CD8A and Anxiety: Previous studies have shown that CD8+ T cells migrate to the brain, and specific CD8+ T cell subsets have been linked to various conditions such as ageing,28 memory deficits,29-31 AD24 and neuropsychiatric complications.32 In alignment with these findings, our study revealed that both HBV and the adoptive transfer of HBV-induced CD3+ T cells prompted the migration of CD8+ T cell subsets into different brain regions, thereby reducing hippocampal neurogenesis and inducing anxiety-like behaviour.