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[2] CHUGAI PHARMACEUT CO LTD,DEPT VET PATHOL,CENT RES LABS,TOSHIMA KU,TOKYO 171,JAPAN
[3] UNIV TOKYO,FAC AGR,DEPT BIOMED SCI,BUNKYO KU,TOKYO 113,JAPAN
[4] INST PUBL HLTH,DEPT VET PUBL HLTH,MINATO KU,TOKYO 108,JAPAN