Recombinant Protein Vaccine Blocks Transmission of Malaria

Development of a vaccine against malaria has taken a significant step forward with the production of a purified recombinant parasite protein that induces an antibody that prevents transmission of the disease.

Investigators from Johns Hopkins University (Baltimore, MD, USA) inserted the gene for the Plasmodium protein Pfs48/45 into cultures of the bacterium Escherichia coli. The purified recombinant protein they obtained was recognized by monoclonal antibodies that had been raised against the native protein.

Results published in the July 22, 2009, online edition of the journal PLoS ONE revealed that mixtures of the recombinant Pfs48/45 protein and various adjuvants elicited production of protective antibodies in both mice and nonhuman primates. A single-dose of the purified protein vaccine provided a 93% transmission-blocking immune response in baboons, which reached greater than 98% after a booster was given several months later.

"This is an exciting beginning to what might become an important tool in the arsenal for malaria control and progressive elimination of malaria transmission,” said senior author Dr. Nirbhay Kumar, professor of molecular microbiology and immunology at Johns Hopkins University. "There is no animal reservoir for human malaria and in that regard it is possible to gradually reduce malaria transmission to a point of almost eradication. Development of a successful transmission-blocking vaccine is an essential step in efforts to control the global spread of malaria. In our study, we demonstrate the relative ease of expression and induction of potent transmission-blocking antibodies in mice and nonhuman primates. This approach provides a compelling rationale and basis for testing a transmission-blocking vaccine in humans,” said Dr. Kumar.

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