Cell wall biochemical alterations during Agrobacterium-mediated expression of haemagglutinin-based influenza virus-like vaccine particles in tobacco.

Summary Influenza virus-like particles (VLPs) have been shown to induce a safe and potent immune response through both humoral and cellular mechanisms. They represent promising novel influenza vaccine. Plant-based biotechnology allows for the large-scale production of VLPs of biopharmaceutical interest using different model organisms, including Nicotiana benthamiana plants. In this platform, influenza VLPs bud from the plasma membrane and accumulate between the membrane and the plant cell wall. A better understanding of the plant cell wall composition of infiltrated tobacco leaves becomes a major interest for the plant-biotechnology industry in order to design and optimize efficient production processes. In this study, we have investigated the alteration of the biochemical composition of cell walls from N. benthamiana leaves subjected to abiotic and biotic stresses induced by the Agrobacterium-mediated transient transformation and the high-level expression of influenza VLPs. By comparison with non-infiltrated leaves, results show that abiotic stress due to vacuum infiltration without Agrobacterium did not induce any detectable modification of the cell wall. In contrast, various chemical changes of the leaf cell walls were observed post Agrobacterium infiltration. Moreover, infection with Agrobacterium induced deposition of callose and lignin as well as modification of pectin methylesterification, increase of arabinosylation of RG-I side chains and expression of arabinogalactan proteins (AGPs). Finally, modifications of the cell wall composition in response to agro-infiltration were slightly more important in plants expressing hemagglutinin-based VLP than in plants infiltrated with the Agrobacterium strain containing the p19 suppressor of silencing alone. This article is protected by copyright. All rights reserved.