Diagnosis of Viral infections Flashcards

1
Q

What is Virus Isolation?

A

Grow virus in lab, Virus needs to have cells to grow.

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2
Q

What are the advantages of virus isolation?

A

Amplified.

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3
Q

What are the disadv of virus isolation?

A

Need to suspect virus, need time, some viruses cannot be cultured.

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4
Q

What is Electron Microscopy? What does it identify about viruses?

A

Uses negative staining under a microscope. Detects virus morphology.

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5
Q

What are the adv of Electron microscopy?

A

Used for viruses that can’t be cultured, identify new virus.

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6
Q

What are the disadv of electron microscopy?

A

Specialised equipment and personell, Low sensitivity.

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7
Q

What is PCR?

A

Viral nucleic acid detected, and can be amplified.

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8
Q

What are the adv of using PCR?

A

Very sensitive, doesn’t require live virus, specific.

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9
Q

What are the disadv of using PCR?

A

Contamination

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10
Q

Outline how an Antigen Elisa is done.

A

Capture antibody used to detect antigen, then enzyme labelled antibody put it. Substrate changes colour if ELA has bound.

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11
Q

Advantages of Antigen Elisa

A

Fast, No live virus required, specific

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12
Q

Disadv of Antigen Elisa

A

No amplification, not specific

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13
Q

What are the three important immunoassays? What do they detect?

A

Immunofluorescence assay, Immunoperoxidase assay, Immunochromotography. All detect antigen.

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14
Q

How is an Immunofluorescence assay carried out?

A

Virus detected using antibody with fluorescent particle attached which binds to antigen.

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15
Q

How is an Immunoperoxidase assay carried out?

A

Elisa on a slide. ELA used to detect antigen, substrate changes colour if it has bound.

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16
Q

How is an Immunochromatography carried out?

A

Labelled antibody added, and then run on chromatography. Antibody at test line will capture antibody will capture antigen if it’s present, labelled antibody then can be identified.

17
Q

What are the adv and disadv of Immunoassays?

A

+ Fast, no live virus, specific

- No amplification, low sensitivity

18
Q

To identify host immune response, how many samples is ideal? When would you take these? What do you test for?

A

2 samples ideal: One when showing clinical signs, and one 2-3 weeks later. Test for IgG.

19
Q

What is a Neutralisation assay? What does it test for?

A

Serum sample should neutralise virus and prevent cell death if there are antibodies present. Tests for host immune response.

20
Q

What is a Haemagglutinin inhibition assay? What does it test?

A

Some viruses agglutinate RBC. If antibody present, the virus cannot agglutinate.

21
Q

What is a positive haemagglutinin inhibition assay?

A

Antibodies present - dot appearance.

22
Q

What is a negative haemagglutinin inhibition assay?

A

Larger dot - no antibodies/

23
Q

What are the adv and disadv of antibody detection?

A

+ Cheap, specific, sensitive.

- Retrospective, negative may mean still in lag phase.