Antibodies against prion protein (PrPC) do not interfere with the intracellular behavior of B. suis. (A) Multiplication of B. suis in THP-1 human macrophages treated with antibodies against PrPC. WT, without pretreatment; Ic, isotype antibody as control; SAF 32, 3F4, and 12F10, monoclonal antibodies used. (B) Multiplication of B. suis in the murine J774 macrophage cell line. WT, without pretreatment; Ic, isotype control; SAF 32 and SAF 61, monoclonal antibodies used. (B, insert) Multiplication of B. suis in murine J774 cells after incubation with a purified polyclonal antibody. Sc, control serum.