HBV

Question 1

How many people have chronic HBV infection?

Answer 1

300-400 million have chronic infection.

Question 2

HBV genome form in virus

Answer 2

3.2 Kb of partial dsDNA. -ive strand complete, but with nick. +ive strand incomplete.

Question 3

HBV RNA dep DNA pol functions.

Answer 3

Priming, reverse transcription/DNA synthesis and RNase H activity.

Question 4

Acute HBV infection

Answer 4

30% of infections show this. Lasts 1-3 months, with chronic infections in 1% of cases.

Question 5

Studying HBV

Answer 5

Does not replicate efficiently in cell cultures.Some replication seen in primary cells.
Model systems appear invaluable.

Question 6

Model systems for HBV

Answer 6

Each has a narrow host range. Good model systems include the woodchuck, the ground squirrel, the pekin duck, and the heron hepadnaviruses.

Question 7

HBV Dane particle

Answer 7

Infectious unit, double shelled.

Question 8

HBV Dane particle contents

Answer 8

HBV surface antigen, core and polymerase linked to genome.

Question 9

HBV Dane particle HbsAg forms

Answer 9

equimolar amounts

Question 10

Types of HBV particles

Answer 10

filaments and spheres are immunological decoys.

Question 11

HBV genome 5’ ends.

Answer 11

Both have 11 nt direct repeats.
-ive strand has 5’ end terminal protein.
+ive strand has short RNA oligonucleotide.

Question 12

4 ORFs of HBV genome.

Answer 12

S - surface antigen
P - polymerase
X - multifunctional protein
C - core.

Question 13

HBV binding

Answer 13

binds sodium taurocholate cotransporting polypeptide (NTCP).

Question 14

HBV entry

Answer 14

Poorly characterised. Genome taken to nucleus.

Question 15

HBV: formation of cccDNA

Answer 15

Relaxed circular DNA converted in nucleus by
Completion of + strand
Removal of 5’ terminal structures
Ligation of strands.

Question 16

cccDNA

Answer 16

Covalently closed circular DNA - HBV, made after entry.

Question 17

HBV transcription products

Answer 17

3 subgenomic RNAs, 1 pregenomic RNA, 1 preC RNA, possibly an alternatively spliced RNA.
All are translated.

Question 18

ε stem loop - HBV

Answer 18

Binding initiates packaging and replication.

Question 19

HBV: replication of genome - priming domain.

Answer 19

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.

Question 20

HBV: packaging of genome - initial recognition.

Answer 20

Of ε stem loop by polymerase. Translation and packaging are competitive.

Question 21

HBV: replication of genome steps

Answer 21

Priming,
first primer shift,
make -ive strand while RNase H degrades template except 5’ end.
second primer shift to make positive strand.