Proteases involved in erythrocyte invasion by the malaria parasite: function and potential as chemotherapeutic targets.

Malaria places an increasing burden on global public health resources. In the face of growing resistance of the malaria parasite to available antimalarial drugs, there is a need for new drugs and the identification of new chemotherapeutic targets. The malaria parasite has a complex life cycle which includes a number of obligate intracellular stages. Clinical malaria results from cyclic asexual replication of the blood-stage parasite in circulating erythrocytes of the human host. Erythrocyte entry and host cell rupture require the activity of parasite proteases, and these enzymes are, therefore, attractive targets for rational approaches to new drug development. Malarial proteases play a role in at least two distinct aspects of host cell invasion; modification of parasite proteins involved in host cell recognition and entry; and restructuring of the host cell itself, during and following invasion, and in order to allow parasite release from the host cell. This review details recent advances in the identification of these proteases, describes current understanding of their activation and functional role, and discusses their potential as targets for protease inhibitor-based drugs.