Overview

• The University of Illinois study, published Sept. 24 in Brain, Behavior, and Immunity, used live influenza A to infect pregnant mice.
• Fluorescent tracers of varying molecular weights revealed that large maternal molecules crossed the placenta into fetal tissues.
• Large tracers and fibrinogen accumulated in the fetal subventricular zone and choroid plexus, indicating leaky blood–brain and cerebrospinal fluid barriers.
• Leakage and protein buildup were most pronounced at the highest viral dose, suggesting a severity threshold for fetal exposure.
• Authors stress the findings come from a mouse model requiring further validation and urge maternal flu vaccination to reduce severe illness.