Genetic engineering of plants - HelhaPHL2010-05 - home

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Dec 12, 2012 (4 years and 10 months ago)

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Projectleader PHL : E. Wirix


Projectleader HELHa:
J. Schmitz


specialization : Biotechnology












Intermediate report

Genetic engineering of plants for the
production of medicines

Start date

:











Final

date

:


11
-
10
-
20
10










15
-
11
-
2010







Group 5:

Iris Hensen




Emanuel
Casagrande

Jan
-
Pieter Ploem



Thibaut Gabriel

Ilse Timmermans

Projectleader PHL : E. Wirix


Projectleader HELHa:
J. Schmitz

Inhoud

Introduction

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3

General: Genetic engineering

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..................

4

What’s genetic engineering?

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...............

4

History

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.................

4

Techniques

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................................
..........

4

Recombinant DNA
-
molecules
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................................
.........

4

Eukaryotic

cloning and expression systems

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....................

4

Genetic engineering of plants

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5

Transformation

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....

5

Dicotyledonous plants

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5

Monocotyledonous plants

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6

Modifying plants

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.

6

Hepatitis B

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6

History

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6

Contagion and pathogenesis

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6

St
ructure of Hepatitis B

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......

Error! Bookmark not defined.

Vaccines

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7

History

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7

New vaccines

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.......

7

How do they work?

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8

Tobacco and hepatitis B

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8

Potatoes and hepatitis B

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9

Comparison genetic engineering medicines and normal medicines

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10

conclusion

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10

References

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Error! Bookmark not defined.

Adapted planning

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12




Projectleader PHL : E. Wirix


Projectleader HELHa:
J. Schmitz

Introduction

Since the beginning of the
earth, humans use plants.
Plants exist even longer
than humans and we are not
still aware of all their
opportunities. Scientists and
people who are interested
by these beautiful things
present in the wil
d life try to
understand how these
plants operate. More and
more, they discover a large
variety of species and the
different effects of each
plant. Still, these days not all
species of plants are
discovered.
This article is going about
the genetic engineer
ing of
plants and making
medicines from it.

The
plants that will be compared
in this article are the tobacco
and potato plant to produce
a vaccine against Hepatitis
B.
Medicines are always
evaluate and we develop
drugs with the most natural
products
.
The
development
in science is also in
progress and we are able to
modify some genetic
aspects. Geneticists are
very advanced in the field of
modifying DNA chain.

They develop new
techniques and methods
every day to transfer genes
to an organism to another.

H
ow does the genetic
process work ? When wer
e
these techniques developed
?
Which are the bacteria
used to develop genetic
modification ?

Which plants
are used to make
medicines?...Most of the
questions will be answered
in this article.


General: Genetic engineering
What’s genetic
engineering?

Everyone knows Dolly the
sheep, the first cloned full
-
grown animal in the world. For
a lot of people, it was the first
acquaintance with genetic

engineering. However, genetic
engineering is not a new
concept, it already exists for a
lot of years.


G
enetic engineering refers to all
techniques that artificially move
or transfer genes from one
organism to another, to produce
new or modified
organisms.
The target material is the
deoxyribonucleic acid (DNA)
molecule found in all living cells
of organisms, where genetic
information is stored.

(J.Craig Venter Institute 2004)

Hist
ory

Genetic Engineering first
appeared in 1972, nineteen
years after the discovery of the
DNA structure. It was Paul
Berg, an American scientist,
who produced the first DNA
-
recombinant molecule.
Recombinant DNA is a type of
DNA that is artificially created

by inserting a strand or more of
DNA into a different set of DNA.
Later, in 1976 they bred the first
genetic modified mice. 10 years
af
ter the
mice, scientist approve
the release of

the first
genetically engineered crop, a
gene
-
altered tobacco. These
days
, genetic modification is
one of the most important
subjects in the biotechnology.

