Immune Activation and Synaptic Dysfunction Underlie Cognitive Impairments Following Mild Zika Virus Infection: Insights from Behavioral and Gene Expression Analyses

Abstract: Background: Zika virus ZIKV is an arbovirus linked to "Congenital Zika Syndrome" and a range of neurodevelopmental disorders NDDs, with microcephaly as the most severe manifestation. Milder NDDs, such as autism spectrum disorders and delays in neuropsychomotor and language development, often go unnoticed in neonates, resulting in longterm social and academic difficulties. Murine models of ZIKV infection effectively replicate the motor and cognitive deficits observed in humans. These can be evaluated through behavioral tests, enabling comparison with gene expression profiles and aiding in the characterization of ZIKVinduced NDDs. Objectives: This study aimed to identify genes associated with behavioral changes following subtle ZIKV infection in juvenile BALBc mice. Methods: Neonatal mice were subcutaneously inoculated with ZIKV MH5447012 on postnatal day 1 DPN at a dose of 6.8x103 PFU. Viral presence in the cerebellum and cortex was quantified at 10 and 30days postinfection DPI using RTqPCR. Neurobehavioral deficits were assessed at 30 DPI through Tmaze, rotarod, and openfield tests. Next Generation Sequencing NGS was performed to identify differentially expressed genes DEGs, which were analyzed through Gene Ontology GO and KEGG enrichment. Gene interaction networks was then constructed to explore gene interactions in the most enriched biological categories. Results: A ZIKV infection model was successfully established, enabling brain infection while allowing survival beyond 30 DPI. The infection induced mild cognitive behavioral changes, though motor and motivational functions remained unaffected. These cognitive changes were linked to the functional repression of synaptic vesicles and alterations in neuronal structure. Conclusions: ZIKV infection in BALBc mice, using the 2016 epidemic strain, caused mild, nonlethal symptoms and triggered a robust immune response in both the cortex and cerebellum. Despite viral control, neurocognitive effects persisted, including memory deficits and synaptic dysfunction, underscoring longterm neurological consequences.