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

炭疽是一种由革兰氏阳性细菌——炭疽芽孢杆菌引起的传染病。最重要的毒力相关蛋白：毒力因子（PA， EF和LF）和胶囊合成因子（CapBCADE）由两个大的独特质粒编码。首先，我们分析了两个大质粒pXO1 （180kb）和pXO2 (95kb)，发现了几个具有分泌信号序列的短orf。然后，我们发现204个orf中有23个来自pXO1, 104个orf中有12个来自pXO2。虽然信号肽酶I （SPI）是由染色体编码的，但人们特别感兴趣的是，新的SPI样蛋白也是由pXO2编码的。为了验证推定的分泌因子，将不同菌株（WT [pXO1+pXO2+]， pXO1-贫[pXO1+]， pXO1-贫[pXO2+]）和两种质粒缺失的炭疽芽孢杆菌)的培养上清加入到培养的细胞中。因此，我们只观察了WT和pXO1+菌株培养上清液处理HeLa和vero细胞的形态学变化。培养细胞的这种形态变化可能与pXO1有关。然后我们试图确认各种细胞反应的可能性，包括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.