Mafie Eliakunda, Rupa Fatema Hashem, Takano Ai, Suzuki Kazuo, Maeda Ken, Sato Hiroshi
Laboratory of Parasitology, United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan.
Laboratory of Microbiology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, 753-8515, Japan.
Parasitol Res. 2018 Mar;117(3):673-680. doi: 10.1007/s00436-017-5717-2. Epub 2018 Jan 15.
Chiropteran mammals worldwide harbour trypanosomes (Euglenozoa: Kinetoplastea: Trypanosomatida) of the subgenus 'Schizotrypanum' in the classical sense. Latterly, these trypanosomes have been referred to as members of the 'Trypanosoma cruzi clade' as their phylogenetic relationships, structure and life cycle conform to T. cruzi, parasitising various terrestrial mammals as well as humans in Latin America. Little is known, however, about the trypanosome species in Asian bats. During a survey on Borrelia spp. in the Eastern bent-winged bat (Miniopterus fuliginosus) living in a cave in Wakayama Prefecture, Japan, incidental proliferation of trypanosomes was detected in two of 94 haemocultures. Squat or slender trypanosomes that proliferated in the cultures were 7.5-20.5 μm in length between both body ends and 1.0-3.8 μm in width with/without free flagella up to 14.5 μm (n = 29). The nucleotide sequences of the small subunit ribosomal RNA gene (SSU rDNA; 2176 bp), large subunit ribosomal RNA gene (1365 bp) and glycosomal glyceraldehyde-3-phosphate dehydrogenase gene (gGAPDH; 843 bp) of the present isolates were characterized to clarify their molecular phylogenetic position in T. cruzi-like trypanosomes. The newly obtained SSU rDNA and gGAPDH nucleotide sequences showed the highest identities with Brazilian and European isolates of Trypanosoma dionisii of the T. cruzi clade, ranging between 99.4 and 99.7% or between 95.6 and 99.3% identities, respectively. Although multiple T. dionisii isolates from the North and South American continents showed the closest molecular genetic relatedness to the present Far East isolates, only short SSU rDNA segments of the former isolates were deposited. Therefore, a definitive conclusion cannot be made until full nucleotide sequencing of at least the American isolates' SSU rDNA is available. This is the first confirmation of a Far East distribution of T. dionisii, demonstrating a wide geographical distribution of the species in the Eurasian and American continents with a limited nucleotide variation.
从传统意义上来说，全球翼手目哺乳动物体内都携带有“裂体锥虫属”的锥虫（眼虫纲：动基体目：锥虫科）。近来，这些锥虫被称为“克氏锥虫进化枝”的成员，因为它们的系统发育关系、结构和生命周期与克氏锥虫相符，寄生于拉丁美洲的各种陆生哺乳动物以及人类体内。然而，对于亚洲蝙蝠体内的锥虫种类却知之甚少。在对日本和歌山县一个洞穴中的东方折翼蝠（Miniopterus fuliginosus）进行伯氏疏螺旋体属调查时，在94份血液培养物中的两份中检测到锥虫意外增殖。在培养物中增殖的矮胖或细长型锥虫，两端体长为7.5 - 20.5μm，宽度为1.0 - 3.8μm，有无可达14.5μm的游离鞭毛（n = 29）。对本次分离株的小亚基核糖体RNA基因（SSU rDNA；2176bp）、大亚基核糖体RNA基因（1365bp）和糖体甘油醛-3-磷酸脱氢酶基因（gGAPDH；843bp）的核苷酸序列进行了特征分析，以阐明它们在克氏锥虫样锥虫中的分子系统发育位置。新获得的SSU rDNA和gGAPDH核苷酸序列与克氏锥虫进化枝的巴西和欧洲的狄氏锥虫分离株的一致性最高，分别在99.4%至99.7%或95.6%至99.3%之间。尽管来自北美洲和南美洲大陆的多个狄氏锥虫分离株与目前的远东分离株显示出最密切的分子遗传相关性，但前者分离株仅保存了短的SSU rDNA片段。因此，在至少获得美洲分离株的SSU rDNA的全核苷酸序列之前，无法得出明确结论。这是狄氏锥虫在远东地区分布的首次确认，表明该物种在欧亚大陆和美洲大陆具有广泛的地理分布，且核苷酸变异有限。
