Transcriptional alterations of P. falciparum 3D7-A heat shock-adapted vs control parasites.

Periodic fever is the most characteristic clinical feature of human malaria. However, how parasites survive malarial febrile episodes, which often involve temperatures of >40ºC, is not known. To understand the molecular basis of heat shock (HS) resistance in Plasmodium falciparum, we took advantage of previously developed P. falciparum lines adapted to periodic HS (3D7-A-HS) and their non-selected controls maintained in parallel (3D7-A). Their ability to adapt in only a few cycles suggested that the parental parasite population contained a selectable subset of parasites resistant to HS. Transcriptomic analysis of both 3D7-A-HS and 3D7-A was used to study the differences at a transcriptional level that could be related with the HS-resistant phenotype. Timecourse transcriptomic analysis of P. falciparum lines adapted to periodic HS (3D7-A-HS) and their non-selected controls maintained in parallel (3D7-A), from two independent biological replicates. Parasites were tightly sinchronized to a 5 h age window, and samples collected from each culture at different hours post-invasion (hpi): 8 hpi, 16 hpi, 24 hpi, 32 hpi and 40 hpi. Reference pool samples were collected from 3D7-A cultures at several stages, covering the full asexual blood cycle. Total RNA was harvested using the Trizol method. A comparative genomic hybridization was performed using gDNA from each parasite population. A total number of 24 individual microarrays was used.