immunization atul

8/2/2019 Immunization ATUL

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Immunization


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Approach for prevention of

infectious diseases

Improvement and maintenance of good

socioeconomic conditions

Preventive engineering Prompt management

Surveillance and diagnostic awareness

Immunization


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Rationale of Immunization

The objective is to produce, without harm

to the recipients a degree of resistance

sufficient to prevent a clinical attack of the

natural infection and to prevent the spread

of infections to susceptible in the

community.


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Passive immunization

1) Artificial passive immunization

Homologous

Heterologus

2) Immunoglobulins


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Active immunization

Vaccines are of various types Attenuated whole cell vaccine Killed whole cell vaccine

Toxoids Recombinant vaccines Subunit vaccines Conjugated vaccines

DNA based vaccines Anti idiotype vaccines Plant based vaccines


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Properties of an ideal vaccine

Promotes effective immunity

Confers lifelong protection

Safe ( no side effects) Stable

Cheap

Seen to be good and effective by thepublic


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Live vaccine

Viral attenuation Serial passage in cell culture. Eg Polio,

Measles, Mumps

Variants from other species. eg Smallpox,

Rotavirus

Resorted genomes. Eg Rota virus, Influenza

Temperature selected mutants. Eg Influenza

Recombinant virus. Eg HSV

Recombinant viral vector. Eg Vaccinia,

Adenovirus


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Live vaccine - Bacterial

Serial subculture BCG

Recombinant Bacteria Eg S typhi (Ty21a)

Recombinant bacterial vector Eg Salmonella,Vibrio


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Live vaccine - Advantages

They activate all phases of immune

system.

They raise immune response to all

protective antigens.

They offer more durable immunity and are

more cross-reactive.

They cost less to produce

They give quick immunity in majority of

vaccinees

Administration is easy

They can lead to elimination of wild type


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Live vaccine Disadvantages

Mutation. This may lead to reversion to virulence Spread of the vaccine virus that is not

standardized and may be mutated

Sometimes there is poor "take" in tropics

Cannot be administered to patients with

immunodeficiency.


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Killed Vaccine

Whole Cell

Bacteria Pertusis, Cholera

Virus Polio, Rabies

Protein based

Natural Hepatitis B

Chemically inactivated TT & DT

Genetically inactivated Pertusis

Recombinant polypeptide Hepatitis B


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Killed Vaccine

Peptide based eg Malaria, Anti Fertility

Polysaccharide based - Hemophilus influenzae b

(Hib), Pneumococcal and Meningococcal


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Killed vaccine - Advantages

They give sufficient humoral immunity if boosters

given

There is no mutation or reversion (This is a bigadvantage)

They can be used with immuno-deficient patients

Sometimes they perform better in tropical areas


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Killed vaccine - Disadvantages

Some vaccinees do not raise immunity

Boosters tend to be needed

There is little mucosal / local immunity (IgA)

Higher cost

failures in inactivation leading to immunization

with virulent virus eg Smallpox


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Newer Strategies - DNA based vaccination

Based on the deliberate introduction of a DNAplasmid into the vaccinee.

The plasmid carries a protein-coding gene that

transfects cells in vivo at very low efficiency and

expresses an antigen that causes an immune

response.


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DNA vaccination - Advantages

Plasmids are easily manufactured in large amounts

DNA is very stable

Storage and transport are straight forward

Sequence can be changed easily in the laboratory.

Antigen produced by this method behaves in the same

way as antigen produced in natural infection would

behave

The plasmid does not replicate


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DNA vaccination - Problems

Potential integration of plasmid into host genome

leading to insertional mutagenesis

Induction of autoimmune responses (e.g.pathogenic anti-DNA antibodies)

Induction of immunologic tolerance


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Newer Strategies Anti idiotype antibodies

Idiotype - unique amino acid structure in the

antibody complementary to epitope is

known as the idiotype


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antibody

New methods

Anti-idiotype vaccine

epitope

Antibody

with epitopebinding site

Virus


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Antibodies (anti-ids) can be raised against

the idiotype by injecting the antibody into

another animal, these anti idiotype antibodieshave a structure that mimics antigenic epitope

structure.


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antibody

Anti-idiotype vaccine cont

Make antibody

against antibody

idiotype

Anti-idiotype

antibody

Anti-idiotype

antibody mimics

the epitope


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The anti-idiotype antibody is injected into a

vaccinee, anti-anti-idiotype antiobodies are

formed that recognize a structure similar to partof the virus and might potentially neutralize the

virus

A i idi ib d


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Anti-anti-idiotype

antibody

Anti-idiotype antibody cont2

Use anti-idiotype antibody as

injectable vaccine

Antibody to anti-

idiotype

antibody

Binds andneutralizes virus

Anti-idiotype

antibody

Anti-anti-idiotype

antibody

Anti-anti-idiotypeantibody

Use as

vaccine


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