Deck 10: Immunodiagnosis of Infectious Diseases

Question 1

Mary went out to eat shellfish last week and is now beginning to feel lethargic. Her urine is tea-colored, and she generally feels bad all over. She recognizes these symptoms and thinks she may have hepatitis A because she got hepatitis last year when she vacationed at the beach. If a physician were to perform a test for hepatitis A antibodies, what class of antibodies would the physician find?

A) IgM
B) IgE
C) IgG
D) IgD

Answer 1

C

Question 2

What is one of the most popular methods for physical removal of IgG?

A) Miniature ion-exchange chromatography columns
B) Thin-layer chromatography
C) High-performance liquid chromatography (HPLC)
D) Mass spectroscopy

Answer 2

A

Question 3

In precipitation assays, what is the precipitate made out of?

A) Complement and protein complex
B) Antibody and protein complex
C) Antigen and antibody complex
D) Antigen and protein complex

Answer 3

C

Question 4

A monoclonal antibody is

A) an antibody that is derived from one cell, exposed to many epitopes.
B) an antibody that is derived from many cells, exposed to one epitope.
C) an antibody that is derived from one cell and exposed to no epitopes.
D) an antibody that is derived from one cell initially, which has been exposed to one epitope.

Question 5

A false-negative serologic test is defined as a

A) positive result for someone who is not infected.
B) negative result for someone who does not have the disease.
C) positive result for someone who does have the disease.
D) negative result for a patient who really is infected.

Question 6

Avidity means the antibodies have

A) strong binding kinetics to specific antigens.
B) weak binding kinetics to specific antigens.
C) strong binding kinetics to specific antibodies.
D) weak binding kinetics to specific antibodies.

Question 7

Serologic tests can help epidemiologists

A) determine if people in a particular area are immune to an infectious agent.
B) identify people that need to get immunizations.
C) identify children that need to get immunizations.
D) determine how widespread an infectious agent is in a given area.

Question 8

A false-negative test may be caused by all the following immune system-mediated reasons, except

A) allergic reaction.
B) no immune response.
C) immunodeficiency disease.
D) immunosuppression.

Question 9

What can cause a false-positive IgM serologic test?

A) The presence of IgG antibodies
B) The presence of rheumatoid factors
C) The presence of Rh factor
D) The presence of cytomegalovirus (CMV) antibodies

Question 10

John goes to his physician complaining of a high fever (38.2° C [102° F]), muscle aches, cough, and a headache. These symptoms came on suddenly, and his physician thinks John may have the flu. What kind of antibody is his body producing against the virus?

A) IgG
B) IgM
C) IgE
D) IgD

Question 11

How can one determine if a person has had a previous illness with an organism?

A) Perform acute and convalescent IgM levels.
B) Perform acute and convalescent IgG levels.
C) Perform an IgM level 1 week after the symptoms start.
D) Perform an IgG level 1 week after the symptoms start.

Question 12

When the antigen-binding sites on the antibody molecule react with specific epitopes and not with other antigens containing different epitopes, this is antibody molecule is displaying

A) high sensitivity.
B) high specificity.
C) low specificity.
D) low sensitivity.

Question 13

Heterophile antibodies are

A) antibodies produced in response to one antigen.
B) antibodies that must be cleared through the thymus before going into circulation.
C) antibodies produced in response to one molecule that also react against an antigen from another species.
D) antibodies produced by T cells.

Question 14

A significant rise in IgG detected during the convalescent phase is diagnostic for infection and is called

A) serologic adaptation.
B) convalescence.
C) seroconversion.
D) acute phase reactant.

Question 15

What is the principle of direct antigen testing?

A) A clinical specimen is mixed with an antigen, then a labeled antibody is added. If the antigen is present, a complex will form.
B) It is a process by which microbial antigens are identified in patient specimens by combining specifically with antibody molecules to form stable complexes.
C) A fluorescent antigen is added to a specimen, then an antibody to form sandwich complexes.
D) Labeled antigen is added to a specimen, and the specimen is read for fluorescence.

Question 16

What tests are performed on newborns to detect congenital infections?

A) TORCH
B) TWAR
C) CMV
D) HIV

Question 17

If a baby were exposed to hepatitis A in utero, what type of antibodies would be produced?

A) IgD
B) IgE
C) IgG
D) IgM

Question 18

Antibodies for many antigens can be passively acquired in

A) vaccinations.
B) flu shots.
C) intravenous immunoglobulin therapy.
D) All of the above

Question 19

When a person is exposed to an antigen for a second time, what type of response is mounted?

A) Anamnestic
B) Tertiary
C) Full blown
D) Allergic

Question 20

What is the principle of the flocculation test?

A) The antigen is incorporated into the agar and the test wells hold the antibody. The antibody and antigen combine at a specific concentration and produce a zone of equivalence.
B) Antibodies are mixed with a labeled antigen, and a sandwich reaction occurs.
C) Antibodies and antigens combine then precipitate out of a solution to the bottom of the tube.
D) The antigen-antibody reaction forms a macroscopically visible clump that remains in solution.

