Dium [3]. On the basis of these preliminary studies in mice, the

Dium [3]. On the basis of these preliminary studies in mice, the aim of the present study was to determine whether orally delivered plant-made vaccines survive passage through the more complex ruminant digestive system and induceOral Immunogenicity of a Model PMV in SheepTable 1. Oral immunisation treatments and number of sheep assigned to each group.Treatment Control hairy root (CtHR) Control leaf (CtLeaf) Transgenic hairy root containing 5mg rLTB (LTB-HR) Transgenic leaf containing 5mg rLTB (LTB-Leaf) doi:10.1371/journal.pone.0052907.tSheep 3 (Sheep #50, 28, 54) 2 (Sheep #37, 73) 5 (Sheep #29, 30, 31, 42, 75) 5 (Sheep #36, 47, 57, 64, 69)immune responses in sheep. Leaf- and root-based LTB vaccines, each formulated in a lipid matrix, were compared and antigenspecific antibody responses localised to specific sites in the sheep GIT and mucosal immune system.Materials and Methods Plant materialsHairy root cultures of transgenic Petunia parodii (petunia) plants producing rLTB were generated and maintained as described previously [3,21]. Control petunia hairy root cultures were stably transformed with the pBinPlus empty vector [21,22]. For vaccine batch processing, hairy root cultures were harvested 22 days after subculture, snap frozen in liquid N2 then freeze-dried using a Dynavac freeze drier (Model FD12) for 48 h with a maximum shelf temperature of 20uC. Nicotiana benthamiana leaves transiently expressing apoplast-targeted LTB or GFP were produced as described previously [3]. Leaves were harvested at 7?0 days postinfiltration, snap-frozen in liquid N2 then freeze-dried using a Dynavac freeze drier (Model FD12) for 48 h with a maximum shelf temperature of 20uC. Freeze-dried plant materials were powdered using a commercial coffee grinder and sieved to standardise particle size to 0.5? mm2. Accumulation 11967625 5 DM in PBST before a 2 h room temperature (22?5uC) incubation with serially diluted crude plant extract starting with 1:100 in PBS. Plates were then incubated with 1:2,000 rabbit anti-LTB (Benchmark Biolabs), then 1:15,000 goat anti-rabbit IgG HRP conjugate (Sigma-Aldrich). Bound LTBFigure 1. LTB-specific IgG antibody titres in serum collected from sheep before immunisation with LTB-Leaf (A), LTB-HR (B) or con.Dium [3]. On the basis of these preliminary studies in mice, the aim of the present study was to determine whether orally delivered plant-made vaccines survive passage through the more complex ruminant digestive system and induceOral Immunogenicity of a Model PMV in SheepTable 1. Oral immunisation treatments and number of sheep assigned to each group.Treatment Control hairy root (CtHR) Control leaf (CtLeaf) Transgenic hairy root containing 5mg rLTB (LTB-HR) Transgenic leaf containing 5mg rLTB (LTB-Leaf) doi:10.1371/journal.pone.0052907.tSheep 3 (Sheep #50, 28, 54) 2 (Sheep #37, 73) 5 (Sheep #29, 30, 31, 42, 75) 5 (Sheep #36, 47, 57, 64, 69)immune responses in sheep. Leaf- and root-based LTB vaccines, each formulated in a lipid matrix, were compared and antigenspecific antibody responses localised to specific sites in the sheep GIT and mucosal immune system.Materials and Methods Plant materialsHairy root cultures of transgenic Petunia parodii (petunia) plants producing rLTB were generated and maintained as described previously [3,21]. Control petunia hairy root cultures were stably transformed with the pBinPlus empty vector [21,22]. For vaccine batch processing, hairy root cultures were harvested 22 days after subculture, snap frozen in liquid N2 then freeze-dried using a Dynavac freeze drier (Model FD12) for 48 h with a maximum shelf temperature of 20uC. Nicotiana benthamiana leaves transiently expressing apoplast-targeted LTB or GFP were produced as described previously [3]. Leaves were harvested at 7?0 days postinfiltration, snap-frozen in liquid N2 then freeze-dried using a Dynavac freeze drier (Model FD12) for 48 h with a maximum shelf temperature of 20uC. Freeze-dried plant materials were powdered using a commercial coffee grinder and sieved to standardise particle size to 0.5? mm2. Accumulation 18325633 of rLTB pentamer, the functional form required for binding to GM1gangliosides on the mucosal surface of the gut epithelium, was confirmed in N. bethamiana leaves and petunia hairy roots as per [3]. In each case, the hairy root and leaf vaccine batches accumulated 300 mg/g dwt rLTB.Capture enzyme-linked immunosorbent assay (ELISA) to determine rLTB in vaccine batchesCrude protein was extracted from freeze-dried plant material by homogenising in 1:60 (w/v) PBST [PBS (137 mM NaCl, 2.7 mM KCl, 10 mM Na2HPO4, 2 mM KH2PO4) supplemented with 0.05 Tween 20] with two 3 mm tungsten carbide beads for 1 min at a frequency of 28/s in a Qiagen Mixer Mill. The homogenate was cleared by centrifugation at 13,000 rpm at 4uC for 5 min. LTB-specific capture ELISA was performed using Costar 9018 96-well microtitre plates (Corning Life Sciences) coated with 50 ml/well of chicken anti-cholera enterotoxin subunit B (CTB) antibody (Sigma-Aldrich) diluted 1:5,000 in PBS. Plates were sealed and incubated at 4uC overnight. Unless stated otherwise, all subsequent incubations were performed at 37uC for 1 h and antibodies diluted in 1 dry skim milk powder (DM) in PBST. Following all incubations, plates were washed three times with PBST. Plates were blocked with 11967625 5 DM in PBST before a 2 h room temperature (22?5uC) incubation with serially diluted crude plant extract starting with 1:100 in PBS. Plates were then incubated with 1:2,000 rabbit anti-LTB (Benchmark Biolabs), then 1:15,000 goat anti-rabbit IgG HRP conjugate (Sigma-Aldrich). Bound LTBFigure 1. LTB-specific IgG antibody titres in serum collected from sheep before immunisation with LTB-Leaf (A), LTB-HR (B) or con.