Schematic representation of the T-DNA bearing the seed-specific expression cassette (A), the PRRSV glycoproteins selected to be included in a vaccine (B) and the antigen formats derived thereof (C).

<p>(A) The T-DNA carrying the neomycin phosphotransferase II gene which confers resistance to the antibiotic kanamycin and the cassette for high seed-specific expression driven by the <i>β-phaseolin</i> promoter, the leader sequence of the tobacco mosaic virus and the <i>arcelin-5I</i> terminator. The cassette is further supplemented with sequences encoding an ER-targeting and retention signal. (B) The full-length PRRSV glycoproteins used in the current study and supplemented with a His₆-tag (purple rod). The jagged line depicts the Tm. The full-length GP3 is placed between brackets as it was never produced as such. Only the GP3 without Tm was expressed, depicted as GP3-Tm in (C). (C) Overview of the manipulations performed on the GPs and the resulting set of antigenic proteins whose coding sequences were cloned into the seed-specific expression cassette. Abbreviations and symbols used: LB and RB, T-DNA left and right border, respectively; 3′<i>ocs</i>, 3′end of the octopine synthase gene; <i>nptII</i>, the neomycin phosphotransferase II gene; P<i>nos</i>, promoter of the nopaline synthase gene; P<i>phas</i>, promoter of the <i>β-phaseolin</i> gene; Ω, leader sequence of the ‘tobacco mosaic virus’; SS, sequence coding for the signal peptide of the 2S <i>Arabidopsis</i> seed storage protein; GOI, gene of interest; KDEL, coding sequence of the ER-retention signal; 3′<i>Arc</i>, terminator of the <i>arceline5-I</i> gene; Tm, transmembrane domain, jagged line; His₆-tag, immobilized metal affinity chromatography tag, purple rod; pFc, porcine IgG3 Fc, chain of blue ovals; mFc2a, murine IgG2a Fc, chain of orange ovals; mFc3, murine IgG3 Fc, chain of yellow ovals; GFP, green fluorescent protein, bright green oval.