Sisti Federico, Fernández Julieta, Rodríguez María Eugenia, Lagares Antonio, Guiso Nicole, Hozbor Daniela Flavia
Instituto de Bioquímica y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata, República Argentina.
Infect Immun. 2002 Apr;70(4):1791-8. doi: 10.1128/IAI.70.4.1791-1798.2002.
Bordetella bronchiseptica is closely related to Bordetella pertussis, which produces respiratory disease primarily in mammals other than humans. However, its importance as a human pathogen is being increasingly recognized. Although a large amount of research on Bordetella has been generated regarding protein virulence factors, the participation of the surface lipopolysaccharide (LPS) during B. bronchiseptica infection is less understood. To get a better insight into this matter, we constructed and characterized the behavior of an LPS mutant with the deepest possible rough phenotype. We generated the defective mutant B. bronchiseptica LP39 on the waaC gene, which codes for a heptosyl transferase involved in the biosynthesis of the core region of the LPS molecule. Although in B. bronchiseptica LP39 the production of the principal virulence determinants adenylate cyclase-hemolysin, filamentous hemagglutinin, and pertactin persisted, the quantity of the two latter factors was diminished, with the levels of pertactin being the most greatly affected. Furthermore, the LPS of B. bronchiseptica LP39 did not react with sera obtained from mice that had been infected with the parental strain, indicating that this defective LPS is immunologically different from the wild-type LPS. In vivo experiments demonstrated that the ability to colonize the respiratory tract is reduced in the mutant, being effectively cleared from lungs within 5 days, whereas the parental strain survived at least for 30 days. In vitro experiments have demonstrated that, although B. bronchiseptica LP39 was impaired for adhesion to human epithelial cells, it is still able to survive within the host cells as efficiently as the parental strain. These results seem to indicate that the deep rough form of B. bronchiseptica LPS cannot represent a dominant phenotype at the first stage of colonization. Since isolates with deep rough LPS phenotype have already been obtained from human B. bronchiseptica chronic infections, the possibility that this phenotype arises as a consequence of selection pressure within the host at a late stage of the infection process is discussed.
支气管败血波氏杆菌与百日咳博德特氏菌密切相关，后者主要在人类以外的哺乳动物中引发呼吸道疾病。然而，其作为人类病原体的重要性正日益得到认可。尽管针对博德特氏菌的蛋白质毒力因子已开展了大量研究，但对于支气管败血波氏杆菌感染过程中表面脂多糖（LPS）的作用仍了解较少。为了更深入地了解这一问题，我们构建并表征了具有尽可能最深粗糙表型的LPS突变体的行为。我们在 waaC 基因上构建了缺陷型突变体支气管败血波氏杆菌 LP39，该基因编码参与LPS分子核心区域生物合成的庚糖基转移酶。尽管支气管败血波氏杆菌 LP39 中主要毒力决定因子腺苷酸环化酶溶血素、丝状血凝素和百日咳杆菌粘附素的产生仍然存在，但后两种因子的数量减少，其中百日咳杆菌粘附素的水平受影响最大。此外，支气管败血波氏杆菌 LP39 的 LPS 与感染亲本菌株的小鼠血清不发生反应，表明这种缺陷型 LPS 在免疫学上与野生型 LPS 不同。体内实验表明，突变体在呼吸道定植的能力降低，在 5 天内从肺部有效清除，而亲本菌株至少存活 30 天。体外实验表明，尽管支气管败血波氏杆菌 LP39 与人上皮细胞的粘附能力受损，但它仍能像亲本菌株一样有效地在宿主细胞内存活。这些结果似乎表明，支气管败血波氏杆菌 LPS 的深粗糙形式在定植的第一阶段不能代表主导表型。由于已经从人类支气管败血波氏杆菌慢性感染中分离出具有深粗糙 LPS 表型的菌株，因此讨论了这种表型在感染过程后期作为宿主内选择压力的结果而出现的可能性。
