Genetically modified Plasmodium highlights the potential of whole parasite vaccine strategies.

A genetically modified malaria sporozoite might breathe new life into the traditional approach to vaccine development, that of using whole organisms. Mueller and colleagues recently knocked out a gene, UIS3, from the rodent parasite, Plasmodium berghei, and demonstrated that the sporozoite forms could not develop beyond the stage of the life cycle in the liver (thus not giving rise to clinical disease, which is associated with blood infection) but could induce protection against subsequent challenge with genetically intact sporozoites. UIS3(-) sporozoites or irradiated sporozoites might find success where subunit approaches are struggling.