Institution: | From the ‡Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Kita 15, Nishi 7, Kita-ku, Sapporo 060-8638 and ;the §Department of Structural Biology, Graduate School of Pharmaceutical Science, Hokkaido University, N-21, W-11, Kita-ku, Sapporo 001-0021, Japan |