Belgian researchers have developed a vaccine against Zika which, they say, should prevent the virus from causing microcephaly and other serious conditions in unborn babies.

Zika capsid.

Computer-generated model of the Zika virus capsid.
Image credits Manuel Almagro Rivas / Wikimedia.

The massive outbreak of Zika that rocked Latin America in 2015 and 2016 is now under control, but the virus is in no way gone. Since mosquitoes are the main carrier of this virus (and mosquitoes tend to be everywhere), the risk of future outbreaks happening is very real. Researchers at the KU Leuven Rega Institute in Belgium hope to nip this risk in the bud, however, with a vaccine that is “very safe and offers lifelong protection.”

“The Zika virus is transmitted by the tiger mosquito and, in most cases, the patient experiences no or only mild symptoms,” says Johan Neyts, a Professor at KU Leuven and paper co-author. “But when a pregnant woman contracts the virus, this can affect the brain development of the foetus. It can lead to microcephaly—whereby the infant has a smaller-than-average head—but also mental and other severe health issues.”

Professor Neyts and his team set out to develop an effective vaccine against the virus, and they started by looking at one of its close relatives — the yellow fever virus. The two pathogens are closely related genetically and are both transmitted by the same mosquito. But, more importantly, we already have a vaccine against yellow fever.

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The team took this vaccine and “replaced a piece of the genetic information of the yellow fever vaccine with the corresponding code of the Zika virus”, according to Dr. Kai Dallmeier, another member of the team. They worked with researchers at the University of Liège to test whether the vaccine was effective in pregnant mice. The mice were administered the vaccines and, after letting the pregnancy develop for a few days, the team injected the normal Zika virus into their placentas.

The pups of vaccinated mothers developed normally and there were no traces of their the virus in their brains or other organs. Dr. Dallmeier says this level of protection is remarkable.

“We now intend to further develop the vaccine, which could then be used to quickly and effectively vaccinate the population in case of a new outbreak of the Zika virus. This should prevent a lot of suffering.”

He also notes that the team used a new technology — one that they themselves developed — to produce this vaccine. Their approach allows vaccines to be produced in “fermenters instead of in fertilized chicken eggs” and will, one hopes, become the norm.

The paper “A yellow fever–Zika chimeric virus vaccine candidate protects against Zika infection and congenital malformations in mice” has been published in the journal Nature.