Fold difference in var gene transcription between NF54 ring-stage parasites isolated from the same volunteer on different days. Genes are sorted by gene groups as defined in . Note that the fold-change scale for volunteer 1 is different from the other panels. Vertical dashed lines mark an arbitrarily defined two-fold cut off value for biologically significant changes in var gene transcription. Experiments with volunteer 1 were repeated three times and results are shown as means ± SD.