Scientists have developed the world’s first plant-based Zika vaccine that may be more effective, safer and cheaper than other vaccines against the mosquito-borne virus. Currently, there are no licensed vaccines or therapeutics available to combat Zika, researchers said. The vaccine developed by researchers from Arizona State University (ASU) in the US works against a part of a Zika viral protein, called DIII, that plays a key role for the virus to infect people.
“All flaviviruses have the envelope protein on the outside part of the virus. It has three domains,” said Qiang Chen, a scientist at ASU. “The domain III has a unique stretch of DNA for the Zika virus, and we exploited this to generate a robust and protective immune response that is unique for Zika,” said Chen, who led the research published in the journal Scientific Reports.
The researchers first grew the envelope protein in bacteria, then prepared the DIII protein domain in tobacco plants.
The team then performed immunisation experiments in mice, which induced antibody and cellular immune responses that have been shown to confer 100 per cent protection against multiple Zika virus strains in mice.
The team’s protein-based vaccine uses the smallest and most unique part of the Zika virus that can still elicit a potent and robust immune response. “In our approach, we make what we call a pseudovirus. It is a fake virus. The pseudovirus displays only the DIII part of the envelope protein on the surface,” said Chen. “We did a test to make sure that the vaccine produces a potent protective immune response, but also, that it does not produce antibodies that may be cross reactive for dengue, West Nile, yellow fever or others,” he said.
The worldwide Zika threat first emerged in 2015, infecting millions as it swept across the Americas. It struck great fear in pregnant women, as babies born with severe brain birth defects quickly overburdened hospitals and public health care systems.