The production of plant produced Newcastle Disease virus like particles for poultry and other avian species

Project summary

Newcastle disease (ND) is a highly contagious viral disease that has a severe impact on poultry production worldwide and results in trade restrictions in affected countries. In order to protect poultry from the potentially lethal effect of ND infection, vaccination against ND is commonly practised around the world. South Africa (SA), a country where poultry is the main source of protein, is the global leader in ostrich production and vaccination of all ostriches against ND is compulsory. However, as the current registered ND vaccine result in lesions in the muscle and subsequently devaluate the meat, we want to explore the use of tobacco plants to produce a cost-effective ND vaccine that can be produced within a short time-frame, does not entail the handling of infectious viral material throughout the production process, and will enable the distinction between vaccinated and non-vaccinated animals. The use of virus-like particles (VLPs) as vaccines have become increasingly popular in recent years. VLPs are self-assembled protein “shells” that looks like a native viral particle, which makes at highly effective in generating an immune response following vaccination, but are non-infectious as it contains no viral genetic material. In the proposed study, we will aim to produce ND VLPs in tobacco plants. In addition, we will make use of tobacco plants (Nicotiana benthamiana) to produce proteins that have previously been shown to enhance the immune response following vaccination. The ND VLPs, with and without the immune response enhancers, will subsequently be tested for effectiveness in ostriches in an immunity study. Vaccination of poultry and other avian species against infectious diseases like ND is of the utmost importance to protect the lucrative export market as well as ensuring food security in a country where poultry is one of the main sources of protein.

Project outcomes

Newcastle disease (ND) is a highly contagious avian disease that places a severe burden on poultry production globally and vaccination against ND forms an important part of disease control. Transient plant-based expression virus-like particles (VLPs), protein “shells” with antigenic epitopes of the native virus displayed in a tight arrangement on its surface without any viral genetic material at its core, has become increasingly popular due to the advantages of a short production timeframe, cost-effective scalability of the production process, as well as the immunogenicity of VLPs when formulated into vaccines. In the present study, a transient plant-based production platform was established for the expression of ND VLPs based on a genotype VII.2 strain. Making use of agroinfiltration and the pEAQ-HT plant-expression vector, the minimal combination of ND proteins to be expressed in order to produce ND VLPs in N. benthamiana leaves were established and the production process was optimised at various stages to maximize yield. The immunogenicity of the partially-purified plant-produced ND VLPs were subsequently tested for immunogenicity in specific pathogen-free chickens. When formulated with a commercial adjuvant, the plant-produced ND VLPs generated strong humoral immune responses two weeks after a single intramuscular immunization. The adaptability of transient plant-based expression is an advantage for viral diseases with a great genetic diversity that require either periodic updating of the vaccine or a vaccine tailored for a specific geographical area to ensure efficacy against circulating field strains. This study is the first step in using transient plant-based expression to develop antigen-matched ND VLP vaccines for poultry and other avian species.

0

Project outputs