1. Department of Biochemistry and Microbiology, Institute of Chemical Technology, Technicka 3, 166 28 Prague, Czech Republic
2. National Institute for Biological Standards and Control, South Mimms, Potters Bar, Herts, EN6 3QG, United Kingdom
3. Emory Vaccine Center, 954 Gatewood Road, Atlanta, Georgia
4. Department of Protein Biochemistry, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague, Czech Republic