Establishing correlates of maternal-fetal cytomegalovirus transmission-one step closer through predictive modeling.

ABSTRACT

BACKGROUND: Determinants of maternal-fetal cytomegalovirus (CMV) transmission and factors influencing the severity of congenital CMV (cCMV) infection are not well understood. METHODS: We conducted a descriptive, multi-center study in pregnant women ≥18 years old with primary CMV infection and their newborns (NCT01251744) to explore maternal immune responses to CMV and determine potential immunologic/virologic correlates of cCMV following primary infection during pregnancy. We developed alternative approaches looking into univariate/multivariate factors associated with cCMV, including a participant clustering/stratification approach and an interpretable predictive model-based approach using trained decision trees for risk prediction (post-hoc analyses). RESULTS: Pregnant women were grouped in three distinct clusters with similar baseline characteristics, particularly gestational age at diagnosis. We observed a trend for higher viral loads in urine and saliva samples from mothers of infants with cCMV versus without cCMV. When using a trained predictive-model approach that accounts for interaction effects between variables, anti-pentamer IgG antibody concentration and viral load in saliva were identified as biomarkers jointly associated with the risk of maternal-fetal CMV transmission. CONCLUSION: We identified biomarkers of CMV maternal-fetal transmission. After validation in larger studies, our findings will guide the management of primary infection during pregnancy and the development of vaccines against cCMV.

The human cytomegalovirus (CMV) is common and usually causes no symptoms in healthy individuals. However, CMV infections can be life-threatening in individuals with improperly functioning or immature immune systems, such as fetuses. Women can become infected with CMV for the first time (primary infection) during pregnancy. If CMV is transmitted from mother to fetus before the second trimester, the infant can suffer from severe disorders such as hearing loss and delayed development. We aimed to identify characteristics of pregnant women with a primary CMV infection that may increase the likelihood of transmitting CMV to the fetus. We considered demographical, clinical, and behavioral characteristics, as well as immune responses and the quantity of virus detected in the women's blood, urine, saliva, and vaginal mucus. Because we could not identify one single characteristic that could predict a high risk of CMV transmission, we developed new data analysis models to study how they can be combined. We found that antibodies targeting a pentameric antigen of the virus envelope and the presence of virus in saliva can together predict the risk of CMV transmission from mother to fetus. Our results can help improve the care of CMV-infected pregnant women and the design of CMV vaccines.