Vaccines KK
Transcript of Vaccines KK
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Vaccines
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The discipline of immunology has it routes in the
early vaccination trials of Edward Jenner and Louis
Pasteur.
Since those pioneering efforts, vaccines have been
developed for many diseases that were once major
afflictions of mankind. The incidence of diseases such as diphtheria, measles,
mumps, pertussis (whooping cough), rubella (German
measles), poliomyelitis, and tetanus has declined
dramatically as vaccination has become morecommon.
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The road to successful development of a vaccine that
can be approved for human use, manufactured atreasonable cost, and efficiently delivered to at-risk
populations is costly, long, and tedious.
Procedures for manufacture of materials that can betested in humans and the ways they are tested in
clinical trials are regulated closely
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Experience has shown that not every vaccine
candidate that was successful in laboratory andanimal studies prevents disease in humans.
Some potential vaccines cause unacceptable side
effects, and some may even worsen the disease they
were meant to prevent.
Live virus vaccines pose a special threat to thosewith primary or acquired immunodeficiency
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Active and Passive Immunization
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Immunity to infectious microorganisms can be
achieved by active or passive immunization. In
each case, immunity can be acquired either bynatural processes
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Vaccine is a Nonpathogenic immunogen thatinduces immunity against a specific antigen whenadministered to a host system.
The first vaccine was developed by EdwardJenner in 1798 against smallpox.
Criteria for being an effective Vaccine
1. Induce long-standing immunity
2. Induce both responses (humoral and cellmediated)
3. Act at appropriate body site
4. Act against specific antigen
5. Must be less expensive or inexpensive6. Easy to store and administrate
7. Be safe
8. Induce Memory
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ClassificationBased on their mode of production
vaccines are divided into two types
1. Conventional vaccines,
2. Newer vaccines
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Conventional vaccines The vaccines that are prepared by using the whole
organism or sub cellular components using simple
techiniques like heat killing, attenuation etc. arecalled conventional vaccines.
Based on the source agent the conventional
vaccines are further sub divided into
(A) Heterologous vaccines
(B) Homologous vaccines
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Heterologous vaccines The vaccines which were produced from
one organism and used against another
organism are called heterologous vaccines
For example the small pox vaccine
produced by Jenner was by using Vaccinia
viruses.
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Homologous vaccines The vaccines which are produced and used against
the same organism are called homologous
vaccines. For example the vaccine produced from Hepatitis
B virus is useful against hepatitis only. The
homologous vaccines are further classified into
(I) Whole organism vaccines
(II) Sub cellular vaccines
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Whole organism vaccines
The vaccines, that are produced by using the
whole organism are called whole organism
vaccines. Many of the currently using vaccines are whole
organism vaccines.
These may be prepared by killing inactivation or
by making avirulent by attenuation. Based on thisthey are divided into two types
(i) Inactivation, (ii) Attenuation.
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Inactivation
The whole organism is inactivated by subjecting toheat or chemicals or irradiation.
With this treatment the organism cannot replicatein the host.
care should be taken so that the epitopes on theorganism should not be lost.
During heat inactivation there is more chance tolose the epitope, as most of the protein epitopes(which are heat sensitive) can lose their structure.
So heat inactivation is generally unsatisfactory. chemical inactivation formaldehyde or alkylating
agents are useful.
For example the polio vaccine salk, is produced byusing the formaldehyde.
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Characteristics of inactivated
vaccines are
Mostly through humoral immunity response
Require repeated booster doses.
More stable
It can never return back to the virulent form
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Attenuation
The loss of ability of a microorganism to cause
significant disease, retaining the capacity to grow
in the inoculated host is called attenuation
(Avirulation).
To attenuate any microorganism it should be
grown for prolonged periods under abnormal
"conditions. This procedure leads to mutations
The mutants which that are suitable for better
growth -in abnormal culture and less suitable to
grow in natural host are used for vaccination.
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Characteristics of attenuated
vaccines The microorganisms in vaccine have the capacity
for transient growth.
They can produce prolonged exposure to immunesystem resulting in production of memory cells
Generally require a single booster
The vaccine is very less-stable
The attenuated viruses can revert to its naturalinfective form.
This is one of the major disadvantage withattenuated vaccines.
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Sub cellular vaccines
vaccines are made of purifiedmacromolecules rather than entiremicroorganisms
Based on the sub cellular component usedfor vaccination Sub cellular vaccines aredivided into
(i)Toxoid vaccines
(ii)Subunit vaccines
(iii) conjugate vaccines
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Toxoid vaccines The vaccines that are produced against the toxins
of microorganisms are called toxoid vaccines.
In case of disease like tetanus, diphtheria and botulism the toxins of the bacteria is only
responsible agent to cause the disease.
The toxoid vaccines induce the antibodies
production against toxin but no immunity is
induced against the .bacteria.
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Subunit vaccines
The vaccines, which are made with
only a single immunogenic protein from thepathogen of interest.
The vaccine hepatitis B is a subunit Vaccine.
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NEWERVACCINES
The conventional vaccine production approachhas been improved with recombinant DNAtechnology, hybridoma technology and automatedantibody synthesis.
Different types of newer vaccines are:
(A)Recombinant vaccines
(B) DNA vaccines
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Recombinant vaccinesThe technique involves isolation of gene,
insertion of gene into carriers (vectors),
introduction of gene and carrier into a
suitable host.
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DNA
vaccines In this method DNA sequence encoding for an
antigen with suitable promoters can be inserted
into a plasmid. Engineered DNA should be administered
intramuscularly
The DNA then codes for its specific protein. This
results in producing long- lasting humoral and cell
mediate immune response to the DNA coded
protein (antigen).