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Diagnostics Final > Virology > Flashcards

Virology Flashcards

1
Q

What are the two major ways we can detect viruses?

A

Host antibodies

Antigen

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2
Q

When testing for antigens in a sample, what specifically might we be looking for?

A

Viral proteins

Nucleic acids

Live virus

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3
Q

ELISAs, lateral flow assay, agar gel immunodeficiency are examples of….

A

Antibody detection tests

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4
Q

In very simple words, how does an antibody detection test work?

A

Test has antigen

Patient antibodies react with test antigen

Reaction visualized (or quantified - titer)

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5
Q

What is the goal of viral isolation?

A

Grow virus from diagnostic sample and identify

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6
Q

__________ is gold standard for virus detection

A

Viral isolation

Only test to prove viable virus

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7
Q

What other additional things can we use viral isolation for?

A

Cytopathic effects
Electron microscopy
Fluorescent antibody testing
Hemagglutination/hemagglutination inhibition
PCR
Sequencing

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8
Q

What cytopathic effects do we see with pox virus?

A

Swollen cells, cytoplasmic inclusions

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9
Q

What cytopathic effects do we see with herpes virus?

A

Cytoplasmic stranding, nuclear inclusion

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10
Q

Pros to viral isolation

A

Detect living virus

Can detect and identify unknown viruses

Sensitive

Can amplify and collect live virus for research

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11
Q

Cons to viral isolation

A

Requires special cell lines and training

Wait time

$$$

Sensitive to contamination

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12
Q

Capture or sandwich assay are types of ______

A

ELISA

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13
Q

How does fluorescent antibody testing work?

A

Direct method identifies presence of antigen in tissue

Fluorescent labeled antibodies bind target antigens

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14
Q

How does lateral flow assays work?

A

Labeled antibodies or antigen conjugate present on platform
Sample containing antigen or antibody added
Positive samples will bind to either antigen or antibody on plate

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15
Q

Pros to lateral flow assays

A

Quick
Minimal equipment
Less expensive
Some done in clinic

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16
Q

Cons to lateral flow assays

A

Less specific
Risk of false positives
Not as likely to be accepted for regulatory purposes
Cross reactivity

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17
Q

Give an example of a lateral flow assay used in practice

A

Parvo (antigen)

FIV (antibody)

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18
Q

BVD is commonly tested for using an ______

A

ELISA

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19
Q

What is a good example of when FA are used?

A

Rabies

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20
Q

PCR =

A

Polymerase Chain Reaction

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21
Q

What is real-time PCR?

A

Quantifies viral load

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22
Q

What type of PCR do we use for RNA virus detection?

A

Reverse transcriptase PCR

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23
Q

Sequencing is another method of detecting nucleic acids. You can either sequence a ________ or the ________ genome

A

Partial or full

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24
Q

Pros to PCR

A

Fast
Sensitive
Reliable

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25
Q

Cons to PCR

A

No distinction between live vs inactive
Can only detect known viruses
May miss if mutated
Contamination can be an issue

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26
Q

Respiratory, abortion, and enteric panels are examples of

A

PCR testing

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27
Q

T/F: Wooden handles and calcium alginate are preferred materials used for PCR sample collection

A

False - inactivate virus and interfere with PCR

28
Q

What kind of swabs are safe for PCR?

A

Synthetic:
Polyester
Dacron
Nylon
Rayon
Flocked = catch more virus

29
Q

T/F: You should always mix samples for laboratory submission to cut down on shipping costs.

A

False - don’t pool tissues and never mix GI samples with other samples

30
Q

What are some characteristics of a virus?

A

DNA or RNA based
Infect animals, plants, bacteria, fungi
CS often vague
Few treatment options
Often have prevention options

31
Q

Why is viral detection important?

A

Prevent introduction

Target care

Limit spread

32
Q

Lateral flow assays are commonly known as _____ tests in clinic

A

SNAP

33
Q

When using an antibody test, what must you take into account?

A

Lag time from infection

34
Q

T/F: antibody tests are the ideal tests to use in an outbreak

A

False - you will always be behind the infection if you are using antibody tests in an outbreaks d/t the lag time from infection

35
Q

What kind of ELISA am I describing?

