Whole-parasite vaccine against malaria shows promise in clinical trials

A study, carried out at the University of Tübingen (Tübingen, Germany) in collaboration with Sanaria Inc. (MD, USA) has demonstrated that a new vaccine for malaria has been up to 100% effective.

Previously there has been a large focus on subunit vaccines utilizing individual molecules from the parasite; however, these have been unable to provide sufficient immunity in trials. The new vaccine, termed Sanaria® PfSPZ-CVac, instead introduces live Plasmodium falciparum malaria parasites into the bloodstream.

The trial included 67 healthy participants, who were given either a placebo or varying doses of the vaccine alongside the antimalarial chloroquine to prevent infection. The team then exposed participants to infectious malarial parasite, under controlled settings, 10 weeks after the final dose of the vaccine.

The best immune response was observed by researchers in patients who received the highest dose of the vaccine three times per week at 4 week intervals. These participants demonstrated 100% protection at the end of the trial.

Individuals receiving lower doses exhibited less, although still statistically significant, protective immunity demonstrating that the whole-parasite approach could incur strong and durable protection. The team demonstrated that Plasmodium falciparum- specific CD4+ T cells appeared to be associated with protection and no adverse effects were observed during the trial.

First author Benjamin Mordmüller, from the University of Tübingen, commented: “By vaccinating with a live, fully active pathogen, it seems clear that we were able to set of a very strong immune response. Additionally, all the data we have so far indicate that what we have here is relatively stable, long-lasting protection.”

This is a promising step forwards in the goal to eliminate malaria; a vaccine could aid malaria control sidestepping resistance issues seen in antimalarial drugs and insecticide strategies. The next step is a Phase II trial, to be carried out over several years in Gabon, to further test the vaccine’s effectiveness.

Sources: Mordmüller B, Surat G, Lagler H et al. Sterile protection against human malaria by chemoattenuated PfSPZ vaccine. Nature. doi:10.1038/nature21060 (2017) (Epub ahead of print); https://www.niaid.nih.gov/news-events/experimental-malaria-vaccine-plus-chloroquine-protects-against-controlled-infection

Want to find out more? Read our exclusive opinion piece by Danielle Stanisic (Griffith University, Australia) where she gives her thoughts on the advantages of whole-parasite vaccines and discusses her own work on this novel vaccine approach.

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