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Viral Vectors and Delivery Systems
Contact: David B Wallace (Ph.D Genetics); Telephone: +27 (0)12 529 9442; Fax: +27 (0)12 529 9249
​Identifying potential vaccine antigens is only the first step in a long process that can ultimately lead to a new vaccine. Delivering those antigens in a way that elicits a protective response is equally important. Poxvirus vectors elicit both humoral and cellular immunity and offer the possibility of protecting against multiple diseases. The capripoxvirus, lumpy skin disease (LSD) virus, has been used to elicit protective immunity in a number of vaccine trials. This vector and its ability to deliver virtually any potential vaccine antigen is the main focus of this laboratory's activities
Co-workers:
Dr Arshad Mather (PhD Biochemistry)
Mr Pravesh Kara (M.Sc Microbiology)
Dr Wallace – molecular veterinary virology with vast experience in recombinant vaccine development using poxviruses (especially LSD virus) as vectors. Experience and working knowledge of the biology, diagnosis and molecular epidemiology of LSD virus and Rift Valley fever virus. OIE Reference Laboratory expert on LSD).
Dr Mather - Dr Mather is a protein-expression specialist with 11 years' experience in livestock vaccine development. He has an acuity for project management, linked to a number of internationally-funded projects.
Develop and utilise vectors such as lumpy skin disease virus (LSDV) for delivering recombinant vaccines against diseases of veterinary importance, and use molecular approaches to develop better vaccines and diagnostic assays.
​ Drs Mather and Wallace received the ARC CEO and President's Choice Award for Excellence for 2016
There is a need for improved live DIVA ("differentiate infected from vaccinated animals") vaccines for a number of ruminant livestock diseases which are either endemic to South Africa, or pose potential threats. LSDV has been shown to be a candidate vector for such vaccines.
There is also a need for an improved LSDV vaccine due to problems such as low antibody titres in vaccinated animals. In addition, international regulations now require molecular-based techniques for the diagnosis of LSDV, and the other capripoxviruses (sheep pox and goat pox viruses).
Malignant catarrhal fever (MCF), caused by gamma-herpesviruses, is an often fatal disease of ruminants and is especially a problem where domestic and wild ruminant species are in close proximity. New vaccines and diagnostic assays are required to help control and prevent further spread of this disease.
Photograph showing immunofluorescence-detection of expression of protective glycoproteins of Rift Valley fever virus from lumpy skin disease virus towards a new vaccine for dual protection against both lumpy skin disease and Rift Valley fever in cattle. Credit: Antoinette Lensink, Electron Microscopy, Department of Anatomy and Physiology, Faculty of Veterinary Sciences, University of Pretoria.
Studies have proven the suitability of LSDV as a vector for recombinant vaccines and a number of vaccine constructs have been developed showing promising results in pilot animal trials. New LSDV-vectored recombinant vaccines are also being developed e.g. against peste des petits ruminants (PPR).
The availability of sequence data for LSDV has enabled us to identify areas of the viral genome which are most likely involved in suppression of the host animal's immune system during infection. We are now using a selective deletion strategy to remove these regions for developing an improved LSDV vaccine and vector.
For improved diagnostic tests for LSD, we have developed, and are evaluating, PCR tests (conventional and real-time), and we are busy evaluating recombinant ELISA tests.
New vaccines and diagnostic assays are also being developed for MCF using similar approaches to those described for LSDV.
Products/Outputs
Recombinant vaccine constructs for diseases such as bovine ephemeral fever, Rift Valley fever, foot-and-mouth disease, MCF and CBPP
Improved capripox vaccine (which protects against sheep pox, goat pox and PPR)
Molecular-based diagnostic test e.g. ELISA
IP (patents etc.), higher degrees, publications.
Publications (selected):
Boshra, H., Truong, T., Nfon, C., Gerdts, V., Tikoo, S., Babiuk, L.A., Kara, P., Mather, A., Wallace, D.B. & Babiuk, S. (2013). Capripoxvirus-vectored vaccines against livestock diseases in Africa. Antiviral Research, 98 (2), 217-227.
Boshra, H., Truong, T, Nfon, C., Embury-Hyatt, C., Bowden, T.R., Gerdts, V., Tikoo, S., Babiuk, L.A., Kara, P., Mather, A., Wallace, D.B. & Babiuk, S. (2015). A lumpy skin disease virus deficient of an IL-10 gene homologue provides protective immunity against virulent capripoxvirus challenge in sheep and goats". Antiviral Research, 123, 39-49.
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