Fig. 4

Quantification of MPER concentration in bacteria via indirect ELISA. (A) From recombinant (EcN-MPER) and non-modified (EcN) bacterial lysates. The antigen concentration was determined using a standard curve plotted with absorbance readings applying a serially diluted HIV-1 gp41 antigen. (B) Quantitation of surface-expressed MPER through a whole cell ELISA of non-modified EcN and recombinant EcN-MPER from combined passages 1, 15, 20, 25 and 30. Samples with viable bacteria are marked with V and with heat-killed – HK. Bars are shown with mean and standard deviation of the 5 different passages. Comparative analysis was performed using (A) Welch’s t test or (B) Mann Whitney test; where *p < 0.05 and **p < 0.005