Scientists modified a tobacco plant to produce a vaccine for norovirus, the viral infection sometimes called the “cruise ship virus.” Researchers led by Charles Arntzen, PhD, a biologist and codirector of the Center for Infectious Diseases and Vaccinology at Arizona State University, believe the novel plant biotechnology methods may someday facilitate rapid development of vaccines for other viruses such as H1N1 influenza, especially when the virus has mutated beyond the effectiveness of established vaccines.
The norovirus is well-known to mutate constantly, a condition, says Arntzen, that makes it a moving target for vaccine developers. “With plant-based vaccines, we can generate the first gram quantities of the drug and do clinical tests within eight to 10 weeks. We could easily scale that up for commercial use in a two to four month period,” said Arntzen in a press release.
The plants were engineered to produce high levels of viruslike nanoparticles in the plants. These nanoparticles are approximately the same size as the norovirus (25 nm), but do not contain the infectious material of the virus. They are made up of only the outer surface of the protein that is recognized by the human immune system, and thereby stimulate an immune response to fight an infection should it occur.
Production costs related to the purification and formulation of plant-based vaccines are also generally lower than those for cell-based vaccines because of the absence of infectious agents. “There are no viruses in plants that can infect humans, so you don’t have to worry about viral removal,” explains Arntzen. “Mammalian and insect-based vaccines are tried and true—some have barely changed in nearly 60 years,” says Arntzen. But that doesn’t necessarily mean they are the best in terms of manufacturing costs or flexibility. It simply means that the industry is not accustomed to using plant biotechnology.