Anaplasma marginale is an intracellular rickettsial bacterium causing anaplasmosis in ruminants. A. marginale is transmitted biologically by ticks and mechanically by blood-sucking vectors. Anaplasmosis occurs in tropical and subtropical areas of the world. This disease causes huge economic losses due to decreasing meat yield and milk production. The aims of this study were to determine the genetic diversity and antigenicity of A. marginale based on the msp1a and msp1b genes in cattle in Thailand. The A. marginale msp1a and msp1b genes were amplified by the polymerase chain reaction (PCR). There have been four copies of MSP1a tandem repeats among A. marginale Thailand strain, and thirteen different MSP1a tandem repeats were found including repeats B, 25, 27, M, 3, S, C, H, β, 80, 4, TH1 and TH2. Notably, this study showed two copies of the novel conserved tandem sequences namely Thailand Type 1 (TH1) and Type 2 (TH2). The phylogenetic analysis revealed that A. marginale msp1a and msp1b genes were genetically diverse and showed 9 and 5 clades with similarity ranging from 98 to 100% and 79.5 to 100%, respectively, when compared within the isolates of this study. The results of diversity analysis showed 18 and 16 haplotypes of the msp1a and msp1b genes, respectively. The entropy analyses of msp1a and msp1b nucleic acid sequences showed 39 and 900 high entropy peaks with values ranging from 0.35 to 0.85 and from 0.41 to 1.48, respectively, while those of MSP1a and MSP1b amino acid sequences exhibited 75 and 72 high entropy peaks with values ranging from 0.35 to 1.06 and from 0.41 to 1.55, respectively. In addition, B-cell and T-cell epitopes have also been investigated in this study. Hence, our results could be employed to improve the insight input of molecular phylogenetics, genetic diversity and antigenicity of A. marginale Thailand strain.

边缘无形体是一种细胞内立克次体细菌，可引起反刍动物无形体病。A. margine通过蜱进行生物学传播，并通过吸血媒介进行机械传播。无形体病发生在世界热带和亚热带地区。这种病害造成肉产量和牛奶产量下降，造成巨大的经济损失。本研究的目的是根据泰国牛的msp1a和msp1b基因确定边缘 A.的遗传多样性和抗原性。所述A.边缘无msp1a和msp1b基因通过聚合酶链反应（PCR）扩增。其中有四个 MSP1a 串联重复副本A. margine Thailand 菌株，发现了 13 个不同的 MSP1a 串联重复序列，包括重复序列 B、25、27、M、3、S、C、H、β、80、4、TH1 和 TH2。值得注意的是，这项研究显示了新的保守串联序列的两个副本，即泰国 1 型 (TH1) 和 2 型 (TH2)。系统发育分析表明，当在本研究的分离株内进行比较时，A. margine msp1a和msp1b基因具有遗传多样性，并显示出 9 个和 5 个进化枝，相似度分别为 98 到 100% 和 79.5 到 100%。多样性分析结果显示msp1a和msp1b基因分别有 18 个和 16 个单倍型。msp1a和msp1b的熵分析核酸序列分别显示39和900个高熵峰，值范围分别为0.35至0.85和0.41至1.48，而MSP1a和MSP1b氨基酸序列显示75和72个高熵峰，值范围为0.35至1.06和分别为 0.41 到 1.55。此外，本研究还研究了 B 细胞和 T 细胞表位。因此，我们的结果可用于改善对A. margine Thailand 菌株的分子系统发育、遗传多样性和抗原性的洞察输入。