HBV pre-S/S open reading frame

Schematic representation of the pre-S/surface open reading frame (ORF), RNA transcripts and translational products. The pre-S/S ORF consists of three in-phase start codons and a common stop codon that divides the gene into pre-S1, pre-S2 and S regions encoding the large (L), middle (M), and small (S) envelope proteins, respectively. The M and S envelope proteins are found in all forms of viral and subviral particles while the L envelope proteins are predominantly found in complete virions.