Serology

Question 1

__________ is the measure of antigen-antibody interactions for diagnostic purposes. It can be used to detect/quantify antigen of interest and/or look for antibodies to determine exposure/disease/immunity.

Answer 1

Immunodiagnostics

Question 2

What are the big 3 things you need to know BEFORE you collect your sample?

Answer 2

1. what are you trying to measure (disease, exposure, or level of immunity)
2. are you looking for antibodies or antigen?
3. know the limitations of test (sensitivity, specificity)

Question 3

__________ is a tests ability to designate an individual WITH disease/exposure AS POSITIVE, truly identifying the disease.

Answer 3

sensitivity

Question 4

_________ is a tests ability to designate an individual who does NOT have disease/exposure AS NEGATIVE, truly identifying the lack of disease.

Answer 4

specificity

Question 5

T/F: there is tradeoff between sensitivity and specificity. If you adjust a test to avoid false positives, then you will likely get more false negatives, and vice versa.

Answer 5

true

Question 6

what are the 4 major immunodiagnostic tests?

Answer 6

1. fluorescent assays
2. immunoenzyme assays
3. agglutination tests
4. virus neutralization

Question 7

Fluorescent assays can direct or indirect. State what each of those detect in a sample.

Answer 7

direct antibody tests - identify presence of ANTIGEN

indirect antibody tests - measure ANTIBODIES in serum or identify ANTIGEN

Question 8

Immunoenzyme assays (such as ELISA) can measure …

Answer 8

both ANTIGEN or ANTIBODIES

Question 9

Agglutination tests are testing for the presence of __________ by measuring agglutination.

Answer 9

ANTIBODIES

Question 10

Virus neutralization uses live cells and live virus to measure _______ that specifically neutralize virus (prevent viral cell entry).

Answer 10

ANTIBODIES

Question 11

T/F: virus neutralization is quantitative (meaning it produces antibody titers).

Answer 11

true

Question 12

_____________ is the highest dilution (lowest concentation) of antibody that will detectably interact with the antigen. It is presented as the inverse of the concentration.

Answer 12

antibody titer

Question 13

T/F:
High titer = more dilutions required = more antibody in sample

Answer 13

true

Question 14

serology is useful with what type of viral infections?

Answer 14

retroviral

Question 14

Can you use serology to diagnose leptospirosis?

Answer 14

yes

Question 15

what type of test should you use to make vaccination decisions based on titers.

Answer 15

serology

Question 16

Why would serology be helpful for a case of west nile virus?

Answer 16

looking for IgM

Question 17

T/F: serology is useful for parasitic diseases and systemic mycoses diagnosis

Answer 17

true

Question 18

What would be an indication to use serology in groups of animals?

Answer 18

to establish “disease free” status

Question 19

What is your interpretation of getting a negative virus neutralization test and a positive BVD antigen ELISA in a cow with suspect BVD.

Answer 19

this is likely a PI animal.

Question 20

T/F: vaccine titers are effective in all cases of determining which vaccines need to be given and which do not.

Answer 20

false – only effective if there are specific challenge studies that correlate protection with specific titer levels for each vaccine.
Distemper, adenovirus, and parvo are the only vaccines with known protective titers.

Question 21

T/F: rabies titers are accepted in leiu of vaccination

Answer 21

false not im most jurisdictions

Question 22

what is the biggest limitation of titers?

Answer 22

you are only measuring HUMORAL immunity and cell-mediated immunity is very important to consider too.

also you are limited to diseases for which protective immunity challenge studies have been performed (Ex. CDV and CPV). There are legal requirements for vaccination with some (ex. rabies). Not all labs that test for titers are accredited. And testing titers can be MORE expensive than vaccinating.

Question 23

what are the risks of using serologic assays in young animals?

Answer 23

maternal antibody is being detected
length of time young animals retain MAB is species-specific and pathogen-specific. You must be able to interpret results in light of MAB and know when to repeat testing.

Question 24

why is serology very useful for lentiviruses?

Answer 24

they cause lifelong infection with SLOW disease progression and antigen levels may be very low (neg PCR is not diagnostic)