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Diagnostics Final > Virology > Flashcards

Virology Flashcards

(65 cards)

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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
Cons to PCR
No distinction between live vs inactive Can only detect known viruses May miss if mutated Contamination can be an issue
26
Respiratory, abortion, and enteric panels are examples of
PCR testing
27
T/F: Wooden handles and calcium alginate are preferred materials used for PCR sample collection
False - inactivate virus and interfere with PCR
28
What kind of swabs are safe for PCR?
Synthetic: Polyester Dacron Nylon Rayon Flocked = catch more virus
29
T/F: You should always mix samples for laboratory submission to cut down on shipping costs.
False - don’t pool tissues and never mix GI samples with other samples
30
What are some characteristics of a virus?
DNA or RNA based Infect animals, plants, bacteria, fungi CS often vague Few treatment options Often have prevention options
31
Why is viral detection important?
Prevent introduction Target care Limit spread
32
Lateral flow assays are commonly known as _____ tests in clinic
SNAP
33
When using an antibody test, what must you take into account?
Lag time from infection
34
T/F: antibody tests are the ideal tests to use in an outbreak
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
What kind of ELISA am I describing? Plate with antigen, patient serum added to plate, enzyme binds to antibody if present
Direct ELISA
36
How does an indirect ELISA differ from a direct ELISA?
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
T/F: when running a competitive ELISA, less of a reaction means more antibody is present
True - this is due to the inhibitor antigen that is present on the plate
38
How can you get a titer from an ELISA?
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
What is agar gel immunodiffusion most commonly used for?
Coggins - EIA
40
Explain how an agar gel immunodiffusion test works
Antigen in center Samples and controls around edges Positives will form a reactive, precipitate line around the center well
41
How does a hemagglutination inhibition test work?
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
T/F: In a plate agglutination test, patient sample is added to a plate with antigen. If patient is negative, clumps will form.
False - clumping indicates presence of antibody in patient sample binding with antigen on plate
43
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.
True
44
What kind of tissue is used for IHC?
Fixed
45
What does IHC show?
Exposes antigen
46
IHC can be used for…
FIP and Marek’s
47
Pros of AGID and HIs
Specific Gold standard for some tests Often accepted for import/export
48
Cons of AGID and HIs
Harder to find Longer incubation Labor intensive Often more expensive
49
Pros to FAs and IHCs
Specific FAs - fast, visualize pathogen location IHCs - option for fixed tissue, visualize pathogen location
50
Cons to FAs and IHCs
Rarely antemortem Can be expensive May be species specific Limited assays
51
Detecting current infection and immunotolerant animals is a benefit of _________ testing
Antigen
52
Detecting previous/chronic infection or detecting vaccination that elicits IgG are benefits of ___________ tests
Antibody
53
T/F: the lower the CT value, the more pathogen present
True
54
Pros to sequencing
Large amount of data (great for epidemiology) ID unknown pathogens Track mutations
55
Cons to sequencing
Expensive Lots of analysis Best on pure sample
56
Virus can be cultured using ________ and ________
Embryos and special cell lines
57
What are some common cell lines?
Embryonic or adult Kidney Liver
58
Rounding of cells, syncytia, plaques, vacuoles, and inclusion bodies are all types of _________
Cytopathic effects
59
What type of stain is crucial in order to utilize electron microscopy?
Heavy metal salts
60
Viral inclusions are usually ___________
Pathognomonic
61
T/F: You can rule out the presence of a virus based on lack of inclusion bodies on histopathology
False - May only be present in one stage of infection or may not be in the sections taken
62
A client wants to prove the absence of avian influenza virus on their farm following an outbreak. What is the best test to choose?
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
What is the difficulty when trying to diagnose FIP?
A lot of tests will test for FCoV, not the mutated virus that causes FIP
64
Does a FCoV negative ELISA mean this cat does not have FIP?
No - in late stage FIP, antibodies drop and may not be detected
65
T/F: the most suggestive test for FIP of all available tests is a fecal PCR
False - positive PCR on abdominal fluid would be the most suggestive, but still not definitive

Diagnostics Final (4 decks)

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