After 2–3 passages, further recombination between the repeated TK flanking regions results in either reversion to the starting virus (MVA–RFP) or formation of the markerless recombinant virus MVA-PfM128. White plaques (expressing neither RFP nor GFP) were picked and purified. Presence of the PfM128 antigen at the TK locus was confirmed by sequencing and PCR. The protein vaccine used was mono-allelic Wellcome strain MSP119 expressed in the yeast P. pastoris (kindly provided by A Holder, NIMR, London) [33]. The full sequence of this antigen is represented within the viral vector vaccines. Protein

in endotoxin-free PBS was mixed find more manually in a syringe immediately prior to immunization with Montanide ISA720 adjuvant (SEPPIC, France), in the ratio 3:7 as previously described [40]. Where applicable, viral vectored vaccines were incorporated in the protein-PBS fraction of this mixture. BALB/c mice were vaccinated at 8- or 14-week intervals with doses as follows (unless otherwise specified): 1010 virus particles (vp) for AdCh63; 107 plaque forming units (pfu) for MVA; and 20 μg of protein. C57BL/6 mice were vaccinated at 8-week

intervals with 108 vp AdCh63, 106 pfu MVA, or 5 μg protein. Blood was obtained for immunological studies using tail bleeds 2 weeks after each immunization and at later time points as described. Ex vivo IFNγ enzyme linked immunosorbent assays (ELISPOT) were performed as previously described [41], using peptides appropriate to the mouse strain as follows: either the overlapping peptides 90 and 91 (NKEKRDKFLSSYNYI and DKFLSSYNYIKDSID) which comprise Alisertib cell line the immunodominant CD8+ T cell epitope in PfMSP133 (Wellcome allele) in BALB/c mice; or the PfMSP119 (3D7 allele)-derived peptide 215 (TKPDSYPLFDGIFCS) recognised out by CD8+ T cells from C57BL/6 mice [5]. Antigen-specific splenic antibody

secreting cells (ASCs) were measured as previously described [42]. In brief, nitrocellulose bottomed 96-well Multiscreen HA filtration plates (Millipore, UK) were coated with 5 μg/ml P. falciparum MSP-119 (Wellcome/FVO allele, expressed in Pichia) [33] and incubated overnight at 4 °C. Plates were washed twice with PBS and blocked for 1 h at 37 °C, 5% CO2 with D10 (MEM α-modification, 10% Fetal Calf Serum, 4 mM l-glutamine, 100 U/ml penicillin and 100 μg/ml streptomycin (all from Sigma, UK); and 50 μm 2-mercaptoethanol (Gibco)). 5 × 105 splenocytes were plated onto the pre-coated ELISPOT plate per replicate well and serially diluted. Plates were incubated for 5 h at 37 °C, 5% CO2. Following incubation plates were washed twice with PBS and incubated overnight at 4 °C with biotinylated anti-mouse γ-chain specific IgG antibody (CALTAG, CA). Assays were developed using colour developing agents (Bio-Rad AP conjugate substrate kit) that were filtered through a 0.2 μm filter (Sartorius, UK).