Flashcards in HBV Deck (21):
How many people have chronic HBV infection?
300-400 million have chronic infection.
HBV genome form in virus
3.2 Kb of partial dsDNA. -ive strand complete, but with nick. +ive strand incomplete.
HBV RNA dep DNA pol functions.
Priming, reverse transcription/DNA synthesis and RNase H activity.
Acute HBV infection
30% of infections show this. Lasts 1-3 months, with chronic infections in 1% of cases.
Does not replicate efficiently in cell cultures.Some replication seen in primary cells.
Model systems appear invaluable.
Model systems for HBV
Each has a narrow host range. Good model systems include the woodchuck, the ground squirrel, the pekin duck, and the heron hepadnaviruses.
HBV Dane particle
Infectious unit, double shelled.
HBV Dane particle contents
HBV surface antigen, core and polymerase linked to genome.
HBV Dane particle HbsAg forms
Types of HBV particles
filaments and spheres are immunological decoys.
HBV genome 5' ends.
Both have 11 nt direct repeats.
-ive strand has 5' end terminal protein.
+ive strand has short RNA oligonucleotide.
4 ORFs of HBV genome.
S - surface antigen
P - polymerase
X - multifunctional protein
C - core.
binds sodium taurocholate cotransporting polypeptide (NTCP).
Poorly characterised. Genome taken to nucleus.
HBV: formation of cccDNA
Relaxed circular DNA converted in nucleus by
Completion of + strand
Removal of 5' terminal structures
Ligation of strands.
Covalently closed circular DNA - HBV, made after entry.
HBV transcription products
3 subgenomic RNAs, 1 pregenomic RNA, 1 preC RNA, possibly an alternatively spliced RNA.
All are translated.
ε stem loop - HBV
Binding initiates packaging and replication.
HBV: replication of genome - priming domain.
TP domain N terminal hydroxyl group of tyrosine = substrate for phosphodiester linkage with dGMP then 4 nt from the 5' bulge are copied as the primer.
HBV: packaging of genome - initial recognition.
Of ε stem loop by polymerase. Translation and packaging are competitive.