LU503901B1 - Anti-Shigella monoclonal antibody and use thereof - Google Patents

Abstract

The present invention relates to an anti-Shigella monoclonal antibody, in particular to an isolated antibody or antigen binding portion thereof including specific sequences that can bind to protein YhdP of Shigclla flexneri. The YhdP monoclonal antibody can be used to treat Shigella infection or detect Shigella flexneri in foods and clinical samples.

Description

Description 0503901

Anti-Shigella Monoclonal Antibody and Use Thereof

TECHNICAL FIELD

The present invention relates to an Anti-Shigella flexneri monoclonal antibody, and use thereof for ireating diseases caused by Shigella flexneri.

BACKGROUND

Shigella flexneri, also known as F's dysentery bacillus, is a non-motile, non-spore-forming, facultative anaerobic gram-negative bacterium that can cause bacterial dysentery clinically, and an inflammatory reaction of the intestine is an important feature of Shigellosis, mainly manifested as colon edema, ulcer and inflammation. About 99% of cases occur in developing countries, with high rates of infection and mortality in children and primates. There is a significant foodborne threat to public health.

Shigella flexneri is mainly transmitted by a fecal-oral route. Other possible modes of transmission may come from ingestion of contaminated food or water and subcutaneous contact with inanimate objects. An infection dose of Shigella flexneri is very low; and only 100-200 bacteria are required to cause clinical infection. However, in recent years, drug resistance to Shigella flexneri has been increasing, which brings great difficulties to clinical treatment. Therefore, it is necessary to further study a mechanism of resisting Shigella flexneri infection, so as to develop a new antibacterial agent for preventing Shigella flexneri.

A bacterial cell envelope is a first line of defense and contact with the environment and other organisms. Thus, the envelope is crucial for the survival and physiology of bacteria and is often a common target for antibacterial agents. Gram-negative bacteria have a multi-layered envelope separated by an inner membrane and an outer membrane (IM and OM, respectively). OM is a barrier to many antibacterial agents because its lipid structure is asymmetric, with phospholipids constituting 1 an inner leaflet and lipopolysaccharide (LPS) constituting an outer leaflet. Since lipid synthesis occurs- {503901 at the IM, phospholipids and LPS are transported through the cell envelope during growth, and assembled asymmetrically at the OM. How phospholipids are transported to the OM remains unknown. Studies have shown that YhdP participates in this process through an unknown mechanism.

YhdP belongs to the AsmA-like clan and contains domains homologous to lipid transporters. The data show that YhdP and its paralogs TamB and YdbH are redundant, but not equivalent, when performing basic functions in the cell envelope. Among the AsmA-like parahomologs, only the combined loss of YhdP, TamB and YdbH is fatal, and these proteins are required for OM lipid homeostasis and are proposed to be phospholipid transporters required for OM biogenesis for a long time. Gram-negative bacteria have the characteristic of having two membranes. À system required for gram-negative outer membrane biogenesis has been determined, but for a system required for the transportation of newly synthesized phospholipids from the inner membrane to the outer membrane,

YhdP protein is related to this process.

Silhavy et al. demonstrates that YhdP may form a hydrophobic channel between the inner membrane and the outer membrane where phospholipids flow, and Angela M Mitchell et al. demonstrates that

YhdP deletion results in a high level of vancomycin and SDS sensitivity, which is independent of the growth stage. À spontaneous inhibitory mutant of YhdP is isolated, which has loss-of-function mutations in an entero-bacterial common antigen (ECA) biosynthesis operon. Deletion of ECA biosynthesis genes inhibits the envelope permeability caused by deletion of YhdP, but is independent of the envelope stress response and interaction with other biosynthetic pathways, demonstrating that the inhibition is directly caused by removal of ECA. In addition, deletion of YhdP changes cellular

ECA levels, and it is found that YhdP and the ECA biosynthesis operon coexist in phylogeny. Cells produce three forms of ECA: ECA lipopolysaccharide (LPS), an ECA chain linked to a core of LPS;

ECA phosphatidylglycerol, a surface-exposed ECA chain linked to phosphatidylglycerol; and cyclic

ECA, a cyclized soluble ECA molecule found in a periplasm. It is determined that inhibition of the envelope permeability by YhdP deletion is caused by loss of the cyclic ECA, although YhdP deletion reduces the level of this molecule. Removal of the cyclic ECA from wild-type cells also results in change in OM permeability. Our data show that the cyclic ECA maintains an OM permeability barrier in a YhdP controlled manner. Therefore, deletion of YhdP disrupts the OM permeability barrier in a 2 periodic ECA-dependent manner, allowing harmful molecules such as antibiotics to enter cells. This- 503901 role of maintaining the envelope permeability barrier is to describe a phenotype of the cyclic ECA for the first time. Since a Gram-negative envelope is generally impermeable to antibiotics, a YhdP antibody is obtained in this application, and understanding a mechanism of YhdP to maintain the barrier and eliminate antibiotics may improve the delivery of antibiotics, which is further applied to the treatment of Shigella flexneri.

