Nelson David E, Taylor Lacey D, Shannon Jeffrey G, Whitmire William M, Crane Deborah D, McClarty Grant, Su Hua, Kari Laszlo, Caldwell Harlan D
Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Cell Microbiol. 2007 Sep;9(9):2289-98. doi: 10.1111/j.1462-5822.2007.00959.x. Epub 2007 May 15.
Chlamydia trachomatis and C. muridarum, human and mouse pathogens, respectively, share more than 99% of open reading frames (ORFs) but differ in a cytotoxin locus. Presence or absence of cytotoxin gene(s) in these strains correlates with their ability to grow in IFN-gamma treated mouse cells. Growth of toxin-positive C. muridarum is not affected in IFN-gamma treated cells, whereas growth of toxin-negative C. trachomatis is inhibited. We previously reported that this difference in IFN-gamma sensitivity is important to the in vivo infection tropism of these pathogens. Here we describe a phenotypic rescue assay that utilizes C. muridarum gamma irradiated killed elementary bodies (iEB) to rescue C. trachomatis infectivity in IFN-gamma treated mouse cells. Rescue by iEB was temporal, maximal early post infection, directly related to multiplicity of iEB infection, and was independent of de novo chlamydial transcription. Lastly, C. muridarum iEB vacuoles and C. trachomatis inclusions were not fusogenic, suggesting the factor(s) responsible for rescue was secreted or exposed to the cytosol where it inactivated IFN-gamma induced effectors. Chlamydial phenotypic rescue may have broader utility for the study of other EB associated virulence factors that function early in the interaction of chlamydiae with host cells.
沙眼衣原体和鼠衣原体分别是人类和小鼠病原体，它们的开放阅读框（ORF）有超过99%相同，但在细胞毒素基因座上存在差异。这些菌株中细胞毒素基因的有无与其在干扰素-γ处理的小鼠细胞中的生长能力相关。毒素阳性的鼠衣原体在干扰素-γ处理的细胞中生长不受影响，而毒素阴性的沙眼衣原体生长受到抑制。我们之前报道过，这种对干扰素-γ敏感性的差异对这些病原体的体内感染嗜性很重要。在此，我们描述了一种表型拯救试验，该试验利用经γ射线照射杀死的鼠衣原体原体（iEB）来拯救沙眼衣原体在干扰素-γ处理的小鼠细胞中的感染性。iEB的拯救作用具有时效性，在感染后早期达到最大，与iEB感染复数直接相关，且与衣原体的从头转录无关。最后，鼠衣原体iEB空泡和沙眼衣原体包涵体不发生融合，这表明负责拯救的因子是分泌型的或暴露于细胞质中，在那里它使干扰素-γ诱导的效应器失活。衣原体表型拯救可能对研究衣原体与宿主细胞相互作用早期起作用的其他与原体相关的毒力因子具有更广泛的用途。
