Unlike DENV and West Nile (WNV) flaviviruses that use the TIM1 receptor for infection as well [30] but do not cause microcephaly [31,32], ZIKV can efficiently use Axl to infect fetal endothelial cells by preferentially binding the Axl ligand Gas6 (Growth Arrest-Specific 6) [33,34]. Here, GAS6 is linked to infection.