Authors
S Draper1; 1 University of Oxford, UK Discussion
Plasmodium falciparum malaria currently affects 200-300 million people annually, resulting in the death of about 0.6 million individuals. Thus, despite increasing implementation of control measures, the burden of malarial death and disease remains far too high.
The most advanced subunit vaccines against P. falciparum, called RTS,S/AS01 and R21/Matrix-M, induce high level antibody responses that aim to block infection by the liver-invasive sporozoite. These vaccines have shown moderate efficacy against clinical disease in young children, but this efficacy then wanes over time. Moreover, with every single sporozoite that slips through the net at the liver, a new blood-stage infection is established that brings renewed risk of clinical disease. An effective subunit vaccine against the parasite’s asexual blood-stage would thus be highly complementary to the existing anti-sporozoite vaccines. Such a vaccine would reduce mortality, morbidity and transmission of malaria, and offer the prospect for a multi-stage vaccine approach to tackle this parasite’s complex lifecycle. However, an effective blood-stage vaccine has proved elusive.
Recently, we have developed next-generation vaccines targeting the P. falciparum reticulocyte-binding protein homologue 5 (RH5) and its wider invasion complex, which mediate a highly conserved and essential invasion pathway into the human red blood cell. The rational design and delivery of these new vaccines has built on our understanding of how vaccine-induced anti-RH5 human antibody responses are able to inhibit parasite growth, coupled with learnings from human experimental medicine studies. This talk will describe our on-going work to understand anti-malarial antibody responses and present data from our most recent Phase I/II clinical trials of RH5-based blood-stage vaccines in the UK and Africa.
Professor Simon J. Draper Department of Biochemistry, University of Oxford E: simon.draper@bioch.ox.ac.uk W: https://draperlab.web.ox.ac.uk/ 
