Mirinda van Kleef (Ph.D)
This unit aims to identify vaccine candidates which have the potential to protect animals against intracellular pathogens. To rationally develop new vaccines, it is important to characterise the immune responses induced by the pathogenic organism and to identify the antigens and epitopes that induce those responses for use in a recombinant vaccine. Thereafter it must be ascertained whether they protect. Currently research is largely focused on heartwater and African horse sickness virus. The heartwater recombinant plasmid DNA vaccines are tested by delivering them to ruminants using a gene gun followed by a laboratory tick challenge. Molecular biology methods used in this laboratory include bacterial protein expression and the development of mammalian plasmid DNA vaccines, while cellular immune assays include lymphocyte proliferation tests, ELIspot assays, cytokine mRNA real time PCR assays, functional assays for cytotoxic lymphocytes, flow cytometry as well as immune transcriptome analyses. We also investigate alternative micro and nanoparticle vaccine delivery systems. We offer flow cytometry analyses, the irradiation of biological samples with Cs137 and heartwater real time PCR diagnostic services.
Dr Mirinda van KleefSpecialist ResearcherTel: +27(0)12 529 9385Email: VanKleefM@arc.agric.za
Dr Alri PretoriusSenior ResearcherTel: +27(0)12 529 9214Email:
Dr Junita LiebenbergSenior ResearcherTel: +27(0)12 529 9229Email: LiebenbergJ@arc.agric.za
Dr Tshifhiwa NefefePost DocTel: +27(0)12 529 9111Email: NefefeT@arc.agric.za
Ms Erika FaberResearherTel: +27(0)12 529 9425Email: FaberE@arc.agric.za
Dr Helena SteynChief TechnicianTel: +27(0)12 529 9205Email: SteynH@arc.agric.za
Thema, N., Pretorius, A., Tshilwane, S.I., Liebenberg, J., Steyn, H., Van Kleef, M. 2016. Cellular immune responses induced in vitro by Ehrlichia ruminantium secreted proteins and identification of vaccine candidate peptides. Onderstepoort Journal of Veterinary Research. Vol 83, No 1 doi: 10.4102/ojvr.v83i1.1170
Faber, F.E., van Kleef, M., Tshilwane, S.I., Pretorius, A. 2016. African horse sickness virus serotype 4 antigens, VP1-1, VP2-2, VP4, VP7 and NS3, induce cytotoxic T cell responses in vitro. Virus Res. 220:12-20. doi: 10.1016/j.virusres.2016.04.007.
Pretorius, A., Faber, F.E. and Van Kleef, M. 2016. Immune gene expression profiling of PBMC isolated from horses vaccinated with attenuated African horsesickness virus serotype 4. Immunobiology. 221:236–244.
Liebenberg, J., Pretorius, A., Faber, F.E., Collins, N.E., Allsopp, B.A., van Kleef, M. 2012. Identification of
Ehrlichia ruminantium proteins that activate cellular immune responses using a reverse vaccinology strategy Veterinary Immunology and Immunopathology. 145:340– 349.
Pretorius, A., Van Kleef, M., Van Wyngaardt, W., Heath, J. 2012. Virus-specific CD8+ T-cells detected in PBMC from horses vaccinated against African horse sickness virus. Veterinary Immunology and Immunopathology. 146:81– 86.
Tshikhudo, N., Pretorius, A., Putterill, J., van Kleef, M. 2010. Preparation and in vitro characterisation of
Ehrlichia ruminantium plasmid DNA and proteins encapsulated into and DNA adsorbed onto biodegradable microparticles. Ticks and Tick-borne Diseases. 1:186–193.
Sebatjane, S.I., Pretorius, A., Liebenberg, J., Steyn, H., Van Kleef, M. 2010.
In vitro and
in vivo evaluation of five low molecular weight proteins of
Ehrlichia ruminantium as potential vaccine components. Veterinary Immunology and Immunopathology. 137:217–225.
Pretorius, A., Liebenberg, J., Louw, E., Collins, N. E., Breyton, K.A., Tshikudo, N., van Strijp, M. F. and Allsopp B. A. 2010. Studies of a polymorphic
Ehrlichia ruminantium gene for use as a component of a recombinant vaccine against heartwater. Vaccine. 28:3531-3539.
Pretorius A, van Kleef M, Collins NE, Tshikudo N, Louw E, Faber FE, van Strijp MF, Allsopp BA. 2008. A heterologous prime/boost immunisation strategy protects against virulent
Ehrlichia ruminantium Welgevonden needle challenge but not against tick challenge. Vaccine. 26:4363-4371.
Pretorius, A., Collins, N.E., Steyn, H.C., van Strijp, F., van Kleef, M. and Allsopp, B.A. 2007. Protection against heartwater with four
Ehrlichia ruminantium open reading frames presented by DNA immunisation. Vaccine. 25:2316-2324.
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