Experimental analysis of symbiosis of Orientia tsutsugamushi and Leptotrombidium

我们对恙虫病东方体11kDa、22kDa、46kDa、56kDa、60kDa蛋白基因、16SrRNA基因和23S-5SrRNA内部转录序列（ITS）进行测序，了解恙虫病东方体Gilliam、Karp、Kato、Kawasaki、Kuroki、Shimokoshi和Ikeda 7株恙虫病东方体的系统发育关系。7个菌株的平均同源性为79.7% ~ 99.3%，每个序列有21个组合。16SrRA和细胞质蛋白（11 kDa和60 kDa）基因差异不大。其他蛋白和ITS序列在不同菌株间差异较大。其他蛋白质位于微生物的外膜，表明环境的选择压力影响了微生物的表面结构。恙虫。这导致抗原变异为0。这取决于56kDa蛋白的结构，其序列在蛋白质中同源性最低。根据同源性推断出的菌株的系统发育关系因基因的不同而不同，这表明从少量基因进行系统发育分析存在困难。然而，Shomokoshi与其他菌株的同源性较低，表明该微生物在幽门发育中处于分离地位。通常用于了解细菌两性关系的ITS序列也显示出菌株之间的巨大差异，但该序列太短，无法绘制出重要的系统发育树。我们正在用随机霰弹枪策略对池田的全基因组进行测序，但重复的序列阻止了完成。当全基因组序列出现后，将通过比较假基因和基因组结构来分析系统发育。

We sequenced 11kDa, 22kDa, 46kDa, 56kDa, 60kDa protein genes, 16SrRNA gene and 23S-5SrRNA internal transcribed sequence (ITS) of Orientia tsutsugamushi to know the phylogenetic relationship of seven strains, Gilliam, Karp, Kato, Kawasaki, Kuroki, Shimokoshi and Ikeda. The average homology among the seven strains, 21 combinations in each sequence, varied from 79.7 to 99.3%. The genes of 16SrRA and cytoplasmic protein (11 kDa and 60 kDa) genes vary a little. The sequences of the other proteins and ITS showed considerable variation among the strains. The other proteins locate in the outer membrane of the microorganism, suggesting that selection pressure of the circumstance affected on the surface structure of 0. tsutsugamushi. This causes the antigenic variation of 0. tsutsugamushi, which depends on structure of the 56kDa protein, the sequence of which showed the lowest homology among the proteins. Phylogenetic relations of the strains deduced from the homologies were different each other depending on the genes, suggesting the difficulty in phylogenetic analysis from a small number of genes. Shomokoshi, however, always showed low homology to the other strains, suggesting separated position in the pylogeny of this microorganism. The ITS, that is frequently analyzed to know bacterial aphlogeny, also showed great variation among the strains, but this sequence was too short to draw a significant phylogenetic tree. We are sequencing the whole genome of Ikeda by random shotgun strategy, but repeated sequences prevent from completion. When the whole genome sequence appears, the phylogeny would be analyzed by comparison of psuedogenes and structure of the genome.