Transcript Vaccines 7.pptx

VACCINES
324 PHT
Dr. Sarah I. Bukhari
PhD in Clinical Microbiology
Department of Pharmaceutics
Office: 06 - 3rd floor
[email protected]
Objectives
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To know about current and developing approaches to
vaccination;
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Define vaccine and explain how vaccination works
Differentiate the following, and provide an example of each:
attenuated, inactivated, toxoid, subunit. and conjugated
vaccines
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Compare and contrast the production of whole-agent
vaccines, recombinant vaccines, and DNA vaccines.
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Define adjuvant.
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Explain the value of vaccines, and discuss acceptable risks
for vaccines.
Vaccine history
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Smallpox
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Chinese physicians
In 1717, Lady Mary Montagu in Turkey learned
about
‘Variolation’
Vaccine history
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Edward Jenner developed
vaccination=the Latin vacca,
meaning cow.
A vaccine is a suspension of
organisms or fractions of organisms
that is used to induce immunity
http://www.youtube.com/watch?v=jJ
wGNPRmyTI
Principles and effects of vaccine
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Principles...?
The injection, by skin scratches, provoked a primary immune
response in the recipients, leading to the formation of
antibodies and long-term memory cells. Later, when the
recipient encountered the smallpox virus, the memory cells
were stimulated, producing a rapid, intense secondary immune
response
The cowpox vaccine was soon replaced by a vaccinia virus
vaccine
Herd immunity
Results from effective vaccination programs (90% vaccinated 
no spread of disease)
Factors affecting herd immunity
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Environment (rural vs. city life)
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Individual’s immune system
Different modes of acquiring immunity
6
Immunity
Natural
Acquired
Passive Active Passive
Igs
IgG
Infection
Active
Vaccination
Passive Immunity
Placental
transfer of IgG
Antibodies or
immunoglobulins
Colostral
transfer of IgA
Immune cells
Types of vaccines
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Whole organism
 Live/attenuated
vaccines
 Killed/inactivated vaccines
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Toxoids
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subunit vaccines
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Recombinant vaccines
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DNA vaccines
Types of Vaccines
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Attenuated whole-agent vaccines
 Attenuated (weakened) microorganisms (or virus)
 Generally provides lifelong immunity
 Live vaccines more closely mimic an actual infection.
 cellular, as well as humoral, immunity usually is induced.
 often achieved without booster immunizations
Inactivated whole-agent vaccine
 Killed bacteria or viruses by heat or chemical means while
assuring that the surface antigens are intact formalin/
phenol
 these vaccines are considered safer than live vaccines.
 often require repeated booster doses
 induce a mostly humoral antibody immunity
Potential safety problems
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Several potential safety problems exist with
live/attenuated vaccines:
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Mutation leading to reversion to virulence
Preparation instability
Contaminating viruses in cultured cells
Heat lability
administration to immunocompromized or pregnant
patients may be dangerous
Types of Vaccines
Subunit vaccine
 Antigenic fragments of a microorganism; includes recombinant
and acellular vaccines.
For example, the vaccine against the hepatitis B virus consists of
a portion of the viral protein coat that is produced by a
genetically modified yeast
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Mechanism:-
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The gene encoding this protein is then identified and isolated
The gene is integrated into a suitable expression vector and
introduced into a suitable host where it expresses the protein
in large quantities
The protein is then isolated and purified from the culture
system
It is used for the preparation of vaccine
Types of Vaccines
Toxoid vaccine
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Inactivated toxin
Antitoxins!!
tetanus and diphtheria
Conjugated vaccine
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To deal with the poor immune response of children to vaccines based
on capsular polysaccharides.
T-independent antigens = stimulate B cells directly without the help of
T cells
combines the desired antigen with a protein that boosts the immune
response.
Haemophilus influenzae type b (Hib),
Types of Vaccines
Nucleic acid (DNA) vaccines
(= genetic immunization)
 Stimulate humoral and cellular immunity;
 Thermostable;
 Easy to produce.
 Gene gun- needles less
 In clinical trials.
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protects horses from West Nile virus
Routes of administration
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Deep subcutaneous or intramuscular route
(most vaccines)
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Oral route (sabine vaccine)
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Intradermal route (BCG vaccine)
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Intranasal route (live attenuated influenza
vaccine)
Other vaccination components:
Adjuvant
- chemicals in the vaccine solution that enhance
the immune response
- e.g. Alum – Ag in the vaccine clumps with the
alum such that the Ag is released slowly, like a
time-release capsule
The Development of New Vaccines
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Viruses for vaccines may be
grown in animals, cell
cultures, or chick embryos.
Recombinant vaccines and
nucleic acid vaccines do
not need to be grown in
cells or animals.
Genetically modified plants
may someday provide
edible vaccines.
Adjuvants improve the
effectiveness of some
antigens.
Principal Vaccines Used in the US to Prevent Bacteria
Diseases in Humans
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DtaP
 Diphtheria: Purified diphtheria toxoid
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Pertussis: Acellular fragments of B. pertussis
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Tetanus: Purified tetanus toxoid
Meningococcal meningitis
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Haemophilus influenzae
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Purified polysaccharide from N. meningitidis
Type b meningitis: Polysaccharides conjugated with protein
Pneumococcal conjugate vaccine:
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S. pneumoniae antigens conjugated with protein
Principal Vaccines Used in the US to Prevent Viral
Diseases in Humans
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Smallpox: Live vaccinia virus
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Poliomyelitis: Inactivated virus
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Rabies: Inactivated virus
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Hepatitis A: Inactivated virus
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Influenza: Inactivated or attenuated virus
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Measles: Attenuated virus
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Mumps: Attenuated virus
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Rubella: Attenuated virus
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Chickenpox: Attenuated virus
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Hepatitis B: Antigenic fragments (recombinant
vaccine)
Thank you