Two clinical trials, in which subjects were vaccinated with genetically engineered Plasmodium parasites and later exposed to the malaria-causing microbe, showed the vaccines to be safe with promising, but not ideal, efficacy. Results of the trials are published in two papers in Science Translational Medicine [May 20].
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[Researcher Robert] Sauerwein and colleagues have instead developed genetically attenuated parasites that should be “cheaper and safer,” [than current techniques] he says. Cheaper because all the parasites are identical so fewer should be needed to elicit the same effect as that seen with irradiated bugs. And safer because there is practically no chance of the parasites reverting to infectious forms (a slim but not zero chance in the case of irradiation), and there is no need for handling the infectious form whatsoever. The rearing of thousands of mosquitoes carrying disease-causing P. falciparum is necessary in the case of irradiation, but Sauerwein’s mosquitoes carry only the engineered, and therefore safe, version.…
[T]he vaccinations were well tolerated and induced anti-CSP antibodies. While none of the subjects were fully protected from subsequent infection with wildtype P. falciparum, the vaccinations did significantly delay the detection of live parasites in the blood.
