2014 11 07_pegs_europe_lisbon_ritala
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Transcript of 2014 11 07_pegs_europe_lisbon_ritala
Molecular farming -
Recombinant barley-produced
antibody for the detection of the major
bovine milk allergen, β-lactoglobulin
PEGS Europe, Lisbon, 6-7.11.2014
Anneli Ritala
VTT Technical Research Centre of Finland
2 11/11/2014 2
Molecular farming - Plants as production host
Häkkinen & Ritala 2010. Medicinal compounds produced in plant cell factories. In: Medicinal Plant
Biotechnology. Arora, R. (ed.). CAB International. Oxfordshire, 13-35.
3
Molecular farming in barley @ VTT
T0 plant T1 plant T2 plant
T1 seeds T2 seeds T3 seeds
Etc.
Isolation and culture of microspores
Regeneration of DH-plants
DH0 plant
DH1 seeds DH2 seeds
DH1 plant
Etc.
Bombardment or Agrobacterium-
infection of immature embryos
Four or three rounds of selection
Regeneration
PCR-analyses of
regenerants
=
2nd stage:
Stable
expression
in barley
cell culture
3rd stage: Stable expression in barley seeds
4th stage:
Stable
expression
in doubled
haploid
barley
seeds
1st stage: Transient expression in barley cell culture (Pokko)
Ritala et al. 2008 Prot. Expr. Purif. 59:274–281; Eskelin et al. 2009 Plant Biotech J. 7:657-672
4
Background of milk
allergy and selection of
milk allergen specific
antibodies
5
BLG is one of the major allergens in
cow's milk
Cow´s milk allergy is most
prevalent in early childhood, with
reported incidences between 2-6%,
and decreases toward adulthood to
occurrence of 0.1–0.5%
b-lactoglobulin (BLG)
The treatment of milk allergy has mainly involved avoidance of the
allergen and symptom-specific treatment of allergic reactions
Milk allergic patients can be divided into two groups:
Heated milk-tolerant
Heated milk-reactive
6
Approximately 75 % of the children with reported milk allergy tolerate
heated milk in an oral food challenge
Heated milk-tolerant patients usually develop less severe reactions when
exposed to unheated milk i.e. indicating a milder food allergy phenotype
The incorporation of heat-denatured milk proteins into the diet accelerated
the development of unheated milk tolerance
These immunotherapeutic effects might therefore be gained via diet
modifications. Thus it would be useful to be able to process low BLG
content milk products which could be safely included to diet of milk
allergic patients
BLG-specific antibodies are needed for diagnostic, therapeutic, food
processing and quality verification applications
Some research findings and needs related
to BLG allergy
7
Member of the lipocalin family comprising proteins with transport functions
Possible physiological role as binding and transporting retinol
A and B variants based on sequence differences
--> Forms an AB heterodimer in cow's milk (up to 4 g/l)
Mw 18 kD (162 aa) with two disulphide bridges and one free cysteine, not
glycosylated
Sakai et al. Protein Sci. 2000 9:1719-1729
b-lactoglobulin (Bos d 5, BLG)
8
Cloning of IgE antibodies from a milk
allergic person
Validated patient blood samples (HUCH)
used for the cloning of IgE responses
Permission of the Ethical Committee of
HUCH granted for the cloning of the IgE
responses
CL CL CL CL VL CL
Lymphocytes
AAAA AAAA
AAAA AAAA
cDNA synthesis
PCR amplification
VH CH1 CH2 CH3
TTTT
5' Primer
3' Primer
VL CL
5' Primer
TTTT
3' Primer
Isolation of mRNAs
Cloning into phagemid vector
~10 6 Ab phages
VL VL VL VL ~10 6 Ab genes
VL VH
VH VL
Serum IgE levels and RAST of the different milk allergic patients
RAST (CAP) kU/l
Patient S-IgE (kU/l) milk BLG casein
1 237 3.4 3.7 1.4
2 1206 6.2 7.2 2.4
3 775 14.9 11.6 16.8
Jylhä et al. 2009. JIM, 350:63–70
Laukkanen et al. 2003, JIM, 278:271-281.
