Serological Testing

Question 1

a ___ dye molecule is attached by ___ bonds to an ___ at the ___ region. Cross reactivity means a tagged ___ can bind to more than one ___

Answer 1

fluorescent, covalent, antibody, Fc, antibody, antigen

Question 2

In ouchterlony, a known ___ is loaded in a well in agarose between two or more unknown ___. The reaction can help the investigator determine the identity of the ___

Answer 2

antibody, antigens, antigens

Question 3

match the patterns of antibody-antigen reactions seen with ouchterlony

Answer 3

pattern of identity A - antibody reacts with both antigens, cannot distinguish differences immunologically

pattern of identity B - antibody reacts more with one antigen than the other

pattern of non-identity C - no reaction between antibody and antigens

Question 4

What is the ELISA test intended to measure

Answer 4

antibody to HIV only

Question 5

What would happen if serum were omitted from the ELISA, but all other steps remained the same and were performed properly

Answer 5

anti-human Ig-conjugate wouldn’t bind and would be washed away and the O.D. values would be nearly the same as the assay control (both a and c)

Question 6

What would happen if the anti-human Ig-conjugate were not washed free of the well before the substrate was added

Answer 6

all well would show uniform over development due to unbound and excess anti-human-Ig enzyme conjugate

Question 7

In general, a second antibody or “conjugate”

Answer 7

binds primary antibody

Question 8

Western Blot Testing: In strip 1, the combining sites of primary antibodies are bound to

Answer 8

HIV antigens

Question 9

What does the Western Blot Activity test measure

Answer 9

antibody to HIV only

Question 10

Which patient(s) is/are HIV positive by Western Blot

Answer 10

Patient C is positive

Question 11

Which of the following has an epitope

Answer 11

an antigen

Question 12

Chlamydia trachomatis is

Answer 12

a bacterium that reproduces inside its host cell

Question 13

The infectious form of Chlamydia that is spread from person to person is the

Answer 13

elementary body that stains green in this activity

Question 14

The goal of the direct fluorescent antibody test is to test for the presence of

Answer 14

antigen

Question 15

In the serology test just performed, the fluorescence is found on the

Answer 15

antibody

Question 16

How is chlamydia disease transmission prevented

Answer 16

abstinence or faithful, mutual monogamy

Question 17

For home pregnancy tests

Answer 17

the antigen is human chorionic gonadotropin

Question 18

Which of the following is true of the indirect ELISA

Answer 18

A positive patient sample contains antibodies specific to the antigen
of interest

Question 19

What does the antigen bind to on the antibody

Answer 19

the variable region

Question 20

Which of the following is true of the direct ELISA

Answer 20

The positive patient sample contains the specific antigen

Question 21

Antibodies are made of

Answer 21

proteins

Question 22

How would you describe the binding site of the secondary antibody

Answer 22

the constant region of primary antibody

Question 23

A positive result for HIV in the indirect ELISA performed contains

Answer 23

antibodies against HIV

Question 24

Which patient needs to be retested

Answer 24

IND

Question 25

When two antigens are identical their precipitin lines form

Answer 25

an arc

Question 26

Antigen and antibody move toward each other because of

Answer 26

diffusion

Question 27

If two antigens form a spur, they

Answer 27

have partial identity

Question 28

The Ouchterlony test relies on the formation of a(n)

Answer 28

precipitate

Question 29

There is a spur between wells 2 and 5 and between wells 3 and 4 because the

Answer 29

antigens have partial identity

Question 30

What is the unknown antigen in well 5 (recall that well 2 contains bovine serum albumin and well 4 contains human serum albumin)

Answer 30

human serum albumin

Question 31

Which of the following best describes this test

Answer 31

Antibodies are used to detect the presence of antigens

Question 32

The antigen-antibody precipitate forms where the ratio of antigen and antibody is

Answer 32

optimum

Question 33

Within a class of antibodies, the _______

Answer 33

constant region has the same sequence of amino acids

Question 34

The fluid portion of the blood with the clotting factors removed is called _______

Answer 34

serum

Question 35

Antibodies are produced by _______

Answer 35

plasma cells

Question 36

In this technique the ___ is found in the patient sample and as a result is considered ___ test

