Functionalized locked nucleic acid system for targeted inhibition of hepatitis B virus C gene in transgenic models

Chronic hepatitis B virus (HBV) infection remains difficult to cure due to the persistence of covalently closed circular DNA (cccDNA). Here, we developed an antigen locked nucleic acid system ( CS-1@LNA ) targeting the conserved 2404–2418 nt region of the HBV C gene, using a functionalized chitosan-based carrier to enhance stability and delivery efficiency. CS-1@LNA exhibited strong nuclease resistance and good biocompatibility. In HBV transgenic mice, tail vein administration of CS-1@LNA (0.5 µg/g) significantly reduced serum HBV DNA, HBsAg, and HBeAg levels, and suppressed hepatic C-mRNA expression without inducing liver or kidney toxicity. In addition, CS-1@LNA modulated apoptosis-related proteins by downregulating Cleaved-caspase-3 and Bax while upregulating Bcl-2. These findings demonstrate that CS-1@LNA effectively inhibits HBV replication and gene expression through a sequence-specific antigen mechanism, highlighting its potential as a safe and efficient nucleic acid–based therapeutic strategy.