Fig 2.

Overview of internal controls of the serology system. (1) A bead containing thioredoxin A (TrxA) is used to control for anti-TrxA antibodies remaining after absorption with free TrxA. (2) An Escherichia coli lysate-coupled bead controls for anti-E. coli antibodies remaining after absorption with E. coli lysate. Both TrxA- and E. coli-containing beads are necessary for controlling the results with recombinant TrxA fusion proteins prepared in E. coli. (3) Antigen-coated beads are used for surveillance of the antigenicity of individual antigens via rabbit antipeptide hyperimmune serum, of overall antigenic performance via the antigenic index (Fig. 4), and of background binding without serum (nontemplate control [NTC]). (4) The presence of antibodies capable of binding to a common antigen was ensured with the Haemophilus influenzae B (Hib)-containing bead. (5) A “naked” bead, without any bound antigen, was used to control for nonspecific binding to the Luminex beads. Weak nonspecific binding is symbolized with a light gray antibody symbol.