Figure 3
Inhibition of parasite growth by combinations of antibodies directed towards MSP-1, MSP-6 and MSP-7. (A) Immunogenicity of recombinant MSP-6 and MSP-636 in rabbits. Endpoint titers were determined against GST (only for αMSP-6, since it was generated using recombinant MSP-6 carrying a GST-tag), MSP-6, MSP-636, and MSP-636Δ. (B) Immunogenicity of recombinant MSP-7 in rabbits. Endpoint titers were determined against GST, MSP-7, and MSP-722. (C) Growth of P. falciparum strain 3D7 in the presence of rabbit antibodies specific for MSP-183, MSP-130, MSP-138, and MSP-142 as well as rabbit antibodies specific for MSP-6, MSP-636 and MSP-7. All antibody preparations were diluted to produce between 10-50% inhibition of parasite growth. The indicated combinations were assayed for growth inhibition of P. falciparum strain 3D7 via activity of parasite-derived LDH [22]. Antibodies were added to the assay mixtures in a volume of 40 μl (40% of final assay volume) containing 10 μl or 20 μl (10 or 20% of final assay volume) of antibody preparations, as indicated, and whenever necessary adjusted to 40 μl with rabbit pre-immune antibody. Pre-immune antibody (40% v/v) was used as a control. Growth inhibition is presented as percent of control. Dark columns, inhibition calculated from the measured contribution of the individual antibody preparations; light columns, inhibition measured. Error bars show standard deviations derived from triplicate assays. Representative results of one of two experiments are shown.