Spliced HBV mRNA
More than ten spliced products of pre-genomic RNA (pgRNA) have been identified. The major 2.2kb variant transcript is spliced between the positions 2447 and 489 (Sommer et al. 2000) Rating=2, (Gunther et al. 1997) Rating=2. Its translation produces the Hepatitis B spliced protein (HBSP protein) which contains the first 47 amino acids residues of polymerase (Soussan et al. 2000) Rating=2. HBSP binds to fibrinogen gamma chain and could inhibit fibrin polymerization (Chen et al. 2010) Rating=1. Anti-HBSP antibodies are found in almost half of sera samples from chronic HBV carriers (Soussan et al. 2003) Rating=1.
A polymerase-surface protein (PS) has also been reported, although only detected in vitro. It is generated by a 2447/2902 splicing of pgRNA (Huang et al. 2000, Park et al. 2008).
The spliced pgRNA can be encapsidated and reverse transcribed giving rise to defective particles (Soussan et al. 2008) Rating=2.
Intronic splicing silencers (ISS) have been identified (Huang et al. 2011) Rating=1, (Chowdhury et al. 2011) Rating=1.
Intronic splicing silencer regions: nt 3131-3163, and nt 1446-1585 (PRE-ISS) which folds into a double-hairpin structure and accounts for the lack of known spliced variants in the surrounding region.
Intronic splicing activator regions: nt 2951-2970, and nt 3051-3070