P. falciparum heat shock response in a PfAP2-HS-defective population compared to its wild type control.

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. Plasmodium falciparum cultures adapted to periodic heat shock were used to identify PfAP2-HS as a transcription factor that is essential for survival at febrile temperatures. Transcriptomic analysis was performed to compare the effect of heat shock in parasites presenting the wild type form of PfAP2-HS (10E) and parasites that have defects in this protein, either a premature stop codon mutation (10G) or the deletion of the entire pfap2-hs gene (10E_pfap2-hs). A timecourse analysis including samples taken before, during and after heat shock revealed that the initial phase of the PfAP2-HS-dependent response is largely restricted to hsp70-1 and hsp90. Time-course transcriptomic analysis of 10E, 10G and 10E_pfap2-hs cultures under control (35C) and heat shock conditions (HS, 41.5C for 3 h). Parasites were tightly sinchronized to a 5 h age window and HS was started at 30-35 hpi (33-38 hpi for the 10E_pfap2-hs line that develops more slowly). Samples for transcriptomic analysis were collected before (0 h), during (1.5 h and 3 h) and after HS (2 h post). The reference pool consisted of RNA from 3D7-A cultures, maintained under control conditions, throughout the asexual blood cycle. Total RNA was harvested using the Trizol method. A total number of 21 individual samples were analysed using the microarray design AMADID-084561 (GEO ID: GPL26985).