Charlotte S Kaetzel1, Jiri Mestecky2, Finn-Eirik Johansen3. 1. Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536; cskaet@uky.edu. 2. Department of Microbiology, University of Alabama at Birmingham School of Medicine, Birmingham, AL 35294; and. 3. UiO:Life Science, University of Oslo, 0316 Oslo, Norway.