L. lactis -derived VLPs display conformational epitopes. ELISA plates were coated with total protein cell extracts (diluted in PBS pH 7.0) obtained from either L. lactis strain and assayed with a conformational anti-HPV16 L1 antibody. The data are the means of two independent experiments. Bars represent the means ± standard deviations. Statistically significant differences (P < 0.05) obtained with JMP software are denoted by an asterisk (*) between recombinant L. lactis strains and control L. lactis (pGK-) strain or by two asterisks (**) between L. lactis (pCYT:L1) and L. lactis (pSEC:L1) strain.