Placenta lacks ACE2 receptors used by COVID-19 virus to cause infection, says NIH study

July 16, 2020 0 By FM

The placental membranes that contain the foetus and amniotic fluid lack the messenger RNA (mRNA) molecule required to manufacture the ACE2 receptor, the main cell surface receptor used by the SARS-CoV-2 virus to cause infection, according to a study led by researchers at the National Institutes of Health. The findings are published in the journal eLife.

The research which was conducted at the Perinatology Research Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) found that the placental tissues also lacked mRNA needed to make an enzyme, called TMPRSS2, that SARS-CoV-2 uses to enter a cell. Both the receptor and enzyme are present in only minuscule amounts in the placenta, suggesting a possible explanation for why SARS-CoV-2 has only rarely been found in foetuses or newborns of women infected with the virus, according to the study authors.

Meanwhile, the placenta contained molecules that previous studies have suggested as potential routes for SARS-CoV-2 infection, including the CD147 receptor and the enzymes cathepsin L and Furin. They also detected in placenta and membrane tissue a type of macrophage (immune cell) that has the ACE2 receptor. However, the authors highlighted that there is little evidence showing that infected macrophages could spread the SARS-CoV-2 virus to the placenta, membranes and foetus in normal pregnancy.