Glossary of Diagnostic Virology
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- Why do diagnostic virology?
- -Therapeutic intervention
-Pregnant females, babies
-Rabies, life-threatening ds
- Why is it important to test pregnant females for viruses?
- If HSV pos, then would do a c-section.
- Why important to test babies?
- CMV and rubella
- What are 3 Diagnostic methods in virology?
- 1. Direct exam on infctd tissue
2. Indirect exam (isolatd virus)
- What are 4 ways to directly examine tissue for virus?
- 1. Antigen detection via ELISA
2. E-microscopy for morphology
3. Light microscopy for histology and inclusion bodies
4. Virus genome detection via probes and PCR.
- What are 3 ways to INDIRECTLY examine for virus?
- 1. Cell culture
- What is cell culture used for?
- 1. CPE observation
- What are Eggs used for?
- Pocks on CAM, hemagglutination, and inclusion bodies.
- What are animals used for?
- inoculating with the virus to observe for death or disease.
- When using viral serology, what are you looking to see?
- -Detection of titers rising >4x between acute and convalescent serums
-IgM indicates acute phase
- What are 4 classical serological techniques?
- 1. Complement fixation
2. Hemagglutination inhibition
- What are 3 Newer techniques?
- 1. RIA
3. Western Blot
- What 3 types of cell cultures are used for isolating viruses?
- 1. Primary cells (Rhesus)
2. Semi-contins cells - diploid
3. Continuous cells - heteroploid
- Which type of cell culture is best? Why?
- Primary; supports the widest range of viruses.
- Which type is easy to handle?
- What two changes may viruses produce in cell cultures?
- 1. CPE - cytopathic effect
- what is hemadsorption?
- When cells in culture acquire the ability to stick to mammalian RBCs. May be characteristic of certain virus.
- What viruses are NOT often isolated via cell culture?
- 1. Measles
4. Coxsackie A
- What are 4 drawbacks of cellculture?
- -Takes a long time
-Poor sensitivity dependent on specimen condition.
-Suscept. to bact/fungal/toxins
-Some viruses won't even grow
- Which 4 viruses won't grow in cell culture?
- 1. Hep B
- What technique has sped up the processof cell culture?
- Rapid culture - spinning inoculated culture allows faster adsorption and growth.
- What is the good thing about testing specimens directly for viral antigen?
- Speeds things up immensely!
- What are the bad things about it?
- -Very reduced sensitivity
-Specimens have to be v. good
-Procedures are tedious, timely, and expensive.
- Is Electron microscopy good for diagnostic virology? Why?
- No; requires high concentration of virus in the specimen.
- What viruses ARE observed better with EM?
- adenovirus, rotavirus, norwalk, HSV, smallpox, papillomavirus..
- what 3 specimens can viruses be isolated from for EM?
- 1. Feces
2. Vesicle fluid
3. Skin scrapings
- How can electron microscopy be enhanced?
- By making it immune EM
- What are 2 variants of immune EM?
- 1. Classical
2. Solid phase
- what is classical immune EM?
- Treat sample w/ spcf anti-sera to make viral particles clump.
- What is solid-phase immune EM?
- Antisera added to solid phase so virus particles stick to that.
- What are the 4 criteria for diagnosing primary infection with serology?
- 1. 4x or more incr in Ab titer between acute and convalesc. stages.
2. IgM present
4. Single high titer IgG
- What are the 2 diagnostic criteria for Reinfection?
- 1. IgM absent or only sl. incr.
2. 1x or more inrese in IgG titer btwn acute/convalesc.
- What's a common serological method?
- Complement fixation in microtiter plates.
- Wht is the test screen for HIV?
- What is the confirm test for it?
- Western Blot
- Which viruses are NOT tested for with serology? Why?
- Respiratory & Diarrheal.
The antibodies are produced long after symptoms/acute phase.
- Name 3 causes of false pos results in serology:
- 1. Antigenic cross-reactivity
2. Patients with Mono/SLE
3. Passive vaccination via blood product transfusion.
- When is CSF used for Ab testing?
- To detect HSV or VZV.
- What are molecular methods based on?
- Detection of viral genome.
- What are some molecular methods?
- PCR and bDNA
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