Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, South Australia, Australia.
Infect Immun. 2011 Dec;79(12):4839-49. doi: 10.1128/IAI.05663-11. Epub 2011 Sep 19.
The capsular serotype has long been associated with the virulence of Streptococcus pneumoniae. Here we present an in-depth study of phenotypic and genetic differences between serotype 3 and serogroup 11 S. pneumoniae clinical isolates from both the general and indigenous populations of Australia. Both serotypes/groups included clonally unrelated strains with differences in well-known polymorphic virulence genes, such as nanA and pspA, as demonstrated by multilocus sequence typing and Western blot analysis. Nonetheless, the serotype 3 strains were consistently and significantly more virulent in mice than the serogroup 11 strains. Despite extensive genomic analysis, noncapsular genes common to one serotype/group but not the other were not identified. Nevertheless, following the conversion of a serotype 11A isolate to serotype 3 and subsequent analysis in an intranasal infection model, it was evident that both capsular and noncapsular factors determine the virulence phenotype in mice. However, it appears that these noncapsular factors vary from strain to strain.
荚膜血清型长期以来一直与肺炎链球菌的毒力有关。在这里，我们对来自澳大利亚普通人群和原住民人群的 3 型和 11 组血清型/群肺炎链球菌临床分离株的表型和遗传差异进行了深入研究。两种血清型/组都包括无克隆相关的菌株，在众所周知的多态性毒力基因（如 nanA 和 pspA）方面存在差异，这一点通过多位点序列分型和 Western blot 分析得到了证实。尽管如此，3 型菌株在小鼠中的毒力始终明显高于 11 组菌株。尽管进行了广泛的基因组分析，但仍未发现一种血清型/组共有的非荚膜基因而另一种血清型/组却没有。尽管如此，在将 11A 型分离株转化为 3 型并在鼻腔感染模型中进行后续分析后，显然荚膜和非荚膜因素都决定了小鼠中的毒力表型。然而，这些非荚膜因素似乎因菌株而异。
