Immunology - Diagnostic Approaches

Question 1

Problems solved with laboratory diagnosis (6)

Answer 1

Exotic disease
Zoonosis
Vet health programs
Eradication
Certificates of freedom
Prevention of virus transfer to recipients

Question 2

Types of diagnosis (5)

Answer 2

Differential
Presumptive (clin signs alone)
Definitive (based on lab tests)
Pathologic (necropsy/biopsy)
Undetermined

Question 3

What do clinical pictures tell us?

Answer 3

Clinical signs, duration, onset, year, species, organ system

Question 4

Top 3 to consider when sampling

Answer 4

Timing
Type
Quality

Question 5

Others to consider when sampling

Answer 5

Quantity
Transport to lab

Question 6

Appropriate samples (6)

Answer 6

Blood
Feces
Skin follicles
Discharge from eye/nose
Vesicle fluid
Tissues collected from necropsy

Question 7

Fresh tissues taken postmortem

Answer 7

Any tissue w gross lesions
Lung
Tissue pool - liver, spleen, kidney
Intestines or feces
Brain

Question 8

What determines the type of diagnostic test?

Answer 8

Type of sample
Clinical screening/questions
Availability of test
Intended use

Question 9

Performance characteristics of tests

Answer 9

Sensitivity
Specificity
Positive or negative predictive values
Reliability

Question 10

Ways to detect organisms

Answer 10

Visual
Detecting protein
Detecting DNA or RNA

Question 11

Tests for visualization

Answer 11

Light or electron microscopy

Question 12

Potential pathogens found using visual tests

Answer 12

Virus, parasite, bacteria

Question 13

Tests for detecting protein

Answer 13

ELISA, IFA, IHC

Question 14

Tests for detecting DNA or RNA

Answer 14

PCR, NGS

Question 15

Advantages of electron microscope

Answer 15

Visualization of virus
Rapid
Detects viruses that can’t be isolated
Live virus not required

Question 16

Disadvantages of electron microscopy

Answer 16

Expensive
High number of virus required
Specialized training
Needle in a haystack

Question 17

Virus isolation advantages

Answer 17

Sensitive
Specific characterization of virus
ID of unknown viruses

Question 18

Disadvantages of virus isolation

Answer 18

Not widely available
Slow results
Specialized training
Costly

Question 19

Antibody-antigen test (protein)

Answer 19

ELISA
Immunoflorescence (IFA)
Immunohistochemistry (IHC)

Question 20

Function of elisa

Answer 20

Antigen capture
Conjugated primary & secondary antibody
Substrate gives color reaction

Question 21

What does ELISA stand for?

Answer 21

Enzyme linked immunosorbent assay

Question 22

Immunofluorescent antibody test

Answer 22

Cell culture or tissues
Antibody has fluorescent tag
Requires high viral titer

Question 23

Immunohistochemistry

Answer 23

Uses paraffin-embedded tissues mounted on glass slides
Sections are incubated, tagged in substrate
Substrate gives color reaction
Allows detection of antigen in lesion or targeted cells

Question 24

Advantages of antibody based tests

Answer 24

Rapid
Sensitive
Easy to use
Can detect different serotypes

Question 25

Disadvantages of antibody based tests

Answer 25

Not available of all organisms Can be difficult to interpret

Question 26

Genomic detection

Answer 26

PCR In-situ hybridization Next generation sequencing

Question 27

PCR

Question 28

In-situ hybridization

Answer 28

Visualize virus in tissue or site Determine which virus is responsible for pathologic lesions

Question 29

Next generation sequencing

Answer 29

Whole genome sequencing Detection of unknown viruses

Question 30

Advantages of DNA based tests

Answer 30

Rapid Sensitive Specific Relatively cheap Potentially applicable to all viruses

Question 31

Disadvantages of dna based tests

Answer 31

Sensitive - detection X=X causation Risk of DNA contamination Must know what to look for