Diagnosis of Viral Infections

Question 1

Which risk group would an organism be in if it had no or low individual and community risk?

Answer 1

Risk Group 1

Question 2

Which risk group would an organism be in if it had moderate individual risk but low community risk?

Answer 2

Risk Group 2

Question 3

Which risk group would an organism be in if it had high individual risk but low community risk?

Answer 3

Risk Group 3

Question 4

Which risk group would an organism be in if it had high individual and community risk?

Answer 4

Risk Group 4

Question 5

What type of lab is the maximum containment lab, and handles dangerous and exotic pathogens belonging to risk group 4?

Answer 5

BSL-4 lab

Question 6

Safety practices implemented within the lab are collectively known as:

Answer 6

Biosafety

Question 7

Protection and control of the biological materials within a lab to prevent misuse or unauthorized access:

Answer 7

Biosecurity

Question 8

Samples for virus isolation should be collected when titers are at their highest, which is at what point in infection?

Answer 8

At the onset of clinical signs

Question 9

For serological testing, when are the 2 blood samples taken?

Answer 9

During the acute phase and during the convalescent phase

Question 10

Samples collected for molecular diagnostics (PCR) should be collected when?

Answer 10

During the early part of the illness

Question 11

Viral transport media consists of what?

Answer 11

Sterile vials and swabs

Question 12

To prevent spillage during transport of samples, how many packages are recommended?

Answer 12

3

Question 13

What are the 3 general methods of identifying viral diseases?

Answer 13

Clinical signs
Necropsy
Histopathology

Question 14

What are the 2 ways to cultivate/isolate viruses?

Answer 14

Tissue culture

Inoculation in eggs

Question 15

How can viruses that can’t be grown in-vitro be detected?

Answer 15

Electron microscopy

Question 16

What is the method and focus of TEM?

Answer 16

Method: transmitted electrons
Focus: see what’s inside

Question 17

What is the method and focus of SEM?

Answer 17

Method: scattered electrons
Focus: sample’s surface and conposition

Question 18

(SEM/TEM) can produce images with higher magnification and greater resolution?

Answer 18

TEM

Question 19

What is the advantage to using SEM over TEM in some scenarios?

Answer 19

SEM produces a 3D image, while TEM only produces a 2D image

Question 20

If the probability that a test has a high rate of detecting true positives, the test has a high ______.

Answer 20

Sensitivity

Question 21

If a test has a high probability of finding true negatives, the sample has a high ______.

Answer 21

Specificity

Question 22

Collection of serum is done with a _____ top tube.

Answer 22

Red

Question 23

Collection of plasma is done with a ______ top tube, or a tube with ______.

Answer 23

Purple; anticoagulant (EDTA)

Question 24

What kind of serological test uses enzyme-coated antibodies and a substrate to detect viral infections?

Answer 24

ELISA

Question 25

In what type of ELISA is the specificity of the primary Ab very important because it is the only one used?

Answer 25

Direct

Question 26

In what type of ELISA are the primary Ab not labeled, but detected by a second, enzyme-conjugated, Ab that recognizes the primary Ab?

Answer 26

Indirect

Question 27

What type of ELISA uses a capture Ab and a detection Ab, which surround the Ag to be detected?

Answer 27

Sandwich

Question 28

Why is it important to choose the capture and detection Ab so carefully in sandwich ELISA?

Answer 28

Prevent cross reactivity or competition for binding sites

Question 29

For which type of ELISA does a decrease in signal (or less of a color change) indicate the presence of Ag in the sample?

Answer 29

Competitive

Question 30

What type of serological test works similar to ELISA but uses a fluorescent dye such as fluorescein to label the antibodies instead of an enzyme?

Answer 30

Fluorescence Antibody Test

Direct FAT
Indirect FAT

Question 31

What serological test uses an enzyme like Horseradish Peroxidase, which will react with a substrate and produce a color change that can be viewed with a light microscope?

Answer 31

Immunohistochemistry

Question 32

Benefits of lateral flow testing devices

Answer 32

Point-of-care
Easy
Fast
No special equipment

Question 33

What serological test relies on the ability of specific Ab to bind many Ag into clumps that can be viewed macro- or microscopically.

Answer 33

Agglutination

Question 34

What serological test relies on the ability of certain viruses to non-specifically agglutinate erythrocytes?

Answer 34

Hemagglutination

Question 35

What is an OIE recommended test that involves placing Ag and Ab in separate wells on an agar gel and looking for a white precipitate line between them, indicating formation of Ab/Ag complexes?

Answer 35

Agar Gel Immunodiffusion Test

Question 36

T/F: Agar Gel Immunodiffusion test is OIE recommended.

Answer 36

TRUE

Question 37

How is a positive result indicated in the Complement fixation test?

Answer 37

RBCs settle to the bottom of the tube because complement has been binded to Ab/Ag complex and there is none left free to hemolyze the blood.

Question 38

How is a negative result indicated in the Complement fixation test?

Answer 38

Hemolysis of RBCs in the tube because, since there is no Ag, there are no Ag/Ab complexes for the complement proteins to bind, and they are free in the sample.

Question 39

_______ is the loss of virus infectivity due to reaction of the virus with a specific Ab.

Answer 39

Neutralization