Development and characterization of a plant-derived norovirus-like particle vaccine.

Background: Norovirus (NoV) is the most common cause of diarrheal episodes globally. Issues with in vitro cultivation systems, genetic variation, and animal models have hindered vaccine development. Plant-derived virus-like particles (VLPs) may address some of these concerns because they are highly immunogenic, can be administered by different routes, and can be rapidly produced to accommodate emerging viral strains.
Methods: NoV VLPs (NoVLP) composed of the surface viral protein (VP) 1 of the GI and GII genogroups were produced in Nicotiana benthamiana using an Agrobacterium tumefaciens-based recombinant transient expression system. Leaves from infiltrated plants were harvested and NoVLPs were extracted and purified. The safety and immunogenicity of the GII.4 NoVLP, the genotype currently causing most human disease, were subsequently examined in rabbits and mice.
Results: Fifteen GI and GII NoVLPs were successfully expressed in N. benthamiana and were structurally similar to NoV virions, as determined by cryogenic transmission electron microscopy. The NoVLP was well-tolerated, with no local or systemic signs of toxicity in rabbits. Three intramuscular doses of the GII.4 NoVLP adjuvanted with aluminum hydroxide induced robust IgG titers, IgG-secreting cells, histo-blood group antigen blocking titers, and IFNγ-secreting T cells in mice. In addition to circulating antibodies, oral administration of the NoVLP in mice induced significant IgA levels in feces, indicative of a mucosal response.
Conclusions: The plant-made NoVLP vaccine was safe and immunogenic in mice and rabbits. Multi-modal vaccination, combining oral and intramuscular administration could be considered for future clinical development to maximize systemic and mucosal immune responses.
Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: GA, DB, MAD, BJW, MMC, MD, POL, SP, and ST are employees of Medicago Inc. JS is employee of the Center for Vaccine Preventable Diseases, Dalla Lana School of Public Health, University of Toronto, ON, Canada, where she is supported by a postdoctoral fellowship from the Canadian Immunization Research Network. HH is employee of Research Institute of the McGill University Health Centre (under MITACS Elevate post-doctorate fellowship), Montreal, QC, Canada. MB and CD are employees of Providence Therapeutics. NL is employee of PharmaJet, CO, USA.
(Copyright © 2023. Published by Elsevier Ltd.)