1. School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences, Glasgow, UK
2. School of Life Sciences, Glasgow, UK
3. Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
4. Sandyford Sexual Health Service, NHS Greater Glasgow and Clyde, Glasgow, UK
5. Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
6. School of Dental Sciences, University of Newcastle, Newcastle upon Tyne, UK