(E.Wirix 2010;J.Craig Venter
Institute 2004)

Techniques


Recombinant DNA
-
molecules

When a DNA
-
molecule consists
of DNA coming fro
m different
sources, It is called
a
recombinant DNA
-
molecule.
Genetic modification can be
applied in bacteria, plants and
in animals.
The process in
plants will be described more in
detail in chapter 2.

Restriction
-
endonucleases cut
the genomic DNA in little
fragments. This enzymes
recogni
ze DNA
-
sequences from
4 to 8 nucleotides long. So, a
certain DNA
-
molecule will
always be cut by

a certain
restriction
-
enzyme in

the same
way.

(E.Wirix 2010)

After the cutting, we have some
restriction
-
fragments. Each
fragment will
be inserted in a
carrier molecule, which is called
a vector.
A vector can be: a
plasmid,

bacteriophages,
viruses or
little artificial
chromosomes.

The

most
restriction
-
endonucleases split the DNA in
a certain way that the
fragments have a single
-
stranded piece at the 3’ or 5’
end. These ends are called the
‘sticky
ends’. Sticky ends can
interact with sticky ends from
other DNA molecules which are
cut with the same restriction
-
enzyme.

Other enzymes that
split the DNA create blunt
ends
1
.
This clutch can be made

permanently by another
enzyme, DNA
-
ligase.




1

blunt end means that the cut
section does not overlap




Afterwards, t
he recombinant
DNA
-
molecule will be inserted
in a living host cell where they
replicate(cloning).

(E.Wirix 2010)

Eukaryotic

cloning and
expression systems

These days, it’s possible to
develop recombinant DNA
-
molecules which will be
inserted in the genome of
multicellular

organisms. When a
zygote
2

transform with the
strange DNA, it will develop in
an organism which conta
ins the
recombinant DNA in

all

cells. If
we breed with these organisms
we can get transgenic
organisms, which contains the
recombinant DNA in all his
cells
.


Plants specific techniques will
be explained in the next
chapter.

(E.Wirix 2010)





2

A zygote is a term to refer to
the
cell

as a result of the fusion
of two
haploid

nuclei during
fertilization

until the first
cleavage
.

1

Simple version of
r
ecombinant DNA
technique
(national health museum
2010)


Genetic engineering of plants


Genetic engineering is a
technique used to introduce
desired traits into a chosen
organism. To achieve this the
scientist has to insert a specific
gene which will encode for a
protein that is responsible for
the expression of a

certain
defined trait. This insertion
followed by the expression of a
new feature is called
‘Transformation’.

It is possible to transform plants
due to their totipotent
3

nature
.
This means that if one

cell is
adjusted, all the cells of the
plant will hav
e the new gene.

Some examples of new traits
are:

herbicide tolerance, drought
tolerance, resistance to
pathogens and insects. But it is
al
so possible to insert a gene
that

is responsible for higher
nutrition values or for the
production of certain product
s
that can be of interest.

The gene used to introduce the
traits can be of any origin.
There is only one condition, the
trait has to be compatible with
the host organism.

To be certain that the plant is a
modified organism the desired
transgene will be acc
ompanied
by a herbicide/antibiotic
resistance inducing gene. By
adding the herbicide or the
antibiotic, to which the modified
plant should be resistant, to the
nutrition medium the scientist
can check if the transformation
worked because only the plants
wi
th the right gene will be able
to grow. The first generation of
transformed plants has to be
grown on a gel
-
like medium on
a petri dish, It is easier to
control the environment and the
growth factors in which the
transformation can take place
and allows th
e cell to



3

Ability to regenerate from a
single cell to become a full grown
plant.

regenerate. Further generations
could be cultivated on the field.
This however is not yet
commonly approved by law.

(J.A.Thompson 2009)

Transformation

To insert this transgene in the
DNA of the plant the scientist
can chose between a few
techniques, one more
favourable than the other.

