An international research group has developed new therapeutics against West Nile virus and other pathogens using the tobacco plant, according to research that appears online in PLOS ONE.

The therapeutics (known as monoclonal antibodies, or MAbs) were shown to neutralize and protect mice against a lethal dose challenge of West Nile virus — even as late as 4 days after the initial infection.

Using young tobacco plants and a protein expression system, researchers were able to rapidly produce MAbs in tobacco plants in as little as ten days. The proteins are harvested in the leaves of the plant.

Therapeutic MAbs target proteins found on the surface of West Nile virus. They are typically made in animal host cells and assembled into Y-shaped complexes and, until now, tetravalent MAbs had never been made in a plant system before.

Previous research created MAbs that proved effective at neutralizing West Nile virus, however, that antibody was not able to accumulate at high levels in the brain.

Tobacco plant as therapeutic against infectious diseases

ASU researchers Qiang Chen and Huafang Lai infiltrate a tobacco plant to produce monoclonal antibodies against West Nile virus. Credit: Biodesign Institute, Arizona State University

“The goal of this latest research was twofold,” said Qiang Chen, a professor and researcher at Arizona State University’s Biodesign Institute. “First, we wanted to show proof-of-concept, demonstrating that tobacco plants can be used to manufacture large and complex MAb-based therapeutics.

“Secondly, we’ve wanted to improve the delivery of the therapeutic into the brain to combat West Nile virus at the place where it does the greatest harm.”

Chen and his team were able to improve upon their original antibody design, making half a dozen new variants that could, for the first time, lead to the development of MAbs that effectively target the brain and neutralize West Nile virus.

In two experiments with the antibodies, they protected up to 90 percent of the mice from lethal infection.

There is currently no cure or drug treatment against West Nile virus, which is spread by infected mosquitoes and targets the central nervous system. It can be a serious, life-altering and even fatal disease.

“This study is a major step forward for plant-based MAbs,” said Chen. “It is our hope that these results may usher in new age of cost-effective, MAbs therapeutics against WNV and other neurological diseases.”