Question 21

What patients are highly susceptible to cytomegalovirus (CMV) infections?

A) Immunosuppressed
B) Immunocompetent
C) Males
D) Females

Question 22

Enzyme immunoassay (EIA) differs from immunofluorescent tests by

A) using a different fluorescent label.
B) using enzymes and a chromogenic substrate.
C) being valid for direct testing only.
D) All of the above

Question 23

The advantages of latex agglutination include all the following, except

A) availability of good quality reagents in complete kit form.
B) good sensitivity.
C) ease of performance.
D) cost of reagents.

Question 24

What is the earliest serologic marker detected in hepatitis B?

A) HAV
B) HBsAg
C) HBcAg
D) HBeAg

Question 25

All of the following controls must accompany the patient specimens in a latex agglutination test for antigen detection, except

A) positive antigen control.
B) negative antigen control.
C) latex suspension control.
D) positive antibody control.

Question 26

What test principle uses microbial antigens that are attached to erythrocytes after chemical treatment of the cells that promotes cross-linking of the antigens?

A) Indirect hemagglutination (IHA)
B) Enzyme immunoassay (EIA)
C) Complement fixation (CF)
D) Latex agglutination (LA)

Question 27

What is used as the indicator in a complement fixation (CF) test?

A) Latex particles
B) Horse red blood cells
C) Rabbit red blood cells
D) Sheep red blood cells

Question 28

What is the difference between dot blots and Western blots? In dot blot testing

A) proteins are blotted to specific areas.
B) proteins are purified and directly blotted to specific locations on the solid surface.
C) DNA is purified and directly blotted to specific locations on the solid surface.
D) RNA is purified and directly blotted to specific locations on the solid surface.

Question 29

A direct fluorescent antibody (DFA) test involves

A) an antigen-specific labeled antibody.
B) an antibody-specific labeled antigen.
C) a bioluminescent label.
D) None of the above

Question 30

Indirect agglutination is also referred to as

A) passive agglutination.
B) incomplete agglutination.
C) active agglutination.
D) flocculation.

Question 31

Confirmatory tests for syphilis include all the following, except

A) FTA-ABS.
B) TP-PA.
C) RPR.
D) MHA-TP.

Question 32

What are the benefits of using membranes to perform enzyme immunoassay (EIA) reactions?

A) They improve specificity and signal strength.
B) They enhance speed and signal strength.
C) They enhance speed and sensitivity.
D) They improve specificity and sensitivity.

Question 33

What is the advantage of using an indirect sandwich assay for EIA?

A) One enzyme conjugated antiimmune antibody can be used for several tests.
B) It is much more specific than direct sandwich EIA.
C) It is much more sensitive than direct sandwich EIA.
D) The lower detection limit is superior to any other EIA test.

Question 34

All of the following are congenital defects produced by rubella, except

A) deafness.
B) blindness.
C) cataracts.
D) congenital heart disease.

Question 35

What test is used to diagnose an Epstein-Barr virus (EBV) infection?

A) ASO
B) EBV antibody
C) Heterophile antibody
D) Cold agglutinin

Question 36

What is ASO used for?

A) To demonstrate serologic response to streptococcal antigen
B) To determine if a strep has been lysogenized
C) To determine if a strep produces a hemolysin
D) To demonstrate serologic response to Streptococcus pyogenes

Question 37

What test has its results reported as the relative amount of a signal generated by the patient's serum when compared with that of a known weakly positive serum?

A) Enzyme immunoassay (EIA)
B) Enzyme-linked immunosorbent assay (ELISA)
C) Radioimmunoassay (RIA)
D) Solid phase immunobead assay (SPIA)

Question 38

All of the following are antigens present in a hepatitis B infection, except

A) HBsAg.
B) HBcAg.
C) HBeAg.
D) VCNA.

Question 39

What is one of the biggest uses for Western blot tests in the laboratory today?

A) Confirming antibodies to HIV
B) Confirming antibodies to cytomegalovirus (CMV)
C) Confirming antibodies to rubella
D) DNA sequencing from herpes

Question 40

Prozone occurs

A) when the relative concentration of an antibody exceeds the concentration of an antigen.
B) when the relative concentration of an antigen exceeds the concentration of an antigen.
C) when there are interfering substances in the specimen.
D) in the equivalence zone.

Question 41

Which organism can cause hospitalization in young children and is detected using fluorescent antibodies?

A) Haemophilus
B) Klebsiella
C) Streptococcus
D) Respiratory syncytial virus (RSV)

Question 42

All of the following are hepatitis antibodies, except

A) EBNA.
B) HBsAg.
C) HBcAg.
D) HBeAg.

Question 43

What is one of the most widely used applications of the direct antigen test?

A) HIV in saliva
B) Group A strep in throat swabs
C) Epstein-Barr virus (EBV) in urine
D) Cytomegalovirus (CMV) in hair follicles

Question 44

Which test is a confirmatory test of enzyme-linked immunosorbent assay (ELISA) HIV?

A) Enzyme immunoassay (EIA)
B) Northern blot
C) Southern blot
D) Western blot