Dipartimento Sanità Pubblica Veterinaria e Sicurezza Alimentare, Istituto Superiore di Sanità, Roma, Italy.
PLoS One. 2011;6(10):e24073. doi: 10.1371/journal.pone.0024073. Epub 2011 Oct 31.
The lipopolysaccharide (LPS) is considered the major virulent factor in Brucella spp. Several genes have been identified involved in the synthesis of the three LPS components: lipid A, core and O-PS. Usually, Brucella strains devoid of O-PS (rough mutants) are less virulent than the wild type and do not induce undesirable interfering antibodies. Such of them proved to be protective against brucellosis in mice. Because of these favorable features, rough strains have been considered potential brucellosis vaccines. In this study, we evaluated the antigenic, immunologic and genetic characteristics of rough strains B. abortus RB51, B. melitensis B115 and B. melitensis B18. RB51 derived from B. abortus 2308 virulent strain and B115 is a natural rough strain in which the O-PS is present in the cytoplasm. B18 is a rough rifampin-resistan mutant isolated in our laboratory. The surface antigenicity of RB51, B115 and B18 was evaluated by testing their ability to bind antibodies induced by rough or smooth Brucella strains. The antibody response induced by each strain was evaluated in rabbits. Twenty-one genes, involved in the LPS-synthesis, were sequenced and compared with the B. melitensis 16M strain. The results indicated that RB51, B115 and B18 have differences in antigenicity, immunologic and genetic properties. Particularly, in B115 a nonsense mutation was detected in wzm gene, which could explain the intracellular localization of O-PS in this strain. Complementation studies to evaluate the precise role of each mutation in affecting Brucella morphology and its virulence, could provide useful information for the assessment of new, attenuated vaccines for brucellosis.
脂多糖（LPS）被认为是布鲁氏菌属中主要的毒力因子。已经鉴定出了几种参与 LPS 三种成分（脂质 A、核心和 O-PS）合成的基因。通常，缺乏 O-PS（粗糙突变株）的布鲁氏菌菌株比野生型菌株的毒力更低，并且不会诱导不良的干扰抗体。这些菌株已被证明在小鼠中具有保护作用，可预防布鲁氏菌病。由于这些有利的特征，粗糙株已被认为是潜在的布鲁氏菌病疫苗。在这项研究中，我们评估了粗糙株布鲁氏菌 B. abortus RB51、B. melitensis B115 和 B. melitensis B18 的抗原性、免疫性和遗传特征。RB51 源自 B. abortus 2308 毒力株，B115 是一种天然的粗糙株，其 O-PS 存在于细胞质中。B18 是我们实验室分离的粗糙 rifampin 抗性突变株。通过测试它们与粗糙或光滑布鲁氏菌菌株诱导的抗体结合能力来评估 RB51、B115 和 B18 的表面抗原性。在兔子中评估了每种菌株诱导的抗体反应。对涉及 LPS 合成的 21 个基因进行测序，并与 B. melitensis 16M 菌株进行比较。结果表明，RB51、B115 和 B18 在抗原性、免疫和遗传特性方面存在差异。特别是，在 B115 中，wzm 基因检测到无义突变，这可以解释该菌株中 O-PS 的细胞内定位。为了评估每个突变在影响布鲁氏菌形态和毒力方面的确切作用，进行互补研究，可以为评估新的、减毒的布鲁氏菌病疫苗提供有用信息。
