Fundamentals of Diagnostics

Question 1

If you want to visualize a virus, parasite, or bacteria, what two diagnostic tests are available for this purpose?

Answer 1

(Light or electron microscopy)

Question 2

What part of a cell is detected when using ELISA, IFA, and IHC?

Answer 2

(Protein)

Question 3

What part of a cell is detected when using PCR, in-situ hybridization, and next generation sequencing?

Answer 3

(DNA or RNA)

Question 4

What tests are antibody-antigen based tests that detect antigen using protein?

Answer 4

(ELISA/enzyme-linked immunosorbent assay (sandwich), immunofluorescence, and immunohistochemistry)

Question 5

(T/F) Immunofluorescent antibody testing can be used on cell cultures or tissues with a wide range of viral titers, from low to high.

Answer 5

(F, requires high viral titers)

Question 6

SNAP tests (FELV/FIV, parvo, heartworm, etc.) are based on what test?

Answer 6

(ELISA)

Question 7

(T/F) All SNAP tests use antibodies to capture antigen.

Answer 7

(F, some use antigen to catch antibodies, for example FIV is an antibody test (so there’s FIV antigen on the test and it captures FIV antibody) but FELV is an antigen test (so there’s FELV antibody on the test and it captures FELV antigen))

Question 8

(T/F) The more cycles it takes for a PCR test to reach the established threshold cycle, the less DNA/RNA is present in the sample being tested.

Answer 8

(T, the opposite is also true so the less cycles it takes for a PCR test to reach the established threshold cycle, the more DNA/RNA is present in the sample being tested)

Question 9

What PCR test is used for identification of clonal lymphocyte populations?

Answer 9

(PCR for antigen receptor rearrangement aka PARR; also used for detection of c-kit mutations in mast cell tumors → the more c-kit mutations you have the higher grade your mast cell tumor is)

Question 10

What DNA/RNA based test allows for visualization of the virus in tissues or at the site of infection?

Answer 10

(In-situ hybridization)

Question 11

What DNA/RNA based test is based on whole genome sequencing and is used for detection of unknown viruses?

Answer 11

(Next generation sequencing)

Question 12

What sample is used for serology testing?

Answer 12

(Serum)

Question 13

What tests are antigen-antibody based tests that detect the host response using antibody?

Answer 13

(This is serology → ELISA (direct and indirect), immunodiffusion, virus neutralization)

Question 14

What is the highly specific test that uses antibodies in serum to inhibit virus replication?

Answer 14

(Virus neutralization → titer is the inverse of the highest dilution needed to neutralize the virus, this method is slow/expensive)

Question 15

(T/F) If you have a neutralizing antibody, this indicates there was an active infection against the virus you are testing at some point in the patient’s past.

Answer 15

(T, vaccines typically produce antibodies that are not as strong as the neutralizing antibodies produced by true infection)

Question 16

What type of testing is best used when determining what organisms are circulating in a population?

Answer 16

(Serology)

Question 17

(T/F) Antibodies can be produced by infection, exposure with no clinical disease, and vaccination.

Answer 17

(T)

Question 18

(T/F) Though the specificity of a test is high, if the prevalence is low in your area, there is a higher chance of false positives.

Answer 18

(T)