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Zika-Related Flaviviruses May Cause Congenital Infection

West Nile, Powassan viruses infect placenta and nervous system, harming developing brain in mice

THURSDAY, Feb. 1, 2018 (HealthDay News) — Emerging neurotropic flaviviruses related to Zika virus (ZIKV) may share ZIKV’s capacity for transplacental transmission, according to a study published online Jan. 31 in Science Translational Medicine.

Derek J. Platt, from the Washington University School of Medicine in St. Louis, and colleagues conducted a study in immunocompetent, wild-type mice to examine the ability of four emerging arboviruses (West Nile virus [WNV], Powassan virus [POWV], chikungunya virus [CHIKV], and Mayaro virus [MAYV]) from related (flavivirus) and unrelated (alphavirus) genera to infect the placenta and fetus.

The researchers found that all four viruses caused placental infection. However, fetal demise occurred only with WNV and POWV infection. Efficient replication was reported for WNV and POWV in second-trimester human maternal (decidua) and fetal (chorionic villi and fetal membrane) explants, while less efficient replication was seen for CHIKV and MAYV. Based on RNA in situ hybridization and histopathological analysis, WNV was found to infect the placenta and fetal central nervous system in mice, injuring the developing brain. Despite evidence of vertical transmission, CHIKV and MAYV did not cause substantial damage to the placenta or fetus.

“On the basis of the susceptibility of human maternal and fetal tissue explants and pathogenesis experiments in immunocompetent mice, other emerging neurotropic flaviviruses may share with ZIKV the capacity for transplacental transmission, as well as subsequent infection and injury to the developing fetus,” the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

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