Retroviruses, AIDS & Tumor Viruses - Middleton

Question 1

_______ are a large and diverse group of viruses.

Answer 1

Retroviruses

Question 2

______ do not cause human disease, but make “foamy” structures inside the cell.

Answer 2

Spumaviruses

Question 3

What are the 2 subfamiles of retroviruses?

Answer 3

• Orthoretroviridae

- Spumaviridae

Question 4

What is the genome for retroviruses?

Answer 4

(-)ssRNA

Question 5

_______ is used to classify retroviruses as simple or complex.

Answer 5

Genome contents ( simple retroviruses only encode the Gag, Pro, Pol and Env genes)

Question 6

Describe the UNIQUE replication process of Retroviruses!

Answer 6

• Attachment
• Entry
• REVERSE TRANSCRIPTION (ssRNA genome –> dsDNA)
• INTEGRATION (virus sDNA into host making provirus)
• Transcription
• Translation
• Assembly
• Release
• Maturation = protease activity

Question 7

What is the defining feature of retroviruses?

Answer 7

Reverse Transcription

• it initiates once nucleocapsid is in cytoplasm
• Needs higher levels of NTP’s present
• Low NTP levels prevent reverse transcription
• Infection cannot progress if reverse transcription does not occur.

Question 8

True or false, Integration of retrovirus into the DNA is permanent?

Answer 8

TRUE! Once it is there, no mechanism can remove it.

Question 9

If integrated into germ-line, then provirus is inherited and called ________.

Answer 9

Endogenous

Question 10

Integration of Retrovirus may disrupt the host genes and cause ________.

Answer 10

Cancer

Question 11

True or false, Many defective viruses are made during the replication of retroviruses?

Answer 11

True, Defective viruses are missing at least one of gag, pol or env.

Question 12

True or false, almost all retrovirus infections are serious?

Answer 12

False, most are benign

Question 13

True or false, Retroviruses are usually not cytopathic?

Answer 13

True

Question 14

What are the 3 retroviruses that can cause significant disease?

Answer 14

• Slow retroviruses = (Leukemia viruses) eventually result in tumorigenesis.
• Cytopathic retroviruses = minor group that cause tissue damage directly.
• Acute retroviruses = Induce rapid tumor formation.

Question 15

What are the four distinct types of Human T-Cell Leukemia Virus (HTLV) and which one is most prevalent in humans?

Answer 15

• HTLV 1, 2, 3 & 4

* HTLV-1 is most often associated with humans.

Question 16

HTLV-1 Transmission?

Answer 16

• Mother to child (breastfeeding)
• Sharing needles
• Blood transfusions
• Sexual Transmissions (Less efficient)

Question 17

What is the latent period for HTLV-1?

Answer 17

30-50 years

Question 18

What are the symptoms of HTLV-1 Disease?

Answer 18

Typically onset 3 years after infection

• bladder control issues
• back and leg pain
• men suffer ED….

Question 19

What specifically does HTLV-1 Infect?

Answer 19

Memory T cells

Question 20

HTLV-1 Prevention and treatment?

Answer 20

• Don’t breastfeed if positive!
• Screening in blood products
• Treatment is specific to the disease
• ATLL treats lymphoma/Leukemia with chemotherapy regardless of HTLV infection.
• HAM/TSP = corticosteroids, interferon yield temporary relief from symptoms.

Question 21

HIV Transmission?

Answer 21

• # 1 is sexual transmission
• Parenteral (transfusion95% & needle sharing1:150)
• Mother to infant 1:4

Question 22

What is the latent period for HIV?

Answer 22

6-24 months

Question 23

Where does HIV infection begin and what does the virus target?

Answer 23

• Begins in blood, bodily fluid to mucosal surface or blood.
• Targets memory T-cells
• intial Acute infection usually 2 weeks after infection

Question 24

What are some common opportunistic infections associated with HIV?

Answer 24

• Candida
• Coccidioidomycosis
• Cryptococcus
• Cytomegalovirus
• Kaposi sarcoma
• Tuberculosis
• Toxoplasmosis
• Wasting due to HIV infection

Question 25

HIV prevention and Treatment?

Answer 25

• Sex behavior and protection
• Blood screening
• NO vaccine available
• Antiviral treatments (AZT, NNRTI, HAART)

Question 26

HIV Genome & Virion?

Answer 26

Genome = diploid (+)ssRNA
Virion = Enveloped!

Question 27

True or false, HIV is a significant cause of certain types of cancer?

Answer 27

True!