Production and secretion of VLPs by L. lactis strains. Electron micrographs of L. lactis (pGK-) (panel A and B), L. lactis (pCYT:L1) (panel C and D) and L. lactis (pSEC:L1) (panel E to H). The different strains were grown and prepared as described in material and methods. L. lactis-derived VLPs (arrows) have diameters ranging from ~30 to 50 nm (red bars = 50 nm). In L. lactis (pSEC:L1) strain, VLPs are localized at the intracellular periphery of the bacteria cells (arrowheads). Bars = 100 nm. Magnifications, A X50,000; B-G: X85,000; H: X140,000.