Fetal inheritance of chromosomally integrated human herpesvirus 6 predisposes the mother to pre-eclampsia

Publication: Nature Microbiology

Francesca Gaccioli, Susanne Lager, Marcus C. de Goffau, Ulla Sovio, Justyna Dopierala, Sungsam Gong, Emma Cook, Andrew Sharkey, Ashley Moffett, Wai Kwong Lee, Christian Delles, Cristina Venturini, Judith Breuer, Julian Parkhill, Sharon J. Peacock, D. Stephen Charnock-Jones & Gordon C. S. Smith

4 May 2020


Summary: 

The placenta is the interface between the mum and the fetus and supports the growth of the baby in the womb. Abnormal function of the placenta is associated with poor pregnancy outcome, including maternal and infant diseases and deaths. In turn, placental dysfunction could be due to viral infections, which are known to cause organ failure. We investigated whether viral infection of the placenta is associated with diseases of human pregnancy related to poor placental function, such as pre-eclampsia (hypertensive disorder in the mother) and fetal growth restriction (impaired growth of the fetus during pregnancy).

Using samples from more than 5,000 pregnancies and data available in the literature, we demonstrated that the presence of inherited human herpesvirus 6 (HHV-6) DNA in the feto-placental unit is associated with an increased risk of the mother to develop pre-eclampsia. The virus can be passed to the fetus and the placenta from both the mother and the father. Importantly, our study did not identify any other viral associations with the 2 studied conditions. HHV-6 was the only clear viral signal observed in a large number of placental samples from pathological and normal pregnancies.

Pre-eclampsia is a condition characterized by high maternal blood pressure and protein levels in the urine in the second half of pregnancy. It represents a major determinant of the global burden of disease. Although pre-eclamspia is known to be associated with poor development and function of the placenta, the causes of placental insufficiency are not fully understood. Identifying those will help us to understand and treat this condition, which affects 5-8% of all pregnant women and is responsible for over 75,000 maternal deaths and 500,000 fetal deaths worldwide every year. Our work demonstates that viral infection of the placenta is not a major cause of pre-eclampsia and that a small proportion of cases is likely to be due to the presence of HHV-6 in the feto-placental unit.

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