Myanmar cattle populations predominantly consist of native cattle breeds (Pyer Sein and Shwe), characterized by their geographical location and coat color, and the Holstein-Friesian crossbreed, which is highly adapted to the harsh tropical climates of this region. Here, we analyzed the diversity and genetic structure of the BoLA-DRB3 gene, a genetic locus that has been linked to the immune response, in Myanmar cattle populations. Blood samples (n = 294) were taken from two native breeds (Pyer Sein, n = 163 and Shwe Ni, n = 69) and a cattle crossbreed (Holstein-Friesian, n = 62) distributed across six regions of Myanmar (Bago, n = 38; Sagaing, n = 77; Mandalay, n = 46; Magway, n = 46; Kayin, n = 43; Yangon, n = 44). In addition, a database that included 2428 BoLA-DRB3 genotypes from European (Angus, Hereford, Holstein, Shorthorn, Overo Negro, Overo Colorado, and Jersey), Zebuine (Nellore, Brahman and Gir), Asian Native from Japan and Philippine and Latin-American Creole breeds was also included. Furthermore, the information from the IPD–MHC database was also used in the present analysis. DNA was genotyped using the sequence-based typing method. DNA electropherograms were analyzed using the Assign 400ATF software. We detected 71 distinct alleles, including three new variants for the BoLA-DRB3 gene. Venn analysis showed that 11 of these alleles were only detected in Myanmar native breeds and 26 were only shared with Asian native and/or Zebu groups. The number of alleles ranged from 33 in Holstein-Friesians to 58 in Pyer Seins, and the observed versus unbiased expected heterozygosity were higher than 0.84 in all the three the populations analyzed. The FST analysis showed a low level of genetic differentiation between the two Myanmar native breeds (FST = 0.003), and between these native breeds and the Holstein-Friesians (FST < 0.021). The average FST value for all the Myanmar Holstein-Friesian crossbred and Myanmar native populations was 0.0136 and 0.0121, respectively. Principal component analysis (PCA) and tree analysis showed that Myanmar native populations grouped in a narrow cluster that diverged clearly from the Holstein-Friesian populations. Furthermore, the BoLA-DRB3 allele frequencies suggested that while some Myanmar native populations from Bago, Mandalay and Yangon regions were more closely related to Zebu breeds (Gir and Brahman), populations from Kayin, Magway and Sagaing regions were more related to the Philippines native breeds. On the contrary, PCA showed that the Holstein-Friesian populations demonstrated a high degree of dispersion, which is likely the result of the different degrees of native admixture in these populations. This study is the first to report the genetic diversity of the BoLA-DRB3 gene in two native breeds and one exotic cattle crossbreed from Myanmar. The results obtained contribute to our understanding of the genetic diversity and distribution of BoLA-DRB3 gene alleles in Myanmar, and increases our knowledge of the worldwide variability of cattle BoLA-DRB3 genes, an important locus for immune response and protection against pathogens.

中文翻译：

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全球牛品种中牛MHC DRB3多样性的特征，重点是缅甸的牛。

缅甸牛群主要由本地牛种（Pyer Sein和Shwe）组成，其特征是地理位置和外皮颜色，以及与该地区恶劣的热带气候高度适应的荷斯坦-弗里斯兰杂交种。在这里，我们分析了缅甸牛群中BoLA-DRB3基因的多样性和遗传结构，该基因位点已与免疫反应相关。取自两个本地品种（Pyer Sein，n = 163和Shwe Ni，n = 69）的血样（n = 294）和分布在缅甸六个地区（Bago，6）的牛杂种（Holstein-Friesian，n = 62）。 n = 38；实皆，n = 77；曼德勒，n = 46； Magway，n = 46； Kayin，n = 43；仰光，n = 44）。此外，该数据库还包含来自欧洲（安格斯，赫里福德，霍尔斯坦，肖特霍恩，Overo Negro，还包括Overo科罗拉多州和泽西岛），Zebuine（Nellore，Brahman和Gir），日本和菲律宾的拉丁美洲人和拉丁美洲克里奥尔人。此外，本分析还使用了IPD-MHC数据库中的信息。使用基于序列的分型方法对DNA进行分型。使用Assign 400ATF软件分析DNA电泳图。我们检测到71个不同的等位基因，包括BoLA-DRB3基因的三个新变体。Venn分析显示，这些等位基因中只有11个仅在缅甸本地品种中检测到，而26个仅与亚洲本地和/或Zebu组共享。等位基因的数量范围从Holstein-Friesians的33个到Pyer Seins的58个，在所分析的所有三个人群中，观察到的和无偏的期望杂合度均高于0.84。FST分析显示两个缅甸本地品种之间（FST = 0.003）以及这些本地品种与荷斯坦-弗里斯兰人之间的遗传分化水平较低（FST <0.021）。所有缅甸荷斯坦-弗里斯兰杂交和缅甸本地居民的平均FST值分别为0.0136和0.0121。主成分分析（PCA）和树木分析表明，缅甸本地居民聚集在一个狭窄的群体中，与荷斯坦-弗里斯兰人口明显不同。此外，BoLA-DRB3等位基因频率表明，虽然来自Bago，曼德勒和仰光地区的一些缅甸本地人口与Zebu品种（Gir和Brahman）关系更为密切，而来自Kayin，Magway和Sagaing地区的缅甸人口却与菲律宾本地居民更加相关。品种。反之，PCA显示，荷斯坦-弗里斯兰人种群表现出高度分散性，这很可能是这些种群中不同程度的天然掺合物的结果。这项研究是首次报道BoLA-DRB3基因在两个本地品种和一个来自缅甸的外来牛杂交中的遗传多样性。获得的结果有助于我们了解缅甸BoLA-DRB3基因等位基因的遗传多样性和分布，并增加了我们对牛BoLA-DRB3基因在世界范围内变异性的认识，这是免疫应答和抵抗病原体的重要场所。这项研究是第一个报告BoLA-DRB3基因在两个本地品种和一个来自缅甸的外来牛杂交中的遗传多样性的研究。获得的结果有助于我们了解缅甸BoLA-DRB3基因等位基因的遗传多样性和分布，并增加了我们对牛BoLA-DRB3基因在世界范围内变异性的认识，这是免疫应答和抵抗病原体的重要场所。这项研究是第一个报告BoLA-DRB3基因在两个本地品种和一个来自缅甸的外来牛杂交中的遗传多样性的研究。获得的结果有助于我们了解缅甸BoLA-DRB3基因等位基因的遗传多样性和分布，并增加了我们对牛BoLA-DRB3基因在世界范围内变异性的认识，这是免疫应答和抵抗病原体的重要场所。