Rv3494c protein recognition. (A) Western blot with rabbit post-third immune serum against M. tuberculosis H37Rv total sonicate (lane 1) and subcellular fractions (lanes 2–5); lane 2 shows M. tuberculosis H37Rv membrane, lane 3 M. tuberculosis H37Rv cell wall, lane 4 the M. tuberculosis H37Rv cytosolic fraction and lane 5 M. tuberculosis H37Rv culture supernatant. The molecular weight marker is shown on the left-hand side of the figure. (B) IEM, upper-left panel: IEM of M. tuberculosis using pre-immune sera. IEM of M. tuberculosis using post-third inoculation sera; the arrows show the presence and location of colloidal gold-labelled antibodies recognizing the Rv3494c protein.