[1] Helmholtz Zentrum Infekt Forsch, Braunschweig, Germany
[2] Tierarztlichen Hsch Hannover, Inst Mikrobiol, D-3000 Hannover, Germany
[3] Univ Giessen, Biochem Abt, Giessen, Germany
[4] Ernst Moritz Arndt Univ Greifswald, Greifswald, Germany
[5] Tech Univ Carolo Wilhelmina Braunschweig, Braunschweig, Germany
[6] Univ Glasgow, Glasgow, Lanark, Scotland