1. a Department of Life and Environmental Science , Chiba Institute of Technology , Chiba, Japan
2. b Department of Virology , Noguchi Memorial Institute for Medical Research , Legon-Accra, Ghana
3. c Department of Life and Environmental Science , Chiba Institute of Technology and High Technology Research Center , Chiba, Japan
4. d National Institute of Infectious Diseases, AIDS Research Center , Tokyo, Japan
5. e High Technology Research Center , Chiba, Japan