禽大肠杆菌病免疫保护机理的研究

以禽病原性大肠杆菌O18、O78分离株制成超声波裂解铝佐剂灭活苗免疫14日龄鸡，以相同或不同外膜蛋白型（Outer membrane protein pattern,OMP型）的O18、O78分离株攻毒。结果表明：O78血清相同和不同OMP型分离株间能获得最大保护；O18血清型相同OMP型分离株间获得最大保护，而不同OMP型分离株间不能保护；上述两个血清型的分离株间不论OMP型是否相同，均缺乏保护。以间接ELISA试验、间接血凝试验分别测定了试验鸡临攻毒前针对大肠杆菌OMPs和脂多糖(Lipopolysaccharide,LPS）的抗体。结果表明：免疫组鸡血清上述两种抗体明显高于攻毒对照组；在免疫组，存活鸡临攻毒前血清中上述两种抗体滴度恒高于死亡鸡，但除3个组外，多数组差异不显著。攻毒对照组这一关系不稳定。结果说明：禽大肠杆菌疫苗的免疫保护，主要与O血清型有关，部分与OMP型有关，如O18分离株，免疫保护性抗原含OMPs,LPS等多个抗原表位。

STUDY ON THE PROTECTION MECHANISM OF THE O 18 AND O_(78) ISOLATES BASED ON ULTRASONIC INACTIVATION VACCINE OF AVIAN ESCHERICHIA COLI

WT5BZ]Laboratory trials were carried out with ultrasonic inactivation of the O 18 and O 78 isolates of avian Escherichia coli vaccine.The results of the challenge revealed that the O 78 isolate vaccine provided greatest protection against the challenge of O 78 isolates with the same or different outer membrane protein pattern (OMP pattern),and the O 18 isolate vaccine provided the best protection against the challenge of O 18 isolate only with the same OMP pattern but not with the different OMP pattern.There was no evidence that these vaccines provided any protection against the other serogroup isolates of avian Escherichia coli no matter whether their OMP patterns were same or not.Antibody responses of chickens to OMPs and lipopolysaccharides(LPS)antigens were evaluated in sera by an indirect enzyme linked immunosorbent assay(ELISA)and an indirect hemagglutination test(IHT).The results suggested that OMPs and LPS antibody titres of sera sampled from five week old chickens immediately before challenge in vaccinated group were higher than those in challenged control group.In the vaccinated group,antibody titres to both OMPs and LPS antigens in survived chickens were always higher than those of died ones,and this difference was not significant( P>0 05 )but for three groups.Meanwhile,it was not positive in challenged control group.Antibody titres to OMPs and LPS of sera sampled from all survived chickens at 10 days post challenge were significantly higher than those before challenge.The major conclusions were that the protection of avian Escherichia coli vaccine was predominantly associated with O serogroups,partialy with OMP patterns of isolates from whom the vaccines developed,and the pathogenic Escherichia coli isolates of chicken origin bore multiple protective antigens which include OMPs,LPS and so on,all serum responses to these antigens added up to the efficacy of the avian Escherichia coli vaccine. WT5HZ]