理化因素对体外培养伊氏锥虫致弱的影响

ATTENUATION EFFECT OF PHYSICAL AND CHEMICAL FACTORS ON TRYPANOSOMA EVANSI

本试验观察了理化因素（γ－射线、紫外线、低浓度杀虫药）对体外培养伊氏锥虫致弱的影响，结果如下：受γ－射线辐照的伊氏锥虫开始时存活数随辐照剂量的增加而减少，随后表现出无规律性，辐照剂量５万ｒａｄ以下对锥虫的存活影响较小，５～１０万ｒａｄ辐照后２ｄ锥虫的存活数明显减少，对小白鼠的感染性消失。伊氏锥虫受紫外线照射的存活曲线为“Ｃ”型，群体抗辐射不均一，平均致死剂量（Ｄ＿（３７））为波长２６５０Ａ的２０Ｗ紫外灯离样品４０ｃｍ处照射约２ｈ。虫体照射后根据体外跟踪观察，其存活数随照射剂量的增大而减少，照射了３ｈ和４ｈ第３天的活虫数近似１００条或不足１００条，对小白鼠的感染性均消失。用０．１μｇ／ｍｌ的苏拉灭和０．８μｇ／ｍｌ的贝尼尔两种低浓度杀虫药在体外对伊氏锥虫诱导４０ｄ仅造成药敏性的改变，未造成毒力减弱。

Attenuation effect of physical and Chemical factors(gamma ray, Ultraviolet ray and low concentration trypanosomacides)on Trypanosoma evansi was observed.(1) The survival number of T. evansi irradiated by gamma ray decreased with the increasing dose of irradiation in the initial stage, but displayed no regularity soon afterwards. The irradiation dose below 50K rads had less influence on the trypanosome. The survival parasite irradiated with 50-100k rads dose decreased in number apparently and lost its infectivity to mice in two days.(2)The survival curve of T. evansi irradiated by ultraviolet ray showed a“C”form. The resistance against the irradiation was not equal in the population.The mean lethal dose(D_(37))was about two hours of exposure at 40cm apart from ultraviolet tube of 2650 wavelength. Following the track of irradiated parasite, its survival number decreased with the increase of the irradiation dose.The survival parasite irradiated for three and four hours was about or below 100 and its infectivity to mice disappeared on the third day.(3)The induction of suramine at 0.1μg/ml and berenil at 0.8μg/ml to T. evansi in vitro for 40 days only resulted in variation of drug sensitivity,but no variation in virulence.