Optimisation of growth inhibition assays. Comparison of one and two cycle parasite growth inhibition assays using the 3D7 AMA1 (1F9) monoclonal antibody (0.5 mg/ml), PfMSP1-19 rabbit antiserum (1 in 10 dilution) and PcMSP1-19 rabbit antiserum (1 in 10 dilution) for (A) the PcMSP1-19 parasite line and (B) the PfMSP1-19 parasite line. Comparison of parasite growth inhibition by samples tested at either 1 in 10 or 1 in 20 dilution in a one cycle growth assay for (C) the PcMSP1-19 and (D) the PfMSP1-19 parasite lines. Growth is expressed as a percentage of controls (sera from non-exposed Australian residents). The mean of duplicate or multiple values is shown and error bars represent the range when tested in duplicate or standard error of the mean for 4 or more values as appropriate.