Genetic Manipulation ofPlasmodium falciparum

Abstract

This chapter reviews historical and technical issues, achievements to date, and future possibilities with respect to transformation of Plasmodium falciparum blood stages. Despite the relatively low efficiency of the P. falciparum transfection system, it was sufficient for both gene targeting and transgene expression approaches to be developed and utilized to analyze gene function in this organism. Given the inability to transfect linear DNA and achieve fast integration into the P. falciparum genome, a key to the success of P. falciparum transfection is the somewhat mysterious ability of transfected plasmids to replicate episomally in parasites. Transfection of P. falciparum blood stages, using transient transfection with the reporter genes chloramphenicol acetyl transferase and luciferase, has been an important tool in the identification of functional characterization of a number of transcriptional control elements from this organism. Plasmid transfection vectors designed to express transgenes have been used extensively in P. falciparum, and this has been useful in a wide variety of studies. A major advance in understanding the molecular dynamics of cellular systems has derived from elegant studies in which the gene encoding green fluorescent protein (GFP) is appended to a gene encoding a protein of interest and transfected into a living cell. Since the development of transfection for Plasmodium berghei and P. falciparum, the need for an inducible expression/conditional knockout system was recognized as a crucial next step to allow the functional analysis of many blood stage genes.