Lecture 7 2/7/24 Flashcards

1
Q

What are the two main ways of diagnosing an infectious disease?

A

-detection of agent or its components
-detection of antibodies elicited by an agent

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2
Q

What is sensitivity?

A

proportion of patients with the disease that test positive; true positives

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3
Q

What is specificity?

A

proportion of patients without the disease that test negative; true negatives

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4
Q

What is positive predictive value?

A

proportion of patients testing positive that have the disease

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5
Q

What is the negative predictive value?

A

proportion of patients testing negative that do not have the disease

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6
Q

What is robustness?

A

test’s capacity to be unaffected by minor variations in test conditions

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7
Q

What are the characteristics of spIN?

A

-if a test is highly SPECIFIC, trust the POS result
-used to rule a disease IN

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8
Q

What are the characteristics of snOUT?

A

if a test is highly SENSITIVE, trust the NEG result
-used to rule a disease OUT

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9
Q

Which type of test is good for screening?

A

sensitive

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10
Q

Which type of test is good for confirmation?

A

specific

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11
Q

What are the important factors involved in sampling?

A

-location specimen is collected from
-timing of collection
-proper transport/storage

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12
Q

What are some examples of send-out tests?

A

-PCR
-sequencing
-FA
-serum neutralization
-virus isolation/ID
-agar gel immunodiffusion

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13
Q

What are examples of send-out or in-house tests?

A

virology and serology testing

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14
Q

What is a direct test?

A

test that looks for the virus directly by identifying protein, nucleic acid, or live virus

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15
Q

What is an indirect test?

A

test that looks for the virus indirectly by identifying antibody responses

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16
Q

What are the characteristics of virus morphology?

A

-done with electron microscopy
-can provide overall size and shape

17
Q

What are the characteristics of virus isolation?

A

-uses primary or continuous cell lines in tissue culture
-need to be aware of how virus might grow in different cell lines and how to visualize the different patterns

18
Q

What are the characteristics of viral nucleic acid detection?

A

-always looking for viral presence
-high sensitivity, with ability to detect past infections
-often done via PCR

19
Q

What are the characteristics of viral enzymatic activity tests?

A

-looking for activity of viral enzymes
-often done at regulated labs only
-example is hemagglutination assay

20
Q

What are the characteristics of a hemagglutination assay?

A

-done with influenza
-hemagglutinin proteins on viral surface bind sialic acid
-RBCs are loaded with sialic acid, thus can titrate out virus and let it react with blood

21
Q

What is the main thing to know about a hemagglutination inhibition assay?

A

example of indirect test

22
Q

What are the characteristics of immunostaining?

A

-less sensitive than PCR
-indicator that pathogen is present/active within host
-fix antibodies tagged with fluorophore or enzyme to specimen

23
Q

How does direct vs indirect immunostaining work?

A

direct: antibody already conjugated to antigen for easy detection
indirect: secondary conjugated detection antibody that reacts with host antibody is needed

24
Q

What is a direct ELISA?

A

-wells are coated with patient sample, which acts as antigen
-primary antibody with substrate added for detection of viral antigen

25
Q

What is an indirect ELISA?

A

-wells coated with antigen
-antibody from patient serum added with a secondary conjugated antibody for detection of patient antibodies

26
Q

What type of ELISA is a SANDWICH ELISA?

A

direct ELISA

27
Q

Which type of ELISA can be either indirect or direct?

A

competitive ELISA

28
Q

What info can be gathered from an ELISA?

A

-roughly quantified levels
-can tell whether Ab response is effective/protective
-can discern between IgM and IgG

29
Q

Why are in-house ELISAs more simple?

A

give a yes/no or +/- result instead of a range that must be interpreted

30
Q

On a canine 4DX snap test, which disease is tested based on antigen?

A

heartworm

31
Q

On a feline FIV/FeLV snap test, which diseases are tested based on antigen?

A

-FeLV
-heartworm