Whether they realize it or not, most people will contract a virus known as cytomegalovirus (CMV) at some point in their lives and experience few or no symptoms. But for babies infected with CMV in utero, the outlook is much different. Congenital CMV causes more cases of childhood disability than any other infectious disease and is a leading cause of deafness in young people.
Each year, some 10,000 children in the U.S. become disabled as a consequence of contracting CMV in utero. The virus can cause cerebral palsy, deafness, intellectual disability, pregnancy loss, and stillbirth, and there is currently no way to treat infections that occur during pregnancy.
Masonic Early Investigator Craig Bierle is determined to unravel how CMV causes severe infections in developing babies.
"Pregnant women catch viruses all the time. Typically, these viruses are controlled by the immune system and don’t impact fetal health," Bierle says. "There is a very short list of bacterial and viral pathogens that can be transmitted across the placenta to the developing baby—CMV is one of them."
With Masonic support, Bierle and his team are working to understand how CMV harms developing babies. They have been especially interested in the role of the placenta, which typically protects the fetus, but may be more vulnerable to the virus during certain stages of pregnancy.
In their recent study with guinea pigs, they found that CMV had very little impact on the placenta early in pregnancy. The discovery came as a surprise because children are more likely to develop severe developmental disabilities when the mother is infected with CMV during the first trimester of pregnancy.
Bierle’s team also found that when the guinea pigs were infected with CMV later in pregnancy there was an immune response in the placenta that may injure the developing pups. They suspect that a similar immune response occurs in humans, likely leading to the fetal growth restriction and stillbirth that is often seen during the third trimester of pregnancy.
"Our research shows that there may be more than one mechanism involved in causing harm to the developing baby,” Bierle explains. “In early infections, CMV may be problematic when the fetus itself gets infected. When infection occurs later in pregnancy, the fetus may be more resistant to infection, but the placenta is the vulnerable piece of the system."
Gaining insight into when CMV is most dangerous to the developing fetus could lead to more targeted treatments for the virus.
"If we knew that a woman had made it past that dangerous window early in pregnancy, but hadn’t yet reached the stage of pregnancy when the virus’s activation of the immune system restricts fetal growth, we may be able to tamp down that immune response to prevent stillbirth and growth restriction," says Bierle.
While some of their research was delayed early in the pandemic, Bierle’s team has made marked progress in recent months. Their next big step will be to expand their research to better understand how the immune response can damage the placenta and injure children. They are currently applying for grant support from the National Institutes of Health to study immune pathways that can cause CMV-related fetal injury.
The impact of Masonic support
For Bierle, who has been a Masonic Early Investigator for two years and the recipient of a Masonic cross-departmental grant, support from Minnesota Masonic Charities has made all the difference in moving this research forward.
Both sources of Masonic funding have helped the team get to where they are today in better understanding CMV, and coming a big step closer to stopping it.
"It’s always humbling to receive support from the Masons,” says Bierle. “I hope that I do a good job of being a steward of those dollars and turning them into results that will make an impact on the health of children."