Purity and quantification of Gag in VLP preparations. Coomassie-stained SDS-PAGE gels of (a) GagTN VLP samples and (b) GagRT VLP samples indicating the purity of the samples. Western blots of (c) GagTN VLP samples and (d) GagRT VLP samples probed with anti-Gag p24 antibody. 0.1 and 0.01 indicate a 1:10 dilution and a 1:100 dilution, respectively, of VLPs loaded per lane. Western blots of Gag p17/p24 (p41) protein (24-240 ng) loaded per lane is indicated and the intensity of these bands was used to determine the Gag content of GagTN and GagRT VLP samples. M = molecular weight marker and arrowheads indicate the migration distance of the respective chimaeric VLPs.