Anti–RSP-2 mAbs recognize a 42-kDa molecule. (A) Western blot analysis using mAbs B4, C10, and D10. Triton X-100 soluble protein extract of rIE^CSA was analyzed. Lane 1, negative control IgG2a; lane 2, anti–RSP-2 C10; lane 3, anti–RSP-2 B4; and lane 4, anti–RSP-2 D10. (B) Western blot with anti–RSP-2 mAb B4 and Triton X-100 protein extracts. Lane 1, nE; lane 2, IE^CSA; lane 3, IE^CD36; and lane 4, IE^ICAM-1. (C) Immunoprecipitation of Triton X-100 extracts of surface-iodinated FCR3^CSA and FCR3^CD36 rIEs using mAb B4. Lane 1, surface-iodinated FCR3^CSA rIEs immunoprecipitated by B4; lane 2, FCR3^CD36 immunoprecipitated by B4; lane 3, FCR3^CSA immunoprecipitated by a pool of immune sera from pregnant women (Senegal); lane 4, FCR3^CSA trypsin treatment (100 μg/mL) before immunoprecipitation by B4; lane 5, FCR3^CD36 trypsin treatment before immunoprecipitation by B4; lane 6, FCR3^CSA trypsin treatment before immunoprecipitation by a pool of immune sera from pregnant women. Controls, FCR3^CSA immunoprecipitation with no mAbs (lane 7) and by anti-PfEMP1 (lane 8). (D) Western blot analysis of E coli extracts expressing RAP-2 GST fusion proteins. Lanes 1 and 3, noninduced cultures; lanes 2 and 4, IPTG-induced cultures. Lanes 1 and 2, mAb B4; lanes 3 and 4, mAb C10. The RAP-2 GST-predicted molecular weight is 71 kDa. The lower band (lane 2) is a degradation product.