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.infection & immunity > Dx tests (based off chart) > Flashcards

Dx tests (based off chart) Flashcards

1
Q

Dx by gross evaluation and histopathology

A

Fixation with 10% neutral buffered formalin
Consult with lab tech
Case history + description on lesions

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2
Q

Inclusion bodies

A

Nuclear or cytoplasmic aggregates of stainable proteins
Sites of viral multiplication (capsid proteins)
Examined with light or EM

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3
Q

Which tests are used for Abs

A

ELISA, WB, HAI, immunodiffusion, neutralization, IgM specific

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4
Q

T/F: Tissue fixation or viruses bound to Abs can mask detection and lower sensitivity of the assay for IF detection

A

TRUE

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5
Q

ELISA

A

Tissues/ serum
Fast
High sensitivity, low specificity (false +)

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6
Q

When do you use ELISA?

A

Target large # of sick animals
Targets Ab and Ag

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7
Q

Advantages of ELISA

A

Rapid (few hours)
15 mins for a single animal
Automated equipment for many

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8
Q

Disadvantages of ELISA

A

Specificity towards altered viral ags

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9
Q

Commercial ELISA kit (SNAP)

A

Detects FeLV (confirmed by IFA) and FIV Ab in blood (confirmed by WB with unvx animals)

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10
Q

What are serological tests used for?

A

Detect prior infection by a virus
Detect immune response to vx
Detection of response to viruses in acute (blood IgM titer) and chronic phases (IgG)
Pair sampling
Distinguishing Abs response as a result of natural infection v. vx

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11
Q

Western Blot (immunoblotting)

A

Serum
Slow and qualitative
Transfer of proteins from gel surface to a special membrane that capture proteins

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12
Q

When do you use WB?

A

Confirmation of Ab test (FIV)

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13
Q

Hemaggluntination test (HAI)

A

Serum
Rapid
Sensitive and specific

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14
Q

When is HAI used?

A

Any virus that agglutinates RBCs ( influenza or parainfluenza)

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15
Q

Immunodiffusion

A

Serum and tissue samples (oldest)
Slow (24-48 hrs)
Specific but not sensitive, use with ELISA

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16
Q

Advantages of immunodiffusion

A

Simple, inexpensive, doesn’t require production of infectious virus

17
Q

Disadvantages of immunodiffusion

A

Qualitative assay (yes/no), lacks sensitivity

18
Q

Neutralization

A

Serum
Slow and expensive
Detects and quantifies virus specific Abs in blood

19
Q

When is neutralization used?

A

Testing efficacy of vx titer
If pet was recently sick
Prevent virus infection of cells by Abs present in blood

20
Q

What is the most common procedure of virus neutralization test

A

Constant virus variable serum method

21
Q

Advantage of virus neutralization test

A

Species independent

22
Q

Disadvantages of virus neutralization test

A

Slow: takes a few weeks to grow a virus
Labor intensive: growing and maintaining cell culture

23
Q

IgM specific

A

Serum
Rapid
Sensitive and specific

24
Q

When is IgM specific used?

A

IgM: acute, less cross reactive with other viruses
IgG: chronic

25
Q

Tests for Ags

A

ImmunoEM (IEM), Immunofluorescent assay (IFA), ELISA and immunoperoxidase

26
Q

ImmunoEM (IEM)

A

Samples from where virus is shed
Tissues, cells, secretions and excretions
Fast but expensive
More sensitive than EM

27
Q

When is IEM used?

A

Dual infections
Low virus concentrations
Non-cultivated viruses

28
Q

Immunofluorescent assay (IFA)

A

Frozen fixed tissue and liquid nitrogen
Fast (3 hrs)
High sensitivity (more specificity than ELISA)

29
Q

Disadvantages of IFA

A

Requires special microscope and cryostat for tissue sectioning of frozen samples
Can’t ID all viruses (enterovirus)

30
Q

Immunoperoxidase (IP)

A

Frozen tissue, has longer shelf-life
Slow >25 hrs
Sensitive and specific

31
Q

Advantages of IP

A

Examined under LM
Duration and stability of signal
Better cellular localization of virus in tissue

32
Q

When is IP used?

A

Better localization of virus (intracytoplasmic or intranuclear)

33
Q

PCR (nucleotide)

A

Fast (2-8 hrs)
High sensitivity and high specificity

34
Q

When is PCR used?

A

Viruses can’t be cultured readily
Non-infectious viruses
Undetectable viruses
Viruses complexed to Abs
Enteroviruses

35
Q

Cytopathic effects

A

Swelling, rounding, shrinking, syncytium formation, clustering, complete destruction of the monolayer

36
Q

Cell cultures

A

When other tests aren’t possible (new pathogen)
Vx manufacturer
If viruses causes disease in a sample of several viruses
Required to examine sublet CPE
Requires confirmatory testing

37
Q

_________ is the most accurate of the quantativative biological assays

A

Plaque assay

38
Q

Plaque assays

A

Cytopathic viruses produce holes in cells monolayer → each virus infectious particle produces a circular visible eye clear zone (plaque= dead cells)

.infection & immunity (12 decks)

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