Foundation in Microbiology 5ed

1. Foundations in Microbiology
Chapter
16
PowerPoint to accompany
Fifth Edition
Talaro
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Immunization and Immune
Assays
Chapter 16

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Immunotherapy – preformed Ab
Immune serum globulin – (gamma globulin)
contains immunoglobulin extracted from
the pooled blood of at least 1,000 human
donors
• Treatment of choice for preventing measles,
hepatitis A and replacing Ab in the immune
deficient
• Lasts 2-3 months

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Immunotherapy – preformed Ab
Specific immune globulin- prepared from
convalescent patients in a hyperimmune state
• Contains high titer of specific Ab
• pertussis, tetanus, chickenpox, hepatitis B
• sera produced in horses are available for
diphtheria, botulism, spider and snake bites
• act immediately & can protect patients for
whom no other useful medication exists

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Vaccines
• Provide an antigenic stimulus that does not
cause disease but can produce long lasting,
protective immunity

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Serology
• A science that attempts to detect signs of infection in a
patient’s serum such as Ab for a specific microbe
• Serological tests based on Abs specifically binding to
Ag.
– Ag of known identity will react with Ab in an unknown
serum sample.
– Known Ab can be used to detect Ag in serum
• Ag-Ab reactions are visible by clumps, precipitates,
color changes or release of radioactivity.
• The most effective tests have high specificity and
sensitivity.

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Types of serological tests
1. Agglutination tests
2. Double diffusion precipitation tests
3. Immunoelectrophoresis
4. Western blot tests
5. Complement fixation tests
6. Immunofluorescence testing
7. Immunoassays

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Types of serological tests
1. Agglutination tests – Ab cross-links whole
cell Ag, forming complexes that settle out
and from visible clumps in the test chamber
– blood type, some bacterial & viral diseases

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2. Double diffusion precipitation tests
involve the diffusion of Ags and Abs in a
soft agar gel, forming zones of precipitation
where they meet

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3. Immunoelectrophoresis – migration of
serum proteins in gel is combined with
precipitation by Ab

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4. Western blot test – separates Ag into bands.
After the gel is affixed to a blotter, it is
reacted with a test specimen and developed
by radioactivity or with dyes

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5. Complement fixation tests detect lysins- Ab
that fix complement and can lyse target cells.
Involves mixing test Ag and Ab with
complement and then with sensitized sheep
RBCs.
If complement is fixed by the Ag-Ab, the RBCs
remain intact and the test is positive.
If RBCs are hemolyzed, specific Ab are lacking
and the test is negative.

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6. Immunofluorescence testing uses
fluorescent Ab either directly or indirectly
to visualize cells or cell aggregates that
have reacted with the FAbs

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7. Immunoassays are highly sensitive tests for
Ag and Ab.
Radioimmunoassay –Ag or Abs are labeled
with radioactive isotopes and traced
Enzyme-linked immunosorbent assay (ELISA)
can detect unknown Ag or Ab by direct or
indirect means. A positive result is visualized
when a colored product is released by an
enzyme-substrate reaction.

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• Tests can differentiate B cells from T cells
and their subtypes.