Cytomegalovirus (CMV) is one of the most common viruses people encounter, often causing mild or unnoticeable symptoms in healthy adults and children. However, when a person contracts a first-time CMV infection during pregnancy, the virus can cross the placenta and pose serious risks to the developing fetus, including lifelong hearing loss and neurodevelopmental problems. CMV is the world’s most commonly transmitted mother-to-child infection, yet the mechanisms of how this happens across pregnancy have been poorly understood.
To shed light on this critical gap, researchers at the Tulane National Biomedical Research Center (Tulane NBRC) conducted a study using a nonhuman primate model that closely mirrors human pregnancy. This model allows scientists to observe how the virus interacts with the immune system and the placenta in a living system – something that can’t be replicated in a non-animal model (NAM). Researchers followed pregnancies in animals that encountered the virus for the first time in the second trimester, monitoring maternal health, placental tissues and fetal development over time.
The research team led by Dr. Amitinder Kaur found that CMV did not behave the same way in every pregnancy. Some pregnancies showed brief or low‑level signs of infection, while others had more extensive viral involvement. Across almost all cases, however, the virus was detected in the placenta, even when fetal tissues showed little or no virus. Notably, pregnancies with higher levels of virus in placental tissues tended to have smaller fetuses at birth, suggesting that the virus may affect fetal growth even without direct fetal infection.
By comparing immune markers in mothers and fetuses, the researchers also identified patterns that may predict a higher risk of transmission. Elevated levels of certain inflammatory signals and changes in other immune factors were linked to cases where the virus crossed the placenta more readily. These potential biomarkers could one day help clinicians identify which pregnancies need closer monitoring or targeted interventions.
Why it matters: Congenital CMV is a major public health concern because there is currently no approved vaccine to prevent it, and existing strategies can’t reliably stop transmission. By mapping how CMV crosses the placenta and influences fetal outcomes, this work from Tulane NBRC lays crucial groundwork for identifying at-risk pregnancies and informing the development of vaccines or other preventive approaches in the future.
