Harvill E T, Preston A, Cotter P A, Allen A G, Maskell D J, Miller J F
Department of Microbiology and Immunology, University of California Los Angeles School of Medicine, Los Angeles, California 90095-1747, USA.
Infect Immun. 2000 Dec;68(12):6720-8. doi: 10.1128/IAI.68.12.6720-6728.2000.
Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica are closely related subspecies that cause respiratory tract infections in humans and other mammals and express many similar virulence factors. Their lipopolysaccharide (LPS) molecules differ, containing either a complex trisaccharide (B. pertussis), a trisaccharide plus an O-antigen-like repeat (B. bronchiseptica), or an altered trisaccharide plus an O-antigen-like repeat (B. parapertussis). Deletion of the wlb locus results in the loss of membrane-distal polysaccharide domains in the three subspecies of bordetellae, leaving LPS molecules consisting of lipid A and core oligosaccharide. We have used wlb deletion (Deltawlb) mutants to investigate the roles of distal LPS structures in respiratory tract infection by bordetellae. Each mutant was defective compared to its parent strain in colonization of the respiratory tracts of BALB/c mice, but the location in the respiratory tract and the time point at which defects were observed differed significantly. Although the Deltawlb mutants were much more sensitive to complement-mediated killing in vitro, they displayed similar defects in respiratory tract colonization in C5(-/-) mice compared with wild-type (wt) mice, indicating that increased sensitivity to complement-mediated lysis is not sufficient to explain the in vivo defects. B. pertussis and B. parapertussis Deltawlb mutants were also defective compared to wt strains in colonization of SCID-beige mice, indicating that the defects were not limited to interactions with adaptive immunity. Interestingly, the B. bronchiseptica Deltawlb strain was defective, compared to the wt strain, in colonization of the respiratory tracts of BALB/c mice beginning 1 week postinoculation but did not differ from the wt strain in its ability to colonize the respiratory tracts of B-cell- and T-cell-deficient mice, suggesting that wlb-dependent LPS modifications in B. bronchiseptica modulate interactions with adaptive immunity. These data show that biosynthesis of a full-length LPS molecule by these three bordetellae is essential for the expression of full virulence for mice. In addition, the data indicate that the different distal structures modifying the LPS molecules on these three closely related subspecies serve different purposes in respiratory tract infection, highlighting the diversity of functions attributable to LPS of gram-negative bacteria.
百日咳博德特氏菌、副百日咳博德特氏菌和支气管败血博德特氏菌是密切相关的亚种，它们可导致人类和其他哺乳动物的呼吸道感染，并表达许多相似的毒力因子。它们的脂多糖（LPS）分子有所不同，分别含有一个复杂的三糖（百日咳博德特氏菌）、一个三糖加上一个类似O抗原的重复序列（支气管败血博德特氏菌），或一个改变的三糖加上一个类似O抗原的重复序列（副百日咳博德特氏菌）。wlb基因座的缺失导致博德特氏菌三个亚种中膜远端多糖结构域的缺失，使得LPS分子仅由脂质A和核心寡糖组成。我们利用wlb缺失（Δwlb）突变体来研究LPS远端结构在博德特氏菌呼吸道感染中的作用。与亲本菌株相比，每个突变体在BALB/c小鼠呼吸道定殖方面均存在缺陷，但在呼吸道中的定殖位置以及观察到缺陷的时间点存在显著差异。尽管Δwlb突变体在体外对补体介导的杀伤更为敏感，但与野生型（wt）小鼠相比，它们在C5（-/-）小鼠的呼吸道定殖中表现出相似的缺陷，这表明对补体介导的裂解敏感性增加不足以解释体内的缺陷。与wt菌株相比，百日咳博德特氏菌和副百日咳博德特氏菌的Δwlb突变体在SCID-米色小鼠的定殖中也存在缺陷，这表明这些缺陷并不局限于与适应性免疫的相互作用。有趣的是，与wt菌株相比，支气管败血博德特氏菌的Δwlb菌株在接种后1周开始在BALB/c小鼠呼吸道定殖方面存在缺陷，但在B细胞和T细胞缺陷小鼠的呼吸道定殖能力上与wt菌株没有差异，这表明支气管败血博德特氏菌中依赖wlb的LPS修饰调节了与适应性免疫的相互作用。这些数据表明，这三种博德特氏菌全长LPS分子的生物合成对于在小鼠中表达完全毒力至关重要。此外，数据表明，修饰这三个密切相关亚种LPS分子的不同远端结构在呼吸道感染中发挥着不同的作用，突出了革兰氏阴性菌LPS功能的多样性。
