We have previously shown that a Pasteurella multocida cexA mutant (PBA875) was impaired in capsule export and highly attenuated in virulence for mice (J. D. Boyce and B. Adler, Infect. Immun. 68:3463–3468, 2000). In this study we show that immunization with high, but not low, doses of PBA875 can confer significant protection against wild-type challenge. We have also constructed a genetically defined acapsular P. multocida strain (AL18) by inactivation of bcbH, a gene predicted to be involved in polysaccharide biosynthesis. AL18 failed to produce immunoreactive polysaccharide as determined by immunofluorescence and Western immunoblot. Immunization of mice with live AL18 conferred significant protection against wild-type challenge, while immunization with similar doses of either killed wild-type or killed AL18 failed to confer protection.
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机译：先前我们已经表明，多杀性巴斯德氏菌cexA突变体（PBA875）的胶囊输出受到损害，小鼠的毒力大大降低（J. D. Boyce和B. Adler，Infect。Immun。68：3463-3468，2000）。在这项研究中，我们显示了以高剂量（但不是低剂量）进行的PBA875免疫可以为野生型攻击提供重要的保护。我们还通过灭活bcbH构建了遗传学上确定的荚膜败血单胞菌菌株（AL18），该基因预计会参与多糖的生物合成。通过免疫荧光和Western免疫印迹确定，AL18不能产生免疫反应性多糖。用活的AL18免疫小鼠可有效抵抗野生型攻击，而用类似剂量的杀死的野生型或杀死的AL18免疫则无法提供保护。
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