1. Retroviruses and Hepatitis B Virus

9. Rous Sarcoma Virus

34. Hepatitis B Virus

35. HBV Genome

36. Genome Organization

38. 4 classes of mRNA in green :
0.9kb, 2.1kb, 2.4kb, 3.5kb
Pregenome RNA blue

39. Outline of Genome Replication
The pregenome RNA acts as template for DNA synthesis.
Initially a 4-nucleotide (−) DNA is synthesized then it is transferred to a complementary sequence in DR1 near the 3 end of the pregenome.
DNA synthesis continues to the 5 end of the pregenome template. The RNase H activity of the P protein degrades the pregenome RNA from the RNADNA duplex.
All the RNA is removed except for a remnant of 15–18 bases including the cap. The –OH group at the 3 end of the RNA remnant acts as the primer for the synthesis of (+) DNA.
During (+) DNA synthesis a nucleocapsid can either migrate to the nucleus to increase the pool of cccDNA or it can undergo a maturation event that enables it to bud through a membrane containing virus envelope proteins
DNA synthesis ceases on budding, as the nucleocapsid is cut off from the pool of nucleotides in the cytoplasm.
This explains why the (+) DNA in the virion is incomplete?

40. Epsilon elements

41. Steps in RT Pathway