| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥1,200,000 (Direct Cost: ¥1,200,000)
|
|---|
| Research Abstract |
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.
|