There is a difference between
the

insertion of a gene in
dicotyledonous and
monocotyledonous plants.

Dicotyledonous plants

There are a few techniques
used to insert a gene in the
genome of the plant.

(J.A.Thompson
2009)


Transformation

by
A.

tumefaciens

There is more and more
progress

in the world of plant
genetic manipulation,
A.
tumefaciens

still is a major
method of choice for
transforming plant cells.
Despite these progresses, we
always work on this bacteria to
a better understanding of the
mechanism of gene transfer . A
lot of important cereals have
now been transformed using A.
tumefacie
ns
(Newell, 2000).


A. tumefaciens

seems to be the
best discovery to realize DNA
implant into plant genomes.
Bacterial vectors such as
Eschericia coli

have already
been used successfully as
vectors in microbiology (Kikkert
et al.
, 1999) ;

that is now
exten
ded to the world of
botany. These techniques have
been applied on several plants,
such as lettuce (Curtis, 1995),
rice (Hiei, 1997) and
tomatoes

(Tzfira
et al.
, 2002). This proves
that

methods with direct gene
transfer,

are not the only way
for transformin
g important crop
plants (Newell, 2000). The
transformation by
A.
Tumefaciens
permits
insertion
of specific DNA
-
sequences
into
the
plant

s genome. This is a
good reason to
choose this
method when compared with
other methods (see below)
although the success

rate is not
100% (Gheysen
et al.
, 1998).
There are however some valid
arguments against the validity
of
A. tumefaciens

mediated
transformation.

Dicotyledonous plants are
plants

which develop from two
cotyledons in the seed. They
can be recognized by the
branching veins in their leaves.
Dicots of commercial value
include many horticultural
plants such as petunias, and
crops such as tobacco,
tomatoes, cotton, soybean and
potatoes
.

Tobacco, due to its
ease of transformation, initially
became the workhorse of plant
genetic engineering, but more
recently the common wall or
thale cress,
Arabidopsis
thaliana
, has become very
popular. It has the advantage of
not requiring tissue culture
during its transformation.

Tomatoes have been
transformed to delay their
ripening, cotton to insect
resistance and herbicide
tolerance, soybeans to
improved oil quality and
herbicide tolerance, and
potatoes to resist viruses.


Other methods

For many years
the only
alternative to
A. tumefaciens
-
mediated transformation was
the direct uptake of naked DNA
by plant protoplasts, achieved
by electroporation or mediated
by polyethylene glycol (PEG).

This depends on the ability of
plants to regenerate from
protoplas
ts, which varies
considerably between species.
For example, there are

many
parameters to be successful
with PEG technique (such ion
concentration, molecular weight
and concentration of PEG,
physical configuration of nucleic
acid,…). Linearized double
-
stran
ded plasmid DNA
molecules are expressed and
integrated most efficiently.

Now the most widely used
alternative to transformation by
A. tumefaciens
is biolistics.
Other (marginals
) techniques
exists, including pollen co
-
cultivation, microinjection of
somatic embryos and liposome
fusion with protoplasts.

(J.A.Thompson 2009)

Monocotyledonous plants

These plants require a different
approach to insert a gene.

Biolistic transformation


This technique of particle
bombardment, or biolistics, is
the most versa
tile and effective
way of creating many
transgenic plant species,
including elite lines.



When this technique is used an
isolated DNA
-
fragment has to
be coated on a metal particle.
Currently gold and tungsten are
often used metals because of
their inert nature.

The coated particles are shot
into the cell with a gene gun, a
biolistic device dri
ven by a gas,
Helium for example.

When the particles pass
through the cell there is a
chance that the new gene will
be introduced in the genome of
the plant. Previous tests had a
success rate of 54%. This
chance is dependent on several
factors like humidit
y, duration
temperature, composition of the
chosen particle and the form of
the used DNA
-
fragment.

