TORTORA • FUNKE
• CASE
Microbiology
AN INTRODUCTION
B.E Pruitt & Jane J. Stein
Chapter 18
Practical Applications of Immunology
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Vaccine History
• Variolation: Inoculation
of smallpox into skin
(18th century)
• Vaccination: Inoculation
of cowpox into skin
• Herd immunity results
when most of a
population is immune to
a disease.
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• On 14th May 1796, Edward
Jenner used cowpoxinfected material obtained
from the hand of Sarah
Nemes, a milkmaid from his
home village of Berkley in
Gloucestershire to
successfully vaccinate 8
year old James Phipps. On
1st July 1796, Jenner
challenged the boy by
deliberately inoculating him
with material from a real
case of smallpox.He did not
become infected!
Jenner
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How
• Trigger your own immune
response
Vaccines work
– Artificially acquired active
immunity
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Virus, Bacterial or Toxins
•Attenuated - no longer virulent
•Inactivated or Killed - formalin, phenol or heat
destroyed
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Attenuated whole agent vaccines:
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Inactivated (killed) vaccines:
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Types of Vaccines
Live, attenuated (weakened) microbes - virus or bacteria
Long term immunity
May back mutate to virulent strain (rare)
Killed by formalin, phenol or heat
Toxoids
Not as long lasting
Safe
Subunit vaccine:
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Uses fragments from virus or bacteria
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Produced by recombinant methods Recombinvac
Safe
Clean
Conjugated vaccines:
–
Bind to larger particle or protein to enhance antigenicity
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Principal Vaccines Used in the United
States to Prevent Bacterial Diseases in
• DTaP - Trivalent (threeHumans
in one)
– Diphtheria: Purified diphtheria toxoid
– Pertussis: Acellular fragments of B. pertussis
– Tetanus: Purified tetanus toxoid
• Meningococcal meningitis: Purified polysaccharide from N.
meningitidis
• Haemophilus influenzae type b meningitis: Polysaccharides
conjugated with protein
• Pneumococcal conjugate vaccine: S. pneumoniae antigens
conjugated with protein
Vaccine Schedule
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Principal Vaccines Used in the United
States to Prevent Viral Diseases in
Smallpox: Live vaccinia
virus
Humans
Poliomyelitis: Inactivated virus
Rabies: Inactivated virus
Hepatitis A: Inactivated virus
Influenza: Inactivated or attenuated virus
Measles: Attenuated virus
Mumps: Attenuated virus
Rubella: Attenuated virus
Chickenpox: Attenuated virus
Hepatitis B: Antigenic fragments (recombinant vaccine)
Other
Diagnostic
Diagnostic
Immunological
tests: applications:
Serological
• Direct tests detect
antigens (from Tests
patient sample)
• Indirect tests detect antibodies (in patient's serum)
Diagnostic Immunology: Precipitation
Reactions
Precipitation Reactions:
• Involve soluble
antigens with
antibodies
• Precipitin Ring test
Figure 18.3
Agglutination Reactions
• Involve particulate
antigens and
antibodies
• Antigens may be:
• On a cell (direct
agglutination)
• Attached to latex
spheres (indirect or
passive
agglutination)
Figure 18.4
Hemagglutination
• Hemagglutination involves agglutination of RBCs.
Figure 18.7
• Antibodies help eliminate the harmful effect of a virus or
Neutralization
Reactions
exotoxin
• Viral hemagglutination inhibition tests for the presence
of antibodies in a patients serum by the antibodies' ability
to prevent viruses from agglutinating RBCs.
Figure 18.8b
Antibody Titer
• Is the
concentration of
antibodies against
a particular antigen
Figure 18.5
Complement Fixation
Figure 18.9.1
Complement Fixation
Figure 18.9.2
Fluorescent Antibody Techniques (Direct)
Figure 18.10a
Fluorescent Antibody Techniques
(Indirect)
Figure 18.10b
Enzyme-Linked Immunosorbent
Assay(Direct ELISA)
Figure 18.12a
Enzyme-Linked Immunosorbent Assay
(Indirect ELISA)
Figure 18.12b
Serological Tests
Figure 18.13
Serological Tests: Summary
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Precipitation: Soluble antigens
Agglutination: Particulate antigens
Hemagglutination: Agglutination of RBCs
Neutralization (inhibition): Inactivates toxin or virus
Fluorescent-antibody technique: Antibodies linked to
fluorescent dye
• Complement fixation: RBCs are indicator
• ELISA: Enzyme linked to antibody amplifies results for
easier visibility and more sensitivity.