Hulse M L, Smith S, Chi E Y, Pham A, Rubens C E
Department of Pediatrics, Children's Hospital and Medical Center, Seattle, Washington.
Infect Immun. 1993 Nov;61(11):4835-41. doi: 10.1128/iai.61.11.4835-4841.1993.
Group B streptococcal (GBS) capsular polysaccharide is an important virulence factor, and its role in invasion of cultured respiratory epithelial cells was investigated. A type III GBS clinical isolate, COH1, and asialo and unencapsulated isogenic transposon capsule mutants of it were compared in an in vitro invasion assay. The results demonstrated that capsule attenuated the invasion process. Invasion was not affected when the A549 epithelial cells were preincubated with purified type III GBS capsular polysaccharide. Polyclonal type III GBS capsule antibody inhibited invasion by COH1 but did not affect invasion by the capsule mutants. Serotypes Ia, Ib, Ia/c, II, and III all invaded respiratory epithelial cells but demonstrated some strain variation in magnitude of invasion. These observations led us to conclude that type III capsular polysaccharide was not essential for invasion of respiratory epithelial cells by GBS and that bacterial factors other than capsule were responsible for respiratory epithelial cell invasion.
B族链球菌（GBS）荚膜多糖是一种重要的毒力因子，对其在培养的呼吸道上皮细胞侵袭中的作用进行了研究。在体外侵袭试验中，比较了III型GBS临床分离株COH1及其去唾液酸和无荚膜的同基因转座子荚膜突变体。结果表明，荚膜减弱了侵袭过程。当A549上皮细胞与纯化的III型GBS荚膜多糖预孵育时，侵袭不受影响。多克隆III型GBS荚膜抗体抑制COH1的侵袭，但不影响荚膜突变体的侵袭。血清型Ia、Ib、Ia/c、II和III均能侵袭呼吸道上皮细胞，但在侵袭程度上表现出一些菌株差异。这些观察结果使我们得出结论，III型荚膜多糖对GBS侵袭呼吸道上皮细胞并非必不可少，除荚膜外的细菌因素是呼吸道上皮细胞侵袭的原因。
