Figure 1.
HBV lifecycle. Virus particles containing partially double-stranded (ds) DNA (∼dsDNA) genomes enter the cell via the NTCP receptor. Following uncoating of surface antigen (small blue circles), the core particles (hexagons) deliver the genome to the nucleus. The ∼dsDNA is repaired by host factors and converted into covalently closed circular (ccc)DNA. The cccDNA serves as the template for HBx-mediated viral transcription. The viral mRNAs (shown in the nucleus) are transported to the cytoplasm for translation. The 3.5-kb pregenomic RNA and a copy of the viral polymerase (small black circles) is encapsidated and reverse transcribed (RT) into the negative-strand DNA, which is then copied into positive-strand DNA. Viral cores move through the endoplasmic reticulum and Golgi, where they acquire surface antigen (envelope) and bud from the cell. Cytoplasmic-core particles may alternatively recycle back to the nucleus.