5 Retroviruses, AIDS, Tumors

Question 1

Retroviruses have a unique replication cycle, specifically they:

Answer 1

Use a DNA intermediate even though they are RNA

Question 2

Retrovirus Biology:

1. Virus
2. Genome
3. Virion
4. Replication

Answer 2

1. Retroviridae (Orthoretroviridae, Spumaviridae)
2. (+)ssRNA, diploid-ONLY ONE (identical copies)
3. Enveloped
4. Reverse transcription (ssRNA to dsDNA), integration into host DNA making provirus

Question 3

Reverse transcription needs higher levels of ____. It occurs within a large complex similar to a _____.

Answer 3

NTP

Nucleocapsid

Question 4

Reverse transcription can do many different _____ when different genomes are in the virion

Answer 4

Recombinations

Question 5

T/F: Integration of virus DNA is permanent, no mechanism can remove it.

Answer 5

True

Question 6

If a retrovirus is integrated into the germ-line then provirus is inherited and it is called ______

Answer 6

Endogenous

Question 7

Retroviruses that are not cytopathic, have little impact to cell replication and physiology, are not eliminated but not very problematic

Answer 7

Benign Retrovirus

Question 8

Retroviruses that cause significant disease:

Answer 8

1. Slow Retroviruses (leukemia viruses)- high-level mutagenesis, tumorigenesis
2. Cytopathic Retroviruses- carry cytopathic genes, cause direct tissue damage
3. Acute Transforming Viruses- rapid tumor formation, carry host genes

Question 9

HTLV (Human T-Cell Leukemia Virus):

1. Virus
2. Transmission

Answer 9

1. Deltaretrovirus

2. Person to person (breastfeeding, needles, sexual, blood transfusions); between infected and naive cells

Question 10

HTLV-1 Disease:

1. Symptoms
2. Prevention
3. Treatment

Answer 10

1. Adult T-cell lymphona/leukemia (ATLL), tumors, Associated Mylopathy / Tropical Spastic Paraparesis (HAM/TSP- infected T-cells enter CNS)- bladder probs, erectile dysfunction
2. No breastfeeding, blood screening
3. ATLL- chemotherapy
   HAM/TSP- corticosteroids, interferon for symptom relief

Question 11

HIV (Human Immunodeficiency Virus):

1. Virus
2. Populations most at risk
3. Latent Period

Answer 11

1. Lentivirus
2. Homosexuals, injection drug users, hemophiliacs, transfusion recipients
3. 6 m to 25 yrs

Question 12

HIV Disease:

1. Target
2. Acute infection (2 weeks after infection) indicated by
3. Symptoms
4. Prevention
5. Treatment

Answer 12

1. T-cells (CD4+)
2. Mucocutaneous ulceration, weight loss, GALT (gut associated lymphoid tissue)
3. More opportunistic infections, TB, wasting, candida
4. Sex protection, blood screening
5. No vaccine; antiviral treatments