Persistent neurological and behavioral alterations after SARS-CoV-2 infection in an optimized K18-hACE2 mouse model.

Introduction: Persistent neurological symptoms are among the most prevalent and debilitating manifestations of post-COVID-19 Condition (PCC), affecting millions of individuals worldwide. PCC is a chronic multisystemic syndrome that develops in over 30% of adults following acute infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite its major clinical and socioeconomic impact, the biological mechanisms underlying PCC remain poorly understood, underscoring the need for robust and translational animal models. Methods: We conducted a longitudinal study in K18-hACE2 mice, integrating virological, immunological, histopathological, and behavioral assessments from acute infection through 60 days post-inoculation. Results: SARS-CoV-2-inoculated mice developed persistent neurobehavioral impairments despite the absence of detectable viral replication in the brain. These alterations were associated with sustained immune dysregulation in both pulmonary and neural tissues, persistent pulmonary pathology, and a reduction in vagus nerve cross-sectional area. Notably, several long-term outcomes exhibited marked sex-dependent differences that mirrored clinical observations in human PCC. Discussion: Our findings demonstrate that K18-hACE2 mice recapitulate key neurological and immunopathological features of PCC and may constitute a valuable experimental model for investigating the mechanisms underlying PCC-associated neurological sequelae. This model may also facilitate the development and preclinical evaluation of targeted therapeutic interventions.