Injectable formulation of malaria parasites achieved controlled infection

Researchers from the Netherlands reported this week that an injectable formulation of malaria parasites might be considered a novel approach to malaria prevention, according to data presented at the American Society of Tropical Medicine and Hygiene Annual Meeting.

Meta Roestenberg, MD, of the Radboud University Nijmegen Medical Center, one of the study authors, said that the results of this study indicate that direct injection of cryopreserved parasites can be used in lieu of mosquito bites.

The study findings eventually could lead to a powerful tool for testing promising malaria drugs and vaccines in trials that involve deliberately exposing subjects to a “controlled human malaria infection,” according to the researchers. Also, they said the injectable formulation of malaria parasites might be considered, by itself, as part of a novel approach to providing protection against malaria.

“Our study shows it’s possible to manufacture and then administer controlled doses of malaria parasites using a needle and syringe to deliver a formulation that can meet regulatory standards for purity and dose consistency,” Roestenberg said.

In a controlled human malaria infection trial conducted from October 2010 to July 2011, researchers injected 18 healthy Dutch volunteers with cryopreserved Plasmodium falciparum malaria sporozoites (PfSPZ Challenge, Sanaria Inc). The study showed that 84% of participants – five of the six volunteers in each group – were safely and successfully infected with no differences among the groups in the time it took for the infection to develop or the presentation of symptoms.

The researchers also said these results could provide evidence for developing “whole parasite” vaccines. Robert W. Sauerwein, MD, PhD, of Radboud University Medical Center, said that these findings imply that infections could be accomplished with a simple shot in the arm could and that could make the whole parasite approach more feasible.

“A major challenge to realizing the potential of whole parasite vaccines is the development of a stable, consistent formulation of sporozoites that can be manufactured, preserved and used like any other vaccine,” Sauerwein said in a press release.

Sanaria is currently pursuing clinical trials to test two different approaches to whole parasite vaccination. Also, researchers are planning additional trials to ensure the infection produced with the cryopreserved sporozoites mirrors what one would experience through bites from infected mosquitoes.

Disclosure: Sanaria Inc. manufactured PfSPZ Challenge, and Protein Potential LLC is affiliated with Sanaria. Thus, all authors associated with Sanaria or Protein Potential have potential conflicts of interest.

For more information:

Bijker E. Symposium 91. Presented at: ASTMH 61st Annual Meeting; Nov. 11-15, 2012; Atlanta.