Answer 36

antigen, a direct

Question 37

The form of Chlamydia that divides inside the host cell is the _______

Answer 37

reticulate body

Question 38

an ___ is entire foreign "particle", which has multiple ___. The ___ binds to the antigenic determinant or ___

Answer 38

antigen, epitopes, antibody, epitope

Question 39

The direct fluorescent antibody test for Chlamydia uses fluorescently labeled _______

Answer 39

antibody to detect antigen in the patient sample

Question 40

A positive result with the negative control would _______

Answer 40

be a "false positive" and invalidate the results (both a and c)

Question 41

The washing steps are necessary to _______

Answer 41

reduce any nonspecific binding that may occur

Question 42

Move each description to the appropriate category: antigens have identity

Answer 42

identical antigens, precipitin lines diffuse into each other to completely fuse and form an arc

Question 43

Move each description to the appropriate category: antigens have non-identity

Answer 43

antigens that are unrelated, precipitin lines intersect to form two spurs that resemble an X

Question 44

Move each description to the appropriate category: antigens have partial identity

Answer 44

antigens that are similar, a spur pointing toward the more similar antigen well forms in addition to the arc

Question 45

Which of the following describes the identity seen between human serum albumin and bovine serum albumin

Answer 45

partial identity

Question 46

In the Ouchterlony technique, a precipitin line forms where _______

Answer 46

the ratio of antigen and antibodies is optimal

Question 47

When two antigens have NO epitopes in common, their precipitin lines form _______

Answer 47

an X

Question 48

Direct ELISA tests directly for ___ whereas indirect ELISA tests for the ___ formed as a result of exposure to ___

Answer 48

antigens, presence of antibodies, antigens

Question 49

In both the direct and indirect ELISA, the substance that changes from colorless to colored in a positive result is the _______

Answer 49

substrate

Question 50

In this activity the ___ antibody binds to ___ of the ___ antibody, so that it can detect the presence of a ___ in the patient's sample

Answer 50

find answer

Question 51

It is possible for a patient to test negative for HIV using the indirect ELISA test and positive at a later date

Answer 51

true

Question 52

Why might a patient infected with HIV initially test negative with the indirect ELISA

Answer 52

The patient has not yet undergone seroconversion

Question 53

Possible reasons for an indeterminate ELISA test include _______

Answer 53

the presence of only small amounts of HIV antibody in the patient sample, failure of the washing steps to remove nonspecific binding of antibody and antigen, and recent HIV infection of the patient (all of these)

Question 54

In the indirect ELISA, _______

Answer 54

the enzyme tagged-secondary antibody binds to the constant region of the primary antibody

Question 55

Match the HIV antigen (measured in the Western Blot) abbreviation with its description; gjp 160

Answer 55

-Glycoprotein 160, a viral envelope precursor

Question 56

Match the HIV antigen (measured in the Western Blot) abbreviation with its description; gp 120

Answer 56

-Glycoprotein 120, a viral envelope protein that binds to CD4

Question 57

Match the HIV antigen (measured in the Western Blot) abbreviation with its description; p 55

Answer 57

-A precursor to the viral core protein p24

Question 58

Match the HIV antigen (measured in the Western Blot) abbreviation with its description; gp 41

Answer 58

-A final envelope glycoprotein

Question 59

Match the HIV antigen (measured in the Western Blot) abbreviation with its description; p 31

Answer 59

-Reverse transcriptase

Question 60

Match the HIV antigen (measured in the Western Blot) abbreviation with its description; p 24

Answer 60

-A viral core protein

Question 61

Western blotting _______

Answer 61

find answer

Question 62

In the Western Blot, after the proteins are separated by electrophoresis, the _______

Answer 62

nitrocellulose membrane is treated with antibodies

Question 63

What is the source of the primary antibodies in this test

Answer 63

patient's serum

Question 64

What does the secondary antibody bind to in this test

Answer 64

constant region of the primary antibody

Question 65

Which of the following is true

Answer 65

The ELISA is easier to perform than the Western blot and the ELISA is less expensive than the Western blot (both c and d)

Question 66

What result(s) would you expect if you had forgotten to add the developing buffer while doing the Western Blot

Answer 66

a "false negative" for the positive control and all of the patients samples would read negative (both b and c)