Generation of TgHsp90 knockout (ΔHsp90) and complementation parasites. (A) Schematic illustration of the strategy used to generate the TgHsp90 knockouts by homologous recombination. The Hsp90 coding region was replaced by the selectable marker Ble; the knockout vector was transfected into the RHΔku80 strain and selected by phleomycin. (B) Diagram of genetic complementation of Hsp90. An Hsp90 coding sequence and the CAT selection marker, which was flanked by T. gondii Tublin promoter and 3′ poly A signal (provided by Professor Liuqun, College of Veterinary Medicine, China Agricultural University), was transfected into the TgHsp90 defective strain to generate the complemented strain.