglutination technique, while anti-inflammatory activity was assessed in a carrageenan-induced mouse paw edema model. In vitro immunomodulatory activity was measured by lysozyme release from neutrophils. Additionally, white blood cell counts were analyzed post-extracts treatment. The MTT assay was employed to determine cytotoxicity, and the biochemical parameters of liver toxicity were evaluated. Remarkably, both extracts exhibited a dose-dependent reduction in paw edema (p < 0.001), with the most significant reduction observed at 1 g/kg (78.13 and 74.27% for ethanolic and methanolic extracts, respectively). Neutrophil degranulation was significantly inhibited in a dose-dependent manner (p < 0.003), reaching maximal inhibition at 100 μg/mg (60.78 and 39.7% for ethanolic and methanolic extracts, respectively). In comparison to the control group, both antibody production and white blood cell counts were reduced. Neither of the extracts showcased any cytotoxicity or toxicity. These findings suggest that A. melegueta extracts exhibit immunosuppressive and anti-inflammatory activities due to the presence of various biomolecules.

Gut Microbial Composition Differs Extensively among Indian Native Chicken Breeds Originated in Different Geographical Locations and a Commercial Broiler Line, but Breed-Specific, as Well as Across-Breed Core Microbiomes, Are Found

Gut microbiota plays an important role in the health and performance of the host. Characterizations of gut microbiota, core microbiomes, and microbial networks in different chicken breeds are expected to provide clues for pathogen exclusion, improving performance or feed efficiency. Here, we characterized the gut microbiota of “finishing” chickens (at the end of production life) of indigenous Indian Nicobari, Ghagus, and Aseel breeds, originating from the Nicobari island, coastal India, and the Indian mainland, respectively, as well as a global commercial broiler line, VenCobb 400, using 16S rDNA amplicon sequencing. We found that diversity, as well as richness of microbiota, was higher in indigenous breeds than in the broiler line. Beta diversity analysis indicated the highest overlap between Ghagus and Nicobari breeds and a very low overlap between the broiler line and all indigenous breeds. Linear discriminant analysis effect size (LEfSe) revealed 82 breed- or line-specific phylotype operational taxonomic unit (OTU) level biomarkers. We confirm the presence of breed specific and across-breed core microbiomes. Additionally, we show the existence of breed specific complex microbial networks in all groups. This study provides the first (and comprehensive) insight into the gut microbiota of three indigenous breeds and one commercial broiler line of chickens reared without antimicrobials, and underscores the need to study microbial diversity in other indigenous breeds.

Genetic diversity at major histocompatibility complex and its effect on production and immune traits in indigenous chicken breeds of India

The genetic diversity at major histocompatibility complex (MHC) in indigenous chicken breeds of India (Ghagus and Nicobari) in comparison with the White Leghorn (WLH) breed was investigated by genotyping the MHC-linked LEI0258 marker. Altogether 38 alleles and 96 genotypes were observed among three breeds. The observed and effective alleles were highest in Ghagus (23, 8.3) followed by Nicobari (14, 3.2) and WLH (10 and 2.2) breeds. The size of alleles ranged from 193 to 489 bp in Ghagus, 193 to 552 bp in Nicobari and 241 to 565 bp in the WLH breed. The number of private alleles was also highest in Ghagus (18) followed by Nicobari (8) and WLH (5) breeds. The most frequent allele was 261 bp in WLH (66 %), 343 bp in Nicobari (50.4 %) and 309 bp in the Ghagus (28.15 %) breed. Observed and expected heterozygosities were highest in Ghagus (0.83, 0.88) followed by Nicobari (0.58, 0.68) and WLH (0.53, 0.54). The genetic distance (Nei) between Ghagus and Nicobari breeds (2.24) was higher as compared to that of Ghagus and WLH (1.23) and that between Nicobari and WLH breeds (0.89). Association analysis revealed significant influence of MHC alleles on body weight, egg production in Ghagus and WLH breeds and antibody titres to Newcastle disease vaccine in the Nicobari breed.

Comparative analysis of silencing expression of myostatin (MSTN) and its two receptors (ACVR2A and ACVR2B) genes affecting growth traits in knock down chicken

Myostatin (MSTN), a growth differentiation factor-8 regulates muscular development through its receptors, ACVR2A (Activin receptor type IIA) and ACVR2B (Activin receptor type IIB) by inhibiting cellular differentiation of developing somites during embryonic stage and diminishing myofibriller growth during post-embryonic period. The objective of this study was to compare the effect of knockdown of expression of myostatin, ACVR2A and ACVR2B genes on growth traits in chicken. The shRNAs for Myostatin, ACVR2A and ACVR2B genes were designed, synthesized and cloned in DEST vector. The recombinant molecules were transfected into the spermatozoa and transfected spermatozoa were inseminated artificially to the hens to obtain fertile eggs. The fertile eggs were collected, incubated in the incubator and hatched to chicks. Silencing of ACVR2B gene showed significantly higher body weight than other single, double and triple knock down of genes in transgenic birds. The carcass traits such as dressing%, leg muscle%, and breast muscle% were found with the highest magnitudes in birds with silencing of the ACVR2B gene as compared to the birds with that of other genes and control group. The lowest serum cholesterol and HDL content was found in ACVR2B silencing birds. The total RBC count was the highest in this group though the differential counts did not differ significantly among various silencing and control groups of birds. It is concluded that silencing of only one receptor of MSTN particularly, ACVR2B may augment the highest growth in chicken during juvenile stage. Our findings may be used as model for improving growth in other food animals and repairing muscular degenerative disorders in human and other animals.