Kim J O, Weiser J N
Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, 19104, USA.
J Infect Dis. 1998 Feb;177(2):368-77. doi: 10.1086/514205.
The pneumococcus undergoes spontaneous phase variation between an opaque and a transparent colony form. In an animal model of systemic infection following intraperitoneal inoculation of mice, the opaque phenotype was significantly more virulent than the transparent for each of 3 strains examined. The opaque phenotype was associated with 1.2- to 5.6-fold greater amounts of capsular polysaccharide compared with the transparent using a sandwich ELISA. A similar technique comparing the amount of total teichoic acid showed that the transparent phenotype had 2.1- to 3.8-fold more immunodetectable teichoic acid. This difference was confirmed by comparing the incorporation of [3H]choline into teichoic acid. Cell fractionation revealed that variation in quantity of incorporated choline was due to differences in cell wall-associated teichoic acid. Results suggest that the pneumococcus phase varies between a virulent form with more capsular polysaccharide and less teichoic acid and an avirulent form with less capsular polysaccharide and more teichoic acid.
肺炎球菌会在不透明菌落形态和透明菌落形态之间自发发生相变。在对小鼠进行腹腔接种后的全身感染动物模型中，在所检测的3种菌株中，不透明表型的毒力均显著高于透明表型。使用夹心酶联免疫吸附测定法（sandwich ELISA）发现，与透明表型相比，不透明表型的荚膜多糖含量高1.2至5.6倍。采用类似技术比较总磷壁酸的含量，结果显示透明表型的可免疫检测磷壁酸多2.1至3.8倍。通过比较[3H]胆碱掺入磷壁酸的情况，证实了这一差异。细胞分级分离显示，胆碱掺入量的变化是由于细胞壁相关磷壁酸的差异所致。结果表明，肺炎球菌的相变发生在一种毒力形式（荚膜多糖较多而磷壁酸较少）和一种无毒力形式（荚膜多糖较少而磷壁酸较多）之间。
