Immunobiology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland. 1] Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands [2] Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland. Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland. Biomathematics and Statistics Scotland, Aberdeen, UK. Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK. 1] Immunobiology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland [2] Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands [3] Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland.