An experimental Zika vaccine developed by scientists is safe and induces an immune response in healthy adults, a study suggests.
Scientists from the National Institute of Allergy and Infectious Diseases (NIAID) in the US developed the investigational vaccine, which includes a small, circular piece of DNA called a plasmid.
They inserted genes into the plasmid that encode two proteins found on the surface of the Zika virus, according to the research published in the journal The Lancet.
After the vaccine is injected into muscle, the body produces proteins that assemble into particles that mimic the Zika virus and trigger the body to mount an immune response.
The experts developed two different plasmids for clinical testing: VRC5288 and VRC5283.
The plasmids are nearly identical, but they differ in specific regions of the genes that might affect protein expression and therefore immunogenicity.
The scientists analysed blood samples obtained from participants four weeks after their final vaccinations.
They found that 60 to 89 per cent of the participants generated a neutralising antibody response to VRC5288, whereas 77 to 100 per cent of the participants generated a neutralising antibody response to VRC5283.
"Following early reports that Zika infection during pregnancy can lead to birth defects, NIAID scientists rapidly created one of the first investigational Zika vaccines using a DNA-based platform and began initial studies in healthy adults less than one year later," said NIAID Director Anthony S Fauci.
"NIAID has begun Phase 2 testing of this candidate to determine if it can prevent Zika virus infection, and the promising Phase 1 data published today support its continued development," he said.