How Zika Virus Crosses The Placental Barrier

The epidemic of Zika Virus (ZV) drastically affected the health of more than one million people in Brazil resulting in twenty-fold increase of microcephaly (head circumference of newborn baby being less than or equal to thirty-two cms) in infected pregnant women. ZV crosses the placental barrier between maternal and fetal compartments. ZV has been found in amniotic fluid and fetal brain tissue of the human pregnancies complicated with ZV infection and microcephaly supporting cause and effect relationship between ZV and microcephaly. New knowledge about how ZV enters into the cells is mandatory for preventive and therapeutic research. ZV is a Flavivirus, therefore the Flavivirus receptors are candidate receptors for ZV too. ZV has been associated with high level of TYRO3 and AXL component of TAM, a Tyrosine Kinase receptor family, expression in the infected skin cells and neuronal stem cells. It predicts that AXL receptors may facilitate ZV entry into the trophoblasts and endothelial cells lining the fetal vessels present in the placenta. This hypothesis stems from the reported studies on ZV and AXL receptor expression, both in human tissues and animal models. If our hypothesis proves to be valid, it would be a great step towards the drug and therapeutic development to prevent ZV crossing the placental barrier and resulting in complications.