Genomic and transcriptomic features of HBV integration in treatment-naïve, HBeAg-positive children with chronic HBV infection.

BACKGROUND: Hepatitis B virus (HBV) integration represents a major obstacle to curing HBV; however, the landscape of HBV integration and local immune response to transcriptionally active viral integration in children with chronic HBV infection remain unclear. Herein, we aimed to elucidate this landscape in this population. METHODS: Genomic analyses using a probe-based capture strategy were performed on 18 children and 28 adults with chronic HBV infection. Spatial transcriptomics (ST) was performed on 12 children from our cohort and 3 adults from a public database. FINDINGS: All patients were hepatitis B e antigen (HBeAg)-positive and treatment-naïve. Genomically, children exhibited significantly lower clonal expansion level of HBV-integrated hepatocytes than adults, despite comparable unique breakpoint counts. After adjusting for confounding variables, age was identified as an independent risk factor for total frequency of unique integration breakpoints (b = 3.22, P = 0.005). Spatially, ST revealed that spots with transcriptionally active viral integration exhibited a sparse distribution and accounted for a low proportion of all spots in children. Notably, at these spots, children showed reduced adaptive immune cells (e.g., CD8+ T cells) but increased innate components (myeloid cells, Kupffer cells, activated dendritic cells) and APC co-stimulation, whereas adults exhibited a uniform reduction of immune cell populations. INTERPRETATION: Compared with adults, children exhibit lower clonal expansion of HBV-integrated hepatocytes and distinct immune profiles in response to transcriptionally active viral integration, offering new insights into their differing clinical course. FUNDING: Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education).