Abstract Title
The unmatched potential of tobacco plant-expressed virus-like particle vaccines to combat avian influenza
Abstract
Virus-like particles (VLPs) are self-assembling structures that resemble the geometry of a native virus, but lack any genetic material and are therefore non-infectious. VLPs can be produced in a variety of expression systems including yeast, mammalian, insect and plant cells. Unlike chemically- inactivated whole virus vaccines, VLPs stimulate both the host cellular and humoral immune responses, and enable differentiation between vaccinated and infected animals. We harnessed Nicotiana benthamiana (tobacco) plants infiltrated with recombinant Agrobacterium tumefaciens to transiently express VLPs that display the viral hemagglutinin (HA) protein, as vaccines against H6N2 LPAI, clade 2.3.4.4B H5Nx HPAI and H7N6 HPAI. Specific pathogen free White Leghorn chickens were prime-boosted with leaf extracts containing 250 HA units of the VLPs mixed with adjuvant. High serum hemagglutination inhibition titers were obtained after the primary and booster inoculations. The VLP vaccines provided 100% protection against morbidity and mortality in vaccinated chickens, and significantly reduced the amount of virus shed compared to non-vaccinated controls in challenge studies with the live viruses. Compared to other vaccine technologies, these VLP vaccines are unmatched in their safety (no live virus is used at any time during production, no toxicity), speed with which they can be produced (5 to 7 days from infiltration to harvest), scalability (infiltrating one tobacco plant or thousands depending on the facility) and potential costs of production (>85,000 vaccine doses per kilogram of leaves, with minimal processing). Their great benefit is the ability to rapidly match the vaccine to the circulating field virus, to prevent disease spread.
Co-Author(s)
Celia Abolnik and Martha M. O'Kennedy
Abstract Category
Diagnostics, vaccination, or other mitigation strategies for poultry and wildlife