Expression of HIV-1 antigens in plants as potential subunit vaccines

Abstract

Background: Human immunodeficiency virus type 1 (HIV-1) has infected more than 40 million people worldwide, mainly in sub-Saharan Africa. The high prevalence of HIV-1 subtype C in southern Africa necessitates the development of cheap, effective vaccines. One means of production is the use of plants, for which a number of different techniques have been successfully developed. HIV-1 Pr55Gag is a promising HIV-1 vaccine candidate: we compared the expression of this and a truncated Gag (p17/p24) and the p24 capsid subunit in Nicotiana spp. using transgenic plants and transient expression via Agrobacterium tumefaciens and recombinant tobamovirus vectors. We also investigated the influence of subcellular localisation of recombinant protein to the chloroplast and the endoplasmic reticulum (ER) on protein yield. We partially purified a selected vaccine candidate and tested its stimulation of a humoral and cellular immune response in mice.

Plant-based vaccines against viruses

“…The other chimaeric L1s did not form distinct particles, and elicited significantly weaker humoral immune responses for the same dose of protein. The L1:L2 [108][109][110][111][112][113][114][115][116][117][118][119][120] particle formation was in contrast to repeated previous expression of this and the other chimaeras in insect cells, where only loose aggregates of capsomers were formed for L1:L2 [108][109][110][111][112][113][114][115][116][117][118][119][120] [95,96].…”

“…All chimaeras were very highly expressed, with yields of up to 1.2 g/kg plant tissue. The L1 chimaera containing L2 amino acids 108-120 (L1:L2 [108][109][110][111][112][113][114][115][116][117][118][119][120] ) was the most successful candidate in that it assembled into small VLPs (~30 nm), and elicited anti-L1 and anti-L2 responses in IM immunised mice, and immune sera neutralised homologous HPV-16 and heterologous HPV-52 pseudovirions. The other chimaeric L1s did not form distinct particles, and elicited significantly weaker humoral immune responses for the same dose of protein.…”

“…As could be expected, HIV vaccines were an early target for plant expression studies, with a variety of targets: indeed, HIV-1 p24 capsid protein was expressed successfully in transgenic tobacco, albeit at low yield (0.35% of TSP), as long ago as 2002 [107]; the suitability of transgenic maize as a production platform for oral delivery of HIV vaccines in seed extracts was tested using SIV major surface glycoprotein gp130 [108]; a novel gp41-derived molecule incorporating a CTB fusion as polymerising agent and adjuvant was produced via agroinfiltration-mediated expression in N benthamiana [109] and shown to produce mucosal and serum antimembrane proximal region (MPR) antibodies in mice after mucosal prime-systemic boost immunisation [110]; a Tat monomer was produced in spinach via rTMV as a potential oral vaccine [111]; epitopes derived from HIV-1 Gag and Env were fused to HBsAg and expressed as VLPs in transgenic tomato fruit [112]; various Gag-derived antigens (p24, p41, p55) were produced in transgenic tobacco and via rTMV in N benthamiana for investigation of their utility as CTL-inducing immunogens by our group [113]; HIV-1 Nef was produced in N benthamiana using an agroinfiltration-mediated transient expression system [114]. The field was comprehensively reviewed recently [115], so this review will be limited discussion of major advances, and more recent work.…”

Techno-Economic Analysis of Horseradish Peroxidase Production Using a Transient Expression System in Nicotiana benthamiana

“…The main factor in the development is to identify the most suitable vector system that will induce high levels of high purity protein production, whilst maintaining plant viability over a period of between 3 to 10 days, which is the typical incubation time for transient expression. The actual incubation time depends on the vector system employed and the heterologous protein being expressed, and needs to be optimised experimentally for each system (22,21).…”

Subunit Vaccine Based on Plant Expressed Recombinant Eimeria Gametocyte Antigen Gam82 Elicit Protective Immune Response against Chicken Coccidiosis

“…Plant expression platform has been an alternative to conventional protein expression systems due to its ease of transformation, low initial investment, high recombinant protein expression, easy scale up and the plant expressed proteins can undergo post-translational modifications [10,11]. Earlier reports had also showed that the recombinant antigens expressed in plants could be used as subunit vaccines [7,[12][13][14]. Present study was aimed at evaluating the plant expressed recombinant E. maxima gametocyte antigen Gam82 against chicken coccidiosis using a bird challenge experiment.…”