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RUSVM Virology Spring17 > Retroviridae > Flashcards

Retroviridae Flashcards

1
Q

What do retroviruses cause?

A

immunosuppression, immune deficiency, cancer

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2
Q

What do all retroviruses need to replicate?

A

Reverse transcriptase

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3
Q

What three scientist discovered the importance of reverse transcriptase in retroviruses?

A

Baltimore, Dubelco, Temin

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4
Q

Reverse transcriptase is a

A

RNA dependent DNA polymerase (found in the virion of all retroviruses)

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5
Q

T/F: Retroviruses are enveloped

A

TRUE

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6
Q

T/F: Retroviruses have a triploid genome

A

FALSE.

Retroviruses have a DIPLOID genome: two single stranded copies of positive sense RNA

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7
Q

T/F: Since retroviruses have positive sense RNA, they directly synthesize proteins

A

FALSE.

Positive sense RNA is used as a template for DNA –> then makes RNA –> protein synthesis

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8
Q

What enzyme allows retroviruses integrate into the host cell genome?

A

INTEGRASE

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9
Q

What shape are retroviruses?

A

Spherical

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10
Q

T/F: Retroviruses are NOT easily inactivated by lipid solvents or heating.

A

FALSE

Easily inactivated by these due to envelope

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11
Q

T/F: Retroviruses are resistant to UV and X-rays

A

TRUE

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12
Q

What are the 4 most important genes retroviruses have, and what do they encode for?

A

gag - encodes for core proteins: capsid, nucleocapsid, matrix
pol - encodes for reverse transcriptase & integrase
env - encodes for surface and transmembrane proteins
pro - encodes for protease

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13
Q

What are the two subfamilies of retroviridae?

A

Supumaretrovirinae

Orthoretrovirinae

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14
Q

What are the genera of the subfamily Orthoretrovirinae?

A 
alpharetrovirus
betaretrovirus
gammaretrovirus
deltaretrovirus
epsilonretrovirus
lentiretrovirus
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15
Q

Which genera of the Orthoretrovirinae subfamily are simple retroviruses?
What is a simple retrovirus?

A

Alpha, beta, gamma
Simple retroviruses have only the core retrovirus genes: gag, pol, pro, env
They are BOTH Endogenous and Exogenous

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16
Q

To which genus does Mouse Mammary Tumor Virus (MMTV) belong?
What is the unique gene it encodes for?
What is the significance of this virus?

A

MMTV is a betaretrovirus. It is often and most commonly used as an experimental virus model. It encodes for the sag gene - super antigen.
Important for research

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17
Q

What does it mean if a virus is Exogenous?

A

It can be transmitted HORIZONTALLY.

rarely in-utero or germline

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18
Q

What does it mean if a virus is Endogenous?

A

The virus is included within the host genome.

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19
Q

What are some alpharetroviruses?

A

Avian leucosis virus
Avian Sarcoma virus
Avian myeloblastosis virus
Rous sarcoma virus

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20
Q

What are some gammaretroviruses?

A

Feline Leukemia virus
Feline sarcoma virus
Avian reticuloendotheliosis virus

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21
Q

Examples of deltaretroviruses?

A

Human T-lymphotropic virus (HTLV)

Bovine leukemia virus

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22
Q

What genus does Walleye dermal sarcoma virus belong to? Who does it infect?

A

Epsilonretrovirus

Fish

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23
Q

HIV is what kind of virus?

A

Lentivirus

Other viruses in the genus: Caprine arthritis-encephalitis virus and Meadi-visna virus

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24
Q

T/F: Epsilonretroviruses are endogenous only

A

TRUE

In fish and reptiles

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25
Q

T/F: Deltaretroviruses are endogenous only

A

FALSE:

Exogenous only

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26
Q

Are lentiretroviruses exogenous, endogenous, or both?

A

Exogenous

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27
Q

What is required for a retrovirus to enter a host cell?

A

Cell surface molecule receptor + envelope proteins on the virion surface
(Retrovirus cell receptors)
Each genus has a specific receptor(s)

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28
Q

When a retrovirus is actively lysing host cells, what stage of disease is present?

A

Acute disease

29
Q

Insertion and or mutation through virus integration is describing what stage of disease?

A

Chronic

30
Q

The process by which a retrovirus acquires a cellular oncogene and modifies it into a viral oncogene is what?

A

ONCOGENESIS

31
Q

What two specific proteins does of FeLV env gene encode for?

A

gp70 - surface protein

p15E - transmembrane protein **BLOCKS T CELL reactivity

32
Q

What specific protein does the FeLV gag gene encode for?

What is its importance?

A

p27 - Many diagnostic tests are based on this protein, including ELISA

33
Q

T/F: FeLV survives well in the environment

A

FALSE

Does not survive well outside of the host. It is easily killed by disinfectants, soap, heating, and drying

34
Q

What is the % prevalence of FeLV in a single cat house hold? Multi-cat house hold?

A

Single cat home - 1%

Multi-cat home - 20%

35
Q

What cats spread FeLV and how?

A

Cats with viremia are the source of infection via: saliva, nasal secretions, feces, and milk
Mutual grooming and cat bites are most common modes of transmission

36
Q

What factors will increase a cats potential of FeLV infection?

