Diagnostic Virology Flashcards

1
Q

What is a maculopapular rash?

A

Some areas are raised and some areas are flat

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2
Q

What is a dermatomal distribution of a rash indicative of?

A

Shingles

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3
Q

What components of the virus can be used in virus detection?

A

Virus isolation and electron microscopy to visualise the virus itself
Protein components (antigens)
Genetic components (RNA or DNA)
The host response (antibody or cell responses)

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4
Q

What is the main method of virus detection?

A

PCR

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5
Q

What technique is used for antibody detection?

A

Enzyme immunoassay – detects antibodies and antigens

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6
Q

Define sensitivity.

A

Low rate of false negatives

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7
Q

Define specificity.

A

Low rate of false positives

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8
Q

What does quantification of the genomes allow assessment of?

A

Viral load

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9
Q

What is the difference between IgM and IgG in terms of when theirlevels rise following infection?

A

IgM is a marker of RECENT infection

IgG rises later on

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10
Q

What does positive IgG and absent IgM indicate?

A

Past infection or immunisation

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11
Q

What is targeted in the detection of HIV?

A

Antibody and p24 antigen

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12
Q

What other investigations are performed on people who are identified as HIV positive?

A

Typing (HIV 1 or HIV2)

Repeat blood sample and EDTA blood for HIV viral load (for genotyping and baseline resistance testing)

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13
Q

What test is used to confirm a positive IgM result?

A

Antibody avidity testing

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14
Q

Describe how antibody avidity changes in infection.

A

Early on in the infection, avidity is LOW
Then you get maturation of the antibody response so the avidity will increase over a period of 3-6 months
If you have HIGH antibody avidity, then it is unlikely that the infection occurred in the last 3 months

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15
Q

What is immunofluorescence useful for?

A

Direct detection of viral antigens

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16
Q

What is the term given to the method of PCR that allows testing for more than one virus using a single test tube?

A

Multiplex PCR

17
Q

What is sampled when testing for meningitis/encephalitis?

A

CSF

Stools and throat swab (for enterovirus detection) Blood

18
Q

What is sampled when testing for causes of diarrhoea/vomiting?

A

Stool (and vomit)

19
Q

What must happen first before PCR is performed to identify the genome of an RNA virus?

A

The RNA must be reverse transcribed by reverse transcriptase to dsDNA dsDNA is the start point of PCR

20
Q

Describe the process of PCR.

A

The dsDNA is denatured by heating it
The primers then bind to the single stranded DNA and Taq polymerase joins complementary nucleotides to the template strand

21
Q

What are the applications of sequencing viral genomes?

A

Antiviral resistance testing Phylogenetic analysis