中华眼镜蛇蛇毒因子(CVF)对补体系统的作用及与人补作C_3和其他蛇毒抗原性关系

中华眼镜蛇蛇毒经DEAE-Sepharose CL-6B。HPLC等多次柱层析分离出有抗补体及溶血活性的眼镜蛇蛇毒因子(Cobra venom factor,CVF),纯化后的CVF在聚丙烯酰胺凝胶电泳图谱上呈单一区带,分子量为225000—230000,等电点为6.20。用二硫苏糖醇还原经SDS-聚丙烯酰胺凝胶电泳得三类亚基,其分子量总和为237,000。 体外抗补体及溶血试验表明,CVF的作用是通过补体旁路途经使总补体活力下降。双向免疫电泳鉴定,发现CVF与人血清作用后,其中补体成分C_3分子的抗原性发生改变,则表明CVF的作用是通过激活补体成分C_3而发挥的。给豚鼠腹腔注射CVF(0.15ug/g体重)后,其血清总补体水平下降到正常值的3％以下,7天后回升,13天后恢复到正常水平。 单相免疫电泳表明,CVF与人补体C_3抗血清间无任何交叉免疫反应,但人血清与CVF抗血清间有微弱的免疫沉淀反应。另外,CVF的氨基酸组成与人补体C_3也较为相似。鉴定还表明眼镜蛇科中四种蛇毒与CVF抗血清有强烈的免疫沉淀反应,蝰蛇毒及海蛇毒也有免疫沉淀反应,但只有眼镜蛇毒具有抗补体活性。

ACTION OF CVF ON THE COMPLEMPLEMENT- SYSTEM AND THE ANTIGENIC RELATIONSHIP OF CVF WITH HUMAN C3 AND OTHER KINDS OF SNAKE-VENOM

Cobra Venom Factor (CVF), an anticomplement factor, had been separated from the venom of Chinese cobra, Naja naja atra. The anticomplementary activity and the hemolytic activity of CVF were observed by methods in vitro. Complement C3 was activated and depleted by CVF through the alternative pathway leading to the decrease of the total complement activity. Cross imm-unoelcctrophoresis showed that antigenicity of C3 had changed after C had been cleaved by CVF. When guinea pigs were injected i. p. with purified CVF about 0.15 u-g per grm body weight, the hemolytic complement activity of guinea pig serum reduced to less than 3 % of normal level within 24 hours and recovered completely after 13 days. No toxic effect of CVF was observed. On rocket immunoelectrophoresis analysis, CVF and its subunits could not cross react with antiserum to human C3, but normal human serum could cross react weakly with antiserum to CVF. Amino acid composition of CVF was found to be similar to human C3 and its physiological cleavage products. The rocket immunoelectrophoresis analysis showed that some kinds of venom of different snake-species, i. e. for of family Elapidae (Naja naja atra), Ophiophagus hannah, Bungarus multicinctus, B. jasciatus), one of Viperinae (Vipera russclli) and two of Hydrophiidae (Hydrophis cyanocinctus, Lapemis hardwickii) had cross reactivity with anti-CVF to some extent, however, these venoms (except the venom of) Naja naja atra had no anticomplementary activity. Venoms of two species of Crotalinae (Agkistrodon acutus, A. halys) did not show such cross-reacting, but they had strong anticomplementary activity.