Transformation by
A.
tumefaciens

This method is used less
frequently but when it can be
used it is the preferred
technique. The problem here is
that some imp
ortant monocots,
such as: maize, rice and wheat
are resistant to
A. tumefaciens

and cannot be transformed.
There have been some efforts
to alter the
A. tumefaciens

to
make it able to infect these
monocots. Until now the
greatest success has been with
rice.

(
J.A.Thompson
)


Modifying plants

Has to be completed



Hepatitis B
Hepatitis B is an infectious
illness ca
used by hepatitis B
virus
which infects the liver of
primates
, including humans,
and causes
an inflammation
called hepatitis. Originall
y
known as "serum hepatitis",

the
disease has caused epidemics
in parts of Asia and Africa, and
it is endemic in China.[2]
about

a third of the world's population,
more than 2 billion people,
have been infect
ed wi
th the
hepatitis B virus.

This includes
350 million chronic carriers of
the virus
. There’s no
relationship between Hepatitis
A and C with B.

(LCI 2008)

History

In 1885, a number of cases of '
Serumhepatitis’ were located in
Bremen (Germany) after
administered the variola
vaccine (that contained human
lymph) to workers. Just in the
years forty and fifty
of the
previous century a clear
distinction was made between '
serumhepatitis' and '
contagious Jaundice' on the
basis of transmission
experiments
4
. In search of
genetic differences, scientists in
1965 found a particular protein
in blood of Aboriginals
that they
called ' Australian
-
antigen'. This
proved to be later the hepatitis
B
-

surface antigen (HBsAg).
The introduction of safe
effective vaccines
(plasma
-
prepared in 1983, and

DNA
vaccines in 1986
) have
increased the possibilities for
worldwide suppre
ssion of
hepatitis b virus (HBV) to
introduce vaccination programs
on child age.

(LCI 2008)




4

Experiment that
examines

the
transfer

of
an infectious disease
from one infected individual to a
susceptible individual
.

C
ontag
ion and
pathogenesis

Hepatitis B is spread mainly by
exposure to infected blood or
body secretions. In infected
individuals, the virus can be
found in the blood, semen,
vaginal
fluid
, breast milk, and
saliva. Hepatitis B is not spread
through food, water,
or by
casual contact.

Hepatitis B also
may be spread from infected
mothers to their babies at birth
(so
-
called 'vertical'
transmission)

After entering
,

the
Hepatitis B
virus
is spread through the
blood through the body
. By
adherence to specific sensors
the

virus is incorporated in liver
cell but
doesn’t
damage

these.
The immunological response of
the
immunocompetent host
to
presence of the Hepatitis B
virus,

determine
s the clinical
picture
.
C
ells that humoral

and
cellular processes of the
immune system fulfill and also

contain the virus antigen, are
removed.
. As a result of a
strong immune response at the
acute stage
,
an
acute

hepatitis
can
show up
.
If the immune
response reacts as needed, the
virus is managed
.

When the
immune system doesn’t
response as needed,
a chronic
infection can arise.


The incubation period lasts 4
weeks to 6 months (usually 2 to
3 months).
The
variation depends on
the amount of virus in
the inoculum, the route
of infection and host
factors such as host
immunity.

The virus particle, (virion)
consists of an outer lipid
envelope and an icosahedral
nucleocapsid core composed of
protein. The nucl
eocapsid
encloses the viral DNA and a
DNA polymerase that has
re
verse transcriptase activity.

The outer envelope contains
embedded proteins which are
involved in viral binding of, and
entry into, susceptible cells.
The virus is one of the smallest
envelope
d animal
viruses, with
a virion diameter of 42 nm, but
pleomorphic forms exist,
including filamentous and
spherical bodies lacking a core.
These particles are not
infectious and are composed of
the lipid and protein that forms
part of the surface of the vi
rion,
which is called the surface
antigen (HBsAg), and is
produced in excess
dur
ing the life cycle of
the virus.

