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INTRO TO VIROLOGY
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INTRO TO VIROLOGY
Virology Diagnostic Methods and Specimen Collection
Study
1
Question
What are the traditional diagnostic methods in virology?
Answer
Cell culture, serology, microscopy (bright field and electron).
2
Question
What are some modern diagnostic methods used in high complexity virology laboratories?
Answer
Immunofluorescence (IF), Enzyme Immunoassay (EIA), rapid tests for detection of viral antigens.
3
Question
What does Viral Serology determine in diagnostic virology?
Answer
The patient's immune response rather than detecting viruses.
4
Question
Why is it important to collect specimens as early as possible in diagnostic virology?
Answer
The sensitivity of viral cultures decreases rapidly 3 days after the onset of symptoms.
5
Question
How should specimens be collected in aseptic conditions in virology?
Answer
Specimens must be collected aseptically to prevent contamination.
6
Question
What are some preferred collection methods for nonsterile specimens in virology?
Answer
Swabs made of Dacron or rayon are preferred over aspirated secretions.
7
Question
What is the recommended transport medium for viral specimens?
Answer
Viral transport medium such as saline or trypticase soy broth is recommended for maintaining specimen viability during transport.
8
Question
What type of specimens should be collected aseptically for virus identification?
Answer
Nonsterile specimens from sites with normal flora
9
Question
Why are swabs preferred over aspirated secretions for specimen collection?
Answer
Swabs are preferred because they reduce contaminants and promote viral growth
10
Question
What should be used to transport tissues in order to prevent them from drying out?
Answer
Viral transport medium (saline or trypticase soy broth) in sterile containers
11
Question
What should be added to most transport media for viral specimens?
Answer
Buffered isotonic solution with protein
12
Question
Why should samples collected without viral transport media not be frozen?
Answer
Freezing can facilitate the formation of ice crystals that disrupt host cells
13
Question
How should viral specimens be processed for culture if immediate processing is not possible?
Answer
Keep at 4°C, do not freeze
14
Question
What type of transport media is preferred for most viral specimens?
Answer
Viral transport medium (saline or trypticase soy broth) in sterile containers
15
Question
What methods are used in diagnostic virology for virus identification?
Answer
Direct detection, nucleic acid detection, isolation in cell cultures, serologic assays
16
Question
What is the purpose of using swabs for specimen collection over aspirated secretions?
Answer
Swabs reduce contaminants and promote viral growth in the sample
17
Question
Why should tissue samples be kept moist during collection and transport?
Answer
To prevent them from drying out, which can affect viral identification and culture
18
Question
What is the role of antifungal and antibacterial agents in transport systems for viral specimens?
Answer
They are added to reduce contaminants and maintain the integrity of the viral sample
19
Question
How can calcium alginate affect viral testing procedures?
Answer
It can inhibit some viruses and interfere with nucleic acid amplification tests
20
Question
What temperature should viral specimens be kept at if immediate processing is not possible?
Answer
4°C, to prevent degradation of the viral sample
21
Question
What type of specimens require processing to reduce contaminants and promote viral growth?
Answer
Nonsterile specimens collected from sites with normal flora
22
Question
What type of specimens should not be placed on media unless for preservation following the production of antibodies?
Answer
Tissue samples
23
Question
What is the purpose of using Dacron or rayon swabs for specimen collection over aspirated secretions?
Answer
Swabs are preferred as they reduce contaminants and promote viral growth in the sample
24
Question
What is the recommended handling of viral specimens for culture?
Answer
Culture specimens should be cultured immediately. If not, they should be kept at 4°C should not be frozen to prevent ice crystals that can disrupt host cells.
25
Question
Why is albumin, gelatin, or serum added to viral specimens for culture?
Answer
To protect less stable viruses during the culturing process.
26
Question
What are the methods used in diagnostic virology?
Answer
1. Direct detection of the virus in clinical specimens 2. Nucleic acid-based detection 3. Isolation of viruses in cell cultures 4. Serologic assays to detect antibodies to the virus.
27
Question
What is the purpose of direct detection of the virus in clinical specimens?
Answer
It allows for quick results, although it is not as sensitive as culture methods.
28
Question
What are the types of microscopy used in virology for virus detection?
Answer
Bright field microscopy for poxviruses and electron microscopy for detecting virions and nonculturable viruses like Norwalk virus.
29
Question
What is cytopathic effect (CPE) and how is it detected?
Answer
CPE is visual changes in infected cells caused by viruses. It can be detected in cell scrapings with bright field microscopy. Tzanck smear can detect Cowdry type A bodies from HSV and VZV lesions. Pap smears can reveal HPV-associated koilocytes.
30
Question
How is rabies diagnosed?
Answer
Rabies is diagnosed by detecting Negri bodies, which are eosinophilic cytoplasmic inclusions in neurons.