Centre for Immunology, Infection and Evolution, Institute of Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom. Kate.Mitchell@lshtm.ac.uk|Centre for Immunology, Infection and Evolution, Institute of Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom. Kate.Mitchell@lshtm.ac.uk|Centre for Immunology, Infection and Evolution, Institute of Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom. Kate.Mitchell@lshtm.ac.uk|Centre for Immunology, Infection and Evolution, Institute of Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom. Kate.Mitchell@lshtm.ac.uk