Laboratório de Patologia Clínica Veterinária, Faculdade de Agronomia e Medicina Veterinária (FAV/UnB), Universidade de Brasília, Campus Universitário Darcy Ribeiro, ICC Centro - Asa Norte, CEP, Brasília, Distrito Federal 70910-900, Brazil.
Department of Clinical Sciences, North Carolina State College of Veterinary Medicine, Raleigh, North Carolina.
Ticks Tick Borne Dis. 2023 Jul;14(4):102181. doi: 10.1016/j.ttbdis.2023.102181. Epub 2023 Apr 19.
Canine piroplasmid infections can be caused by Babesia spp., Theileria spp. and Rangelia vitalii. In Brazil, canine babesiosis caused by Babesia vogeli is endemic and reported throughout the country. On the other hand, Rangeliosis caused by R. vitalii has only been described so far in the South and Southeast regions. Despite that, studies analyzing the laboratory and molecular characterization of these hemoprotozoa are still scarce. To investigate the occurrence, the laboratory features, the molecular characterization, and the diversity of piroplasmids from Midwestern Brazil, a survey was performed using blood samples obtained from 276 domestic dogs from Brasília, Federal District, Midwestern Brazil. A broad-range quantitative PCR (qPCR) targeting the mitochondrial large subunit ribosomal DNA (LSU4) was used to detect piroplasmid DNA. The overall molecular occurrence of piroplasmids was 11.2% (31/276), with 9.7% (27/276) of the sequences identified as Babesia vogeli (98-100% identity to B. vogeli isolate from the USA). Based on a partial 18S rRNA sequence pairwise alignment (-250 bp), 1.4% (4/276) of the sequences showed only 76.8% identity with B. vogeli but 100% identity with opossum-associated Babesia sp. (MW290046-53). These findings suggest the exposure of dogs from Brazil to a recently described Babesia sp. isolated from white-eared opossum. None of the analyzed dogs was positive for Theileria spp. or R. vitalii. Subsequently, all positive sequences were submitted to three additional PCR assays based on the 18S rRNA, cox-1, and cytb genes, aiming at performing a haplotype network analysis. Haplotype network using cox-1 sequences showed the presence of six different haplotypes of B. vogeli; one of them was shared with isolates from Brazil, the USA, and India. When including animals co-infected with other vector-borne diseases, piroplasmid-positive dogs had 2.3 times higher chance of having thrombocytopenia than the negative ones. The molecular results demonstrated that the compared Babesia vogeli sequences showed a low variability as well as evidence of exposure to a putative novel opossum-associated Babesia sp. in dogs from Midwestern Brazil.
犬巴贝斯虫病可由巴贝斯虫属、泰勒虫属和兰格尔氏泰勒虫引起。在巴西，由伯氏巴贝斯虫引起的犬巴贝斯虫病呈地方性流行，并在全国范围内有报道。另一方面，由兰格尔氏泰勒虫引起的兰格尔病迄今仅在南部和东南部地区有描述。尽管如此，分析这些血液原生动物的实验室和分子特征的研究仍然很少。为了调查中西部巴西的流行情况、实验室特征、分子特征和巴贝斯虫的多样性，对来自巴西首都巴西利亚的 276 只家养犬的血液样本进行了一项调查。使用靶向线粒体大亚基核糖体 DNA (LSU4)的广谱定量 PCR (qPCR)来检测巴贝斯虫 DNA。巴贝斯虫的总分子发生率为 11.2%（31/276），其中 9.7%（27/276）的序列被鉴定为伯氏巴贝斯虫（与来自美国的 B. vogeli 分离株的同源性为 98-100%）。基于 18S rRNA 序列的部分比对（-250 bp），1.4%（4/276）的序列与伯氏巴贝斯虫的同源性仅为 76.8%，但与白耳负鼠相关的巴贝斯虫的同源性为 100%（MW290046-53）。这些发现表明，巴西的犬只接触了一种最近从白耳负鼠中分离出来的新型巴贝斯虫。分析的犬只均未检测到泰勒虫属或兰格尔氏泰勒虫。随后，所有阳性序列均提交给基于 18S rRNA、cox-1 和 cytb 基因的另外三个 PCR 检测，以进行单倍型网络分析。基于 cox-1 序列的单倍型网络显示，有六种不同的伯氏巴贝斯虫单倍型；其中一种与来自巴西、美国和印度的分离株共享。当包括同时感染其他经媒介传播疾病的动物时，感染巴贝斯虫的犬血小板减少的可能性比阴性犬高 2.3 倍。分子结果表明，比较的伯氏巴贝斯虫序列显示出较低的变异性，以及巴西中西部犬只接触一种新型白耳负鼠相关巴贝斯虫的证据。
