Helmholtz Centre for Infection Research, Braunschweig, Germany. vsukhorukov@yahoo.com|Helmholtz Centre for Infection Research, Braunschweig, Germany. vsukhorukov@yahoo.com|Helmholtz Centre for Infection Research, Braunschweig, Germany. vsukhorukov@yahoo.com|Helmholtz Centre for Infection Research, Braunschweig, Germany. vsukhorukov@yahoo.com