HBV genome and open reading frames Hepatitis b virion genome is a small circular, partially double stranded dNA with 3. 2kb long Four open reading frames(ORF) coded on the minus strand: C, S, X, and p region S regions: encode pre-s1, pre-S2 and HBSAg C region included pre-C and c gene, encode HBeAg and HBCAg X region encodes HBxAg P region encodes dNA polymeraseHBV genome and open reading frames  Hepatitis B virion genome is a small circular, partially double stranded DNA with 3.2kb long.  Four open reading frames (ORF) coded on the minus strand: C, S, X, and P region: S regions: encode pre-s1, pre-s2 and HBsAg. C region included pre-C and C gene, encode HBeAg and HBcAg X region encodes HBxAg P region encodes DNA polymerase