Scientists at USC have discovered biomarkers for fetal birth defects in the blood of pregnant women infected with Zika.
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This breakthrough finding could result in a diagnostic test to screen fetuses for Zika-associated birth defects whilst still in the womb. This would reassure expectant mothers that their babies are healthy.
The Zika virus is transmitted by the bite of the Aedes species of mosquito. It produces no or very mild symptoms such as low fever.
However, a pregnant woman infected with the virus has a high risk of giving birth to a child with very severe developmental defects.
One such defect is an abnormally reduced fetal head size, called microcephaly. This anomaly became well-known after many babies were born with the defect in Brazil in 2015.
These children sometimes fail to develop normally, being blind, unable to chew, talk or walk, in which case they will require permanent care, according to the Centers of Disease Control and Prevention in the USA.
The importance of the current research finding lies in its potential to detect cthe presence of birth defects caused by the virus with clarity, simplicity, and safety during pregnancy.
While ultrasound scans are in routine use during pregnancy, they often fail to show such defects.
On the other hand, magnetic resonance imaging can visualize fetal development at a particular point in time with high resolution, but are not recommended in the first trimester for fear of causing genetic damage to the fetus.
However, says Suan-Sin Foo, the study’s first author, "The highest risk of birth defects is from Zika virus infection during the first and second trimester. A prenatal test has the potential to relieve the concerns of many expectant mothers."
For this reason, the present work could be tremendously helpful in screening for Zika-associated anomalies at any stage of pregnancy.
Our findings identified a panel of biomarkers which may potentially be useful in predicting Zika-associated fetal outcomes regardless of pregnancy stages, simply by evaluating the mothers' blood."
Weiqiang Chen, Co-first author
Though Aedes mosquitoes have been found in Los Angeles, the Los Angeles County Department of Public Health says that none are positive for the Zika virus.
However, the US alone has reported 2483 women infected with Zika in pregnancy, resulting in 116 babies with congenital defects caused by the virus, in just the three years since 2015.
The current study used blood samples taken from 30 pregnant women in Brazil with Zika infection and 30 and 14 healthy pregnant women in Brazil and Los Angeles, respectively.
In particular, the pattern of blood chemicals called cytokines, which are released by cells in response to infections and other stresses, was examined. These are important in signaling within and between cells.
The researchers screened these women using a 69-cytokine panel, and found significant differences in 16 cytokines in pregnancies associated with Zika-linked birth abnormalities.
Despite this, they could not identify whether the cytokines identified as abnormal actually caused the birth defects or were part of the body’s response to some other process.
The work could also help understand how these defects are caused by Zika infection.
We still have a lot to learn about how Zika virus affects the immune responses in the mother, and how infection can negatively impact her baby."
Suan-Sin Foo, Co-first author
The study was published in the journal Clinical Investigation Insight on November 2, 2018.
It was led by Jae Jung, distinguished professor and chair of the Department of Molecular Microbiology and Immunology of USC, with other scientists from other countries.
Biomarkers may predict Zika-related birth defects.