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Plasmodium vivax
Image by Mae Melvin
Results of a phase 1 trial suggest a vaccine candidate does not prevent Plasmodium vivax malaria.
The vaccine, VMP001/AS01B, did not prevent malaria in any of the 30 subjects tested, although it did significantly delay parasitemia in 59% of subjects.
Lieutenant Colonel Jason W. Bennett, of the Walter Reed Army Institute
of Research (WRAIR) in Silver Spring, Maryland, and his colleagues reported these results in PLOS Neglected Tropical Diseases.
The vaccine antigen VMP001 is an Escherichia coli-produced, synthetic, chimeric, recombinant protein that incorporates the 3 major domains of circumsporozoite protein but is distinct from the native molecule. The VMP001 antigen was adjuvanted with AS01B, a proprietary liposome-based adjuvant system from GlaxoSmithKline.
For this phase 1 study, the investigators tested VMP001/AS01B in 30 healthy volunteers. The subjects received 3 intramuscular injections of VMP001 at 15 μg (n=10), 30 μg (n=10), or 60 μg (n=10), respectively, all formulated in 500 μL of AS01B at each immunization.
Fourteen days after the third immunization, the subjects were exposed to mosquitoes carrying P vivax. Six non-vaccinated control subjects were exposed to the mosquitoes as well.
The investigators said VMP001/AS01B was well tolerated and generated robust immune responses. However, it did not protect the subjects from malaria infection.
Still, the vaccine induced a “small but significant” delay in time to parasitemia in 59% of vaccinated subjects, when compared to controls.
Colonel Robert Paris, director of the US Military Malaria Research Program at WRAIR, believes the investigators can use the results of this study to design a better vaccine for P vivax malaria.
“Findings from the analysis of the immune response of vaccinated subjects have given us clues to improve vaccine candidates,” he said. “[S]tudies are now underway at WRAIR to develop next-generation vivax vaccines.” 
Plasmodium vivax
Image by Mae Melvin
Results of a phase 1 trial suggest a vaccine candidate does not prevent Plasmodium vivax malaria.
The vaccine, VMP001/AS01B, did not prevent malaria in any of the 30 subjects tested, although it did significantly delay parasitemia in 59% of subjects.
Lieutenant Colonel Jason W. Bennett, of the Walter Reed Army Institute
of Research (WRAIR) in Silver Spring, Maryland, and his colleagues reported these results in PLOS Neglected Tropical Diseases.
The vaccine antigen VMP001 is an Escherichia coli-produced, synthetic, chimeric, recombinant protein that incorporates the 3 major domains of circumsporozoite protein but is distinct from the native molecule. The VMP001 antigen was adjuvanted with AS01B, a proprietary liposome-based adjuvant system from GlaxoSmithKline.
For this phase 1 study, the investigators tested VMP001/AS01B in 30 healthy volunteers. The subjects received 3 intramuscular injections of VMP001 at 15 μg (n=10), 30 μg (n=10), or 60 μg (n=10), respectively, all formulated in 500 μL of AS01B at each immunization.
Fourteen days after the third immunization, the subjects were exposed to mosquitoes carrying P vivax. Six non-vaccinated control subjects were exposed to the mosquitoes as well.
The investigators said VMP001/AS01B was well tolerated and generated robust immune responses. However, it did not protect the subjects from malaria infection.
Still, the vaccine induced a “small but significant” delay in time to parasitemia in 59% of vaccinated subjects, when compared to controls.
Colonel Robert Paris, director of the US Military Malaria Research Program at WRAIR, believes the investigators can use the results of this study to design a better vaccine for P vivax malaria.
“Findings from the analysis of the immune response of vaccinated subjects have given us clues to improve vaccine candidates,” he said. “[S]tudies are now underway at WRAIR to develop next-generation vivax vaccines.”
Plasmodium vivax
Image by Mae Melvin
Results of a phase 1 trial suggest a vaccine candidate does not prevent Plasmodium vivax malaria.
The vaccine, VMP001/AS01B, did not prevent malaria in any of the 30 subjects tested, although it did significantly delay parasitemia in 59% of subjects.
Lieutenant Colonel Jason W. Bennett, of the Walter Reed Army Institute
of Research (WRAIR) in Silver Spring, Maryland, and his colleagues reported these results in PLOS Neglected Tropical Diseases.
The vaccine antigen VMP001 is an Escherichia coli-produced, synthetic, chimeric, recombinant protein that incorporates the 3 major domains of circumsporozoite protein but is distinct from the native molecule. The VMP001 antigen was adjuvanted with AS01B, a proprietary liposome-based adjuvant system from GlaxoSmithKline.
For this phase 1 study, the investigators tested VMP001/AS01B in 30 healthy volunteers. The subjects received 3 intramuscular injections of VMP001 at 15 μg (n=10), 30 μg (n=10), or 60 μg (n=10), respectively, all formulated in 500 μL of AS01B at each immunization.
Fourteen days after the third immunization, the subjects were exposed to mosquitoes carrying P vivax. Six non-vaccinated control subjects were exposed to the mosquitoes as well.
The investigators said VMP001/AS01B was well tolerated and generated robust immune responses. However, it did not protect the subjects from malaria infection.
Still, the vaccine induced a “small but significant” delay in time to parasitemia in 59% of vaccinated subjects, when compared to controls.
Colonel Robert Paris, director of the US Military Malaria Research Program at WRAIR, believes the investigators can use the results of this study to design a better vaccine for P vivax malaria.
“Findings from the analysis of the immune response of vaccinated subjects have given us clues to improve vaccine candidates,” he said. “[S]tudies are now underway at WRAIR to develop next-generation vivax vaccines.”