9
Selection of IgE antibodies
Recombinant IgE antibodies specific to cow's milk allergen, b-lactoglobulin (BLG)
Two different
selection
strategies Selection
with the
immobilised
BLG
Unspecific
elution
with low
pH
Isolation of
antibodies
recognising
the heat-
treated
BLG
Selection
with the
soluble,
biotinylated
BLG
Specific
elution
with
soluble
BLG
Isolation of
antibodies
recognizing
the native
BLG
Anti-BLG
scFv
D1/H2
Anti-BLG
scFv
A3/G1
Fab fragment
human IgG CH1 and CL regions
VH
CH1 CL
VL VH VL
scFv IgE VH and or VL
Production and purification
of D1 and A3 Fab fragments
Enrichment of bound phages
Jylhä et al. 2009. JIM, 350:63–70
10
0
20
40
60
80
100
120
0,0001 0,001 0,01 0,1 1 10
rela
tive
A4
05 (
%)
native
denaturated
D1 Fab
0
20
40
60
80
100
120
0,0001 0,001 0,01 0,1 1 10
rela
tive
A4
05
(%
)
native
denaturated
A3 Fab
Competitive ELISAs
BLG (µM) BLG (µM)
Native
Denatured
(15', 95oC)
Native
Denatured
(15', 95oC)
Binding properties of the IgE antibodies
Anti-BLG D1 Fab fragment
0
100
200
300
400
500
0 200 400 600 800 1000
time(s)
RU
1,23nM
2,47nM
4,94nM
9,88nM
19,75nM
39,5nM
79nM
Fab
fragment
KD (M) x10-9
D1 Fab 1.30 ± 0.66
A3 Fab 142 ± 88
The values are averages ± SD
of three (D1) or two (A3)
independent runs with seven
(D1) or six (A3) different Fab
concentrations.
The binding kinetics by BIAcore
11
30 kD -
20 kD -
D1 Fab A3 Fab
Immunoprecipitation of BLG from cow's milk
s1- casein -
BLG -
0' 15' 30' 60' BLG D1 Fab
+95oC ctrs
0' 15' 30' 60' BLG A3 Fab
+95oC ctrs
0
0,5
1
1,5
2
2,5
1 0,1 0,01 0,001 0,0001 0,00001 0,000001
BLG (g/l)
A405
D1
Sandwich ELISA
Detection limit
1-10 µg / l
BLG detection from cow's milk
* Immobilisation of the biotinylated D1 Fab fragment
onto SA-coated wells
* Addition of different amounts of BLG
* Detection using D1 scFv-myc and AP-conjugated
anti-myc Ab
12
The 3D structure of allergen-IgE immunocomplex
Niemi et al. 2007. Structure, 15:1413-1421
Niemi et al. 2008. Acta Crystallographica Section F64:25-28
Rouvinen et al. 2010. PLoS One, 5:1-9
13
Barley-produced BLG
specific antibody, D1
scFv
14 14
Construction of barley expression vectors
Use Constructs
Stable expression in
barley cell cultures after
nuclear transformation
UBI-I-ss-D1scFvb-His6-HDEL with hygromycin selection marker (pD1b02)
Production of transgenic
barley plants by nuclear
transformation
UBI-I-ss-D1scFvb-His6-HDEL with hygromycin selection marker (pD1b02)
GLUB1-ss-D1scFvb-His6-HDEL with hygromycin selection marker (pD1b03)
GLUB1-ss-D1scFvb-His6 with hygromycin selection marker (pD1b07)
Maize UBIQUITIN promoter and first intron (UBI-I) or
Rice endosperm-specific GLUTELIN promoter (GLUB1)
Arabidopsis basic chitinase signal sequence ss
D1scFv_b Single chain variable fragment of b-lactoglobulin-specific IgE D1 antibody,
b refers to codon usage optimization for barley, His6 to Histidine tag and
HDEL to ER retention signal
D1scFv_b_His6_(HDEL) ss Hyg selection marker P
P
Ritala et al. 2014. Transgenic Res. 23:477-487
15 11/11/2014 15
Agrobacterium mediated
transformation and selection
rounds
Transgenic callus clones
Transformation of barley to express BLG
