GENE TARGETING IN MALARIA PARASITES

Gene targeting, which permits alteration of a chosen gene in a predete rmined way by homologous recombination, is an emerging technology in m alaria research. Soon after the development of techniques for stable t ransformation of red blood cell stages of Plasmodium falciparum and Pl asmodium berghei, genes of interest were disrupted in the two species. The main limitations of gene targeting in malaria parasites result fr om the intracellular growth and slow replication of these parasites. O n the other hand, the technology is facilitated by the very high rate of homologous recombination following transformation with targeting co nstructs (similar to 100%). Here, we describe (i) the vector design an d the type of mutation that; may be generated in a target locus, (ii) the selection and screening strategies that can be used to identify cl ones with the desired modification, and (iii) the protocol that was us ed for disrupting the circumsporozoite protein (CS) and thrombospondin -related anonymous protein (TRAP) genes of P. berghei. (C) 1997 Academ ic Press.