Chapter 10 Flashcards

1
Q

Samples for virus identification mus be collected ______ if possible.

A

aseptically

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2
Q

Avoid ________ of the area where samples are collected.

A

contamination

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3
Q

What are the four general approaches to diagnostic virology?

A
  1. Detection of viral antigen
  2. Detection of antibody response
  3. Detection of viral nucleic acid
  4. Virus isolation… effect on cells
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4
Q

What is the ideal temperature for proper storage of sample?

A

at 4C or

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5
Q

If you are using dry ice to store a tissue sample what must you make sure to do and why?

A

You must make sure to properly seal the sample because the pH of the sample can decrease in the presence of CO2 (dry ice) if not closed

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6
Q

What is the goal of serological diagnosis of virus infections?

A

detection of IgM or IgG in previously naive animals

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7
Q

What are the 5 most common serological assays?

A

Serum virus neutralizaiton (SVN), ELISA, Agarose gel diffusion, Hemagglutination inhibition, and complement fixation test

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8
Q

What are the steps of the SVN assay for antibody?

A
  1. Serum is serially diluted in 2-fold increments, and same amount of each dilution is added in duplicate to wells in a microtiter plate
  2. Constant amount live virus of known specificity added to each well
  3. Serum/virus mixture incubated specific time
  4. MPs incubated specific # of days and then viewed for presence or absence of virus
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9
Q

What is defined as the endpoint of SVN assays?

A

The last dilution that shows neutralization of the virus is defined as the endpoint

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10
Q

What is defined as the titer of the serum in SVN assays?

A

the titer of the serum is the reciprocal of the endpoint dilution

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11
Q

What are ELISA values reported as?

A

optical density (OD)

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12
Q

The higher the OD, the greater the _____ ______.

A

AB titer

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13
Q

What type of diagnostic test is the Coggins test?

A

The agar gel diffusion test

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14
Q

What type of viruses are hemagglutination inhibition assays used with? Provide two examples.

A

Used with viruses that have proteins that agglutinate rbc’s

ex: Influenza virus, avian paramyxovirus serotype 1

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15
Q

What do hemagglutination inhibition assays detect?

A

Ag-Ab interaction

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16
Q

What is used as an indicator of Ab/Ag interaction in HI assays?

A

the inhibition of hemagglutination

17
Q

What are 3 methods of the diagnosis of virus disease by detecting virus or its components?

A
  1. Virus isolation (VI) and identification
  2. Detecting viral protein/virus particles in tissue, secretions (saliva, tears) or excretions (feces)
  3. Detecting virus nucleic acid by the PCR
18
Q

What samples to collect for detection of virus is dependent on what?

A

the disease

19
Q

What type of cells are used for isolating equine herpesviruses?

A

vero cells

20
Q

What type of cells are used for isolating bovine respiratory viruses?

A

bovine turbinate cells

21
Q

What type of cells are used for isolating unknown viruses?

A

primary cells

22
Q

For the SVN assay, what is used as antigen?

A

supernatant containing unknown virus

23
Q

Results of the SVN when used to ID an unknown virus is expressed as the ____ ____.

A

Neutralization index

24
Q

What is the neutralization index?

A

the difference in log values between end points of control serum and test serums

25
Q

What are three methods that are used to detect virus AG, particles, secretions, and excretions?

A

Immunofluorescence and Immunohistochemistry
Antigen capture ELISA
Electron microscopy

26
Q

What type of tissues is used in immunofluorescence and immunohistochemistry detection?

A

frozen or fixed thin sections of tissue from specific organs, or of fixed cell culture monolayers

27
Q

What are some examples of viruses that are detected by ELISA?

A

FeLV, rotavirus, influenza virus

28
Q

What does PCR stand for?

A

polymerase chain reaction

29
Q

What must be known for in order for identification target sequences and primers in PCR?

A

the genomic nucleotide sequence of a pathogen

30
Q

What are the three steps of the standard PCR?

A
  1. Extraction of nucleic acid from the sample
  2. Amplify target in RNA, ssDNA, or dsDNA viral genomes
  3. Detection and identification of target
31
Q

What are primers and where are they located?

A

short 10-20 nucleotide sequences that flank the 3’ and 5’ ends of the target sequence

32
Q

What are the disadvantages of standard PCR?

A

Time consuming and contamination is easy

33
Q

What are the advantages of realtime PCR?

A

Greater sensitivity, contamination by amplified target reduced, target identity confirmed by amplification as probes used in qPCR are specific for the target, qPCR is quantitative