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Mother’s Previous Exposure to Dengue May Worsen Zika-Infected Baby’s Brain Abnormality

New research uncovers previously unknown mechanism behind why some, but not all, Zika virus infections during pregnancy lead to fetal brain abnormalities.

Some, but not all, Zika virus infections during pregnancy lead to fetal brain abnormalities.

Researchers at Duke-NUS Medical School and their colleagues have identified a surprising interaction between dengue and Zika viruses that sheds lights on the significant fetal brain abnormalities linked to Zika virus.

They wanted to know if the severity of fetal infection had anything to do with previous infection of the mother with dengue virus, which is closely related to Zika and often circulates in the same regions of the world.

The study employed on animal model analysed the physical differences between the fetuses of mothers who had never been exposed to dengue, or previously had dengue and have developed antibodies against the virus.

The team found that Zika virus infection in mothers with antibodies against dengue resulted in fetuses with smaller body mass and head circumferences, and more significant damage to the brain tissue.

Further, when a receptor called neonatal Fc receptor (FcRN), was blocked, Zika virus transmission from mother to fetus was reduced, resulting in a larger head circumference and less brain damage.

The team also showed that dengue antibodies can promote transmission of Zika virus across human placental cells through the formation of an immune complex.

The researchers thus determined that fetal mouse brain damage was much worser if the mothers infected with Zika also had dengue antibodies.

But further research is needed to determine if previous dengue virus infection has the same effect on human babies born to pregnant women infected with Zika.

The novel mechanism that leads to Zika virus transfer from mother to fetus could also be relevant in other viral infections that can also be transmitted from mother to fetus, such as HIV and cytomegalovirus.

The current Zika virus epidemic regions overlap to large extent with those of dengue viruses, making the findings very significant.

Their findings are reported in Science Advances.

The team next aims to employ their findings to develop better treatment options for Zika virus infection during pregnancy. [APBN]

Source: Rathore APS, Saron WAA, Lim T, Jahan N and St John AL (2019). Maternal immunity and antibodies to dengue virus promote infection and Zika virus-induced microcephaly in fetuses. Science Advances. DOI: 10.1126/sciadv.aav3208