[1] Sankyo Co Ltd, Exploratory Chem Res Labs, Shinagawa Ku, Tokyo 1408710, Japan
[2] ChemTech Lab Inc, Shinagawa Ku, Tokyo 1408710, Japan
[3] Sankyo Co Ltd, Biol Res Labs, Shinagawa Ku, Tokyo 1408710, Japan
[4] Natl Inst Infect Dis, Dept Biochem & Cell Biol, Shinjuku Ku, Tokyo 1628640, Japan