Assays used to detect MSP1 and antibodies to MSP1.

aPolyclonal anti-MSP142 was resuspended in carbonated-bicarbonated buffer (pH 9.6) and used to coat the ELISA plates as described in the materials and methods section. As a standard, recombinant MSP142 was resuspended in the same media used for the test samples (i.e. plasma from N. American subjects or perfusates) and added to the wells coated with anti-MSP142 at serial two-fold dilutions starting at 4 ng/ml. Sensitivity of the assay was approximately 200 pg/ml.
bPlates were coated with rMSP142 in PBS.
cPlates were coated with streptavidin in PBS (Pierce Biotechnology Inc). Standards used for this experiment were bMSP142 or pooled human plasma containing anti-MSP1 (25%) combined with bMSP142 as described in the text. The assay had a sensitivity ∼175–200 pg/ml to detect the bMSP142 in the samples.
dPerfusate was added at 1∶5 dilution to wells coated with streptavidin and incubated overnight at 4°C. Plates were washed thoroughly (6 times) with 0.1% Tween as described in the text to remove any unbound antibody prior to adding goat anti-human IgG. Control experiments using MSP142 incubated with normal serum had <0.15 OD and the mean+2 SD was subtracted from background described in figure 4.