Post-Doctoral Fellowhip, University of Cape Town/ Biopharming Research Unit
Rift Valley fever (RVF) is a haemorrhagic fever agent caused by RNA Rift Valley fever virus (RVFV). The virus is spread by infected mosquitoes and affects ruminants and humans, causing high numbers of newborn fatalities in animals and occasional fatalities in humans, posing serious health and agricultural problems. The disease can be prevented by vaccination, but there is currently no Food and Drug Administration approved RVFV vaccine that can be used outside endemic areas, while there are two live attenuated vaccines available for use in prevalent areas. These vaccines have a potential for reversion, therefore they are not recommended for use in countries where RVFV is not prevalent. This indicates the need for more RVFV vaccine research and development.
The research is focused on the development of a RVFV vaccine candidate using the South African isolate M35/74. Gene was modified for recombinant protein expression in plants, that would allow for differentiation between infected and vaccinated animals as well as humans and would not revert to pathogenicity. The research is aligned with the primary objective of the bioeconomy strategy with regards to strengthening agricultural biosciences innovation to provide food security, enhance nutrition and improve health
Abstract: Cowpea mosaic virus (CPMV) is a bipartite RNA plant virus which has proved to be useful both for epitope presentation and as a polypeptide expression system. For epitope presentation, short antigenic sequences are expressed on the surface of the assembled virus. Chimaeric virus particles produced in this way can stimulate protective immunity in experimental animals. For polypeptide expression, we have created a vector in which foreign sequences can be inserted near the 3' end of RNA-2 and have successfully expressed a number of polypeptides in plant tissue. To extend the utility of the CPMV-based systems, we have recently developed a combined virus vector/transgenic expression system in which RNA-2 expressed from a transgene is replicated by RNA-1.
Pub.: 01 Mar '05, Pinned: 28 Jul '17
Abstract: The zoonotic Rift Valley fever virus affects livestock and humans in Africa and on the Arabian Peninsula. The economic impact of this pathogen due to livestock losses, as well as its relevance to public health, underscores the importance of developing effective and easily distributed vaccines. Vaccines that can be delivered orally are of particular interest.
Pub.: 08 Jul '16, Pinned: 28 Jul '17
Abstract: Rift Valley fever virus (RVFV) is an emerging mosquito-borne virus causing significant morbidity and mortality in livestock and humans. Rift Valley fever is endemic in Africa, but also outside this continent outbreaks have been reported. Here we report the evaluation of two vaccine candidates based on the viral Gn and Gc envelope glycoproteins, both produced in a Drosophila insect cell expression system. Virus-like particles (VLPs) were generated by merely expressing the Gn and Gc glycoproteins. In addition, a soluble form of the Gn ectodomain was expressed and affinity-purified from the insect cell culture supernatant. Both vaccine candidates fully protected mice from a lethal challenge with RVFV. Importantly, absence of the nucleocapsid protein in either vaccine candidate facilitates the differentiation between infected and vaccinated animals using a commercial recombinant nucleocapsid protein-based indirect ELISA.
Pub.: 09 Jan '10, Pinned: 28 Jul '17
Abstract: Rift Valley fever virus (RVFV) is a mosquito-transmitted Bunyavirus that causes high morbidity and mortality among ruminants and humans. The virus is endemic to the African continent and the Arabian Peninsula and continues to spread into new areas. The explosive nature of RVF outbreaks requires that vaccines provide swift protection after a single vaccination. We recently developed several candidate vaccines and here report their efficacy in lambs within three weeks after a single vaccination. The first vaccine comprises the purified ectodomain of the Gn structural glycoprotein formulated in a water-in-oil adjuvant. The second vaccine is based on a Newcastle disease virus-based vector that produces both RVFV structural glycoproteins Gn and Gc. The third vaccine comprises a recently developed nonspreading RVFV. The latter two vaccines were administered without adjuvant. The inactivated whole virus-based vaccine produced by Onderstepoort Biological Products was used as a positive control. Five out of six mock-vaccinated lambs developed high viremia and fever and one lamb succumbed to the challenge infection. A single vaccination with each vaccine resulted in a neutralizing antibody response within three weeks after vaccination and protected lambs from viremia, pyrexia and mortality.
Pub.: 28 Mar '12, Pinned: 28 Jul '17
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