Retrovirus, AIDS, and Tumor Viruses

Question 1

Retrovirus Genome

Answer 1

(+)ssRNA

Question 2

Retrovirus Virion

Answer 2

Enveloped

Question 3

Retrovirus Incubation

Answer 3

Varies

Question 4

Retrovirus Strains

Answer 4

A-Type
B-Type
C-Type
D-Type

Question 5

Retrovirus A-Type

Answer 5

Shell and hollow center

Immature particle

Question 6

Retrovirus B-Type

Answer 6

Circular nucleus

Eccentric location

Question 7

Retrovirus C-type

Answer 7

Circular nucleus

Central location

Question 8

Retrovirus D-Type

Answer 8

Cylindrical nucleus

Central location

Question 9

Retrovirus Replication

Answer 9

As it enters the cell, it undergoes reverse transcription - ssRNA genome becomes dsDNA
The viral dsDNA integrates itself into the host, making it a provirus

Question 10

Reverse Transcription

Answer 10

Defining Feature of Retroviruses
Occurs within a large complex similar to nucleocapsid
Infection cannot progress if reverse transcription does not occur

Question 11

What initiates Reverse Transcription

Answer 11

Initiates once the nucleocapsid is inside the cytoplasm

Question 12

What is necessary for Reverse Transcription to occur?

Answer 12

Need higher levels of NTP

Low levels of NTP prevent reverse trasncriptase

Question 13

What happens to Revers Transcription between genome copies

Answer 13

Silent when the copies are identical

Many different recombinations can occur when different genomes are in the virion

Question 14

What is necessary for Integration of a Retrovirus to occur

Answer 14

The retrovirus must access the nucleus

Question 15

When does a Retrovirus access the nucleus?

Answer 15

During Mitosis

It can infect non-dividing cells, but the mechanism is unknown

Question 16

Integration

Answer 16

3’ end of processing dsDNA atacks the target DNA, creating a nick
Host repairs the nick, but in doing so, integrates the viral DNA
Integration is permanent

Question 17

Endogenous provirus

Answer 17

If a retrovirus is integrated into the germ-line

Question 18

Retrovirus Complications

Answer 18

Integration may disrupt host genes, causing diseases such as cancer

Question 19

Retrovirus Symptoms

Answer 19

Many infections are benign

But they can cause significant disease

Question 20

Slow Retrovirus

Answer 20

Effect is like high-level mutagenesis

Eventually results in tumorigenesis

Question 21

Cytopathic Retrovirus

Answer 21

Minority of Retroviruses carry cytopathic genes

Cause tissue damage directly

Question 22

Actute Transforming Viruses

Answer 22

Induce rapid tumor formation
Carry host genes - mitogenic or antiapoptotic
Often replication defective because host gene replaces an essential gene

Question 23

Human T-Cell Leukemia Virus Genome

Answer 23

(+)ssRNA

Question 24

Human T-Cell Leukemia Virus Virion

Answer 24

Enveloped

Question 25

What are the two diseases of Human T-Cell Leukemia Virus?

Answer 25

Adult T-Cell Lymphoma/Leukemia (ATLL) | HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)

Question 26

Human T-Cell Leukemia Virus Incubation

Answer 26

ATLL - 30-50 years | HAM/TSP - 3 years

Question 27

What are the types of Human T-Cell Leukemia Virus?

Answer 27

Types 1, 2, 3, 4 | Type 1 is the most common in humans

Question 28

Human T-Cell Leukemia Virus Replication

Answer 28

Cytoplasm

Question 29

ATLL Symptoms

Answer 29

Tumors, Immunosuppression

Question 30

HAM/TSP Symptoms

Answer 30

Bladder issues, LL back pain, Leg weakness, ED, and impotence

Question 31

Human T-Cell Leukemia Virus Transmission

Answer 31

Person to person: - Mother-to child via breastfeeding - Sharing needles - Blood transfusions - Sex

Question 32

How does Human T-Cell Leukemia Virus spread in the body?

Answer 32

Via infected cells being in contact with naive cells

Question 33

ATLL

Answer 33

Occurs in 2-4% of cases of HTLV-1 Antigen activation triggers transcription of provirus Virus tax protein and others stimulate cell proliferation Cells become transformed generating tumors

Question 34

HAM/TSP

Answer 34

Occurs in 1-2% of cases Following transfusions Infected T-cells enter the CNS -activates astrocytes and microglial cells -recruit inflammatory cells and cause further tissue damage

Question 35

Human T-Cell Leukemia Virus Prevalence

Answer 35

Millions of people worldwide

Question 36

Human T-Cell Leukemia Virus Prevention

Answer 36

Eliminate breastfeeding for HTLV-1 positive mothers | Increased screening for blood products

Question 37

Human T-Cell Leukemia Virus Treatment

Answer 37

ATLL - treat the leukemia/lymphoma with chemotherapy regardless of HTLV infetions HAM/TSP - corticosteroids, interferon yields temporary relief of symptoms

Question 38

HIV Genome

Answer 38

(+)ssRNA

Question 39

HIV Virion

Answer 39

Enveloped

Question 40

HIV Incubation

Answer 40

HIV - 2 weeks | AIDS - 6 months-25 years

Question 41

HIV Strains

Answer 41

Two main types in humans - Types 1 and 2

Question 42

HIV Replication

Answer 42

In the Cytoplasm

Question 43

HIV immune response inhibition

Answer 43

Targets memory T-cells (CD4+)

Question 44

HIV Symptoms

Answer 44

Immunosuppression | Wasting - weight loss

Question 45

HIV Transmission

Answer 45

Sex Needle sharing Mother to infant

Question 46

HIV Complications

Answer 46

Immunosuppression and AIDS development

Question 47

HIV Prevalence

Answer 47

Worldwide pandemic | Highest impact is in Sub-Saharan Africa

Question 48

HIV Prevention

Answer 48

Sexual behavior and protection | Blood screening

Question 49

HIV Treatment

Answer 49

Antiviral treatments - Nucleoside reverse transcriptase inhibitor - Protease inhibitors - Non-nucleoside RT inhibitor - Highly active antiretroviral therapy