Diagnostics introduction Flashcards
Molecular diagnostics is a qualitative or quantitative measure of what 2 things?
- DNA or RNA
- Proteins
What does the choice of diagnostic test depend on?
(5 things)
- the type of sample
- clinical question (are you screening or diagnosing – antibody vs antigen)
- availability of test
- intended use
- performance characteristic of test (sensitivity, specificity, PPV, NPV, reliability)
What are 4 DIRECT diagnostic testing methods?
- electron microscopy
- genome identification (PCR)
- antigen detection
- bacterial culture
Why is virus isolation considered an INDIRECT testing method as opposed to a direct method?
virus isolation is looking at the EFFECT of the virus on the cell culture.
what type of diagnostic method is used for antibody detection IgM and IgG?
serology
What 7 tests allow for the detection of ORGANISMS?
- light microscopy
- electron microscopy
- ELISA
- IFA
- IHC
- PCR
- NGS
What diagnostic test is good for detecting organisms that cause diarrhea, such as coronavirus or rotaviruses, even in non-clinical animals.
electron microscopy
What is the biggest downside to virus isolation and is the reason it is not readily performed unless in a state lab with lots of resources?
virus isolation requires cell cultures which is expensive and takes lots of time.
What 3 diagnostic tests detect antigen (protein)?
- ELISA
- Immunofluorescence (IFA)
- Immunohistochemistry (IHA)
What is the key component in ELISA that allows for the color change to occur?
substrate is added and the enzyme converts it into a detectable product. a color change occurs during this process.
____________ uses cell culture or tissue samples. Antibodies have fluorescent tags, so they fluoresce under microscopic light.
immunofluorescent antibody test (IFA)
T/F: IFA tests are extremely sensitive and can detect low viral titers.
false – they require high viral titers.
__________ uses paraffin-embedded tissues mounted on glass slides. The samples are incubated with specific antibodies tagged with a substrate (chromogen) to give a color reaction. This test allows for the detection of antigen IN THE LESION or in specific cells.
immunohistochemistry
What is the most commonly used diagnostic test to diagnose neoplasia?
Immunohistochemistry
Immunohistochemistry is characterized by ________ against tumor markers to detect: cells of origin, stage of differentiation, and prognostic indicators.
antibodies