The development of African horse sickness virus-like particle vaccines produced in plants

25 January 2022

African horse sickness is a devastating, infectious, but non-contagious disease that causes great suffering and many fatalities amongst the horse population in sub-Saharan Africa. It is caused by African horse sickness virus (AHSV), an orbivirus of the family Reoviridae, and is spread by midges. The disease has significant economic consequences for the equine industry both in southern Africa, and increasingly further afield as the geographic distribution of the midge vector broadens with global warming. Commercially available live attenuated vaccines have been in use in South Africa with relative success for more than five decades, but there is a risk of reversion to virulence as well as re-assortment of the segmented genome between outbreak and vaccine strains. Furthermore, the vaccines lack DIVA capacity, the ability to distinguish between vaccine-induced immunity and that induced by natural infection. The Biopharming Research Unit at the University of Cape Town in South Africa has developed a virus-like particle (VLP) vaccine candidate made in plants which has been shown to be safe and immunogenic both in guinea pigs and horses – the main target animal. Serum from immunised guinea pigs and horses has also been shown to have strong serotype-specific neutralising capabilities in vitro. This evidence suggests they are excellent vaccine candidates as the lack of viral genetic material abrogates the risk of reversion to virulence or re-assortment with wild virus strains and they are DIVA compliant.

This webinar was presented by Dr Ann Meyers, Senior Research Officer in the Biopharming Research Unit, University of Cape Town, South Africa. Dr Meyers's talk was followed by a question-and-answer session moderated by IVVN Network Management Board member Professor Brian Perry.

Dr Ann Meyers

Dr Ann Meyers is a Senior Research Officer in the Biopharming Research Unit (BRU) in the Department of Molecular and Cell Biology at the University of Cape Town, South Africa. She obtained her PhD at the University of Cape Town in 1999 and started work on biopharming-related projects in the BRU in 2001. She is an established researcher with a C2 National Research Foundation rating (South Africa). Her first project, under BRU director Prof Ed Rybicki, was funded by the South African Aids Vaccine Initiative and involved exploring the possibilities of producing a HIV vaccine in plants. This event marked the beginning of her work on the production of virus-like particles (VLPs) in plants as vaccine candidates. The exploration of the expression of recombinant proteins/vaccines in plants was new to the research group at the time and involved the establishment of many new techniques and protocols in the laboratory. She has since worked on an international project involving the development of bluetongue virus (BTV) VLP vaccine candidates in plants which expanded into more recent work on the development of AHSV VLPs as vaccine candidates. She also leads other projects in the BRU involved in making diagnostic reagent proteins in plants for One Health Initiative-relevant viruses including Crimean-Congo haemorrhagic fever, Rift Valley fever (RVFV).Chikungunya, Shuni and West Nile viruses. Ann has co-authored publications and several patents and supervised many honours, Masters’ and PhD postgraduates during her 20 years in the BRU.

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