A plant-produced virus-like particle generated an immune response against the West Nile Virus in mice, researchers report.
The mosquito-borne virus was first isolated in 1937 from the blood of a local woman in the West Nile district of Uganda. Since then, the virus has spread and become endemic in countries across Africa, the Americas, the Middle East, West Asia and Australia.
Many species can be infected, with the highest incidence of infection observed in birds, humans, and horses.
Infections in humans can result in fever and, although neurological problems are less common, they can cause serious illness and even death. There is no antiviral treatment and no available human vaccine.
About 20% of the infections in horses result in disease development, of which 90% involve neurological symptoms, with fatality rates of 30 to 40%.
As with humans, there is no antiviral treatment available for horses. However, several equine West Nile vaccines are produced in the United States and Europe are licenced for use.
Jennifer Stander and her fellow researchers, writing in the journal Frontiers in Plant Science, said these vaccines can be difficult and expensive to obtain in low and middle-income countries, with regards to import permits, the cost of the vaccines, and the need for annual vaccination. Most existing West Nile vaccines also require high levels of biosafety for their manufacture, they noted.
The researchers described their efforts to make a vaccine candidate made transiently in plants as a more cost-effective and safer means of production. They employed Nicotiana benthamiana, a close relative of the tobacco plant.
The resulting vaccine candidate was tested in mice and elicited what they described as a potent immune response to the West Nile Virus.
The study presents the potential for plants to be used as biofactories for making significant pharmaceutical products, they said. The technique could be used to address the need for local production of vaccines in low- and middle-income countries.
The authors said the global distribution of the West Nile Virus meant there was demand for the development of an affordable and effective vaccine.
“With little to no infrastructure for the development of these therapeutics in developing countries, the high costs associated with the importation of these products and the difficulties associated with the regulatory procedures for the procurement of permits further necessitate the local development of these products.”
The study team comprised Stander, Edward Rybicki and Ann Mayers, with the University of Capetown in South Africa; and Aleyo Chabeda, with the University of Massachusetts Medical School in the US.
Stander J, Chabeda A, Rybicki EP and Meyers AE (2021) A Plant-Produced Virus-Like Particle Displaying Envelope Protein Domain III Elicits an Immune Response Against West Nile Virus in Mice. Front. Plant Sci. 12:738619. doi: 10.3389/fpls.2021.738619