AsianScientist (Mar. 13, 2019) – Researchers in Singapore have discovered that fetal brain abnormalities caused by Zika infection are worsened if the mother has had prior exposure to the dengue virus. Their findings are published in Science Advances.
The Zika virus is a mosquito-borne pathogen that is known to cause mild symptoms such as fever and rashes in most people. More worrisome, however, are the cases of microcephaly and congenital malformations reported in children born to Zika-infected mothers. Scientists still do not fully understand how these malformations occur.
In the present study, scientists led by Assistant Professor Ashley St. John at Duke-National University of Singapore Medical School, Singapore, demonstrated in mice that fetal brain damage caused by Zika infection is worse if the mothers also has dengue antibodies.
The team found that Zika virus infection in mothers with antibodies against the dengue virus resulted in fetuses with smaller body mass and head circumferences and more significant damage to the brain tissue. Moreover, when a receptor called neonatal Fc receptor was blocked, Zika virus transmission from mother to fetus was reduced, resulting in offspring with larger head circumference and less brain damage.
The scientists also showed that antibodies to dengue can promote transmission of Zika virus across human placental cells, but further research is needed to determine if previous dengue virus infection has the same effect on human babies born to women infected with Zika during pregnancy.
“Our research indicates that previous immunity of the mother to dengue could be a risk factor for severe outcomes in infants born to mothers infected with Zika virus during pregnancy,” said St. John. “This is highly significant, since current Zika virus epidemic regions overlap to a large extent with those of dengue viruses, and this work informs our understanding of mechanisms that could influence the severity of infection with Zika virus.”
The mechanism that leads to Zika virus transfer from mother to fetus could also be relevant in other viral infections that can be transmitted from mother to fetus, such as HIV and cytomegalovirus, St. John added.
The team aims to employ their findings to develop better treatment options for Zika virus infection during pregnancy.
The article can be found at: Rathore et al. (2019) Maternal Immunity and Antibodies to Dengue Virus Promote Infection and Zika Virus–induced Microcephaly in Fetuses.
Source: Duke-NUS Medical School; Photo: Shutterstock.
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