Exam 3 Retrovirology

Question 1

Central dogma

Answer 1

DNA to RNA to protein

Question 2

Retroviruses use a _____ template, which means they violate _____

Answer 2

RNA; Central dogma

Question 3

Retroviruses make ____ from an RNA template

Answer 3

RNA to DNA to RNA to protein

Question 4

Retroviruses use _____ to get from RNA to DNA

Answer 4

Reverse transcription

Question 5

Retroviruses - characterization

Answer 5

• group of enveloped RNA (positive strand) viruses
• unique mode of viral replication

Question 6

Retroviruses use what enzyme for viral replication?

Answer 6

• RNA-dependent DNA polymerase
• Reverse transcriptase

Question 7

Reverse transcriptase is abbreviated as:

Answer 7

RT or RTase

Question 8

Retroviruses enter the cell as a ____ RNA accompanied by ____

Answer 8

Positive strand RNA; RNA enzyme (RT)

Question 9

After DNA is made from RNA template, what happens?

Answer 9

It is integrated into host DNA (provirus)

Question 10

Provirus is located in the:

Answer 10

Nucleus

Question 11

Two classifications of retroviruses (families)

Answer 11

• Oncovirinae (onco-rna-viruses)
• Lentivirinae (Lentiviruses)

Question 12

What virus is a part of the oncovirinae?

Answer 12

HTLV

Question 13

What virus is a part of the lentivirinae?

Answer 13

HIV

Question 14

HTLV stands for:

Answer 14

Human T-lymphotrophic virus

Question 15

HIV stands for:

Answer 15

Human immunodeficiency virus

Question 16

What is the morphology of the HTLV capsid?

Answer 16

C-type (central, spherical)

Question 17

What is the morphology of the HIV capsid?

Answer 17

D-type (central, cone-shaped cylindrical)

Question 18

Characteristics of retroviral infective virion

Answer 18

• Enveloped nucleocapsid
• Two copies of positive strand ssRNA
• Reverse transcriptase (RTase)
• Integrase

Question 19

The retroviral envelope is acquired from _____ and contains _____

Answer 19

Host plasma membrane; viral proteins

Question 20

The retroviral nucleocapsid contains:

Answer 20

• Two identical copies of positive strand (+) ssRNA virus
• Multiple copies of RTase
• Integrase

Question 21

What glycoprotein is found in HTLV envelope?

Answer 21

gp62

Question 22

What glycoprotein is found in HIV envelope?

Answer 22

gp160

Question 23

Components of gp62

Answer 23

gp46 and gp21

Question 24

In the gp62 glycoprotein of HTLV, ____ is for docking and ____ is for fusion

Answer 24

gp46; gp21

Question 25

In the gp160 glycoprotein of HIV, ____ is for docking and ____ is for fusion

Answer 25

gp120; gp41

Question 26

The docking protein on the viral envelope determines ____, and the smaller protein promotes _____

Answer 26

Tropism; fusion

Question 27

What are the three major retrovirus genes?

Answer 27

- GAG - POL - ENV

Question 28

What does the GAG retrovirus gene code for?

Answer 28

Capsid, matrix, and binding proteins

Question 29

What does the POL retrovirus gene code for?

Answer 29

Polymerases, proteases, integrases

Question 30

What does the ENV retrovirus gene code for?

Answer 30

Envelope glycoproteins (ex. gp46)

Question 31

The retrovirus lifecycle includes unique steps such as:

Answer 31

Reverse transcription and integration

Question 32

In HIV, what is the most distal, external portion on the envelope?

Answer 32

gp120

Question 33

gp120 (HIV) binds ____ on the host

Answer 33

CD4 (primary receptor)

Question 34

HIV uses co-receptors such as _____ found on the ____ to get into the T cell

Answer 34

CCR5 and CXCR4; host

Question 35

HTLV gp46 binds ____ along with ____

Answer 35

CD4; co-receptors

Question 36

What are the functions of RTase?

Answer 36

- Reverse transcription from RNA into DNA (forms RNA-DNA hybrid) - Ribonuclease H function (degrades RNA-DNA hybrid) - DNA polymerase function (synthesizes + DNA)

Question 37

Reverse transcriptase error rate

Answer 37

1 error per 2,000 bases (highly error prone)

Question 38

What is a provirus?

Answer 38

Integrated viral genome in host DNA (formed after integrase activity)

Question 39

Retrovirus incubation periods

Answer 39

May be long (months or years for HIV and HTLV)

Question 40

Provirus may remain in ____ until ____ activates cells which may activate the virus

Answer 40

Latency; immune response

Question 41

Transcription factors in immune response

Answer 41

NFkB; also bind LTR (long terminal repeats) | activate HIV or HTLV

Question 42

Retroviruses are released by ____ and may form ____

Answer 42

Budding; syncytia

Question 43

_____ are fused, multi-nucleated cells

Answer 43

Syncytia

Question 44

tax is a transcription factor found in ____

Answer 44

HTLV

Question 45

tat is a transcription factor found in ____

Answer 45

HIV

Question 46

Tax transcription factor is involved with _____ production

Answer 46

IL-2 and IL-2R (autocrine and paracrine)

Question 47

Tax promotes:

Answer 47

Viral replication

Question 48

There are several types of HTLV presentations, such as:

Answer 48

- HTLV-1: **ATL** - HTLV-2: Atypical **hairy cell (cutaneous) leukemia**

Question 49

What is ATL?

Answer 49

Adult acute T-cell lymphocytic leukemia

Question 50

There are several types of HTLV-related oral symptoms, such as:

Answer 50

- Xerostomia - Fissured tongue - Loss of tongue papilla

Question 51

HTLV-1 radiographic findings

Answer 51

- Unusual presentation of **bone invasion** and **osteolysis** - **Raindrop skull**

Question 52

Raindrop skull can be caused by:

Answer 52

- Myeloma - HTLV

Question 53

_____ is the most common form of cutaneous T-cell lymphoma

Answer 53

HTLV-2 hairy cell leukemia

Question 54

For HTLV diagnosis and treatment, ____ is indicated to look for _____ or _____

Answer 54

Serology; leukemia or lymphoma

Question 55

HTLV involves proliferation of ____

Answer 55

T cells