(LCI 200
8;Nettleman M.
et al. 2010;Renaldo E.
and ph D. 2000)

Vaccines
Our immune system
has the important task
to defend the body. It
attacks the pathogens
and eliminate them.
Where the defense
misconduct,

a vaccine
is the solution. A
vaccine is a remedy
that encourage a
immune response
without making the
human sick. Most
vaccines are
administered in the form of a
shot or a liquid that is
consumed by mouth. However,
some vaccines are inhaled as
aerosols or
powders.

(Ri
jkers G. et al. 2009)

History

The vaccine exists longer than
the most people think. In 1800,
Edward Jenner was the first
one who experimented with
terms like immunology and
vaccination. He saw that
milkmaids, which had smallpox
infection from cows by
milking
cows, receive no human
smallpox. Jenner thought that
people could made immune to

the human smallpox by infect

them first with cow smallpox.
His way of thinking was right.
But the people were suspicious.
However, after Jenner his
results, a big vacc
ination
campaign was set. In the fifties,
doctors started to vaccinate
children against diphtheria,
whooping
-
cough, tetanus and
polio. These days, 95% of the
Belgian children is vaccinated.

New vaccines

Recently we see more and
more the appearance of new
v
accines in the pharmaceutical
market. The improvement of
classical biochemistry,
recombinant DNA
technology, peptide
synthesis, molecular
genetics and protein
purification has laid the
foundations for the
development of new,
genetically modified
vaccines.

New vaccines
have a lot of
advantages, but they
have also
disadvantages.


First, the new generation
vaccines, would be cheaper,
safer, fewer side effects and
more effective. But a
disadvantage of live vaccines is
to ensure that the virus is
sufficiently a
ttenuated to not
cause disease but still respond
to the immune sy
stem to
produce these antigens.
Another disadvantage is the
possibility that the vaccine virus
can recombine with other viral
strain.

(Rijkers G., Kroese M., &
Kallenberg M. 2009)

Has to be completed

2
: illustration of hepatitis B virus (university of
washington 2008)


How do they work?

The vaccines can be made of
living weakened micro
-
organisms or dead micro
-
organisms. By dead micro
-
organisms it’s important that the
antigen, which the protective
immune response must be
formed, stays intact. Examples
of working vaccines
that exists
of dead micro
-
organisms are
the bacteria
Bordetella
pertussis, Salmonella typhi

and
Vibrio cholera
.

The living weakened micro
-
organisms form more powerful
vaccines than the vaccines
made of dead micro
-
organisms.
Weakening or attenuating
means t
hat by different
techniques a variant has been
made with strong reduced
malice. Attenuating can be
reached by high temperatures,
bred micro
-
organisms in
another animal species or by
recombinant techniques. With
recombinant techniques it’s
possible to use
micro
-
organisms from other animal
species and put relevant
antigens into it for the vaccine.
After this they put the micro
-
organism in other animal
species. There’re a two reasons
that a living weakened micro
-
organisms vaccine is more
effective than vaccin
es made of
dead micro
-
organisms. First of
all, the micro
-
organism can
multiply himself and confront
the immune system with a
higher dose that’s longer
present. A second reason is
that in case of viral living
vaccines the naturally target
cells can be infec
ted. Of
course, dead viruses can’t
infect the host cell and multiply
himself. So the immune
response that’s been caused by
vaccines made of micro
-
organisms is better to compare
with the natural immune
response. However, living
weakening vaccines are
disco
uraged by patients with a
less strong defense because a
potential danger provides that
attenuated micro
-
organisms go
back to his not
-
attenuated
situation. It gets back to the
originally malice. Examples of
living weakened vaccines are
parotitis

viruses, me
asles
viruses and rubella virus.

If it’s known to which part from
a micro
-
organisms manage the
protective immune response,
there’s a possibility to use only
this antigen in the vaccine.
These vaccines called
subunitvaccines. Examples of
this vaccine is th
e hepatitis B
and tetanustoxoïd vaccine.

