Transcript HIV and ELISA - Clayton State University

 Study
of the immune system
 How the body protects itself against foreign,
potentially disease-causing microorganisms
 Three main functions:
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To recognize intruders
To respond appropriately to intruders in a way
that protects the body
To respond the next time the intruders are
encountered

Innate immunity
 Nonspecific

Adaptive Immunity
 Specific

Induced resistance to a specific pathogen
 Humoral

versus cell-mediated
B cells versus T cells
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A substance that causes the body to produce
specific antibodies or sensitized T cells
Protein or polysaccharide (lipids and nucleic acids
when combined with proteins or polysaccharides)
Found in capsule, cell walls, flagella, fimbrae, and
toxins of microbes
Pollen, egg white, blood cell surface, tissue
surface
Antigenic determinants (epitopes)
 Specificity
 Each bacterial cell has many different epitopes
Figure 17.1
Globular proteins
(immunoglobulins) made by B
cells in response to an antigen
 Highly specific

 Antigen-binding
sites
First
diagnosed in 1981
Over
20 million deaths worldwide,
over a half million in the United
States
Over
40 million currently infected,
over a million in the United States
Half
of all new infections are in
people younger than 25
Education
has been effective in
limiting the spread of HIV/AIDS
 HIV
is an RNA Retrovirus
 Transmitted
by exchange of body fluids, sharing
needles, or blood transfusion
 Infects
T-Cells in the immune system and thus
destroys the immune system
 Flu-like
symptoms within 1-2 months followed by
latent period of up to 10 years
 HIV
may have spread from an animal host to
humans
 Treated
but not cured by drugs which inhibit the
action of HIV enzymes
 High
error rate of replication (1/2000
nucleotides)
Figure
16-11b
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Diagnostic techniques help us determine the
etiology of the disease
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Diagnostic techniques
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Microscopy
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Culture
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Test biochemical properties of microbe
Molecular
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Use PCR to amplify a gene associated with the disease
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Identify the gene on a gel
Immunological
 Diagnostic
immunology involves using
the principles of the immune system or
antibody—antigen reaction to diagnose
diseases or detect antigens in bodily
fluids
 Important
diagnostic tests
Direct agglutination
 Indirect agglutination
 Hemagglutination
 ELISA
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 Physician
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Antigen sample
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A bodily fluid that contains the infecting microbe or the
microbes toxin
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collects a sample
Urine, feces, blood, skin, pus, throat swab, mucous, etc.
Blood antiserum sample
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Blood antiserum contains the antibodies that the patient
made against an infection; if the patient is infected with the
suspected pathogen then his/her serum has those antibodies
in it.
 If
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the sample is…
Antigen then the physician exposes it to pre-made
antibodies for the suspected pathogen
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Antibodies are produced by a rabbit that was infected with
that organism; they are collected in sterile vials and sold by
pharmaceutical companies
Blood antiserum then physician exposes it to an
antigen from the suspected pathogen
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Antigen from microorganism is prepared by pharmaceutical
company
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It could be a toxin, an inactivated whole agent, or any subunit
from the suspected pathogen
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Enzyme Linked Immunosorbent Assay (ELISA)
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Enzyme reacts with substrate to produce colored
product
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Initial diagnostic test used for HIV detection
 Done on women in labor before delivery to determine
infection status
 Patients following an accidental needlestick injury
Very sensitive
How ELISA works
 Microplates
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Made of polystyrene which binds proteins by
hydrophobic interaction.
Primary and secondary antibodies
Color producing enzyme substrate
Modified from Specter, S. C., R. L. Hodinka and S. A. Young. Clinical Virology Manual, Third
Edition . ASM Press, 2000.