2784. Increased Frontal Lobe Volume and Density in Macaques Exposed to Zika Virus In Utero

Background In utero Zika virus (ZIKV) infection causes birth defects and neurodevelopmental deficits in neonates. We reasoned that a translational macaque model of congenital ZIKV infection could define disease pathophysiology not possible in human clinical studies. Methods We inoculated 5 pregnant rhesus macaques with a Puerto Rican isolate of ZIKV (ZIKV-PRVABC59) during the first trimester, monitored infection with plasma viral RNA (vRNA) loads, and evaluated infants for birth defects and neurodevelopmental deficits during their first week of life. Assessments included neurobehavioral assessments, ophthalmic examinations, optical coherence tomography, electroretinography with visual evoked potentials, hearing examinations, brain magnetic resonance imaging (MRI), and tissue histopathological analyses. Results All five pregnant dams demonstrated plasma viremia and seroconversion following ZIKV inoculation. One of the five pregnancies resulted in a stillbirth. All liveborn infants had decreased feeding volumes and weight gain compared with control infants. A comprehensive voxel-based morphometric comparison of ZIKV-exposed and control infant brain MRIs identified increased gray matter volume and density in the frontal lobe in the ZIKV-exposed infant group, which corresponds to the pharyngeal motor cortex responsible for coordinating swallowing. Ocular studies identified differences between ZIKV-exposed and control infants in retinal layer thicknesses (inner plexiform, outer nuclear layers, photoreceptor outer segment) and visual evoked potentials (increased amplitude of waveforms). While ZIKV vRNA was detected in the decidua of 2/5 pregnancies, no ZIKV vRNA was identified in infant tissues and none of the infants developed an anti-ZIKV IgM response. Conclusion In utero ZIKV exposure resulted in decreased feeding volumes and weight gain, which may be related to the gray matter changes identified in the pharyngeal motor cortex. Changes in retinal layer thicknesses and increased cortical visual pathway waveform amplitude suggest vision may be impaired. These changes occurred despite the lack of evidence of vertical transmission, suggesting that ZIKV exposure without measurable vertical transmission affects fetal brain development. Disclosures All authors: No reported disclosures.