Results from ZDAs performed in the presence of inactive human serum.

(a)Protein G-purified IgG from mice were used at a final concentration of 1 mg/ml. Polyclonal IgG purified from mice immunised with a non-malaria-related antigen was used as a negative control (Control). The IgG used originated from mice immunised either with the RFP-Pf38 fusionprotein or with Pf38 alone. (b)Counts of round forms are given in percentages, and the mean number of round forms in controls was defined as 100%. Means and standard deviations were calculated from the counts of three 0.1 µl aliquots of each sample using a hemocytometer. (c)Student's t-test was used to statistically analyse the difference in counts of round forms between samples supplemented either with control IgG or test IgG. P-values below 0.05 were considered significant.