In a first, US scientists have developed a plant-based Zika vaccine that could be more potent, safer and cheaper to produce than other medicines being developed for the disease.

Immunisation experiments on mice showed a 100 per cent success in inducing antibody and cellular immune response to protect against multiple Zika virus strains, the researchers said."Our vaccine offers improved safety and potentially lowers the production costs more than any other current alternative, and with equivalent effectiveness," said lead researcher Qiang "Shawn" Chen scientist at the Arizona State University in the US.The vaccine, developed using tobacco plant, targets a key protein -- called DIII -- which envelopes the outside of the Zika virus and plays a key role for the virus to infect people.By developing this protein without the dangerous virus within it, it could be used to immunise people to the real strain of Zika, the researchers said.

"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," Chen said, in the paper published online in the journal Scientific Reports.However, although the virus is effective, it may not be foolproof, and can cause serious side effects, the researchers noted."Above all, we have to ensure the utmost safety with any Zika vaccine, especially because the people who will need it most, pregnant women, have the most worries about their own health, and the health of the foetus. This has to be 100 per cent safe and effective," Chen explained. 

The worldwide Zika threat first emerged in 2015, infecting millions as it swept across the Americas and led to the birth of babies with severe brain birth defects.Chen hopes to begin the first phase of a human clinical trial in the next two years.