克隆伊氏锥虫对安锥赛抗药性的培育

为了深入观察伊氏锥虫对安锥赛抗药性的形成,将伊氏锥虫浙江水牛株克隆,克隆繁殖后的虫体一部分作为原种对照组,即C01组;一部分虫体连续经环磷酰胺免疫抑制的小鼠,再用安锥赛亚治疗剂量治疗该小鼠,使其伊氏锥虫对安锥赛产生7个不同程度的抗药性组,即C1～C7组;另一部分虫体也连续经环磷酰胺免疫抑制的小鼠,作为伴随C7的同步繁殖组,即不用药物的C02组.结果C01、C02、C1～C7组所用安锥赛剂量依次为0、0、6、16、40、80、196、406、638mg/kg,它们经小鼠传代数依次为0、28、1、3、6、9、15、22、28代.用体外生长繁殖抑制法测得它们的ICs0值依次为0.015 50、0.016 87、0.082 60、0.102 37、1.409 29、1.922 90、9.923 30、23.563 00、43.84000.结果表明,安锥赛亚治疗剂量与伊氏锥虫抗药性的IC50值呈曲线关系,从C1到C4的IC50值上升较缓慢,从C4后的ICs0值上升较快,并且几乎呈直线上升;伊氏锥虫所经小鼠的代数与它们的IC50值的关系呈抛物线型,从C1到C4的ICs0值上升很慢,C4以后的IC50值上升很快.用体内试验测试C01～C4组的CD100值,每个组感染35只小鼠,每只小鼠接种1.0×104条锥虫,其中30只小鼠分为安锥赛的3个剂量治疗小组,另5只小鼠为不治疗对照组.结果C01组和C1组的CD100值分别为7.0、13.0 mg/kg,这表明C1组只经1代免疫抑制小鼠,注射安锥赛剂量3×2 mg/kg,就使该组伊氏锥虫对安锥赛的抗药性提高了6 mg/kg,并且它们的IC50值C1是C01的6.6倍.C2、C3和C4组由于抗药性程度过高均不能治愈,因此尚未测到它们的CD100值.这些结果表明,伊氏锥虫经免疫抑制小鼠对安锥赛产生抗药性的速度是非常快的.

Development of Resistance of Trypanosoma evansi to Antrycide

A clone of T.evansi,C 01,from Zhejiang buffalo strain was sensitable to antrycide Trypanosomes from C 01 developed seven levels of resistance to antrycide,C 1-C 7,through 1,3,6,9,15,22 and 28 generation of immunosuppressed mice(cyclophosphamide) treated with antrycide at sub-dose by i.p.Another trypanosomas from C 01 were as C 02 through 28 generation of immunosuppressed mice treated without drug.The inhibiting growth assay was used to determine their sensitivities to antrycide.The IC 50 of the C 01,C 02,C 1,C 2,C 3,C 4,C 5,C 6 and C 7 was 0.015 50, 0.016 87, 0.082 60, 0.102 37, 1.409 29, 1.922 90, 9.923 30, 23.563 00 and 43.840 00 in turn.The results showed that the relationship between used total quantities of antrycide and IC 50 was a curve pattern,meaning slow rise of the resistance to antrycide from C 1 to C 4 and then fast rise of it from C 4 to C 7.On the other hand,the relationship between the quantities of used immunosuppressed mice and the IC 50 was a parabola pattern.The treated mouse test was used to determine CD 100 of C 01,C 1,C 2,C 3 and C 4.The CD 100 of C 01 and C 1 were measured to be 7.0 mg/kg and 13.0 mg/kg,respectively.The CD 100 of the other 3 groups were not obtained because of their heavy resistance to antrycide.These results indicated that the resistance of cloned T.evansi to the drug could develop rapidly through immunosuppressed mice.