Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Parasitol Res. 2013 Aug;112 Suppl 1:149-62. doi: 10.1007/s00436-013-3439-7.
Cryptosporidium species are major pathogens severely affecting the health of neonate animals, in particular calves, but also cause life-threatening infection of immunocompromised humans. Currently, only halofuginone is approved for prophylactic and metaphylactic treatment of calves but this drug suffers from its limited safety margins. For treatment of immunodeficient human patients, only nitazoxanide and paramomycin are used but data regarding their efficacy are controversial. Aim of the present study was to test a substituted benzimidazole (BAY-AF76184) and a heterocyclic substituted 1,2,4-triazin (BAY-AB24992), both drugs with known anti-protozoal activity, for their potential ability to interfere with Cryptosporidium parvum development in vitro. Development of C. parvum in HCT-8 cells treated with these compounds was compared to negative controls and parasites treated with paromomycin or halofuginone using real-time PCR targeting the 18S rDNAs of parasites and host cells as template. Potential cytotoxic and anti-proliferative effects of drugs were analysed using a lactate dehydrogenase and a WST-1 assay, respectively. BAY-AF76184 and paromomycin dose-dependently inhibited development of C. parvum with EC50 values of 2.37 μM and 69.5 μM, respectively. Although high concentrations of halofuginone and BAY-AB24992 also significantly inhibited parasite development, effects of lower concentrations were very heterogeneous preventing calculation of EC50 values. Halofuginone and BAY-AF76184 dose-dependently interfered with host cell proliferation (EC50 values of 0.35 μM and 9.07 μM, respectively) and the latter also had direct cytotoxic effects (EC50=48.78 μM). However, drug concentrations required for cytopathic were higher than those for effects against C. parvum. Therefore, both BAY-AB24992 and BAY-AF76184 should be considered for further evaluation, e.g. using in vivo models.
隐孢子虫是主要的病原体，严重影响新生动物的健康，特别是小牛，但也会导致免疫功能低下的人类致命感染。目前，只有哈尔福林酮被批准用于预防和治疗小牛的隐孢子虫病，但这种药物的安全性有限。对于免疫缺陷的人类患者，只有硝唑尼特和帕拉米韦可用，但关于其疗效的数据存在争议。本研究的目的是测试一种取代的苯并咪唑（BAY-AF76184）和一种杂环取代的 1,2,4-三嗪（BAY-AB24992），这两种药物都具有已知的抗原生动物活性，以测试它们在体外干扰微小隐孢子虫发育的潜力。用实时 PCR 以寄生虫和宿主细胞的 18S rDNA 为模板，比较用这些化合物处理的 HCT-8 细胞中微小隐孢子虫的发育与阴性对照和用帕拉米韦或哈尔福林酮处理的寄生虫。用乳酸脱氢酶和 WST-1 测定分别分析药物的潜在细胞毒性和抗增殖作用。BAY-AF76184 和帕拉米韦剂量依赖性地抑制微小隐孢子虫的发育，EC50 值分别为 2.37 μM 和 69.5 μM。尽管高浓度的哈尔福林酮和 BAY-AB24992 也显著抑制寄生虫的发育，但较低浓度的作用非常不均匀，无法计算 EC50 值。哈尔福林酮和 BAY-AF76184 剂量依赖性地干扰宿主细胞的增殖（EC50 值分别为 0.35 μM 和 9.07 μM），后者也具有直接的细胞毒性作用（EC50=48.78 μM）。然而，细胞病变所需的药物浓度高于对抗微小隐孢子虫的浓度。因此，BAY-AB24992 和 BAY-AF76184 都应考虑进一步评估，例如使用体内模型。
