4- Diagnosis I

Question 1

Why is it important that a diagnosis is established with a minimum of delay?

Answer 1

• Allows for effective control of disease
• economically-important situation
• identify zoonotic disease
• provides surveillance for emerging/foreign disease

Question 2

What are some things to look at when selecting specimens?

Answer 2

• Titer (number os viral particles) of virus
• some diseases have a viremia
• secondary bacterial infection

Question 3

What are some broad laboratory techniques used for virus detection?

Answer 3

• Virus isolation
• virus visualization
• viral antigen detection
• characteristic gene sequence

Question 4

What are examples of laboratory techniques for virus isolation?

Answer 4

• cell culture and CPE
• laboratory animals
• egg culture

Question 5

What are some examples of laboratory techniques for virus visualization?

Answer 5

electron microscopy

Question 6

What are some examples of laboratory techniques for viral antigen infection?

Answer 6

• immunohistochemistry/immunofluorescence
• enzyme-linked immunosorbent assay (ELISA)
• in situ hybridization
• hemagglutination

Question 7

What are some examples of laboratory techniques for characteristic gene sequence?

Answer 7

• polymerase chain reaction (PCR)
• whole genome sequencing
• metagenomics

Question 8

Briefly describe the process for virus detection by isolation in cell culture

Answer 8

You have a specimen —–> inoculated to cultured cells as a monolayer —–> observe for 2-10 day and recognize characteristic cytopathic effect

Question 9

Briefly describe the process for virus detection by negative staining electron microscopy

Answer 9

Have a clinical sample —-> stain it with 2% phosphotungstic acid —–> add to copper grid —–> dry —–> put in big machine and look at it under 20k magnification

Question 10

Briefly describe the process for virus detection by hemagglutination assay.

Answer 10

• some viruses naturally bind to the surface of red blood cells and cause them to agglutinate
• use round-bottom assay plate, allows for red blood cells to settle

Question 11

One diagnostic tool is antigen detection. These techniques allow identification of viruses in _______, _______, and ______. The use of cell culture allows for the propagation of the virus from infected animals. PCR detects ________ ________.

Answer 11

lesions, fluids, and tissues

viral genome

Question 12

Another diagnostic tool is antibody detection through _______ or measurement of __________ _________.

Answer 12

ELISA
antibody titers

Question 13

What are some limitations of diagnostic techniques?

Answer 13

• need sophisicated laboratories
• Cost
• Selecting the proper specimen
• Interpretation of findings