血吸虫感染新模型兔血清对童虫的体外杀伤实验

IN VITRO EFFECTS OF THE RABBIT SERA FROM A NEW MODEL OF SCHISTOSOMIASIS ON SCHISTOSOMA JAPONICUM

目的 在已建立的一种血吸虫感染伴随免疫新模型的基础上 ,观察该模型兔血清对童虫的体外杀伤作用 ,探讨该血清抗体在抗日本血吸虫感染保护性免疫中的作用。 方法 用倒置显微镜观察并比较不同稀释度的日本血吸虫感染伴随免疫新模型兔血清 (A血清 )与日本血吸虫感染常规模型兔血清 (B血清 )对体外培养童虫的杀伤作用 ,并经甲基蓝染色后计算童虫死亡率。 结果 对体外童虫的杀伤作用 ,新模型兔血清随浓度的降低而逐渐减弱 ,血清浓度越低 ,童虫死亡率亦越低。但常规模型兔血清随浓度的降低则呈现先上升后下降的趋势 ,以 1/ 10左右稀释度时最高。比较A、B两种血清对童虫的杀伤作用 ,前者强于后者 ,1/ 2血清稀释度培养 48h观察到的童虫死亡率分别为 (4 1.2 3±1.0 8) %和 (2 7.2 7± 2 .86) % (P <0 .0 5 ) ;先加入后者 4h后再加入前者能部分抑制前者的杀童虫作用 ,童虫死亡率为(3 7.63± 2 .3 3 ) % ,介于两者之间。常规模型血清组部分童虫体表出现膜状或泡状物质包绕 ,但童虫却未受到明显杀伤。结论 日本血吸虫感染伴随免疫新模型兔血清在体外对童虫的杀伤作用强于常规模型兔血清 ,推测前者可能以杀伤抗体占优势 ;而后者可能以封闭抗体占优势。

Objective To study in vitro effects of the lethal antibody in rabbit sera from a new model of schistosomiasis on Schistosoma japonicum schistosomula. Methods The mechanically transformed schistosomula were incubated in culture media containing different rabbit serum dilutions, which were obtained respectively from a normal model (group B), 5 rabbits infected with S. japonicum for 42 days, and a new model (group A), another 5 rabbits infected with S. japonicum for the same time and injected intra-peritoneally with allyl thiourea at the dose of 300 mg/kg·d from day 20 to day 42 post-infection to inhibit the female adult worms producing eggs, then schistosomula were dyed by methyl blue and the their mortality rates were calculated under microscope after incubating for 24 h, 48 h, 72 h and 96 h respectively. Results With the decrease of rabbit serum concentration in culture media, the mortality rate of schistosomula in the new model group decreased, but in the normal model group increased initially and then declined. Some schistosomula with a coat', perhaps complex of schistosomula member antigen with antibody, were observed in the normal model group. The mortality rates of schistosomula in the new model group were higher than those in the normal model group. For example, 48 h after incubation in culture media containing 1/2 rabbit serum dilution, the mortality rates of schistosomula were (41.23±1.08)% and (27.27±2.86)% ( P <0.05) respectively in the new model group and the normal model group. In addition, it was also observed that rabbit sera from the normal model could partly inhibit the effect of rabbit sera from the new model on schistosomula. Conclusion Rabbit sera from the new model of schistosomiasis had more stronger lethal effect on S. japonicum schistosomula in vitro than rabbit sera from the normal model of schistosomiasis. (For Fig. 1-4, to see inside back cover)