Some chemicals, like
aluminiumsalts, amplify the
antibodies response to a certain
antigen. These chemicals are
called adjuvants. Adjuvants
amplify at different methods the
immune response. First they
can concentrate

the antigen at
one place, which provide an
optimal absorption by antigen
-
presenting cells
5

and activation from the immune
system. Activation from the
immune system can now
happen and it leads to form
from little granulomas
6

where



5

Cells that are crucial for a good
function of the human immune
response. The function from these
cells is to present a
n antigen to the
defence cells.

6

a medical term for a roughly
spherical mass of immune cells
that forms when the immune
system attempts
to wall off
substances that it perceives as
foreign but is unable to eliminate.




the antigen will be hold for a
long time. A second manner
how adjuvants can work, is the
optimalisation from a signal
which means an increased
expression from co
-
stimulatory
molecules by antigen
-
presenting cells and secretion
from cytokines. This happened
especially by activation from
toll
-
like receptors (TLR’s)
7

at
antigen
-
presenting cells.

(Rijkers G., Kroese M., &
Kallenberg M. 2009)

Tobacco and hepatitis
B

The Tobacco plant or the
Nicotiana tabacum (scientific
name), is a perennial
8

herbaceous
9

plant that’s only
found in cultivation. It
commercially grows in a lot of
countries to be processed into
tobacco. The tobacco plant is
easy to recognize at his pink
flowers and big leaves.

(Anon 2008)


The first ever experimental
immunogenic protein that was
produced in plants, was the
hepatitis B vaccine in tobacco.
Since 19
89, antibodies (also
called plantibodies) can be
produced by plants. This give a
lot of possibilities in the passive
immunotherapy. Passive





7

proteins that play a key role in
the innate immune system. They
are single, membrane
-
spanning,
non
-
catalytic receptors that
recognize structurally conserved
molecules derived from microbes.

8

A perennial plant is a
p
lant that
lives for more than two year
s

9

A herbaceous plant is a plant that
has leaves and stems that die down
at the end of the growing season to
the soil level


immunotherapy means that the
human body doesn’t make the
antibodies by themselves, but
they are consummated from
ou
tside.

For the production of antibodies

against Hepatitis B in tobacco,
first
the plant must have the
Hepatitis B surface antigen.
This is a protein that is present
on the surface of the virus.
Therefore, recombinant
hepatitis B surface antige
n
must be in
serted in the plant.
This can happen with the help
of a bacteria, in this case

Agrobacterium
tumefaciens

which is a natural carrier of the
Ti
-
plasmid. This means that Ti
-
plasmid is a vector. The
Hepatitis B surface antigen will
be inserted in the Ti
-
plasmid
and forms a recombinant
hepatitis B surface antigen.
Now, they put the antigen in the
tobacco plant.
The plant brings
the recombinant antigen at
expression so the plant will start
making a lot of antibodies,
which are abbreviated
anti
-
HBsAg
, to defense himself
against this recombinant
hepatitis B surface antigen.
After this process, the leaves of
the plan
t will be harvested and
the antibodies will be extracted
from the leaves. Then the
anti
-
HBsAg

will be cleaned and are
now ready to make of a
vaccine.

Just as the potato plant, the
vaccine is only tested in mice.

T
-
cells, or also called the T
lymphocytes, a
re belong to a
group of white blood cells which
play an important role in the
immune response. They were
obtained from mice primed with
the tobacco
-
derived
recombinant hepatitis B surface
antigenic peptide that
represents part of the
determinant of hepatit
is B
surface antigen. The mice were
administer tobacco smoke for 3
days, 18 weeks or 28 weeks.
Mice exposed to smoke for 3
days or 18 weeks produced a
reduction in the magnitude and
the duration of the primary
immune response. Mice
exposed to smoke for 28
weeks
have a better immune
response. The results prove
that tobacco smoke extracts
stimulated immune responses
to tobacco leaf antigens in
mice.

