Mutated Zika virus led to spike in brain defects in newborns
Older, more dangerous, strain causes fetuses to abort, research shows
A recent mutation may have created a strain of the Zika virus that has triggered a huge rise in the number of babies born with microcephaly, genetics researchers say.
The more dangerous form of Zika is believed to cause fetuses to abort, said Feiran Zhang, a researcher at Emory University. The new strain appears to trigger an immune response that allows the fetus to survive, but not without devastating brain defects.
“So, microcephaly is not the worst outcome of Zika — spontaneous abortion is,” said Zhang, who presented the new findings at the annual meeting of the American Society of Medical Genetics in Vancouver this week.
The mosquito-borne Zika virus has been detected in at least 23 countries in North and South America and has been linked to thousands of cases of babies born with microcephaly, a form of incomplete brain development. More than 2,000 children have been born with microcephaly in Brazil alone since the beginning of 2016, according to that country’s ministry of health.
Zhang and his colleagues at Johns Hopkins and Florida State universities found that Zika interferes with the development of cells that grow into neurons during gestation. Zika strongly affects the expression of genes related to DNA replication and repair.
The virus appears to act as a “Trojan Horse,” entering human cells and hijacking the machinery that regulates gene expression, producing RNA molecules that alter brain development, he explained.
When the researchers compared the effects of the Asian strain of the virus with the African strain, they found that cells were better able to resist the Asian strain because the virus triggered a powerful protective immune response. The Zika spreading in the Americas is most similar to the Asian virus.
“Zika has been around for 70 years and only recently have we seen this outbreak of microcephaly, so we think the virus has changed,” Zhang told Postmedia News.
While devastating, the massive increase in microcephaly is an improvement over the effect of the more dangerous version of Zika, which is fetal death. Zhang and his colleagues will release their find- ings to groups pursuing vaccines and treatments for Zika.
The Public Health Agency of Canada recommends that women who are pregnant or planning to become pregnant avoid travel to countries or regions where Zika has been reported, including parts of Florida.
To date, 348 cases of Zika have been reported in Canada, including two cases of transmission between pregnant women and their unborn babies.
One baby showed evidence of Zika-related anomalies.