Zhang Jian-zhi, Popov Vsevolod L, Gao Si, Walker David H, Yu Xue-jie
Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
Cell Microbiol. 2007 Mar;9(3):610-8. doi: 10.1111/j.1462-5822.2006.00812.x. Epub 2006 Sep 20.
Ehrlichia chaffeensis, an obligatory intracellular bacterium, has two forms in mammalian cells: small dense-cored cells (DC) with dense nucleoid and larger reticulate cells (RC) with uniformly dispersed nucleoid. We have determined by electron microscopy that DC but not RC attaches to and enters into the host cells and RC but not DC multiples inside the host cells. Analysis of outer membrane protein expression by confocal microscopy showed that RC expressed the 28 kDa outer membrane protein (p28), the intermediate form, which were transforming from RC to DC, expressed both gp120 and p28, and the mature DC expressed gp120 only. The TCID50 of DC is 6 log10 higher than RC. We conclude that E. chaffeensis has a developmental cycle, in which the DC attaches to and enters into the host cells, and transforms into RC and the RC multiplies by binary fission for 48 h and then matures into DC at 72 h.
恰菲埃立克体是一种专性细胞内细菌，在哺乳动物细胞中有两种形态：具有致密类核的小致密核心细胞（DC）和具有均匀分散类核的较大网状细胞（RC）。我们通过电子显微镜确定，是DC而非RC附着并进入宿主细胞，是RC而非DC在宿主细胞内增殖。通过共聚焦显微镜分析外膜蛋白表达表明，RC表达28 kDa外膜蛋白（p28），从RC向DC转化的中间形态同时表达gp120和p28，而成熟的DC仅表达gp120。DC的半数组织培养感染剂量（TCID50）比RC高6个对数10。我们得出结论，恰菲埃立克体有一个发育周期，其中DC附着并进入宿主细胞，转化为RC，RC通过二分裂增殖48小时，然后在72小时成熟为DC。
