1. Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
2. Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa
3. Division of Medical Virology, Department of Pathology, University of Cape Town and National Health Laboratory Service, Groote Schuur Hospital, Observatory 7925, South Africa