Yokoyama Naoaki, Sivakumar Thillaiampalam, Tuvshintulga Bumduuren, Hayashida Kyoko, Igarashi Ikuo, Inoue Noboru, Long Phung Thang, Lan Dinh Thi Bich
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
Infect Genet Evol. 2015 Mar;30:288-295. doi: 10.1016/j.meegid.2014.12.035. Epub 2015 Jan 6.
The genes that encode merozoite surface antigens (MSAs) in Babesia bovis are genetically diverse. In this study, we analyzed the genetic diversity of B. bovis MSA-1, MSA-2b, and MSA-2c genes in Vietnamese cattle and water buffaloes. Blood DNA samples from 258 cattle and 49 water buffaloes reared in the Thua Thien Hue province of Vietnam were screened with a B. bovis-specific diagnostic PCR assay. The B. bovis-positive DNA samples (23 cattle and 16 water buffaloes) were then subjected to PCR assays to amplify the MSA-1, MSA-2b, and MSA-2c genes. Sequencing analyses showed that the Vietnamese MSA-1 and MSA-2b sequences are genetically diverse, whereas MSA-2c is relatively conserved. The nucleotide identity values for these MSA gene sequences were similar in the cattle and water buffaloes. Consistent with the sequencing data, the Vietnamese MSA-1 and MSA-2b sequences were dispersed across several clades in the corresponding phylogenetic trees, whereas the MSA-2c sequences occurred in a single clade. Cattle- and water-buffalo-derived sequences also often clustered together on the phylogenetic trees. The Vietnamese MSA-1, MSA-2b, and MSA-2c sequences were then screened for recombination with automated methods. Of the seven recombination events detected, five and two were associated with the MSA-2b and MSA-2c recombinant sequences, respectively, whereas no MSA-1 recombinants were detected among the sequences analyzed. Recombination between the sequences derived from cattle and water buffaloes was very common, and the resultant recombinant sequences were found in both host animals. These data indicate that the genetic diversity of the MSA sequences does not differ between cattle and water buffaloes in Vietnam. They also suggest that recombination between the B. bovis MSA sequences in both cattle and water buffaloes might contribute to the genetic variation in these genes in Vietnam.
编码牛巴贝斯虫裂殖子表面抗原（MSAs）的基因在遗传上具有多样性。在本研究中，我们分析了越南牛和水牛中牛巴贝斯虫MSA - 1、MSA - 2b和MSA - 2c基因的遗传多样性。采用牛巴贝斯虫特异性诊断PCR检测法对越南承天顺化省饲养的258头牛和49头水牛的血液DNA样本进行筛查。然后对牛巴贝斯虫阳性DNA样本（23头牛和16头水牛）进行PCR检测，以扩增MSA - 1、MSA - 2b和MSA - 2c基因。测序分析表明，越南的MSA - 1和MSA - 2b序列在遗传上具有多样性，而MSA - 2c相对保守。这些MSA基因序列的核苷酸同一性值在牛和水牛中相似。与测序数据一致，越南的MSA - 1和MSA - 2b序列分散在相应系统发育树的几个分支中，而MSA - 2c序列出现在单个分支中。牛和水牛来源的序列在系统发育树上也经常聚集在一起。然后采用自动化方法对越南的MSA - 1、MSA - 2b和MSA - 2c序列进行重组筛查。在检测到的7个重组事件中，分别有5个和2个与MSA - 2b和MSA - 2c重组序列相关，而在所分析的序列中未检测到MSA - 1重组体。牛和水牛来源的序列之间的重组非常普遍，并且在两种宿主动物中都发现了产生的重组序列。这些数据表明，越南牛和水牛中MSA序列的遗传多样性没有差异。它们还表明，牛和水牛中牛巴贝斯虫MSA序列之间的重组可能有助于这些基因在越南的遗传变异。
