A US study has determined how the Zika virus impairs babies’ developing brains during pregnancy.
- Aedes mosquitoes, including Aedes aegypti and Aedes albopictus, are the primary vectors of Zika virus disease.
- The Zika virus affects the developing brain of fetuses.
- In Brazil, in 2015-2016, hundreds of babies were born with microcephaly, i.e. a normally smaller head, after prenatal exposure to the Zika virus.
Like dengue fever, chikungunya and yellow fever, the Zika virus disease is transmitted by a bite from a mosquito of the genus Aedes, of which Aedes aegypti And Aedes albopictus. In case of infection, two types of complications can occur: neurological disorders, including Guillain-Barré syndrome (GBS), and birth defects.
Prenatal Zika virus infection may promote micocephaly in infants
In 2015-2016, Brazil was hit by a major outbreak of the Zika virus. Due to prenatal exposure to the virus, hundreds of babies have been born with microcephaly, or an abnormally smaller head.
In a recent study, American researchers looked at how the Zika virus affects the developing brain of fetuses, in order to anticipate future epidemics and prevent the risk of congenital disorders. The results of this work have been published in the journal IScience.
Zika virus prevents brain development
As part of this research, the scientists combined proteomics (the study of proteins) and transcriptomics (the study of RNA). The goal? Determine potential targets for developing therapies to protect babies’ developing brains.
The authors of the work injected the Zika virus into the placenta of pregnant mice with a normal immune system. They thus reproduced the fetomaternal infection of the Zika virus, which is transmitted to the fetus by the mother’s blood via the placenta. The embryos were therefore exposed at an early stage to the virus.
In a second step, the team compared the RNA and the proteins of the brain of the infected embryos with those of healthy embryos. Multiple molecular changes during the infection process were observed. This prevented the normal development of the brain of the contaminated fetuses.
Zika virus and congenital disorders: 61 potentially targetable genes for future treatments
According to the researchers, infection with the Zika virus led to a significant increase in the levels of immune proteins in the brains of developing mice. The virus would therefore trigger an important immune response, which contributes to microcephaly. “The immune system attacks cells infected with the virus (…) If you manage to kill these cells, the outcome is usually good. But if you start killing actively dividing brain cells, especially in the early gestation, it can have devastating effects on brain development.”explained Judith Steen, lead author of the study and neurobiologist at the FM Kirby Center for Neurobiology at the Boston Children’s Center (USA).
The results also revealed that Zika virus infection decreased levels of RNA and proteins related to the cell cycle, ie the process that allows cells to grow, replicate their DNA and divide. Due to this disruption of normal cell cycle progression, the brains of infected embryos are unable to develop properly.
In their conclusions, however, the scientists distinguished 61 potentially targetable genes for possible treatments in the event of prenatal exposure to the Zika virus. The molecules that target them could be tested on mice at different stages to see if the disturbances observed by the team normalize.
