Targeting Plasmodium liver stages: better late than never

Abstract

The worldwide burden of malaria can be substantially reduced using existing public health interventions. However, elimination of Plasmodium will require fundamentally different approaches. Novel experimental attenuation strategies for active immunization using knockout strains have recently stimulated renewed interest in whole-parasite vaccine approaches. Preventive drug administration during transmission of wild-type sporozoites is a complementary strategy for eliciting protective immune responses. These whole-cell immunization strategies are based on one fundamental principle: inducing protection by blocking parasite conversion from the clinically silent liver phase to the pathogenic intra-erythrocytic replication cycle. Here, we review the basis, evidence and targets for whole-cell-based vaccination strategies against the liver stage bottleneck in Plasmodium infections and discuss preclinical and clinical research opportunities.