Hepatitis B virus X-region messenger RNA (HBx mRNA) (HBx mRNA)

Hepatitis B virus X-region messenger RNA (HBx mRNA) is the transcript encoding the HBx protein, a multifunctional regulatory protein essential for the Hepatitis B virus (HBV) life cycle and pathogenesis (Frontiers in Microbiology, 2022). HBx acts as a potent transactivator that modulates host gene expression, signal transduction pathways (such as PI3K/AKT and NF-kB), and DNA repair mechanisms to facilitate viral replication and persistence (NIH, 2023). It plays a pivotal role in the development of hepatocellular carcinoma (HCC) by promoting cell survival, genomic instability, and the suppression of host immune responses (Cancer Science, 2006). Because the X-region is highly conserved and overlaps with other viral transcripts, it serves as an ideal target for RNA-targeted therapeutics (ResearchGate, 2023). Drugs such as small interfering RNAs (siRNAs) like JNJ-3989 and antisense oligonucleotides (ASOs) like bepirovirsen are designed to bind and degrade HBx mRNA, thereby silencing the production of HBx and other viral proteins like HBsAg (GSK, 2024; Ionis, 2024). This strategy aims to achieve a functional cure for chronic hepatitis B by reducing viral load and restoring the host's immune control over the infection (MDPI, 2022). The HBx protein is a 154-amino acid regulatory factor that is required for efficient transcription of the viral covalently closed circular DNA (cccDNA) template (NIH, 2022). By targeting the mRNA transcript, these therapies can effectively reduce the levels of all viral antigens, including those derived from integrated HBV DNA (Frontiers in Immunology, 2025).

Other names

HBV X mRNAHBx transcriptHepatitis B virus X gene mRNA0.7 kb HBV mRNA

RNA interference and antisense-mediated mRNA degradation leading to silencing of viral protein synthesis.