Practical Applications of
Immunology
Chapter 18
I. Vaccines
• A. Definition – A suspension of organisms or
fractions of organisms that is used to induce
immunity (immunologic memory).
• The mechanism of memory is mediated by memory T
and B cells that provides a quick and effective
secondary response to pathogenic antigens (e.g.
Hepatitis B, tetanus toxin).
• In general, polysaccharide antigens found in bacteria
do not stimulate production of effective antibodies
as well as protein antigens found in viruses.
II. Principles and Effects of Vaccination
• A. Herd Immunity – Immunity that results when most
of the population is immune. Outbreaks are reduced
to sporadic cases because there are not many
susceptible individuals.
II. Principles and Effects of Vaccination
• B. Principle Vaccines used in US to Prevent Bacterial Diseases
II. Principles and Effects of Vaccination
• C.
Principle Vaccines Used in US to Prevent Viral Diseases
II. Principles and Effects of Vaccination
• D. Schedule of Childhood Immunizations
III. Types of Vaccines and Their Characteristics
• A. Attenuated Whole-Agent Vaccines
– Consist of live attenuated (weakened) microorganisms that
mimic an actual infection.
– Attenuated virus vaccines generally provide life-long
immunity (Sabin polio and MMR).
• B. Inactivated Whole-Agent Vaccines
– Consist of killed bacteria or viruses (Salk polio, influenza,
and pneumococcal).
• C. Toxoids
– Inactivated toxins directed to make antibodies that
inactivate toxins produced by pathogens.
– Usually need booster immunization every 10 years or so
(tetanus and diphtheria toxoids).
– Examples: tetanus and diphtheria toxoids.
III. Types of Vaccines and Their Characteristics
• D. Subunit Vaccines
– Consist of only antigenic fragments of a microorganism
that induce the best immune response.
– Includes recombinant vaccines (hep B fragments produced
by yeast) and acellular products that retain desired
antigenic fractions.
– Newer pertussis vaccines are acellular. Safer because they
cannot reproduce in recipient.
• E. Conjugated Vaccines
– Combine the desired capsular polysaccharide antigen
(weak immunizer in young children) with a protein that
boosts the immune response in children under 2 years old.
– Example: Hemophilus influenza (Hib) capsular antigen
with diphtheria protein toxoid.
r-HBvax
r-HBvax is a non-infectious, inactivated
recombinant subunit viral vaccine
derived from HBsAg Produced in yeast
cells using recombinant DNA
technology developed by Korea Green
Cross Corporation. It is a whitish turbid
liquid which is produced by culture of
genetically engineered yeast cells
which carry the relevant gene of
HBsAg, purified and inactivated by
several physico-chemical steps such
as ultra centrifugation, column
chromatography and formaldehyde
treatment.
Pentacel®, Diphtheria and Tetanus Toxoids
and Acellular Pertussis Adsorbed, Inactivated
Poliovirus and Haemophilus b Conjugate
(Tetanus Toxoid Conjugate) Vaccine.
Pentacel® vaccine is indicated or active
immunization against diphtheria, tetanus,
pertussis, poliomyelitis, and invasive disease
due to Haemophilus influenzae type b (Hib).
“Pentacel® vaccine will help simplify the
immunization schedule by reducing the
number of injections infants and young
children will receive in their first two years of
life,” said Wayne Pisano, President and Chief
Executive Officer, sanofi pasteur.
III. Types of Vaccines and Their Characteristics
F. Nucleic Acid Vaccines or DNA Vaccines Under development.
Foreign DNA injected and foreign protein made by host cell
until the DNA is degraded.
“With DNA vaccines the individual is
not injected with the viral antigen,
but with DNA encoding the antigen.
DNA vaccines are injected into
patients either as “naked” DNA or
DNA carried by a non-pathogenic
virus vector. In either case, the DNA
gains access to cells where the
antigen protein is synthesized by
normal cell mechanisms and
presented to the immune system to
stimulate the immune response to
it.”
Immunomic Therapeutics, Inc.
Immunomic Therapeutics, Inc.
III. Types of Vaccines and Their Characteristics
• G. Safety of Vaccines
– No vaccine is perfectly safe or effective, but still remains
the most safe and effective means of preventing infectious
disease in children.
– Most parents never see a case of polio or measles and are
remote abstractions to them. Reports or rumors of
harmful effects are rarely accurate, but lead parents to
avoid vaccination for themselves or children.
Opposition to vaccination, from a wide array of vaccine critics, has existed since
the earliest vaccination campaigns.
The Cow-Pock—or—the Wonderful Effects of the New Inoculation! (1802)