Plate with antigen, patient serum added to plate, enzyme binds to antibody if present

A

Direct ELISA

36
Q

How does an indirect ELISA differ from a direct ELISA?

A

Instead of adding just an enzyme to the plate to bind the antibody, you will be adding a secondary antibody that has the enzyme bound to it

37
Q

T/F: when running a competitive ELISA, less of a reaction means more antibody is present

A

True - this is due to the inhibitor antigen that is present on the plate

38
Q

How can you get a titer from an ELISA?

A

Presence of color in the well = positive

If you dilute the sample across multiple wells, the last well with color present is the highest tighter (inverse of dilution)

39
Q

What is agar gel immunodiffusion most commonly used for?

A

Coggins - EIA

40
Q

Explain how an agar gel immunodiffusion test works

A

Antigen in center

Samples and controls around edges

Positives will form a reactive, precipitate line around the center well

41
Q

How does a hemagglutination inhibition test work?

A

Typically, blood will clot if left in a well

Certain viruses bind the surface of the RBC and don’t allow clot formation leading to a flat layer along the well

For inhibition test, we add RBCs, virus, and patient serum to see if the antibodies bind the virus, allowing the RBCs to clot

42
Q

T/F: In a plate agglutination test, patient sample is added to a plate with antigen. If patient is negative, clumps will form.

A

False - clumping indicates presence of antibody in patient sample binding with antigen on plate

43
Q

T/F: Lateral flow assays can be used to identify antigen or antibody in a patient sample. It just depends on what conjugate is on the plate.

A

True

44
Q

What kind of tissue is used for IHC?

A

Fixed

45
Q

What does IHC show?

A

Exposes antigen

46
Q

IHC can be used for…

A

FIP and Marek’s

47
Q

Pros of AGID and HIs

A

Specific
Gold standard for some tests
Often accepted for import/export

48
Q

Cons of AGID and HIs

A

Harder to find
Longer incubation
Labor intensive
Often more expensive

49
Q

Pros to FAs and IHCs

A

Specific
FAs - fast, visualize pathogen location
IHCs - option for fixed tissue, visualize pathogen location

50
Q

Cons to FAs and IHCs

A

Rarely antemortem
Can be expensive
May be species specific
Limited assays

51
Q

Detecting current infection and immunotolerant animals is a benefit of _________ testing

A

Antigen

52
Q

Detecting previous/chronic infection or detecting vaccination that elicits IgG are benefits of ___________ tests

A

Antibody

53
Q

T/F: the lower the CT value, the more pathogen present

A

True

54
Q

Pros to sequencing

A

Large amount of data (great for epidemiology)
ID unknown pathogens
Track mutations

55
Q

Cons to sequencing

A

Expensive
Lots of analysis
Best on pure sample

56
Q

Virus can be cultured using ________ and ________

A

Embryos and special cell lines

57
Q

What are some common cell lines?

A

Embryonic or adult
Kidney
Liver

58
Q

Rounding of cells, syncytia, plaques, vacuoles, and inclusion bodies are all types of _________

A

Cytopathic effects

59
Q

What type of stain is crucial in order to utilize electron microscopy?

A

Heavy metal salts

60
Q

Viral inclusions are usually ___________

A

Pathognomonic

61
Q

T/F: You can rule out the presence of a virus based on lack of inclusion bodies on histopathology

A

False - May only be present in one stage of infection or may not be in the sections taken

62
Q

A client wants to prove the absence of avian influenza virus on their farm following an outbreak. What is the best test to choose?

A

Viral isolation! Only test that shows presence of viable virus

RT-PCR drawback would be detection of inactivated and live virus - may make client wait longer

63
Q

What is the difficulty when trying to diagnose FIP?

A

A lot of tests will test for FCoV, not the mutated virus that causes FIP

64
Q

Does a FCoV negative ELISA mean this cat does not have FIP?

A

No - in late stage FIP, antibodies drop and may not be detected

65
Q

T/F: the most suggestive test for FIP of all available tests is a fecal PCR

A

False - positive PCR on abdominal fluid would be the most suggestive, but still not definitive

Diagnostics Final (4 decks)

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