Gowane G R, Sharma Priya, Kumar Rajiv, Misra S S, Alex Rani, Vohra V, Chhotaray S, Dass Gopal, Chopra Ashish, Kandalkar Yogesh, Vijay V, Choudhary Abhinav, Magotra Ankit, Rajendran R
Animal Genetics & Breeding Division, ICAR-National Dairy Research Institute, Karnal, India.
Animal Genetics & Breeding Division, ICAR-Central Sheep & Wool Research Institute, Avikanagar, India.
Anim Biotechnol. 2023 Dec;34(7):2928-2939. doi: 10.1080/10495398.2022.2125404. Epub 2022 Sep 25.
In sheep, MHC variability is studied widely to explore disease association. The aim of the current study was to explore the genetic diversity of -DRB diversity across sheep breeds of India. Here, DRB1 locus was studied across 20 sheep breeds. DRB1 was amplified (301 bp) and sequenced using a PCR-sequence-based typing approach. Results revealed a high degree of heterozygosity across breeds (mean: 73.99%). Overall mean distance for DRB1 was highest in Sangamneri (0.18) and lowest in Madgyal sheep (0.10). There was a higher rate of transition, across breeds. Further, 39 alleles were isolated in different breeds, out of which 10 were new. To allow easy access and use of the immune-polymorphic database, an online database management system was launched (http://www.mhcdbms.in/). Nucleotide content across breeds for the DRB1 region revealed the richness of GC content (59.26%). Wu-Kabat index revealed vast genetic variation across peptide binding sites (PBS) of DRB1. Residues 6, 66, 69, 52, and 81, were polymorphic showing utility for antigen presentation. All breeds were under positive selection for DRB1 locus (dN > dS). Study revealed the importance of DRB locus diversity for beta chain specifically at PBS across sheep breeds of the Indian subcontinent and presented evidence of positive selection for DRB owing to its evolutionary significance.
在绵羊中，主要组织相容性复合体（MHC）的变异性被广泛研究以探索疾病关联。本研究的目的是探究印度绵羊品种间-DRB多样性的遗传多样性。在此，对20个绵羊品种的DRB1基因座进行了研究。采用基于PCR测序的分型方法扩增（301bp）并测序DRB1。结果显示各品种间杂合度较高（平均：73.99%）。DRB1的总体平均距离在桑加姆内里羊中最高（0.18），在马德贾尔羊中最低（0.10）。各品种间转换率较高。此外，在不同品种中分离出39个等位基因，其中10个是新的。为便于免疫多态性数据库的访问和使用，启动了一个在线数据库管理系统（http://www.mhcdbms.in/）。DRB1区域各品种的核苷酸含量显示GC含量丰富（59.26%）。吴-卡巴特指数显示DRB1的肽结合位点（PBS）存在巨大的遗传变异。第6、66、69、52和81位残基具有多态性，显示出在抗原呈递中的作用。所有品种的DRB1基因座都处于正选择状态（非同义替换率>同义替换率）。研究揭示了DRB基因座多样性对β链的重要性，特别是在印度次大陆绵羊品种的PBS处，并提供了DRB因其进化意义而受到正选择的证据。
