Papillomaviruses And Retrovirus- 10/22/21

Question 1

Papillomavirus genome

Answer 1

Double stranded DNA, circular, 8 kB around 8 proteins

Question 2

Papillomavirus capsid shape

Answer 2

Icosahedral

Question 3

Papillomavirus naked or envelope?

Answer 3

Naked

Question 4

Papillomavirus example

Answer 4

HPV

Question 5

Papillomavirus entry

Answer 5

RME, binds to the heparan sulfate, infect basal cells

Question 6

Control of HPV gene expression

Answer 6

Attached to host DNA, use Nested mRNAS and Alternative splicing

Question 7

HPV E2

Answer 7

Regulates gene expression, expressed first

Question 8

HPV E6

Answer 8

Targets p53 for degradation to prevent apoptosis

Question 9

HPV E7

Answer 9

Sequesters pRB to continue cell cycle (needed to continue dividing)

Question 10

Egress of papilloma virions

Answer 10

Through sloughing off of the skin

Question 11

How HPV causes cancer

Answer 11

Random integration of E6 and E7 into genome, loses regulation all control

Question 12

Retrovirus replication

Answer 12

Replicate through a DNA intermediate (provirus) integrated into the host genome— defining feature of a retrovirus

Question 13

Retrovirus genome

Answer 13

Single stranded RNA plus strand, 7-10 kB, <20 proteins

Question 14

Retrovirus capsid

Answer 14

Pseudoicosahedral (collapsed)

Question 15

Are retroviruses enveloped

Answer 15

Yes

Question 16

Protein encapsulated in retrovirus virion (3)

Answer 16

• Protease
• Reverse transcriptase (RT)
• Inegrase

Question 17

Retrovirus cell entry

Answer 17

Membrane fusion triggered by binding to CD4

Question 18

Retrovirus DNA synthesis

Answer 18

Carried out by viral RT, needed cell tRNA primer, primer “jumps” from one end to another happens within the capsid

Question 19

Retrovirus DNA integration

Answer 19

Carried out by a viral integrase, insertion is largely random, but only occurs at sites of active transcription

Question 20

Genes expressed in genome retrovirus (3)

Answer 20

Gag, pol, env

Question 21

Retrovirus gag

Answer 21

Capsid and matrix

Question 22

Retrovirus pol

Answer 22

Protease, RT, and integrase

Question 23

Retrovirus Env

Answer 23

Envelope glycoprotein

Question 24

Retrovirus multiple protein methods

Answer 24

Polyprotein and alternative splicing

Question 25

Examples of retrovirus

Answer 25

HIV

Question 26

HIV egress

Answer 26

Budding from plasma membrane

Question 27

Mechanisms by which retroviruses can cause cancer (2)

Answer 27

• LTR (promotor) downstream of proto oncogene, constitutive expression
• Retrovirus encoded oncogene