Galay Remil Linggatong, Maeda Hiroki, Aung Kyaw Min, Umemiya-Shirafuji Rika, Xuan Xuenan, Igarashi Ikuo, Tsuji Naotoshi, Tanaka Tetsuya, Fujisaki Kozo
Department of Pathological and Preventive Veterinary Science, The United Graduate School of Veterinary Science, Yamaguchi University, Yoshida, Yamaguchi, Japan.
Trop Anim Health Prod. 2012 Feb;44(2):343-8. doi: 10.1007/s11250-011-0027-7. Epub 2011 Nov 20.
Babesiosis is one of the most important tick-borne diseases affecting livestock that can cause major economic losses worldwide particularly in the tropics. Control relies on controlling both the protozoan parasite and the tick vector. Antiprotozoal drugs are most commonly used for treatment, but problems on emergence of resistant strains and food residues are encountered. Longicin, a defensin-like peptide identified from the hard tick, Haemapysalis longicornis, as well as one of its synthetic partial analogs (P4), were previously reported to exert antimicrobial, fungicidal, and parasiticidal activity. Both longicin and P4 showed babesiacidal activity, in vitro and in vivo. Here, peptide fragments of P4 were studied for in vitro activity against bovine Babesia parasites. One of the peptide fragments, antimicrobial peptide 1 (AMP1), reduced the parasitemia of Babesia bigemina. No peptide had significant effect on Babesia bovis. The sequence of AMP1 corresponded to the longicin sequence which is associated with antiparasitic activity. Although AMP1 caused reduction in parasitemia of B. bigemina, the difference in morphology of the parasite compared with the control group was not statistically significant. However, the percentage occurrence of piroplasms decreased, whereas the abnormal pycnotic form increased. The results demonstrated that this shorter peptide retained the anti-babesial activity of the parent peptide, exerting an antiparasitic effect against a bovine Babesia species. Therefore, this short peptide can be considered for chemical synthesis as an alternative therapeutic agent for babesiosis.
巴贝斯虫病是影响家畜的最重要的蜱传疾病之一，在全球范围内，尤其是在热带地区，可造成重大经济损失。控制该病依赖于控制原生动物寄生虫和蜱虫传播媒介。抗寄生虫药物是最常用于治疗的药物，但存在耐药菌株出现和食品残留等问题。Longicin是从硬蜱长角血蜱中鉴定出的一种防御素样肽，及其一种合成部分类似物（P4），此前有报道称它们具有抗菌、杀真菌和杀寄生虫活性。Longicin和P4在体外和体内均表现出杀巴贝斯虫活性。在此，对P4的肽片段进行了体外抗牛巴贝斯虫寄生虫活性研究。其中一个肽片段，即抗菌肽1（AMP1），降低了双芽巴贝斯虫的虫血症。没有肽对牛巴贝斯虫有显著影响。AMP1的序列与具有抗寄生虫活性的longicin序列相对应。尽管AMP1导致双芽巴贝斯虫的虫血症降低，但与对照组相比，寄生虫形态的差异在统计学上并不显著。然而，梨形虫的出现百分比下降，而异形固缩形式增加。结果表明，这种较短的肽保留了母体肽的抗巴贝斯虫活性，对一种牛巴贝斯虫物种发挥了抗寄生虫作用。因此，这种短肽可考虑进行化学合成，作为巴贝斯虫病的替代治疗剂。
