Microarrays contained 7665 70mer oligonucleotide probes representing 5150 Plasmodium falciparum ORFs kindly provided by Dr. Joseph DeRisi (University of California, San Francisco; San Francisco, California). The majority of the oligonucleotides for printing the array corresponded to the Qiagen Operon set (Operon Biotechnologies, Inc.; Huntsville, Alabama), but some additional sequences matched ORFs in the original P. falciparum sequence reads. The oligonucleotides were printed on polylysine-coated slides using a new generation, ultra fast, linear servo driven DeRisi microarrayer.