Fig. 2

Production of rPb51 and immunization. a rPb51 was purified from E. coli and analysed by SDS-PAGE under reducing conditions. Molecular weight markers are shown on the left. b Anti-rPb51 antibody titres after immunizations. Serum samples were collected on days 14, 29 and 44 post-immunization. Antibody titres correspond to the last dilution of the anti-rPb51 serum, wherein OD490 values were above the cut-off values in ELISA. Cut-off value was defined as that of the pooled sera from control mice. Serum samples were tested at 1: 200–1:102,400 serial dilutions, 1:200 dilutions were used and the data represent three separate experiments. Error bars indicate mean ± SD. *P < 0.05, **P < 0.01 (Student’s t test)