Retroviruses

Question 1

What important enzyme is found in all retroviruses?

Answer 1

reverse transcriptase, RNA-dependent DNA polymerase

Question 2

genome of retroviruses

Answer 2

two copies of ssRNA (+)

Question 3

Which enzyme is responsible for integrating the retrovirus genome into the host genome?

Answer 3

integrase

Question 4

two subfamiles of retroviridae

Answer 4

orthoretrovirinae and spumaretrovirinae

Question 5

T/F Type B retroviruses have a round centrally positioned inner core

Answer 5

F: eccentrically positioned

Question 6

T/F retro virions are resistant to UV or X rays

Answer 6

T

Question 7

What does the gag gene encode

Answer 7

capsid, nucleocapsid, matrix

Question 8

What does pol encode?

Answer 8

RT and IN

Question 9

What does env gene encode?

Answer 9

surface and transmembrane envelope proteins

Question 10

What does the pro gene encode?

Answer 10

protease

Question 11

What is the role of Nef protein?

Answer 11

essential for replication in target hosts; may downregulate CD4 or alter activation status of target cells

Question 12

What type of morphology do alpharetroviruses have?

Answer 12

Type C: concentric core

Question 13

What virus represents alpharetroviruses?

Answer 13

avian leucosis and sarcoma virus (ALSV)

Question 14

T/F exogenous retroviruses are those viruses included in the genome of most animals

Answer 14

F: endogenous

Question 15

T/F exogenous retroviruses are transmitted vertically

Answer 15

F : horizontally

Question 16

What morphology are betaretroviruses?

Answer 16

type B (eccentric core) or D (cylindrical core)

Question 17

What is an important betaretrovirus?

Answer 17

mouse mammary tumor virus (MMTV)

Question 18

What type of morphology do gammaretroviruses have?

Answer 18

C type

Question 19

Important gammaretrovirus?

Answer 19

FLV

Question 20

Morphology of deltaretroviruses?

Answer 20

type C

Question 21

example of a deltaretrovirus?

Answer 21

bovine leukemia virus

Question 22

Which retro genus has rex and tax regulatory genes?

Answer 22

deltaretroviruses -> control synthesis and processing of viral RNA

Question 23

Are there any known endogenous deltaretroviruses?

Answer 23

no

Question 24

What is an example of an epsilonretrovirus?

Answer 24

Walleye dermal sarcoma virus

Question 25

Important lentiviruses?

Answer 25

HIV, caprine arthritis-encephalitis virus, visna virus

Question 26

Important spumavirus?

Answer 26

human foamy virus

Question 27

receptors for retroviruses

Answer 27

alpha: membrane anchored glycoprotein beta: transferrin receptor tfr-1 gamma: GLVR1 or FeLIX delta: AP-3 complex lenti: CD4

Question 28

Where does uncoating occur?

Answer 28

cytoplasm

Question 29

Where does integration occur?

Answer 29

nucleus

Question 30

Which end of virla dsDNA is processed by IN?

Answer 30

3'

Question 31

Is integration site specific?

Answer 31

no, but transcriptionally active preferred

Question 32

When is viral DNA called a provirus?

Answer 32

after integration into the host cell chromosome has completed

Question 33

What happens to produced viral RNA?

Answer 33

spliced and transported to cytoplasm

Question 34

What are the two pools of viral mRNA in cytoplasm of infected cell?

Answer 34

full length : packaged into virions as viral RAN | spliced: express structural proteins (gag, pol, env)

Question 35

How are virions released?

Answer 35

budding from the cell membrane

Question 36

Which genus causes cell death?

Answer 36

lentivirus -> formation of syncytium and apoptosis

Question 37

What is necessary for acute transformation?

Answer 37

v-onc

Question 38

How do retroviruses cause chronic transformation?

Answer 38

intertion/mutation through random integration into genome of host

Question 39

Two forms of endogenous gammaretroviruses

Answer 39

enFeLV nad RD114 virus

Question 40

T/F prevalence of FeLV in individually kept cats is high

Answer 40

false 1%

Question 41

Where is FeLV shed in infected cats?

Answer 41

saliva, nasal secretions, feces, milk

Question 42

How is FeLV transmitted?

Answer 42

bites and mutual grooming

Question 43

T/F aged cats become resistant to FeLV infection

Answer 43

T

Question 44

What is the main determinant of pathogenicity in FeLV?

Answer 44

SU protein

Question 45

What tissue does FeLV have tropism to?

Answer 45

lymphoid tissue

Question 46

What is the effect of FeLV on T cells?

Answer 46

reduced the number of CD4 cells

Question 47

T/F Cats with FeLV have normal IgM levels

Answer 47

F: reduced IgM levels but normal IgG levels

Question 48

symptoms of FeLV

Answer 48

immunosuppression, anemia, lymphoma and leukemia

Question 49

Diagnosis of FeLV?

Answer 49

virus isolation in cell culture if the ultimate criterion (also p27 ELISA)

Question 50

What causes FIV?

Answer 50

lentivirus

Question 51

Why are lentiviruses called slow viruses?

Answer 51

long incubation period (up to 6 years)

Question 52

In what cells does FIV replicate?

Answer 52

CD4 mostly, also B cells and macs

Question 53

How is FIV transmitted?

Answer 53

deep bite wounds and scratches

Question 54

Can FIV be transmitted from mother to kittens during passage through birth canal?

Answer 54

yes occasionally

Question 55

clinical signs of FIV

Answer 55

poor coat, persistent fever, gingivitis, lethargy, upper resp infections

Question 56

treatment for FIV?

Answer 56

treated symptomatically, can't eliminate the virus

Question 57

T/F If a cat has antibodies for FIV, it has the virus.

Answer 57

False - the vaccine will cause cats to be FIV antibody positive