Biochemical structure of HBV DNA. The molecule is open circular. The minus-strand has full length within the core particle and even a redundancy of 9 bases at the ends around the nick. The plus-strand is incomplete leaving a large single-stranded gap. The 5′ end of the minus-strand is covalently linked to the primase domain of the DNA polymerase which is present with its active center of the reverse transcriptase domain at the 3′ end of the plus-strand. The 5′ end of the plus-strand contains still its primer which is - in this case- derived from the 18 capped 5′ terminal bases of the degraded pregenomic HBV mRNA.