Agricultural and Livestock Microbiology Graduation Program, School of Agricultural and Veterinarian Sciences, São Paulo State University (UNESP), Jaboticabal, Brazil.
Laboratory of Immunoparasitology, Department of Veterinary Pathology, Faculdade de Ciências Agrárias e Veterinárias/Universidade Estadual Paulista (FCAV/UNESP), Via de Acesso Prof. Paulo Donato Castellane, s/n, Zona Rural, Jaboticabal, São Paulo, 14884-900, Brazil.
Parasitol Res. 2019 Jul;118(7):2027-2040. doi: 10.1007/s00436-019-06337-3. Epub 2019 May 11.
Babesia bovis is the etiological agent of bovine babesiosis, a disease transmitted by Rhipicephalus microplus, which affects cattle herds in tropical and subtropical regions of the world, causing significant economic losses due to decreasing meat and milk yield. This study used molecular techniques to determine the occurrence and genetic diversity of B. bovis, based on the genes encoding the spherical body protein (sbp-2) and the merozoite surface antigens (MSAs) genes, in a herd of 400 Nellore (Bos indicus) sampled from beef cattle farms in the Pantanal region, state of Mato Grosso do Sul, Midwestern Brazil. The results of the nested PCR assays based on the sbp-2 gene indicated that 18 (4.5%) calves were positive for B. bovis; out of them, while 77.7% (14/18) were positive for the B. bovis msa-2b fragment, 66.6% (12/18) were positive for the msa-2c fragment. The phylogenetic analysis based on the maximum likelihood method using 14 sequences from msa-2b clones and 13 sequences from msa-2c clones indicated that the sequences detected in this study are clearly distributed in different cladograms. These findings corroborated the diversity analysis of the same sequences, which revealed the presence of 14 and 11 haplotypes of the msa-2b and msa-2c genes, respectively. Furthermore, the entropy analyses of amino acid sequences revealed 78 and 44 high entropy peaks with values ranging from 0.25 to 1.53 and from 0.27 to 1.09 for MSA-2B and MSA-2C, respectively. Therefore, the results indicate a low molecular occurrence of B. bovis in beef cattle sampled in the Brazilian Pantanal. Despite this, a high degree of genetic diversity was found in the analyzed B. bovis population, with possibly different haplotypes coexisting in the same animal and/or in the same studied herd.
牛巴贝斯虫是牛巴贝斯虫病的病原体，这种疾病通过微小扇头蜱传播，影响世界上热带和亚热带地区的牛群，导致肉产量和奶产量下降，造成重大经济损失。本研究使用分子技术，基于编码球形蛋白（sbp-2）和裂殖体表面抗原（MSAs）基因的基因，在巴西中西部南马托格罗索州潘塔纳尔地区的牛肉农场中采集的 400 头尼洛牛（Bos indicus）中，确定了 B. bovis 的发生和遗传多样性。基于 sbp-2 基因的巢式 PCR 检测结果表明，18 头（4.5%）小牛对 B. bovis 呈阳性；其中，77.7%（14/18）对 B. bovis msa-2b 片段呈阳性，66.6%（12/18）对 msa-2c 片段呈阳性。基于最大似然法对 14 个 msa-2b 克隆序列和 13 个 msa-2c 克隆序列进行的系统发育分析表明，本研究中检测到的序列明显分布在不同的系统发育树中。这些发现与相同序列的多样性分析相吻合，该分析显示 msa-2b 和 msa-2c 基因分别存在 14 和 11 个单倍型。此外，氨基酸序列的熵分析显示，MSA-2B 和 MSA-2C 的值分别为 0.25 至 1.53 和 0.27 至 1.09，分别有 78 个和 44 个高熵峰。因此，结果表明在巴西潘塔纳尔地区采集的牛肉牛中 B. bovis 的分子发生频率较低。尽管如此，在所分析的 B. bovis 群体中发现了高度的遗传多样性，可能在同一动物和/或同一研究牛群中存在不同的单倍型。