Because, the test on mice
was very successful (the mice
become immune for hepatitis
B), the next big step is te
sting
the vaccine on humans.

(Diederick 2010;G.B.Sunil
KumarT. et al. 2007;I.Smets
2010;M.Keulenmans 2008;Ross
I. 2008)

Potatoes and hepatitis
B

The potato or Solanum
tuberosum

is a starchy tuber
originally from South America.
It’s cultivated all over the world,
and more than thousand
varieties are known but only a
fraction of this number are
cultivated commercially. Most of
all, the potato is used as food,
but in these days ful
l of
techniques, the potato has a
new goal. They are used to
produce medicines.

(S.E.Smith 2010)


If you have the choice

between
a needle in your arm and a few
lunches of (raw) potato chips
containing a vaccine, which
would you prefer?

The oral immunogenicity (how
strong it provokes an immune
response) of hepatitis B
recombinant surface antigen
(HBsAg) produced in yeast is
compared to the hepatitis B
recombinant surface antigen in
transgenic potatoes (not
cooked or processed).

Just like
the tobacco, Ti
-
plasmids from
the bacteria Agrobacterium
tumefaciens

are used to bring
the HBsAg in the potato plant
so that the potato create
antibodies. But in this case,
they don’t extract the
antibodies, they leave them in
the raw potato. Scientists ho
pe
that by eating raw potatoes,
you’re vaccinated against
hepatitis B.

So the scientists fed mice three
doses of raw potatoes
containing the hepatitis B
surface antigen (HBsAg) and
also gave them cholera toxin.

Cholera toxin is an oral
adjuvant, which is
used to
increase immune responses.

After three weeks, the mice
developed antibodies against
hepatitis B; this response
declined within weeks. But
when the mice were injected
with a low dose of a commercial
vaccine at this point ("low"
meaning not enough to

make
them immune), the antibodies
came back to very high levels.
Thus, the potato vaccine had
probably created memory cells
that the injection activated.

Transgenic plant material
containing HBsAg gave the
best response in mice (Best
induction of a primar
y immune
response in mice and
preparation of an additional
booster injection of HBsAg).
Protective levels of 10
milliunits/ml antibody is
achieved when the transgenic
HBsAg mice were fed with the
HBsAg
-
transgenic potatoes
produced HBsAg and you also
get a
strong long lasting
secondary antibody response.

The advantage of oral vaccines
are that it’s easy to use and
there’s a better control of

intake. There’s also a better
immune response at the level of
mucosa, wich is important for
pathogens that enter enter
ic,
respiration, or sexual systems.
They stimulate the humoral
immunity that is based on
antibodies. And because the
tradition vaccine is very
expensive : edible crops can be
produced at low cost and can
spot out in areas where the
vaccine is needed.

The n
ext step will be to test the
effects of the potato hepatitis
vaccine in humans. This testing
has already been done with
edible vaccines against the
Norwalk virus and against
pathogenic forms of E.coli,
which both cause diarrhea.
Ultimately, a cheap plant
v
accine for hepatitis B could
help the two billion people who
are infected, many of them in
developing countries.

The existing vaccine to prevent
HBV infection is a
biotechnology product that falls
in the category of “subunit
vaccines.” The gene encoding
th
e hepatitis B surface antigen
(HBsAg) is expressed in yeast
cells grown by fermentation; the
cells are broken, the protein is
collected, and the HBsAg is
caused to refold by chemical
treatment to yield virus
-
like
particles that can be formulated
for inject
ion. However, it is
technology
-
intensive so it’s very
expensive.

(C.J.Arntzen 2001;G.B.Sunil
KumarT., R.Ganapathi, &
V.A.Bapat 2007)


Comparison genetic
engineering
medicines and normal

medicines


H
as to be completed

conclusion

Has to be completed




References


Tabaksplant. 2008.

