Retroviruses and Hepatitis B Virus

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 pregenometemplate. 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 nucleocapsidcan either migrate to the nucleus to increase the pool of cccDNAor it can undergo a maturation event that enables it to bud through a membrane containing virus envelopeproteins • DNA synthesisceases 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