Secretion of empty or complete hepatitis B virions: Envelopment of empty capsids versus mature nucleocapsids

HBV replicates its DNA genome, a partially double-stranded, relaxed circular DNA, via reverse transcription of an RNA intermediate called pre-genomic RNA by its reverse transcriptase. A major characteristic of HBV replication is the selective envelopment and secretion of relaxed circular DNA-containing mature capsids and empty capsids with no DNA or RNA, but not those containing pre-genomic RNA or the single-stranded DNA replication intermediate. In this review, the potential mechanisms of HBV virion morphogenesis will be discussed, with a focus on key determinants of both the capsid and envelope proteins for the selective secretion of complete and empty virions.