Newly identification of virulence plasmid-encoded factor(s) secreted by Bacillus anthracis

炭疽病是一种由革兰氏阳性细菌炭疽杆菌引起的传染病。毒力相关蛋白中最重要的毒力因子（PA、EF、LF）和荚膜合成因子（CapBCADE）由两个独特的大质粒编码，我们首先对两个大质粒pXO1（180kb）和pXO2（95kb）进行了电子分析，发现了几个含有分泌信号序列的短ORF。然后，我们发现204个ORF中的23个来自pXO 1，104个ORF中的12个来自pXO 2。尽管信号肽酶I（SPI）是由染色体编码的，但新的SPI样蛋白也是由pXO 2编码的。为了检测可能的分泌因子，将不同菌株的培养上清，WT [pXO 1 + pXO 2 +]，pXO 1缺失的[pXO 1 +]，pXO 1缺失的[pXO 2 +]，以及两种质粒都缺失的B.anthracis加入到几种培养细胞中。结果表明，WT和pXO 1+菌株培养上清单独作用于HeLa和Vero细胞后，细胞形态发生了变化。这种形态学变化可能与pXO 1有关。然后，我们试图证实各种细胞反应的可能性，包括细胞凋亡和肌动蛋白聚合。

Anthrax is an infectious disease caused by gram-positive bacteria, Bacillus anthracis. The most important virulence-related proteins : the virulence factors (PA, EF & LF) and the capsule synthesis factors (CapBCADE) are encoded by two large unique plasmids.First, we analyzed two large plasmid pXO1 (180kb) and pXO2 (95kb) in silico, we found several short ORFs with secretion signal sequence. Then, we found 23 of 204 ORFs form pXO1, and 12 of 104 ORFs from pXO2. Although signal peptidase I (SPI) is encoded by chromosome, it is especially interested that newly SPI-like protein is also encoded by pXO2.To test the putative secreted factors, culture supernatant of various strains, WT [pXO1+pXO2+], pXO2-depleted [pXO1+], pXO1-depleted [pXO2+], and both plasmids-depleted B.anthracis, were added to several cultured cells. As a result, we observed morphology change of HeLa and vero cell only treated by the culture supernatants of WT and pXO1+ strains. This morphology change of cultured cell might be attributed to pXO1. Then we tried to confirm the possibility of various cellular responses including apoptosis and actin-polymerization.