EFFECT OF GENETIC SWITCHING OF CAPSULAR TYPE ON VIRULENCE OF STREPTOCOCCUS-PNEUMONIAE
EFFECT OF GENETIC SWITCHING OF CAPSULAR TYPE ON VIRULENCE OF STREPTOCOCCUS-PNEUMONIAE
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DOI：
10.1128/iai.62.5.1813-1819.1994
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发表时间：
1994-05-01
影响因子：
3.1
通讯作者：
YOTHER, J
中科院分区：
文献类型：
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作者：
KELLY, T;DILLARD, JP;YOTHER, J
为了评估荚膜血清型在肺炎链球菌毒力中的作用，我们构建了仅在表达的荚膜类型上不同的同基因衍生物。通过转化和选择与 3 型荚膜基因座连锁的红霉素抗性标记，将 2、5 和 6B 型菌株转化为 3 型。表征研究表明，这些 3 型衍生物在限制性内切酶片段模式和肺炎球菌表面蛋白 A (PspA) 的表达方面与 2 型、5 型和 6B 型亲本菌株没有区别。 3型荚膜的表达并没有改变具有类似毒力的2型毒株的小鼠毒力。然而，胶囊类型的改变对 5 型和 6B 型衍生物的毒力产生了深远的影响。高毒力的5型菌株在表达3型荚膜时基本上是无毒力的。相反，当表达3型荚膜时，相对无毒力的6B型菌株的50%致死剂量减少>100倍。因此，表达的荚膜的血清型对毒力有主要影响，并且这种影响取决于受体菌株的遗传背景。
To assess the role of capsular serotypes in the virulence of Streptococcus pneumoniae, we have constructed isogenic derivatives differing only in the type of capsule expressed. Strains of types 2, 5, and 6B were converted to type 3 by transformation and selection for an erythromycin resistance marker linked to the type 3 capsule locus. Characterization studies revealed that these type 3 derivatives were indistinguishable from the type 2, type 5, and type 6B parental strains in terms of restriction enzyme fragment pattern and expression of pneumococcal surface protein A (PspA). Expression of the type 3 capsule did not alter the mouse virulence of the similarly virulent type 2 strain. However, alteration of capsule type had a profound effect on the virulence of the type 5 and type 6B derivatives. The highly virulent type 5 strain was essentially avirulent when expressing the type 3 capsule. Conversely, the 50% lethal dose of the relatively avirulent type 6B strain was reduced > 100-fold when the type 3 capsule was expressed. Thus, the serotype of capsule expressed has a major effect on virulence, and this effect is dependent upon the genetic background of the recipient strain.