Callaby Rebecca, Kelly Robert, Mazeri Stella, Egbe Franklyn, Benedictus Lindert, Clark Emily, Doeschl-Wilson Andrea, Bronsvoort Barend, Salavati Mazdak, Muwonge Adrian
Centre for Tropical Livestock Genetics and Health, The Royal (Dick) School of Veterinary Studies, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom.
The Royal (Dick) School of Veterinary Studies, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom.
Front Genet. 2020 Nov 17;11:550215. doi: 10.3389/fgene.2020.550215. eCollection 2020.
Bovine Tuberculosis (bTB) caused by is a livestock disease of global economic and public health importance. There are currently no effective vaccines available for livestock and so control relies on animal level surveillance and pasteurization of dairy products. A new alternative control approach is to exploit the genetic variability of the host; recent studies have demonstrated that breeding European taurine cattle, such as Holsteins for increased resistance to bTB is feasible. The utility of such an approach is still unknown for African cattle populations. This study aims to assess genetic variation in bTB resistance and the underlying genomic architecture of cattle in Cameroon. We conducted a cross-sectional study of 2,346 slaughter cattle in Cameroon. Retropharyngeal lymph node samples were collected and cultured on Lowenstein Jensen media and the BACTEC MGIT 960 system, and was identified using the Hain® Genotype kits. A total of 153 cattle were positive for and were archived along with a random selection of negative samples. In this study, we genotyped archived samples from 212 cattle. Their genomic diversity was characterized using PCA, hierarchical clustering and admixture analysis. We assessed genetic variation in bTB resistance using heritability analysis and compared quantitative trait loci. Previous research on this study population have shown that Fulani cattle are more susceptible to bTB than mixed breeds. However, here we show that these apparent phenotypic differences in breeds are not reflected by clear genomic differences. At the genetic level, both the Fulani and mixed cattle show similar patterns of admixture with evidence of both taurine and indicine ancestry. There was little European taurine introgression within the studied population. Hierarchical clustering showed clusters of cattle that differed in their susceptibility to bTB. Our findings allude to bTB resistance being polygenic in nature. This study highlights the potential for genetic control of bTB in Africa and the need for further research into the genetics of bTB resistance within African cattle populations.
牛结核病（bTB）是一种对全球经济和公共卫生具有重要意义的家畜疾病。目前尚无有效的家畜疫苗，因此控制措施依赖于动物层面的监测和乳制品的巴氏杀菌。一种新的替代控制方法是利用宿主的遗传变异性；最近的研究表明，培育欧洲牛（如荷斯坦牛）以增强对bTB的抗性是可行的。对于非洲牛群而言，这种方法的实用性仍不明确。本研究旨在评估喀麦隆牛群中bTB抗性的遗传变异及其潜在的基因组结构。我们对喀麦隆的2346头屠宰牛进行了横断面研究。采集咽后淋巴结样本，在罗-琴培养基和BACTEC MGIT 960系统上进行培养，并使用海因®基因分型试剂盒进行鉴定。共有153头牛检测出bTB呈阳性，并与随机选取的阴性样本一起存档。在本研究中，我们对212头牛的存档样本进行了基因分型。使用主成分分析（PCA）、层次聚类和混合分析对它们的基因组多样性进行了表征。我们使用遗传力分析评估了bTB抗性的遗传变异，并比较了数量性状基因座。此前对该研究群体的研究表明，富拉尼牛比杂交品种更容易感染bTB。然而，我们在此表明，这些品种间明显的表型差异并未反映在明显的基因组差异上。在遗传层面，富拉尼牛和杂交牛都表现出相似的混合模式，有欧洲牛和印度牛祖先的证据。在所研究的群体中，几乎没有欧洲牛的基因渗入。层次聚类显示了对bTB易感性不同的牛群聚类。我们的研究结果表明bTB抗性本质上是多基因的。本研究强调了非洲bTB遗传控制的潜力以及对非洲牛群中bTB抗性遗传学进行进一步研究的必要性。
