In this lecture, Prof. Mohamed Labib Salem, Prof. of Immunology, Faculty of Science, Tanta University, Egypt presents information on the role of animals in proofing ideas in bench and make it available to clinical trials. The lecture van useful for both undergraduate and postgraduate students in genetics, molecular biology and biomedical sector.

1. Biotechnology and LABORATORY
ANIMALS
Prof. Mohamed Labib Salem
For 4th Year Students
Industrial Biotechnology
Faculty of Science, Tanta University, Egypt

3. Because of biomedical research both
humans and animals now have:

8. S
ome of the many health problems affecting
both humans and animals include:
 glaucoma
 diabetes
 bronchitis
 leukemia
 deafness

10. Phase II study
Phase III study
In vitro
models
Preclinical Studies
Phase I study
Industry
(Market)
BENCH
CLINIC
Biotechnology Phases of Drug Discovery
From Bench to Industry

11. Biotechnology
phases
of
drug
discovery
from
bench
to
industry

12. 5
4
3
2
1
Establish Effective and Toxic Doses
Screen the Drug in the Assay
Develop a Bioassay
Indentify a Drug Target
Biotechnology Phases of drug discovery
From Bench to industry

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What are the Alternative tests to
animanls?
Must undergo validation procedure, provided by
ICCVAM (Interagency Coordinating Committee on
the validation of alternative methods). Every new
alternative method is peer reviewed by an
international group of experts, who are not
financially interested in the results. For some
time both methods can be used simultaneously.

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What are the Alternative tests to
animals?
According to ECVAM (European Centre for
the Validation of alternative methods) 21
scientifically verified alternative methods
(namely tests of phototoxicity, skin
irritability, embryotoxicity, pyrogenity) are
approved at present time.

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• Neutral Red assay:
examined substance is added to the culture together with contrast
dye which is absorbed by living cells only.
• HeLa cells:
an immortal cell line used in oncological research derived from
cervical cancer cells taken from Henrietta Lacks 1951.
• 3T3 NRU phototoxicity test:
tested substance is added to cell cultures in various concentrations,
then UV radiation is applied
• EYETEX screen test
protein solution prepared from beans – replacement of DRAIZE test
of eye irritability. Destruction caused by the chemical leads to
opacification of the solution.
Examples of in vitro methods

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Test of mutagenicity by Ames’s test using
Microorganisms
1. Tested substance is added to agar with
Salmonella typhimurium with defective gene for
histidine synthesis.
2. If the substance is mutagenous, it causes reverse
mutation and the bacteria became able to
reproduce → bacteria survives.
3. Number of bacterial colonies is proportional to
mutagenous potential of the substance.
Examples of in vitro methods

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• Generalizing models, quality of the prediction
depends on the quality of input data
• During making the model replacing use of
laboratory animals, it is necessary to use
numerous animals to acquire enough data
fore estimation which is derived from the
model has to be verified by an experiment.
Computer and mathematic models: in
silico methods

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Tests in lower animals of lower ontogenetic
stadium
• Chicken embryo – replacement of DRAIZE test;
embryonic membranes are vascularized but
without inervation
• Heddles – tests of LD50
• eggs of African clawed frog (Xenopus laevis) –
tests of mortality, malformations, growth inhibition
More alternative models

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The most important species of laboratory animals

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• Test of toxicity of xenobiotics:
Reduction of number of animals, health setback
is evidence toxicity and test is terminated.
• Eye irritability
is not examined when the substance irritates the
skin or when the substance is a potent acid or
alkali (in such cases eye irritability is expected)
More alternative models

24. Almost all lab.
Animals belong to
mammalia class

35. https://www.jax.org/

37. www.criver.com

38. www.taconic.com

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1. Isogenic
genetically defined strains.
(isogenicity= genetic uniformity of all
individuals)
2. Non-isogenic
genetically undefined strains
1. Genetically semi-defined strains
GENETICS OF LABORATORY ANIMALS

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• Isogenic (Inbred) strains
• Coisogenic strains
• Congenic strains
Isogenic strains

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 Source: Obtained by close breeding for more than 20
generations (brother + sister or offspring + one of
the parents)
 Homozygosity: higher than 98 %.
 Isogenicity, phenotype uniformity (low variability of
reactivity), usually low fertility, disposition to
diseases
 Advantages: homogenous statistical set, lower
number of individuals is sufficient
 Disadvantages: a risk, that the findings are strain-
specific and are not valid for other strains,
Isogenic (inbred) strains

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 Coisogenic strains (mutant strains):
Strain differs from the original strain only in one gene, in
which a mutation occurred
 Congenic strains:
Strains originated by cross-breeding of two strains and
following back-cross- breeding with one of the original
strains (at least 10 times, selection of some specific
feature)
presence of specific genes of one strain on genetical
background of the second strain
Isogenic strains

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Recombinant-inbred strains
crossing of 2 strains, the hybrids give origin of new lines which are then
crossed brother x sister, what leads to establishing of a new strain
Rekombinant-congenic strains
crossing of 2 strains followed with 3 back-crosses to one of the original
strains and inbreeding with crossing brother x sister (at least 14 times)
Consomic strains
a complete chromosome of one strain is transferred on the background
of the second strain with back-crosses (similarly as for individual genes
in congenic strains, but the process is more complicated)
Isogenic strains

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• Definition: Genetically heterogeneous
population. crossbreeding is avoided.
• Features: higher variability of phenotype and
reactivity, higher fertility and resistance to
diseases.
• Advantages: cheaper and easier production,
the findings have more general validity
• Disadvantages: less homogeneous set,
higher number of animals is necessary
Non-isogenic strains: Outbred lines

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Genetically heterogeneous lines:
originate by crossing of several inbred
strains followed with breeding according to
principles of outbred population.
Outbred selected lines:
in an outbred population given phenotype
feature is selected
Non-isogenic strains: Outbred lines

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• Mutant animals
• Transgenic animals
• Knock-out animals
Animal models of diseases

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