1. Division of Virology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road Scheme-XM, Beliaghata, Kolkata 700010, India
2. Department of Zoology, University of Calcutta, Ballygunge Circular Road, Kolkata 700019, India
3. Department of Hygeine, Sapporo Medical University, S-1 W-17, Chuo-ku, Sapporo 060-8556, Japan
4. Department of Virology and Parasitology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan