The Study on the Virulence of Trypanosoma cruzi

Research Project

Project/Area Number	63570177
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	寄生虫学(含医用動物学）
Research Institution	Nagasaki University
Principal Investigator	KANBARA Hiroji Prof. Dept. Prot. Inst. Trop. Med., 熱帯医学研究所, 教授 (20029789)
Co-Investigator(Kenkyū-buntansha)	UEMURA Haruki Res. Assoc. Dept. Prot. Inst. Trop. Med., 熱帯医学研究所, 助手 (60184975) NAKAZAWA Shusuke Res. Assoc. Dept. Prot. Inst. Trop. Med., 熱帯医学研究所, 助手 (20180268) FUKUMA Toshihide Assoc. Prof. Dept. Prot. Inst. Trop. Med., 熱帯医学研究所, 助教授 (90125146)
Project Period (FY)	1988 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1989: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000)
Keywords	Trypanosoma cruzi / Virulence / Transformation / Kinetoplast DNA / Effect of low pH / トリポマスチゴ-ト / アマスチゴ-ト / 細胞表面成分 / キネトプラスト / トランスフォ-メ-ション / クルーズトリパノソーマ / トリポマスチゴート / 細胞表面 / 脂質様成分
Research Abstract	Although the process of transformation of Trypanosoma cruzi trypomastigote to amastigote seemed to take place spontaneously, it was demonstrated that the process was accelerated by keeping trypomastigotes at low pH that was adjusted by 10 mM citrate-phosphate buffer. The process required certain nutrients and involved the separation of chemical substances which lysed even parasites. The lytic effect was neutralized by bovine albumin, accordingly the transformation was rapidly completed in tissue culture medium at low pH, 4.5-6.0, supplemented with 1% bovine albumin. Low pH adjusted by 10 mM acetate buffer was highly toxic to parasites. The interesting point is that the lytic effect was much stronger in high-virulent clone or strains than in low virulenct. Characterization of the lysin suggested that it might be lipid. The presence of serum in media at pH 7.4 suppressed the transformation, resulting in the long maintenance of the trypomastigote stage. Bovine albumin cloud replace whole serum but the ability to maintain the trypomastigote was less. Comparison of minicircle DNA of the kinetoplast after digestion by various restricted enzymes revealed that the pattern of DNA fragments digested by EcoRl in the high-virulent clone or strains was very distinct from the low-virulent clone or strains, which shared the same pattern. Hybridization test using the probe obtained from the distinct fragment demonstrated presence of the specific sequence to the high-vireulent clone.