LECTURE #5-Retroviruses AIDS tumor viruses

Question 1

What is specific of Retrovirus?

Answer 1

1. Unique replication cycle (reverse trans.)
2. ubiquitous in vertebrae
3. large divers group

Question 2

Can Retrovirus cause serious disease?

Answer 2

Yes. Even cancer. Many are benign causing causing little or no impact on host cell or host animal.

Question 3

What are the subfamilies of retrovirus?

Answer 3

Orthoretrovirinae and Spumavirinae

Question 4

What genus is found within the subfamily orthoretrovirinae?

Answer 4

1. Alpharetrovirus
2. Betaretrovirus (think mouse)
3. Gammaretrovirus
4. Deltalretrovirus (think Human T-cell leuk.)
5. Lentivirus (think HIV)

Question 5

What genus is found within the subfamily spumavirinae?

Answer 5

Spumavirus

Question 6

What are some examples of Alpharetrovirus?

Answer 6

1. ASLV - Avian leucosis sarcoma virus (ASLV)

2. RSV – Rous Sarcoma virus (RSV)

Question 7

What are examples of Betaretrovirus?

Answer 7

Mouse mammary tumor virus (MMTV)

Question 8

What are examples of Gammaretrovirus?

Answer 8

Murine Leukemia virus (MLV)

G for guns & M for Marines

Question 9

Examples of Deltaretrovirus?

Answer 9

HTLV1
HTLV2
HTLV5

Question 10

Examples of Lentivirus?

Answer 10

HIV 1, HIV 2

Question 11

What are examples of Spumavirus?

Answer 11

Simian foamy virus (SFV)

Question 12

What are specifics of spumavirus ?

Answer 12

Do not cause human disease and make a “foamy” structure inside the cell

Question 13

What is the genome of the retrovirus?

Answer 13

(+)ssRNA – diploid , identical copies

Question 14

Virion of retrovirus?

Answer 14

Enveloped

Question 15

What are the proteins found in Retrovirus?

Answer 15

1. Reverse Transcriptase RNA –> DNA
   DNA –> DNA
2. Protease
3. integrase

Question 16

How was Retrovirus characterized in the past?

Answer 16

By nucleocapsid structure and location in the particle.

1. Type A: shell and hollow center, immature particles
2. Type B: circular NC , eccentric location
3. Type C: circular NC, central location
4. Type D: cylindrical NC, central location

Question 17

How is retrovirus characterized now?

Answer 17

by the genome contents to classify retroviruses as simple or complex.

Question 18

What are specifics about a simple retrovirus?

Answer 18

Only encodes for gag, pro, pol, and env genes

Question 19

What are specifics about complex retrovirus?

Answer 19

Include those from simple retrovirus plus other genes

Question 20

What is unique to the retrovirus replication system?

Answer 20

1. Uses reverse transcription from RNA to DNA or DNA to DNA
2. Integration into host DNA
3. Slow progression of disease

Question 21

What are the steps involve in retrovirus replication?

Answer 21

Attachment
Entry
Reverse transcription (ssRNA genome to dsDNA) 
Integration (Virus dsDNA into host making provirus) 
Transcription from provirus 
Translation
Assembly 
Release
Maturation-protease activity

Question 22

How does reverse transcription occur in retrovirus?

Answer 22

1. Initiated once nucleocapsid is in cytoplasm, need higher levels of NTPs present (low NTP levels prevents reverse transcription)
2. Occurs within a large complex similar to nucleocapsid,
3. Infection cannot progress if reverse transcription does not occur