Isolation of temperature-sensitive mutants of Plasmodium falciparum.

Temperature-sensitive mutants of a malaria parasite, Plasmodium falciparum, have been isolated. A culture of parasites was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine and repeatedly subjected to a selective pressure designed to favor the enrichment in the culture of parasites that either grew more slowly or ceased growing at 39 degrees C. Cloned parasites derived from cultures subjected to selective pressure were subsequently examined for their ability to grow at 38.5, 39 and 39.5 degrees C. Two temperature-sensitive mutants were isolated that exhibited reduced growth at 39.5 degrees C and one of them also exhibited reduced growth at 39 degrees C. A previously described aphidicolin-resistant mutant of P. falciparum also exhibited reduced growth at 39 degrees C.