Yamasaki Masahiro, Watanabe Nao, Idaka Natsuki, Yamamori Tohru, Otsuguro Ken-Ichi, Uchida Naohiro, Iguchi Aiko, Ohta Hiroshi, Takiguchi Mitsuyoshi
Laboratory of Veterinary Small Animal Internal Medicine, Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka 020-8550, Japan.
Laboratory of Veterinary Internal Medicine, Department of Veterinary Clinical Sciences, Division of Veterinary Medicine, Faculty of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
Exp Parasitol. 2017 Dec;183:92-98. doi: 10.1016/j.exppara.2017.10.016. Epub 2017 Nov 6.
The mechanism of the development of diminazene aceturate (DA) resistance in Babesia gibsoni is still unknown even though DA-resistant B. gibsoni isolate was previously developed in vitro. To clarify the mechanisms of DA-resistance in B. gibsoni, we initially examined the intracellular DA content in the DA-resistant isolate using high-performance liquid chromatography, and compared it with that in the wild-type. As a result, the intracellular DA content in the DA-resistant isolate was significantly lower than that in the wild-type, suggesting that the decreased DA content may contribute to DA-resistance. Additionally, the glucose consumption of the DA-resistant isolate was significantly higher than that of the wild-type, indicating that a large amount of glucose is utilized to maintain DA-resistance. It is possible that a large amount of energy is utilized to maintain the mechanisms of DA-resistance. It was reported that as the structure of DA is similar with that of adenosine, DA may be taken up by the P2 transporter, which contributes to the uptake of adenosine, in Trypanosoma brucei brucei, and that the uptake of adenosine is decreased in DA-resistant T. brucei brucei. In the present study, the adenosine incorporation in the DA-resistant B. gibsoni isolate was higher than in the wild-type. Moreover, the adenosine incorporation in the wild-type was not inhibited by the presence of DA. These results suggest that adenosine transport in B. gibsoni is not affected by DA and may not mediate DA-resistance. To clarify the mechanism of the development of DA resistance in B. gibsoni, we should investigate the cause of the decreased DA content in the DA-resistant isolate in the future.
尽管之前已在体外培育出对乙酰氨基苯脒（DA）耐药的吉氏巴贝斯虫分离株，但吉氏巴贝斯虫对DA产生耐药性的机制仍不清楚。为阐明吉氏巴贝斯虫对DA耐药的机制，我们首先使用高效液相色谱法检测了耐药分离株细胞内的DA含量，并将其与野生型进行比较。结果显示，耐药分离株细胞内的DA含量显著低于野生型，这表明DA含量降低可能与耐药性有关。此外，耐药分离株的葡萄糖消耗量显著高于野生型，这表明大量葡萄糖被用于维持耐药性。可能需要利用大量能量来维持DA耐药机制。据报道，由于DA的结构与腺苷相似，在布氏布氏锥虫中，DA可能通过有助于腺苷摄取的P2转运体被摄取，而在对DA耐药的布氏布氏锥虫中，腺苷摄取减少。在本研究中，耐药吉氏巴贝斯虫分离株中腺苷的掺入量高于野生型。此外，野生型中腺苷的掺入不受DA存在的抑制。这些结果表明，吉氏巴贝斯虫中的腺苷转运不受DA影响，可能不介导DA耐药性。为阐明吉氏巴贝斯虫对DA耐药性产生的机制，我们未来应研究耐药分离株中DA含量降低的原因。
