Department of Parasitology, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
Department of Radiation Oncology, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
J Eukaryot Microbiol. 2024 Nov-Dec;71(6):e13055. doi: 10.1111/jeu.13055. Epub 2024 Aug 19.
Entamoeba nuttalli is genetically the closest to Entamoeba histolytica, the causative agent of human amebiasis. E. nuttalli is found in Macaca species, exhibiting no symptoms while potentially virulent. Using comparative genomics of Entamoeba species, we identified a gene encoding an E. nuttalli-specific protein containing 42 repeats of an octapeptide (PTORS). In the present study, we analyzed the genes in E. nuttalli strains derived from various geographic locations and host species. Sequence analysis of genomic DNA from four strains indicated 43, 44, and 48 repeat types in addition to 42 repeats and remarkable genetic diversity in the repeat region, although all nucleotide substitutions were synonymous. In contrast, the sequences of the N-terminal side region and C-terminus were identical among the strains. Monoclonal antibodies prepared against recombinant PTORS were reactive to the repeat regions but not to the N-terminal side regions. Polyclonal antibodies did not react with the N-terminal region, demonstrating that the repeat region had higher antigenicity. Analysis using synthetic peptides revealed that the two repeats of the octapeptide functioned as epitopes. Immunofluorescence microscopy using monoclonal antibodies demonstrated the surface localization of PTORS. These results suggest that the repeat region of PTORS plays an important role in host-parasite interactions.
内蜒阿米巴（Entamoeba nuttalli）在基因上与溶组织内阿米巴（Entamoeba histolytica）最为接近，后者是人类阿米巴病的病原体。E. nuttalli 存在于猕猴属物种中，虽然具有潜在的毒力，但没有表现出症状。通过对内阿米巴物种的比较基因组学研究，我们鉴定了一个编码内蜒阿米巴特异性蛋白的基因，该蛋白包含 42 个八肽（PTORS）重复序列。在本研究中，我们分析了来自不同地理来源和宿主物种的 E. nuttalli 菌株中的基因。对来自四个菌株的基因组 DNA 的序列分析表明，除了 42 个重复序列外，还存在 43、44 和 48 种重复类型，并且重复区域存在显著的遗传多样性，尽管所有核苷酸取代都是同义的。相比之下，菌株之间的 N 末端侧区和 C 末端序列是相同的。针对重组 PTORS 制备的单克隆抗体与重复区反应，但与 N 末端侧区不反应。多克隆抗体与 N 末端区不反应，表明重复区具有更高的抗原性。使用合成肽的分析表明，八肽的两个重复序列作为表位起作用。使用单克隆抗体的免疫荧光显微镜显示了 PTORS 的表面定位。这些结果表明，PTORS 的重复区在宿主-寄生虫相互作用中发挥重要作用。
