Advances in molecular genetic systems in malaria

The ability to genetically manipulate the malaria parasite to discover the functions of its genes has provided a powerful technique to gain detailed insight into Plasmodium spp. biology and to identify and characterize potential targets for antimalaria intervention.The human malaria species Plasmodium falciparum and the rodent malaria species Plasmodium berghei have been the species predominantly used for gene manipulation studies. Although the genetic systems for these species vary in their efficiency and their approach and whether they are used in vitro or in vivo, their results can often be very complementary.As a result of the haploid nature of malaria parasites, genes that have an important role in the blood stages of Plasmodium spp. cannot be genetically targeted for disruption using conventional knockout approaches, as this would lead to parasite death or severe growth defects. This has forced the development of conditional systems to rapidly regulate gene expression.An array of conditional systems that are capable of regulating gene expression at the genome, transcript or protein level are now available for Plasmodium spp.. Each system has advantages and drawbacks, which should be considered carefully before choosing a system to regulate a gene of interest.A variety of methods can be used to edit the Plasmodium genome. These include the use of piggyBac transposons that integrate randomly into the genome, or more precise editing tools such as the CRISPR–Cas9 system, zinc-finger nucleases and integrases.Improvements to transfection efficiency and investment in the development of more robust genetic tools and phenotypic assays should lead to large-scale forward-genetic screens being possible in Plasmodium spp..