Download Microbiology ELISA questions

Shaylyn Robison
ELISA Questions
Micro Lab BIOL 2065
W 10 am-11:50 am
ELISA Questions
1.) ELISA stands for Enzyme-Link Immunosorbent Assay. It is a test that uses a
catalyzed color reaction to detect antigens or antibodies. There are two types of ELISA:
Direct or Indirect. Direct ELISA is used in testing for virus particles from samples. It
tests for toxins and pregnancies. The Indirect ELISA detects antibodies such as anti-HIV
antibodies in AIDS testing and other important clinical testing. The ELISA test is
sensitive because you use specific antibodies that are specific to certain antigens. It is
necessary to block unoccupied binding sites in the wells so that antigens do not bind to
the walls of the wells. The positive control is the primary antibody and it is important to
have a control because so that you know if the results yielded are correct. The control
well contains viral antigens and the anti-IgG peroxidase conjugate; it should not change
color during the experiment.
2.) It takes several years for a person to show the symptoms of AIDS because first
the person must be infected by HIV. HIV degrades the immune system slowly and the
person then becomes susceptible to other diseases after their immune system becomes
damaged. AIDS is the combination and culmination of rare diseases and cancers that
people develop who are infected with HIV.
3.) Anti-HIV-1 IgG is screened instead of the virus itself so that the ELISA is able
to detect the antibodies because it is such a sensitive test. The ELISA is designed to be
easy to perform and inexpensive, and is used as a first, initial test for HIV. Detecting the
virus directly is deemed “impractical” which is why the antibody is used in the ELISA
test.
4.) T helper cells are the first cells to detect a foreign substance and will alert B
cells and an immune response. By destroying T cells, HIV eliminates the body’s ability to
mount a counter offense because the T cells cannot alert B cells nor help in the
coordinated immune system response. HIV attaches itself to the T cell and injects its
RNA into the cell, which then becomes a host cell. This process renders the T cell useless
and therefore weakens the immune system.
5.) There are so many variants of HIV because of mutation and reverse
transcriptase (the enzyme that does the replication process) does not proofread it’s work.
6.) To make the primary antibody into an enzyme conjugate would make the
ELISA test more sensitivity and not as specific. Proteins that may cross-react with
antibodies or the enzyme and bind to the antibody-conjugate in the ELISA test could
create a false positive.