- There is no licensed vaccine that protects against Zika, a mosquito-borne virus that can result in birth defects.
- Researchers at the University of Adelaide in Australia recently created a vaccine that can neutralise the virus in mice.
- The experiment hasn’t been replicated in humans yet, but it’s showing early signs of promise.
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Panic unfurled across the Americas in early 2015, as the Zika virus spread.
The World Health Organisation declared an international emergency in response to the epidemic in February 2016. By the time the emergency lifted at the end of that year, the virus had spread to 60 countries and been sexually transmitted in six (Argentina, Chile, France, Italy, New Zealand, and the US).
The crisis has generated a race among scientists to find a way to ward off the virus. But there is still no licensed vaccine that protects against Zika.
There is, however, some encouraging research.
In a paper published in the journal Science Advances on Wednesday, researchers from the University of Adelaide in Australia report the results of an experiment that successfully protected mice against Zika infections. The experiment hasn’t been replicated in humans yet, but the vaccine shows early signs of promise, according to the researchers.
A DNA vaccine could protect people from future outbreaks
The Zika virus, which is transferred to humans through infected mosquitoes, was first detected in Brazil. Infections often cause no symptoms, but they can result in birth defects and Guillain-Barré Syndrome, a rare neurological disorder that can lead to paralysis in adults.
The virus can also be sexually transmitted between partners even if symptoms aren’t present.
When a person contracts Zika, their antibodies try to fight off the infection by attacking the virus’ envelope, which shields it from our immune defences.
Many Zika vaccine trials have targeted this envelope, but preliminary studies suggest that approach could wind up making a person more vulnerable to similar viruses, such as dengue, in the future.
So the University of Adelaide researchers tried a different approach. The vaccine they created uses genetically engineered DNA to stimulate the immune system so that it neutralizes the virus. This type of vaccine has shown potential to ward off multiple types of flaviviruses (the family to which Zika belongs).
To test it out, the researchers injected the vaccine into the ears of 6- to 8-week-old albino mice. The mice each received three doses of the vaccine over the course of several weeks. By the end of the experiment, the vaccine had generated a strong immune response that helped protect the mice against the Zika virus.
Scientists often use mice to test early versions of medications and vaccines, but many of those experiments fail once they move on to human trials. That means the researchers still have a long way to go before they can deliver a safe and effective Zika vaccine to the public.
But based on the results so far, the vaccine gets us a step closer to finding a way to protect the global population from Zika. According to the researchers, the vaccine “could be easily manufactured on a large scale at low cost.” It would also be “safe for children and women of reproductive age,” they write.
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