Expression of hemagglutinin-neuraminidase glycoprotein of newcastle disease Virus in agroinfiltrated Nicotiana benthamiana plants.

The worldwide need for producing safer and less expensive vaccines with minor manufacture and processing requirements, together with the advances made through biotechnology, has promoted the development of efficient alternative tools to conventional vaccines. One of these is the use of plants or plant cell culture as production platforms of vaccine antigens with potential use as immunogens. We have already described the use of transgenic potato plants as immunogens against Newcastle Disease Virus (NDV), although the amount of the recombinant antigen recovered was low. The main objective of the work presented here was to enhance the expression of the HN glycoprotein of NDV through a protein targeting strategy and a promoter change. We have cloned the HN coding region under the regulation of the rubisco small subunit promoter in 5 different versions in a subcellular localization strategy, and we have established that the construct harboring the complete HN gene with its own signal peptide, fused to KDEL retention peptide, rendered the best expressed/accumulated HN protein level whether a transient or a stable transformation assay was performed. We conclude that agroinfiltration results in a simple and useful tool for selecting suitable genetic constructions to be used in stable plant transformation and, moreover, it could be used as a method to produce immunogens for vaccine developments.