specific antibody, D1scFv Isolation of
immature
barley
embryos
Transgenic barley plants expressing D1scFv
Transgenic barley cell cultures expressing D1scFv
16 11/11/2014 16
Barley cell culture clones expressing BLG
specific antibody, D1 scFv
D1 scFv accumulation in the five best producing barley cell culture
lines assayed by ELISA
17 11/11/2014 17
Barley cell culture clone expressing BLG
specific antibody, D1 scFv
0.8 – 1.2 mg D1scFv / kg (FW)
Stable production over 21d
Best harvesting time at 14d
Bio
ma
ss
(g
, F
W)
D1 s
cF
v m
g/k
g (
FW
) D
1 s
cF
v µ
g /
sh
ak
e f
las
k (
V=
25
ml)
Time (d)
Time (d)
WT
D1scFv clone
18 11/11/2014 18
Transgenic barley plants expressing BLG
specific antibody, D1 scFv
Construct Number of
infected
embryos
Proportion of embryos
giving transgenic T0 plants
(% of all infected embryos)
Number of
transgenic T0
plants
UBI-I-ss-D1scFvb-His6-HDEL 75a 5 (6.6) 29b
GLUB1-ss-D1scFvb-His6-HDEL 150 8 (5.3) 24
GLUB1-ss-D1scFvb-His6 150 15 (10.0) 46b
3 different 375 28 (7.5) 99
aOnly part of the calli was plated on regeneration. The main focus was in the production of transgenic cell culture lines bOne plant died before seed-set
A half-grain analytical procedure for the non-embryo part of the grain was
developed in order to screen the D1scFv accumulation levels
The embryo parts can be stored at +14°C for a month. Thus only the embryo
halves from best lines were propagated to generate the next generation plants
19 11/11/2014 19
Transgenic barley plants expressing BLG
specific antibody, D1 scFv
20 11/11/2014 20
Transgenic barley plants expressing BLG
specific antibody, D1 scFv
21 11/11/2014 21
Purification of BLG specific antibody, D1 scFv,
from barley grains
After IMAC purification:
1. LMW
2. Grain extract
3. Flow through
4. Wash buffer 1
5. Wash buffer 2
6. 50 mM imidazole elution
7. 75 mM imidazole elution
8. 100 mM imidazole elution
9. 200 mM imidazole elution
10. 500 mM imidazole elution.
After SEC:
1. Sample subjected to SEC
2. Flow through
3. LMW
4. - 10. Different fractions from SEC
D1 scFv
D1 scFv
Grain pool of 50 g - Accumulation level of 55 mg D1scFv / kg seeds
Purified barley-produced D1scFv functional in ELISA
22 22
Immunoprecipitation of BLG from cow's milk
using barley-produced D1 scFv
1. LMW
2. Commercial BLG
3. Purified D1 scFv
4. Native milk sample with D1
scFv-Co-Sepharose matrix
5. Milk sample after the heat
treatment with D1 scFv-Co-
Sepharose matrix
6. No milk sample with D1
scFv-Co-Sepharose matrix
BLG
23 23
Conclusions
Barley-based production system for BLG-specific antibody D1scFv established
Barley cell cultures served as a proof-of-concept
Reasonable production levels in barley grains with glutelin-specific
promoter combined with ER targeting and retention signals
Successful purification with affinity-based chromatography
Functionality of barley-produced BLG-specific antibody D1scFv verified
Ritala et al. 2014. Transgenic Res. 23:477-487
ACKNOWLEDGEMENTS:
Vanga Siva Reddy
Sadhu Leelavathi
Marja-Leena Laukkanen
Sirpa Jylhä
Kristiina Takkinen
Kirsi-Marja Oksman-Caldentey
TECHNOLOGY FOR BUSINESS