In UteroExposure to Zika Virus Results in sex-Specific Memory Deficits and Neurological Alterations in Adult Mice

Abstract

Transplacental transmission of Zika virus (ZIKV) during early pregnancy may lead to several neurological alterations, known as congenital Zika syndrome. We have previously shown that intravaginal infection of immunocompetent dams with ZIKV during the early stage of pregnancy triggers neuroinflammation in fetuses, characterized by increased brain expression of inflammatory factors, including IL-6, IL-18, CCL2, CXCL1, and CXCL10. The present study sought to understand the long-term consequences of these early cerebral alterations. For that, pregnant FVB/NJ immunocompetent females were infected intravaginally on the gestational day (GD) 4.5 and experiments were performed when offspring reached between 4 to 5 months of age. The exposure to ZIKV promoted significant neuronal cell loss detected in the CA1 region of the hippocampus of adult mice. However, only females showed reduced expression levels of brain-derived neurotrophic factor (BDNF), postsynaptic density protein 95 (PSD95), and syntaxin-1A, which are important genes related to neuronal function and synaptic plasticity. Moreover, the protein levels of the pre- and postsynaptic markers, SNAP25 and PSD95, respectively, were decreased exclusively in ZIKV-exposed female mice, indicating that ZIKV exposure in utero induces synaptic loss. Additionally, only females exposed to ZIKV showed risk-taking behavior and hippocampal-dependent spatial memory deficit. Together, these results demonstrate that intravaginal infection of mice on GD4.5 induces neurological alterations in the offspring detectable in their adulthood and that female mice, rather than male mice, are more susceptible to ZIKV-induced neurobehavioral alterations. Summary Statement In utero exposure to ZIKV leads to decreased number of neurons in adult mice. Female mice exposed to ZIKV in utero exhibit lower levels of BDNF, a decrease in synaptic markers, memory deficits, and risk-taking behavior during adulthood.

Sex-specific effect of antenatal Zika virus infection on murine fetal growth, placental nutrient transporters, and nutrient sensor signaling pathways

“…A previous study by our group showed that maternal exposure to ZIKV affects placental function, including placental ultrastructure and ABC transporter protein expression, even in the absence of vertical transmission and that these effects are dependent on viral infective titers and maternal immune status (Andrade et al, 2021). Despite their importance to fetal growth and development and their role in response to infections, there is limited information about GLUT and SNAT transporter expression profiles and OGT nutrient-sensing pathway activity in the placenta of ZIKV-infected dams.…”

“…The i.v. injections were performed at GD12.5, and virus preparation was undertaken as previously described (Coelho et al, 2017;Andrade et al, 2021). At 18.5, all animals were weighed and euthanized with 5% isoflurane by inhalation.…”

“…All negative controls were performed with the omission of the primary antibody. Analysis were performed as previously described (Andrade et al, 2021). All analyses were conducted blind to the group.…”

“…Differences were considered significant when p<0.05. Litter parameters were evaluated using the mean value of all fetuses and/or placentae in the litter per dam and not the individual conceptus (Bloise et al, 2012;Connor et al, 2020).…”

“…Similar to other flaviviruses, ZIKV requires a variety of intricate interactions with host factors for successful infection, such as reprogramming of cellular metabolism underpinning ZIKV pathogenesis (Thaker et al, 2019;Chen et al, 2020;Yau et al, 2021). In the placenta, ZIKV is able to cause lipid reprogramming, mitochondrial dysfunction, and inflammatory immune imbalance, contributing to placental damage (Chen et al, 2020;Andrade et al, 2021;Creisher et al, 2022).…”