HBV Flashcards Preview

ZZPathology undergraduate year 3, first term. > HBV > Flashcards

Flashcards in HBV Deck (21):
1

How many people have chronic HBV infection?

300-400 million have chronic infection.

2

HBV genome form in virus

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

3

HBV RNA dep DNA pol functions.

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

4

Acute HBV infection

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

5

Studying HBV

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

6

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.

7

HBV Dane particle

Infectious unit, double shelled.

8

HBV Dane particle contents

HBV surface antigen, core and polymerase linked to genome.

9

HBV Dane particle HbsAg forms

equimolar amounts

10

Types of HBV particles

filaments and spheres are immunological decoys.

11

HBV genome 5' ends.

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

12

4 ORFs of HBV genome.

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

13

HBV binding

binds sodium taurocholate cotransporting polypeptide (NTCP).

14

HBV entry

Poorly characterised. Genome taken to nucleus.

15

HBV: formation of cccDNA

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

16

cccDNA

Covalently closed circular DNA - HBV, made after entry.

17

HBV transcription products

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

18

ε stem loop - HBV

Binding initiates packaging and replication.

19

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.

20

HBV: packaging of genome - initial recognition.

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

21

HBV: replication of genome steps

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