1. Department of Infection Biology, Research Institute for Medical Sciences, Chungnam National University School of Medicine, Daejeon 301-131, Korea.
2. Department of Parasitology, Chungbuk National University College of Medicine, Cheongju 361-763, Korea.
3. Department of Applied Biology, Chungnam National University College of Agriculture and Life Sciences, Daejeon 301-131, Korea.
4. Department of Dairy Science and Industry, Chungnam National University College of Agriculture and Life Sciences, Daejeon 301-131, Korea.