Figure 1. Schematic representation of immune complex mimics (ICM) based on Acr-Ag85B fusion protein and an anti-Acr mAb (A) and the classical immune complexes (IC) based on Ag85B antigen of MTB and polyclonal Abs (B).

For ICM, the fusion protein is depicted as a trimer, which is one of the predominant molecular forms for Acr in solution. Each mAb molecule must bind to a different monomer unit of Acr (A); in contrast, polyclonal Abs can bind to the same Ag85B molecule (B).