Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
Novartis Vaccines and Diagnostics, Siena, Italy.
J Med Microbiol. 2011 Aug;60(Pt 8):1168-1173. doi: 10.1099/jmm.0.029710-0. Epub 2011 Feb 24.
The aim of this study was to investigate the S-layer proteins (SLPs) of the hypervirulent Clostridium difficile PCR ribotype 027 and compare them with those of PCR ribotype 001 and other PCR ribotypes involved in C. difficile infection and outbreaks, by molecular analysis and immunological assays. It has been demonstrated previously that PCR ribotype 027 SlpA is conserved in C. difficile strains belonging to this PCR ribotype and that it is a new variant, showing 88 % identity with SlpA of PCR ribotype 001. As the low-molecular-weight (LMW) SLPs of C. difficile are immunodominant antigens, attention was focused on this region of the genome. Sequencing of strains of different PCR ribotypes (001, 012, 014, 017, 027 and 078) showed that SlpA was conserved among strains belonging to the same PCR ribotype. Comparison of the LMW SLP region among these strains identified ten regions with sequence identity between PCR ribotypes 027 and 001, and low conservation with the other PCR ribotypes. In particular, two of these regions corresponded to areas predicted to be surface exposed. Three specific peptides, including those of the two surface-exposed regions, were recognized by human sera against PCR ribotypes 027 and 001 and by a rabbit polyclonal serum against the SLPs of PCR ribotype 027. In contrast, these peptides were not recognized by a polyclonal serum against the SLPs of PCR ribotype 012 used as a control. These results confirm the antigenic role of the LMW SLP and suggest that it may have a role in evasion of the host immune response.
本研究旨在通过分子分析和免疫检测，研究产毒力更强的艰难梭菌 PCR 型 027 的 S- 层蛋白（SLP），并与 PCR 型 001 以及其他与艰难梭菌感染和爆发相关的 PCR 型进行比较。先前的研究已经证实，PCR 型 027 的 SlpA 在属于该 PCR 型的艰难梭菌菌株中是保守的，它是一种新的变体，与 PCR 型 001 的 SlpA 具有 88%的同源性。由于艰难梭菌的低分子量（LMW）SLP 是免疫显性抗原，因此该基因组区域受到了关注。对不同 PCR 型（001、012、014、017、027 和 078）的菌株进行测序表明，SlpA 在属于同一 PCR 型的菌株中是保守的。对这些菌株的 LMW SLP 区域进行比较，确定了 10 个与 PCR 型 027 和 001 具有序列同一性的区域，与其他 PCR 型的保守性较低。特别是，其中两个区域对应于预测的表面暴露区域。三个特异性肽段，包括两个表面暴露区域的肽段，被针对 PCR 型 027 和 001 的人类血清以及针对 PCR 型 027 的 SLP 的兔多克隆血清识别，但针对用作对照的 PCR 型 012 的 SLP 的多克隆血清则不能识别这些肽段。这些结果证实了 LMW SLP 的抗原作用，并表明它可能在逃避宿主免疫反应方面发挥作用。
