Download GENE THERAPY

Most developments in biotechnology
originated for their potential applications in
health care.
 Contribution of biotechnology:
1. Diagnosis of diseases
2. Therapeutic agents
3. Correction of genetic disease-Gene therapy
4. Fertility control
5. Forensic medicine
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Disease prevention
Disease detection
Therapeutic agents
Correction of genetic diseases
Fertility control
Forensic medicine
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Should not be toxic or pathogenic.
Should have very low levels of side effect.
Should not cause problems in individual with
a weak immune system.
Should not contaminate the environment.
Technique of vaccine should be simple.
Should have long-term effect.
Should be cheap so that is generally
affordable.
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CONVENTIONAL VACCINES
Live vaccines
Inactivated pathogen
PURIFIED ANTIGEN VACCINES
RECOMBINANT VACCINES
Recombinant protein or Subunit molecule
Whole protein molecule
Polypeptide
DNA vaccine
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Microscopic examination of specimen.
Culture of the specimen to allow specific
pathogens to grow.
Immunologic assays for specific antigens
present on the surface of pathogens.
Detection and measurement of the pathogenspecific antibodies produced by the patient in
response to the invasion by pathogen.
DNA/RNA Probes :
Small nucleotide sequence used to detect the
presence of complementary sequence in
nucleic acid samples. Both RNA and DNA are
used as probes.
• ADVANTAGES:
1. Highly specific, relatively rapid and much
simpler.
2. Extremely powerful when combined with PCR.
3. Applicable to such organisms which could be
cultured, pure probes are easily available.
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PCR
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Monoclonal Antibodies:
Specific antigenic determinant of a single
antigen.
Auto antibodies:
specific to those antigens, which are
normally tolerated by immune system and
are typically constituents of cells and tissues
of the animal in question; such antigens are
called autoantigens.
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Commercial Potential Of Diagnostics:
Diagnostic is a tool that greatly facilitates an
accurate diagnosis of a health condition.
Detection Of Genetic Diseases:
Genetic diseases are generally produced by
single recessive mutagen. Identification of
the gene responsible for genetic disease is
very important.
The foetal cells are used for detection of
genetic disorder.
Treatment of disease utilizes a wide variety of preparation
of both biological and abiological origins.
 Products From Non-Recombinant Organisms:
• Microorganisms
• Plant cell cultures
• Animal cell cultures
 Product From Recombinant Organisms:
• Genetically engineered microorganisms. Ex: production of
human insulin, production of human growth hormone.
• Animal cell cultures. Ex: HGH, tissue plasminogen
activator, erythropoietin (anemia), blood clotting factor 8
(Haemophilia).
• Transgenic plants. Ex: Bt cotton, Bt corn, golden rice.
BT CORN
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Introduction of a normal functional gene into
cells which contain the defective allele of
concerned gene with the objective of
correcting a genetic disorder or an acquired
disorder.
It also includes the attempts to cure any
disease by the introduction of a cloned gene
into the patient.
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Identification of the gene that plays a key role
in the development of genetic disorder.
Determination of the role of its product in
health and disease.
Isolation and cloning of gene.
Development of an approach for gene
therapy.
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Germ-Line Gene Therapy
Somatic Cell Gene Therapy
Additional/Augmentation Gene Therapy
Targetted Gene Transfer
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Germ cells i.e. sperms or eggs are modified
by the introduction of function genes which
are integrated into their genomes.
The change due to therapy would be heritable
and would be passed onto later generations.
The gene is introduced only in somatic cells
especially of those tissues in which expression
of the concerned gene is critical for health .
 This therapy eliminates the symptoms of the
disorder but this effect is not heritable.
• Two divisions:
1. Addition/Augmentation Gene Therapy
2. Targetted Gene Transfer
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The functional gene is introduced in additon to
the defective gene endogenous to the cell i.e. the
modified cells contain both the detective as well
as the normal copies of the gene.
There were two approaches to augmentation
therapy.
The first approach was used in the first two
patients on whom gene therapy was detected to
correct the genetic disorder called SCID
syndrome produced by ADA defeciency.
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Normal ADA gene copies were produced by
cloning.
They were packed in defective retrovirus,
most of the viral genes were replaced by the
ADA gene.
Lymphocytes were isolated from the patients.
The recombinant retroviruses were used to
infect the lymphocytes.
The infected cells expressing the ADA Gene
were injected back into the pateint.
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The second approach is the direct injection of
DNA into the tissues either as protein
complexes or even as naked DNA into muscle
or skin.
These cells take up DNA and express the
gene product.
It uses homologous recombination to replace the
endogenous gene with the functional introduced
gene.
 The first case of such a gene transfer was used to
disrupt the human Beta- globin gene in cultured
cells.
 Can be used either to inactivate a functional
endogenous gene or to correct a defective one.
 Two types of vectors employed:
• Insertion vector
• Replacement vector
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Who makes the decision that a given individual should be tested?
Should the individual be informed about the findings from the
test?
Should the result from the genetic tests be made available to
insurance companies, employers etc. ?
Even when the individual has the mutant allele responsible for a
genetic disease, what is the likelihood that this allele will be able
to express itself?
If a foetus has a genetic disease that will become manifest at the
age of , say, 50 years, should the foetus be aborted?
There is a genuine fear that individuals having genetic disorders
may be discriminated against
There are doubts that the result from genetic testing may not
always be reliable.