Medical Parasitology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
Radiation Biology Department, National Center for Radiation Research and Technology (NCRRT), Egptian Atomic Energy Authority, Cairo, Egypt.
Exp Parasitol. 2022 Sep;240:108341. doi: 10.1016/j.exppara.2022.108341. Epub 2022 Jul 31.
Blastocystis hominis is a worldwide common enteric parasite. Its pathogenic potential has not yet been established, although many reports suggest that it may cause the development of various gastrointestinal symptoms. The aim of the present study is to evaluate the destructive effect of different doses of cytotoxic gamma (γ) irradiation combined with and compared to metronidazole (MTZ) on Blastocystis spp. in vitro. The detection of the parasite in the stool specimen was conventionally done by light microscopic examination of direct smears, cultivation, followed by PCR-sequencing. Evaluation of γ-irradiation and MTZ effects on B. hominis was carried out by trypan blue exclusion assay, caspase activity detection, acridine orange staining, DNA fragmentation assay and transmission electron microscopic (TEM) examination. The current study demonstrated that exposure to γ-irradiation in a dose of 0.5 kGray (kGy) significantly (P < 0.05) reduced the viability of B. hominis subtype 2 by 95.2% compared to the untreated and MTZ-treated parasites (87.1%) after 48 h incubation. Combining the same dose of irradiation (0.5 kGy) with MTZ yielded a viability reduction of 94.2% and 94% after 24 and 48 h respectively, which were statistically significant (P < 0.05) compared to MTZ alone. Moreover, our results showed features of programmed cell death in the form of morphological, biochemical, and molecular changes (TEM abnormalities, caspase-like activity, and DNA fragmentation, respectively) with the high doses of γ-irradiation (0.3 and 0.5 kGy) either singly or combined with MTZ. In conclusion, cytotoxic γ-irradiation plays an important role in the inactivation of Blastocystis spp., so, it can be a promising prophylactic water-sterilizing tool against blastocystosis.
人芽囊原虫是一种全球范围内常见的肠道寄生虫。尽管有许多报告表明它可能导致各种胃肠道症状的发展，但它的致病潜力尚未确定。本研究旨在评估不同剂量的细胞毒性γ（γ）辐照与甲硝唑（MTZ）联合应用对体外芽囊原虫的破坏作用，并与 MTZ 进行比较。寄生虫在粪便标本中的检测通常通过直接涂片的光镜检查、培养后进行 PCR 测序来完成。通过台盼蓝排斥试验、半胱天冬酶活性检测、吖啶橙染色、DNA 片段化试验和透射电镜（TEM）检查来评估 γ 辐照和 MTZ 对人芽囊原虫的影响。本研究表明，与未经处理和 MTZ 处理的寄生虫（87.1%）相比，在孵育 48 小时后，暴露于 0.5 kGy 的γ 射线剂量显著（P < 0.05）降低了人芽囊原虫 2 型的活力，降低了 95.2%。将相同剂量的照射（0.5 kGy）与 MTZ 联合使用，在 24 和 48 小时时分别导致活力降低 94.2%和 94%，与单独使用 MTZ 相比具有统计学意义（P < 0.05）。此外，我们的结果显示，在高剂量γ射线（0.3 和 0.5 kGy）单独或与 MTZ 联合使用时，以形态学、生化和分子变化的形式表现出程序性细胞死亡的特征（TEM 异常、半胱天冬酶样活性和 DNA 片段化）。总之，细胞毒性γ 辐照在芽囊原虫的失活中起重要作用，因此，它可以成为一种有前途的针对芽囊原虫病的预防性水消毒工具。