Ref Type: Online Source

C.J.Arntzen.

Oral immunization with hepatitis B surface antigen expressed in transgenic plants .
2001.

Ref Type: Online Source

Diederick. Biotechnologie. 2010.

Ref Type: Unpublished Work

E.Wirix 2010, "Biotechnologie,"
In Van Gen tot Populatie, deel 1
.

G.B.Sunil K
umarT., R.Ganapathi, & V.A.Bapat 2007,

Production of Hepatitis B Surface Antigen in
Recombinant Plant Systems: An

Update
.

I.Smets. Biotechnologie Planten.
2010.

Ref Type: Slide

J.A.Thompson 2009,
Genetic Engineering of plants
.

J.Craig Venter Institute. Genetics and Genomics Timeline. 2004.

Ref Type: Online Source

LCI 2008.
Hepatitis B.

M.Keulenmans. De terugkeer van tabak. nwt . 2008.

Ref Type: Magazine Article

national health museum. Recombinant DNA technique. 2010.

Ref Ty
pe: Art Work

Nettleman M., MD, MS, & l Mortada M. Hepatitis B. 2010.

Ref Type: Online Source

Renaldo E. & ph D. 2000.
Genetically modified organism: it's implications to food safety and
consumers protection
.

Rijkers G., Kroese M., & Kallenberg M. 2009.
Immunologie
.

Ross I. 2008.
Medicinal plants of the world
.

S.E.Smith. What's a potato? 8
-
9
-
2010.

Ref Type: Online Source





Adapted p
lanning


Week

Date

Task

Remarks

Week 1

20 sept.


27 sept.


-

decide what we’re


going to put in the


article + start to write


the work plan

OK

Week 2

27 sept.


4 oct.

-

correct the work plan

-

continue writing on the


work plan

OK

30 sept.

Meeting 1

OK

Week 3

4 oct.


11 oct.

-

discuss the final work


plan

-

select the most


important pieces out of


the collected


information.

-

discuss the subject


OK

7 oct.

Meeting 2

OK

Week 4

11 oct.


18 oct.

-

going to search some


information in the


libraries of our school.

OK

14 oct.

Meeting 3

OK

11 oct.

Deposit final
workplan

OK

Week 5

18 oct.


25 oct.

-

everybody write his


piece

Because we had some
trouble by finding
information about
Hepatitis B, we’ve
decided to change the
subject to Hepatitis B.

21 oct.

Meeting 4

Change of

p
ermanent
tasks

(
absence

Ilse )

Week 6

25 oct.


1 nov.

-

unifying all parts and


discuss about it

Everybody star
ts

to write
his piece.

28 oct.

Meeting 5

OK

Week 7

1 nov.


8 nov.

-

discuss the finished


intermediate report

-

correct each other’s


parts if necessary

E
veryone continues to
write his
own
piece
.

4 nov.

Meeting 6

9 nov.

Week 8

8 nov.


15 nov.

-

correct the


intermediate report

Unifying all parts, discuss
about it

Correct the intermediate
rapport

11 nov.

Meeting 7

No meeting because of
Armistice

Week 9

15 nov.


22 nov.

-

writing further on the


intermediate report

-

correct where


necessary

OK



18 nov.

Meeting 8


15 nov.

Deposit intermediate report

OK

Week 10

22 nov.


29 nov.

-

Discuss the final report

-

read again the final


report

OK

25 nov.

Meeting 9

OK

Week 11

29 nov.


6 dec.

-

read again final report

OK

2 dec.

Meeting 10

1 dec

3 dec.

Deposit temporary report

OK

Week 12

6 dec.


13 dec.

-

read again final report


9 dec.

Meeting 11


Week 13

16 dec.

Hand in final article


Week 14

23 dec.

Presentation