Institution: | a Immunology Section, Onderstepoort Veterinary Institute, Private Bag x5, Onderstepoort 0110, South Africa;b University of Pretoria, Department of Veterinary Tropical Diseases, Faculty of Veterinary Sciences, Private Bag x4, Onderstepoort 0110, South Africa;c Research and Development Laboratory, Biotechnology Division, National Bioproducts Institute, Pinetown 3610, South Africa |