Amino acid signatures in the Ovar-DRB1 peptide-binding pockets are associated with Ovine Pulmonary Adenocarcinoma susceptibility/resistance

Exploring genetic diversity and variation of Ovar-DRB1 gene in Sudan Desert Sheep using targeted next-generation sequencing

INTRODUCTION

The Ovar-DRB1 gene, a crucial element of the Major Histocompatibility Complex (MHC) Class II region, initiates adaptive immunity by presenting antigens to T-cells. Genetic diversity in sheep, particularly in MHC Class II genes like Ovar-DRB1, directly influences the specturm of presented antigens impacting immune responses and disease susceptability. Understanding the allelic diversity of Ovar-DRB1 gene in Sudan Desert Sheep (SDS) is essential for uncovering the genetic basis of immune responses and disease resistance, given the the breeds significance in Sudan's unique environment.

METHODS

Utilizing Targeted Next-Generation Sequencing (NGS) we explore allelic diversity in Ovar-DRB1 gene within SDS. Successfully ampliying and and sequencing the second exon of this gene in 288 SDS samples representing six breeds provided a comprehensive allelic profile, enabling a detalied examination of the gene's genetic makeup.

RESULTS

We identifed forty-six alleles, including four previously unreported, enrichness the genetic diversity of SDS breeds. These alleles exhibiting non-uniform distribution, varying frequencies across breeds, indicating a breed-specific genetic landscape. Certain alleles, known and novel, show higher frequencies in specific populations, suggesting potential associations with adaptive immune responses. Identifying these alleles sets the stage for investigating their functional roles and implications for disease resistance. Genetic differentiation among SDS breeds, as indicated by FST values and clustering analyses, highlights a unique genetic makeup shaped by geographic and historical factors. These differentiation patterns among SDS breeds have broader implications for breed conservation and targeted breeding to enhance disease resistance in specific populations.

CONCLUSION

This study unveils Ovar-DRB1 gene allelic diversity in SDS breeds through targeted NGS and genetic analyses, revealing new alleles that underscore the breeds' unique genetic profile. Insights into the genetic factors governing immune responses and disease resistance emerge, promising for optimization of breeding strategies for enhanced livestock health in Sudan's unique environment.

Association of Ovar-DRB1 alleles with innate immune responses in sheep

Background

Major histocompatibility complex (MHC) is the best characterised genetic region associated with adaptive immune responses, including humoral and cell‐mediated immunities.

Objectives

In this study, the association of MHC class II alleles with inflammatory cytokines and acute‐phase proteins was evaluated in sheep population.

Methods

Allelic diversity of second exon of ovine DRB1 locus (Ovar‐DRB1.2) was determined in 100 indigenous Iranian Lori‐Bakhtiari fat‐tailed sheep using restriction fragment length polymorphism and direct sequencing methods. The association of DRB1.2 alleles with inflammatory cytokines (interleukin‐1β, IL‐1β; IL‐6 and tumour necrosis factor‐α) and acute‐phase proteins (serum amyloid A, alpha‐1‐acid glycoprotein and haptoglobin) was examined using generalised linear model and multivariate regression analysis.

Results

Seven distinct RsaI restriction patterns and fourteen alleles were identified in this population. Allele DRB1*2101 showed a negative influence on the IL‐6 response and was associated with lower serum level of IL‐6. DRB1.2 heterozygous individuals also showed higher haptoglobin concentration than homozygotes.

Conclusions

These results provide additional support for the association between Ovar‐DRB1 alleles and regulation of immune responses in sheep population. Description of MHC polymorphism and its role in the controlling of immune responses will increase our understanding of host–pathogen interactions, and ultimately facilitate the selection of disease‐resistant flocks in genetic breeding programs.