Wessels M R, Moses A E, Goldberg J B, DiCesare T J
Channing Laboratory, Brigham and Women's Hospital, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1991 Oct 1;88(19):8317-21. doi: 10.1073/pnas.88.19.8317.
Mucoid strains of group A Streptococcus have been associated with recent outbreaks of acute rheumatic fever. The mucoid colony morphology of these strains is a result of abundant production of capsular polysaccharide, which is composed of hyaluronic acid. To study the role of the hyaluronic acid capsule in virulence, we derived an acapsular mutant from a mucoid strain of group A Streptococcus by transposon mutagenesis. M protein expression was not altered in the mutant strain. The mucoid wild-type strain grew in fresh human blood and was resistant to phagocytic killing in vitro. In contrast, the acapsular mutant failed to grow in fresh human blood and was sensitive to phagocytic killing in vitro. Loss of capsule was associated with a 100-fold reduction in virulence of the organisms in mice. We conclude that the hyaluronic acid capsule protects mucoid group A streptococci from phagocytosis and has an important role in virulence.
A组链球菌的黏液样菌株与近期急性风湿热的暴发有关。这些菌株的黏液样菌落形态是由大量产生的荚膜多糖所致，该多糖由透明质酸组成。为了研究透明质酸荚膜在毒力中的作用，我们通过转座子诱变从A组链球菌的黏液样菌株中获得了一个无荚膜突变体。突变菌株中的M蛋白表达未改变。黏液样野生型菌株能在新鲜人血中生长，并且在体外对吞噬杀伤具有抗性。相比之下，无荚膜突变体无法在新鲜人血中生长，并且在体外对吞噬杀伤敏感。荚膜的缺失与该生物体在小鼠体内毒力降低100倍有关。我们得出结论，透明质酸荚膜可保护黏液样A组链球菌免受吞噬作用，并在毒力中起重要作用。
