3. INTRODUCTION
Vaccine is an antigenic substance prepared from the
causative agent of a disease or a synthetic substitute,
used to provide immunity against one or several
diseases.
The administration of vaccine capable of
evoking an immune response against specific antigen
thereby making the individual immune to it and protected
from contracting the disease. This practice is known as
VACCINATION / IMMUNIZATION.
4. HISTORY GUIDES
THE FUTURE
Edward Jenner- The term vaccine
derives from Edward's Jenner 1796 use of
the term cow pox ( Latin: Vacca – Cow)
which, when administered to humans ,
provided them protection against small
pox.
Louis Pasteur- In 1885, generalised
Jenner’s vaccines idea by developing a
rabies vaccine .
6. TYPE OF VACCINES
• Whole Organism Vaccines.
• Subunit Antigen Vaccines.
• DNA Vaccines.
• Recombinant Vector Vaccines.
7. WHOLE ORGANISM VACCINE.
Live attenuated vaccines :- These are prepared by
attenuating pathogenic organisms by
growing them in unfavourable conditions
so that they cant cause disease.
Inactivated / Killed vaccines :- Produced
by heating or chemical treatment,
radioactivity and antibiotics.
8. SUBUNIT ANTIGEN VACCINE
Composed of molecules that best
stimulate immune system, purified
directly from pathogen –
•Toxoids
•Capsular polysaccharides
•Recombinant microbial antigens / Surface
antigens
9. • Toxoids – These vaccines are used when bacterial
toxin is the main cause of illness. Toxoids are
chemically altered toxins.
• Capsular polysaccharides – Coating of capsule
with Ab to increase the ability of macrophages and
neutrophils to phagocytose such pathogens.
• Recombinant antigen vaccine- In these
vaccines, gene encoding any immunogenic protein can
be cloned and expressed in bacteria, yeast,
mammalian cells using recombinant DNA technology.
11. DNA VACCINE
• Fragments of pathogen's genome encoding antigenic
proteins are injected directly into host cells.
• DNA then instruct those cells to make the antigen molecule.
• In other words, body’s own cells become vaccine making
factories, creating an Ag necessary to stimulate the immune
system.
12.
13. RECOMBINANT VECTOR
VACCINES
• Genes encode antigens isolated from pathogens can
be inserted into nonvirulent / attenuated viruses or
bacteria to introduce to cells of host body.
• Such recombinant microorganisms serve as vectors,
replicating within the host and expressing the gene
product of the pathogen-encoded antigenic proteins.
16. IMPORTANCE OF IMMUNIZATION
PROGRAMMES
• Each year vaccines prevent more than 2.5
million child deaths globally. An additional 2
million child deaths could be prevented
each year through immunization with
currently available vaccines.
• For example, between 2000 and 2008,
vaccination reduced global deaths from
Measles by 78% (from
750 000 deaths to 164 000 deaths
per year)
• There are now over 30 vaccine
preventable diseases of the more than
400 known pathogens that are harmful
to man.
17.
18.
19. The Quest for the
AIDS vaccine
continues
HIV Vaccine – Best long term hope for controlling the
AIDS pandemic.
Various national and international organisation are
committed for development of an effective vaccine.
•Globally, 14,000 infected every day.
•Over 40 million infected worldwide.
•Over 28 million have already died from HIV .
20. Challenges of an HIV Vaccine
Development
• In an infected person, HIV continually mutates
to evolve into new strains of virus that differ
slightly from the original infecting virus.
• HIV attacks immune cells that are sent by the
body to kill it off.
• HIV infected cells remain latent making it
impossible for killer T cells to identify them
21. Approaches towards AIDS vaccine…
DNA vaccine :
Synthetic copies of HIV genes are injected into the body resulting in the
production of antigens that hopefully can produce a strong immune
response.
Bacterial and viral vector vaccine
Copies of HIV genes are inserted into weakened
bacteria or viruses that do not harm humans.
These bacteria or viruses carry the synthetic HIV genes into the body to
induce an immune response
Other approaches include peptide vaccines or protein subunits
22. EDIBLE VACCINES
As Hippocrates said “ Let thy food be thy medicine and thy medicine be your food”
• In Edible vaccine , Transgenic plants are used as vaccine
production systems.
• Gene encoding immunogenic protein is introduced by
Agrobacterium Mediated transformation or
electroporation.
• Gene encoding antigens of bacterial and viral
pathogens can be expressed in plants in a
form in which they retain native immunogenic
properties..
25. MMR DEBATE
• Measles, Mumps ,Rubella (MMR) vaccine is a live vaccine against these
three diseases.
• 1998- Wakefield and colleagues published a paper that suggested that the
MMR vaccine was linked to cases of autism.
• Only one study of 12 children in Japan.
• Numerous studies carried out since.
• No link proven – MMR safe
• But immunization rates for the MMR shot have never fully recovered.
26.
27. CONCLUSION
Challenge to the biomedical research
community is to develop better, safer , cheaper
and easier to administer forms of these vaccines.
So that world wide immunization becomes a
reality.
