| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2012: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2011: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2010: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
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| Research Abstract |
Babesia microti, the main causal agent of human babesiosis, is a species-complex comprised of at least four taxa (the U.S., Kobe, Munich and Hobetsu). To further assess micro-evolutionary history and genetic variability within the taxon, we used a set of 6 introns in the CCT7 gene as a rapidly evolving DNA marker. Phylogenetic and comparative sequence analysis subdivided the U.S. taxon into three geographic subclades - North America, western to central Eurasia, and northeastern Eurasia. The Kobe taxon, which occurs only in a few geographic foci in Japan could further be subdivided into two subgroups. The Munich and Hobetsu taxa, common to Europe and Japan, respectively, exhibited little or no pairwise sequence divergence among geographically diverse samples, suggesting an extreme population bottleneck in the recent histories. We further conducted a field investigation at Nemuro on Hokkaidoisland and Sumoto on Awaji island, where up to two lineages co-occur with similar frequency in reservoir. Lineage specific PCR for rDNA-positive samples demonstrated that I. ovatus and I. persulcatus carried, respectively, the Hobetsu and U.S. parasites. No Kobe-parasote carrying tick was detected. This result indicate that, for the first time, Hobetsu and U.S. parasites are vectored by different Ixodid species.
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