1. BK21 Project Team, College of Pharmacy, Chosun University, 375 Seosuk-dong, Dong-gu, Gwangju 501-759, Republic of Korea, Choong Ang Vaccine Laboratory, 59-3 Hwaam-dong, Yuseong-gu, Daejeon 305-348, Republic of Korea, and College of Pharmacy, Chungnam National University, Daejeon 305-764, Republic of Korea