Mirelman D, Bracha R, Chayen A, Aust-Kettis A, Diamond L S
Exp Parasitol. 1986 Aug;62(1):142-8. doi: 10.1016/0014-4894(86)90017-2.
In xenic culture, isolates of Entamoeba histolytica from asymptomatic carriers are characterized, with rare exception, by possession of a nonpathogenic zymodeme. During the process of axenizing such an isolate, strain CDC:0784:4, a change in the pattern of the isoenzymes from nonpathogenic zymodeme I to pathogenic zymodeme II was observed 40 days after the amebae had been transferred from a medium for xenic cultivation to one used for axenic cultivation, but before axenization of the amebae had actually occurred. Axenization was accomplished by feeding the amebae lethally irradiated bacteria while suppressing and finally eradicating with antibiotics the bacterial flora accompanying the amebae in the original xenic culture. The change in zymodeme was accompanied by a change in virulence as evidenced by the ability of the amebae to produce hepatic abscesses in hamsters and to destroy monolayers of tissue culture cells. Two explanations are offered for the observed changes in zymodeme and virulence: a zymodeme is not a stable inherent property of the ameba. Alternatively, the original isolate consisted of two zymodeme populations and the conditions of growth selected for one or the other of the populations. In either case, our results suggest that the finding of a particular zymodeme in a culture of E. histolytica isolated from an asymptomatic carrier of the parasite cannot be used to predict a clinical condition or serve as a basis for the recommendation of therapy.
在共生培养中，来自无症状携带者的溶组织内阿米巴分离株，除极少数例外，其特征是具有非致病性酶谱型。在对这样一个分离株（菌株CDC:0784:4）进行无菌培养的过程中，当变形虫从共生培养基转移到无菌培养基后40天，但在变形虫实际实现无菌培养之前，观察到同工酶谱型从非致病性酶谱型I转变为致病性酶谱型II。无菌培养是通过给变形虫喂食经致死剂量照射的细菌，同时用抗生素抑制并最终根除原始共生培养中与变形虫相伴的细菌菌群来完成的。酶谱型的变化伴随着毒力的改变，这可通过变形虫在仓鼠体内产生肝脓肿以及破坏组织培养细胞单层的能力得到证明。对于观察到的酶谱型和毒力变化，提出了两种解释：酶谱型不是变形虫稳定的固有特性。或者，原始分离株由两个酶谱型群体组成，生长条件选择了其中一个群体。无论哪种情况，我们的结果表明，从该寄生虫的无症状携带者分离的溶组织内阿米巴培养物中发现特定的酶谱型，不能用于预测临床状况或作为推荐治疗方法的依据。
