Conlon J A, Shewen P E, Lo R Y
Department of Veterinary Microbiology, University of Guelph, Ontario, Canada.
Infect Immun. 1991 Feb;59(2):587-91. doi: 10.1128/iai.59.2.587-591.1991.
The recombinant leukotoxin (rLKT) of the bacterium Pasteurella haemolytica A1 was examined for its ability to protect cattle from experimental challenge with logarithmic-phase P. haemolytica. Six different vaccines were utilized in the experiment: P. haemolytica culture supernatant, P. haemolytica culture supernatant enriched with rLKT, rLKT alone, P. haemolytica culture supernatant enriched with Escherichia coli supernatant not containing LKT, E. coli supernatant alone, and phosphate-buffered saline. rLKT alone showed no protective capacity against development of clinical signs of respiratory disease or against development of postmortem lung lesions after experimental challenge. It was, however, shown to enhance the efficacy of the culture supernatant vaccine and decrease clinical signs and pneumonic lesions. The complexity of protective immunity in this disease is emphasized in this study, and, although LKT is an important virulence factor of the organism, an immune response to LKT alone does not protect animals against disease.
对溶血巴斯德氏菌A1的重组白细胞毒素（rLKT）进行了检测，以评估其保护牛免受对数期溶血巴斯德氏菌实验性攻击的能力。实验中使用了六种不同的疫苗：溶血巴斯德氏菌培养上清液、富含rLKT的溶血巴斯德氏菌培养上清液、单独的rLKT、富含不含LKT的大肠杆菌上清液的溶血巴斯德氏菌培养上清液、单独的大肠杆菌上清液以及磷酸盐缓冲盐水。单独的rLKT在实验性攻击后对呼吸道疾病临床症状的发展或死后肺部病变的发展没有保护能力。然而，它被证明可以增强培养上清液疫苗的效力，并减少临床症状和肺部病变。本研究强调了这种疾病中保护性免疫的复杂性，并且，尽管LKT是该生物体的一种重要毒力因子，但仅对LKT的免疫反应并不能保护动物免受疾病侵害。
