Okubo K, Wilawan P, Bork S, Okamura M, Yokoyama N, Igarashi I
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
Parasitology. 2006 Sep;133(Pt 3):289-94. doi: 10.1017/S0031182006000436. Epub 2006 Jun 2.
Ethylene glycol bis (beta-aminoethylether)-N,N,N,N-tetraacetic acid (EGTA) is a chelating agent capable of binding to positively-charged metal ions, including a calcium-ion (Ca2+). Here, we demonstrated the inhibitory effect of the chemical on the in vitro asexual growth of the equine protozoan parasites, Babesia caballi and Babesia equi. The growth of both B. caballi and B. equi was significantly inhibited in the presence of EGTA (IC50=1.27 and 2.25 mM, respectively). Under microscopical observation, increased percentages of extracellular merozoites in the total parasites were detected in both of the cultures treated with high concentrations of EGTA. In contrast, further addition of Ca2+ to the EGTA-treated cultures prevented the parasites from clearing and the percentages of extracellular merozoites from increasing. As for B. caballi, an invasion test using high-voltage pulsing proved that EGTA has an inhibitory effect to their erythrocyte invasion. These results suggest that Ca2+ is involved in erythrocyte invasion by equine Babesia parasites.
乙二醇双（β-氨基乙基醚）-N,N,N,N-四乙酸（EGTA）是一种螯合剂，能够与带正电荷的金属离子结合，包括钙离子（Ca2+）。在此，我们证明了该化学物质对马原生动物寄生虫巴贝斯虫（Babesia caballi）和马巴贝斯虫（Babesia equi）体外无性生长的抑制作用。在EGTA存在的情况下，B. caballi和B. equi的生长均受到显著抑制（IC50分别为1.27 mM和2.25 mM）。在显微镜观察下，在两种用高浓度EGTA处理的培养物中，总寄生虫中细胞外裂殖子的百分比均有所增加。相反，向EGTA处理的培养物中进一步添加Ca2+可防止寄生虫清除，细胞外裂殖子的百分比也不再增加。对于B. caballi，使用高压脉冲进行的入侵试验证明EGTA对其红细胞入侵具有抑制作用。这些结果表明Ca2+参与马巴贝斯虫对红细胞的入侵。
