Teratogenic effects of the Zika virus and the role of the placenta

Abstract

The mechanism by which the Zika virus can cause fetal microcephaly is not known. Reports indicate that Zika is able to evade the normal immunoprotective responses of the placenta. Microcephaly has genetic causes, some associated with maternal exposures including radiation, tobacco smoke, alcohol, and viruses. Two hypotheses regarding the role of the placenta are possible: one is that the placenta directly conveys the Zika virus to the early embryo or fetus. Alternatively, the placenta itself might be mounting a response to the exposure; this response might be contributing to or causing the brain defect. This distinction is crucial to the diagnosis of fetuses at risk and the design of therapeutic strategies to prevent Zika-induced teratogenesis.

Neuroimaging findings of Zika virus infection: a review article

“…The earlier the mother is infected, the more severe the abnormalities will be because the main process of organogenesis takes place during the first trimester and early second trimester. The brain damage may be a consequence of either direct viral invasion and apoptosis of fetal neuronal tissue, or an inflammatory response due to inflammatory mediators released from the placenta in the infected pregnant woman [31]; however, Mlakar et al [32] have isolated ZIKV from the brain of an aborted fetus affected by Zika infection which proves the neurotropism of this virus and favors the first pathomechanism against the second one.…”

Zika virus: what do we know about the viral structure, mechanisms of transmission, and neurological outcomes?

“…Placental structure and function seem to be preserved during Zika virus infection (64) , since the reduction in newborn size and trophoblastic invasion and preterm deliveries are not so frequent (73) . Furthermore, normal blood flow from the mother to the fetus was observed despite focal calcifications in villi and decidua (30) .…”

Vulnerability of primitive human placental trophoblast to Zika virus

“…embryonic stem cell | placenta | pregnancy | trophoblast | Zika virus A lthough the placental syncytiotrophoblast (STB) is an effective barrier to many pathogens (1,2), including viruses (3), the extent to which it protects against vertical transmission of a flavivirus, such as the Zika virus (ZIKV: Flaviviridae; Flavivirus) at different stages of pregnancy is largely unknown (4). In the case of ZIKV, clinical symptoms in adults are generally mild, yet infection of a woman during her pregnancy has been associated with fetal death, placental insufficiency, fetal growth restriction, and central nervous system abnormalities (5).…”