INACTIVATED PNEUMOLYSIN AS AN AID TO VACCINE DESIGN

基因工程类毒素分子已被评估为潜在的 肺炎链球菌壳多糖蛋白结合物载体的研究 疫苗。基因工程类毒素免疫小鼠的实验研究 保护小鼠免受强毒肺炎球菌对 更大程度上是野生型毒素。一种灭活的肺炎溶血素， “肺炎杆菌B(PDB)”是从一种突变型基因中制备出来的。 含DNA的1型PLY基因pJCP20的定点突变 肺炎溶血素Try433的编码片段被改变为Phe。 类毒素与肺炎球菌19F PS的结合增强了 PS和溶血球抗原的免疫原性。 19F PS-PDB结合物在孕期和/或 哺乳，并在出生后给幼崽额外的免疫原。二 在最后一次注射几周后，免疫的幼鼠被攻击 19F肺炎链球菌。对照组几乎所有的幼鼠都没有收到 免疫原，在攻击后前3天内死亡(存活率为5%)， 而免疫组的大多数小鼠存活(71.4-75%0。因此， 小鼠19F PS与灭活肺溶血素偶联的实验研究 赋予对肺炎球菌感染的保护性免疫力。

Genetically engineered toxoid molecules have been evaluated as potential protein carriers for pneumococcal capsular polysaccharide in a conjugate vaccine. Immunization of mice with genetically engineered toxoids protected mice from subsequent challenge with virulent pneumococci to a greater extent that wild type toxin. An inactivated pneumolysin, "pneumolysoid B (PdB)" was prepared from a mutant gene constructed by the site-directed mutagenesis of type 1 ply gene, pJCP20 plasmid in which DNA fragment that encodes for Try433 of pneumolysin was changed to Phe. Conjugation of the toxoid to pneumococcal type 19F PS enhanced the immunogenicity of both PS and pneumolysoid antigens. The 19F PS-PdB conjugate was given to maternal mice during gestation and/or lactation and an additional immunogen was given to young after birth. Two weeks after last injection, the immunized young mice were challenged with 19F pneumococci. Almost all young mice in control group not receiving immunogen, died within first 3 days after challenge (5% survival rate), while most mice in the immunized group survived (71.4-75%0. Thus, the injection of mice with 19F PS conjugated with inactivated pneumolysin has conferred protective immunity to pneumococcal infection.