2D DIGE of liposoluble proteins extracted from M. agalactiae PG2T and two field strains. Overlay image: image generated from the superimposition of the signals generated by the three samples. White indicates presence of the protein spot in all three isolates. Panels A, B, and C represent isolates PG2T, Nurri, and Bortigali, respectively. Panels D, E, and F represent the superimposition of Nurri/Bortigali, PG2T/Nurri, and PG2T/Bortigali, respectively.