Magliano Ana C M, da Silva Flávia Maia, Teixeira Marta M G, Alfieri Silvia C
Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, CEP 05508-000 São Paulo, SP, Brazil.
Exp Parasitol. 2009 Nov;123(3):231-5. doi: 10.1016/j.exppara.2009.07.006. Epub 2009 Jul 29.
Acanthamoeba spp., known to cause keratitis and granulomatous encephalitis in humans, are frequently isolated from a variety of water sources. Here we report for the first time the characterization of an Acanthamoeba sp. (ACC01) isolated from tap water in Brazil. This organism is currently being maintained in an axenic growth medium. Phylogenetic analysis based on SSU rRNA gene sequences positioned the new isolate in genotype T4, closest to the keratitis-causing isolate, A. polyphaga ATCC 30461 ( approximately 99% similarity). Acanthamoeba ACC01 and A. polyphaga 30461 both grew at 37 degrees C and were osmotically resistant, multiplying in hyperosmolar medium. Both isolates secreted comparable amounts of proteolytic enzymes, including serine peptidases that were optimally active at a near neutral/alkaline pH and resolved identically in gelatin gels. Incubation of gels at pH 4.0 with 2mM DTT also indicated the secretion of similar cysteine peptidases. Altogether, the results point to the pathogenic potential of Acanthamoeba ACC01.
棘阿米巴属（Acanthamoeba spp.）已知可在人类中引起角膜炎和肉芽肿性脑炎，常从各种水源中分离得到。在此，我们首次报告了从巴西自来水中分离出的一种棘阿米巴（ACC01）的特征。该生物体目前保存在无共生生长培养基中。基于小亚基核糖体RNA（SSU rRNA）基因序列的系统发育分析将新分离株定位在基因型T4中，与引起角膜炎的分离株多食棘阿米巴（A. polyphaga）ATCC 30461最接近（相似度约为99%）。棘阿米巴ACC01和多食棘阿米巴30461均在37℃生长且具有渗透压抗性，能在高渗培养基中增殖。两种分离株分泌的蛋白水解酶量相当，包括在接近中性/碱性pH下活性最佳且在明胶凝胶中迁移情况相同的丝氨酸肽酶。在pH 4.0和2mM二硫苏糖醇（DTT）条件下孵育凝胶也表明分泌了相似的半胱氨酸肽酶。总之，结果表明棘阿米巴ACC01具有致病潜力。