A

young age
high population density
poor hygiene

37
Q

What are the two versions of the feline leukemia virus?

A 
Endogenous FeLV (enFeLV)
RD114 virus
38
Q

What are the different Subtypes of FeLV

A

Subtype A, B, C, T

39
Q

What occurs when a pregnant cat is FeLV positive?

A

Abortion
still birth
or viremic kittens are born (carriers)

40
Q

What is the progression of FeLV? (Where does infection begin and spread)

A

Infection typically begins in the oral or pharyngeal tissue then progresses to the lymphoid tissue.
The virus will spread to peripheral tissue via Monocytes and lymphocytes
Viremia occurs within a few weeks - months

41
Q

Where does the FeLV virus have a tropism for?

A

T-lymphocytes and lymphoid tissue

42
Q

What receptors does the FeLV virus use to attack T-lymphocytes?

A

Pit1 (phosphorus transportation protein 1)

FeLIX (FeLV infectivity X-essory protein)

43
Q

What is the cellular consequence of FeLV?

A

Decrease in CD4+Tcells = immunosuppression = highly susceptible to secondary infections
Wasting syndrome and atrophy of the thymus due to recurrent infections

44
Q

T/F: When a patient has FeLV, they can fight off other infections with their cellular immunity

A

FALSE

FeLV ruins the cellular immune response

45
Q

What is the GOLD STANDARD Dx test for FeLV?

A

Isolation of virus from cell culture is the BEST diagnostic (but it can be $$$$$ and not all labs perform this test)
ELISA and IFA are good dx
Real time PCR and Reverse transcriptase PCR (DNA confirms virus, RNA confirms live/active infection)

46
Q

Is the FeLV vaccine 100% effective?

A

NO

47
Q

T/F: You should recommend euthanasia if a cat tests positive for FeLV

A

FALSE
These cats can live a long life. They should be kept INDOOR ONLY to prevent further spread of the virus and secondary infections. These cats should be in a single cat home.

48
Q

What is the most common mode of FIV transmission?

A

DEEP BITE WOUNDS

49
Q

What age group is most susceptible to FIV infections?

A

ALL AGES

Outdoor cats and Feral cats are the most susceptible

50
Q

What doctors discovered the FIV infection at UC Davis in 1986?

A

Yamato and Pederson

51
Q

What percentage of cats are FIV positive in the United States?

A

25%

52
Q

What genus is FIV in?

A

Lentivirus

53
Q

What is the best dx test for FIV?

A

ELISA

54
Q

What clinical signs may you seen in a cat with FIV?

A 
Persistent fever and DHR
Decreased appetite
weight loss
gingivitis and stomatitis
recurrent skin infections, UTI, URIs

Sometimes cancer and blood dz

CNS signs = terminal phase

55
Q

T/F: there is treatment to eliminate FIV

A 
FALSE
There is no tx to eliminate FIV - can only tx symptomatically
AB for secondary infections
Appetite stimulants
Corticosteroids
Immune modulators etc
56
Q

T/F: A cat that is vaccinated for FIV, will always test positive in the future

A

TRUE

They will always be FIV antibody positive

57
Q

What are the two types exogenous avian retroviruses?

A

Replication Competent: usually non pathogenic in most chickens

Replication Defective: virus goes immediately into DNA, acquires viral oncogene(s) and causes malignant tumors

58
Q

What differs in the pathogenicity in chickens who get an avian retrovirus that is replication defective via horizontal transmission or via vertical transmission?

A

Horizontal: chickens are usually infected @ 5 days old, will have transient viremia and are unlikely to develop leukemia

Vertical: congenital or genetic infections - persistent viremia, tends to progress to leukemia

59
Q

T/F: Chickens with lymphoid leukosis will produce large amounts of IgM

A

TRUE

60
Q

T/F: Lymphoid leukosis is the most common form found in chickens 4-30wks of age

A

TRUE

61
Q

If you run a Coggins test, what are you trying to diagnose and who is your patient?

A

Equine Infectious Anemia - Horse of course ;)

62
Q

Where does equine infectious anemia replicate?

A

Infects monocytes - then replicates in macrophages

63
Q

What kind of hypersensitivity is associated with equine infectious anemia?

A

Type II hypersensitivity

think blood!

64
Q

What are some clinical signs of equine infectious anemia?

A

Anemia and Thrombopenia = petechial, edema, lethargy, fever, weight loss, splenomegaly, depression

65
Q

T/F: Flies can transmit equine infections anemia

A

TRUE
When a fly is interrupted in feeding - it is more likely to bite again right away. This is when virus transmission is most likely

66
Q

T/F: A horse with EIA will always be symptomatic

A

FALSE

there are asymptomatic carriers

67
Q

T/F: Horses can pass EIA to their foals via milk and colostrum

A

TRUE
MOT: blood - via insects or instruments
Venereal, milk, colostrum

68
Q

What avian diseases are caused by retroviruses?

A

lymphoid leukosis
osteoporosis “Thick leg syndrome”
Eythroblastosis

RUSVM Virology Spring17 (23 decks)

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