- Michelle Roberts
- BBC Health Editor
16 avril 2022
Photo credit, EPA
The virus has been linked to cases of microcephaly
A new outbreak of zika virus is entirely possible, researchers warn, and a single mutation could be enough to trigger an explosive spread.
The disease caused a global medical emergency in 2016, with thousands of babies born with brain damage after their mothers were infected during pregnancy.
American scientists say the world should be on the lookout for new mutations.
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The laboratory work, described in the scientific journal Cell Reports, points out that the virus can easily transform and create new variants.
According to the La Jolla Institute of Immunology team, recent infection studies indicate that these variants may be effective in transmitting the virus, even in countries that have acquired immunity from previous zika outbreaks. .
Experts said the findings, while theoretical, are interesting – and a reminder that viruses other than the one that causes covid may pose a threat.
Viruses change shape
Zika is transmitted through the bites of infected Aedes mosquitoes. These insects are found throughout the American continent – except in Canada and Chile, where it is too cold for them to survive – and throughout Asia.
While for most people zika is a mild disease with no lasting effects, it can have catastrophic consequences for babies still in the womb.
If a mother contracts the virus during pregnancy, it can harm the developing fetus, causing microcephaly and brain tissue damage.
Photo credit, SPL
Zika is transmitted by the Aedes aegypti mosquito, which is most active during the day.
These viruses
- Although the virus is mainly transmitted by mosquitoes, it can also be sexually transmitted;
- Few people die from zika and only one in five infected people develop symptoms. These may include fever, rashes and joint pain;
- As there is no treatment, the only option is to reduce the risk of being bitten by the insect;
- Scientists have started working on a zika vaccine to help protect pregnant women.
The researchers recreated what happens when zika passes between mosquitoes and humans, using live cells and mice in their experiments.
When zika passes between mosquito cells and mice in the laboratory, small genetic changes occur.
This means that it was relatively easy for zika to mutate in a way that allowed the virus to grow and spread, even in animals that already had some immunity to an infection transmitted by the same mosquito: the dengue.
More research
The study’s lead researcher, Professor Sujan Shresta, said “the zika variant we identified evolved to the point that the cross-protective immunity provided by previous dengue infection was no longer effective in mouse”.
“Unfortunately for us, if this variant becomes prevalent, we could have the same problems in real life.”
“We’ve heard a lot about the rapid evolution and emergence of coronavirus variants lately, but this study is a timely reminder that shape-shifting is a common feature of many viruses,” the BBC told the BBC. Professor Jonathan Ball, virus specialist at the University of Nottingham.
“This work shows how quickly a single-letter change in a virus’s genome sequence can occur and the dramatic impact it can have on a virus’s ability to cause disease. But viruses that share these changes are not often seen in outbreaks. And, as the authors point out, this intriguing information needs further investigation.”
Clare Taylor of the Society for Applied Microbiology warns that “although these results have been observed in laboratory experiments and therefore have limitations, they show that there is potential for the emergence of worrying variants over the course of of the normal cycle of Zika transmission and remind us of the importance of monitoring the evolution of viruses.”
According to her, it might be possible to predict which variants could cause significant problems in the future and to intervene in time.
Professor Paul Hunter, professor of medicine at the University of East Anglia, said previous zika infections may still offer some protection against newer variants, as has been the case with covid.