Bujanover Shay, Katz Uriel, Bracha Rivka, Mirelman David
Department of Biological Chemistry, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel.
Int J Parasitol. 2003 Dec;33(14):1655-63. doi: 10.1016/s0020-7519(03)00268-6.
Entamoeba histolytica, the protozoan parasite which causes amoebiasis, is an exclusively human pathogen so developing a vaccine could effectively impact the spread of the disease. Recently we developed a genetically modified avirulent strain, termed G3, from the virulent E. histolytica strain HM-1:IMSS. The new strain lacks the important virulence factor, the amoebapore-A. The objective of our current study was to investigate the avirulence of the attenuated strain as well as to examine the antigenic and immunogenic responses of these trophozoites as potential candidates for a live vaccine. Functional assays were conducted to characterise the virulent behaviour of the G3 strain. This behaviour was compared to the virulent strain HM-1:IMSS and the non-virulent strain Rahman. Western blots were conducted to confirm the lack of amoebapore-A in the E. histolytica G3 strain and to demonstrate that it had no influence on the presence of other virulence factors. Results of these two sets of tests proved the G3 strain to be phenotypically similar to the avirulent Rahman strain while antigenically identical to the virulent HM-1:IMSS, apart from the lack of the amoebapore-A protein. Intraperitoneal immunisation of hamsters with G3 trophozoites compared to sham immunised hamsters resulted in IgG anti-HM-1:IMSS antibodies. The level of humoral response was variable and further testing has to take place before introducing this new strain as a vaccine.
溶组织内阿米巴是一种导致阿米巴病的原生动物寄生虫，是一种仅感染人类的病原体，因此开发疫苗可有效影响该疾病的传播。最近，我们从有毒力的溶组织内阿米巴菌株HM-1:IMSS中开发出一种基因改造的无毒力菌株，称为G3。新菌株缺乏重要的毒力因子——阿米巴穿孔素-A。我们当前研究的目的是调查减毒株的无毒力，并检查这些滋养体作为活疫苗潜在候选物的抗原和免疫反应。进行功能测定以表征G3菌株的毒力行为。将这种行为与有毒力的菌株HM-1:IMSS和无毒力的拉赫曼菌株进行比较。进行蛋白质免疫印迹以确认溶组织内阿米巴G3菌株中不存在阿米巴穿孔素-A，并证明其对其他毒力因子的存在没有影响。这两组测试的结果证明，G3菌株在表型上与无毒力的拉赫曼菌株相似，而在抗原性上与有毒力的HM-1:IMSS相同，只是缺乏阿米巴穿孔素-A蛋白。与假免疫的仓鼠相比，用G3滋养体对仓鼠进行腹腔免疫产生了抗HM-1:IMSS IgG抗体。体液反应水平各不相同，在将这种新菌株作为疫苗引入之前还必须进行进一步测试。