SUMMARY

For the above problems, the present invention aims to provide a hybridoma cell line capable of producing a monoclonal antibody against YhdP, a YhdP monoclonal antibody, and a preparation method for the antibody, and use of the antibody.

The present invention employs the following technical solution: in one aspect, an embodiment of the present invention discloses a hybridoma cell line capable of producing a YhdP monoclonal antibody, and a preparation method for the YhdP monoclonal antibody.

The method includes:

Step (1) immunizing an animal, i.e., Balb/c mice with purified recombinant YhdP protein as an immunogen,

Step (2) fusing myeloma cells SP2/0 with B lymphocytes of the immunized animal to obtain hybridoma cells;

Step (3) screening positive clones of specific hybridoma cells, performing cell cloning on the positive clones, and screening hybridoma cells stably secreting a YhdP monoclonal antibody, wherein screening the positive clones of the specific hybridoma cells is conducted by ELISA; and

Step (4) obtaining the YhdP monoclonal antibody.

Further, in the step (4), obtaining the YhdP monoclonal antibody includes: culturing the hybridoma cells stably secreting the YhdP monoclonal antibody in vitro, and isolating and purifying the resulting culture solution to obtain the YhdP monoclonal antibody. 3

An embodiment of the present invention also provides use of the YhdP monoclonal antibody described above for treatment of Shigella flexneri infection in combination with antibiotics.

A type of the monoclonal antibody of the present invention is identified as an IgG2b type by ELISA.

In one aspect, an embodiment of the present invention discloses an isolated antibody or antigen binding portion thereof, which binds to protein YhdP of Shigella flexneri, wherein the antibody or antigen binding portion thereof includes a heavy chain variable region including HCDR1 as shown in SEQ ID NO: 1, HCDR2 as shown in SEQ ID NO: 2, and HCDR3 as shown in SEQ ID NO: 3, and alight chain variable region including LCDR1 as shown in SEQ ID NO: 4, LCDR2 as shown in SEQ

ID NO: 5, and LCDR3 as shown in SEQ ID NO: 6.

In one embodiment, the heavy chain variable region (VH) of the isolated antibody or antigen-binding portion thereof has an amino acid sequence of SEQ ID NO: 7, and the light chain variable region (VL) of the isolated antibody or antigen-binding portion thereof has an amino acid sequence of SEQ ID

NO: 8.

In one embodiment, the isolated antibody or antigen binding portion thereof includes a heavy chain as shown in SEQ ID NO: 9 and a light chain as shown in SEQ ID NO: 10.

Provided is a nucleotide encoding the isolated antibody or antigen-binding portion thereof described above.

Provided is a vector, including a nucleic acid molecule capable of encoding the isolated antibody or antigen binding portion thereof described above.

Provided is a cell, including the vector described above. 4

Provided is a pharmaceutical composition, including the antibody or antigen binding portion thereof 7205901 described above.

A pharmaceutical composition including a YhdP monoclonal antibody is used for the treatment of

Shigella infection. A combination of the antibody and antibiotics can enhance the effect of antibiotics and avoid the problem of antibiotic resistance.

Provided is use of the isolated antibody or antigen binding portion thereof in the manufacture of a medicament for the treatment of Shigella infection.

The beneficial effects of the present invention are as follows: the method of the present invention uses the recombinant YhdP protein as the immunogen to immunize the Balb/c mice, and adopts a classical cell fusion technology to obtain the hybridoma cells stably secreting the YhdP monoclonal antibody. The YhdP monoclonal antibody secreted thereof can be used for treatment of Shigella flexneri infection in combination with antibiotics.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 Inhibitory effect of a YhdP antibody and a combination of the YhdP antibody and antibiotics on Sf301 replication;

Fig. 2 Immunofluorescence detection of localization after infection of a Shigella flexneri 2a strain 301; and

Fig. 3 Western Blot monitoring at Oh, 6h, 12h, 24h, 36h and 48h after infection.

DETAILED DESCRIPTION

The present invention provides an anti-Shigella flexneri YhdP antibody, a preparation method therefor, and use of the YhdP antibody for the treatment of Shigella flexneri infection. 5

The present invention provides a method for producing an anti-Shigella flexneri YhdP antibody 7503901 including the following steps of: fusing spleen cells of antibody-producing mice previously immunized with a Shigella flexneri whole cell lysate with myeloma B cells; culturing a hybridoma cell line to produce a monoclonal antibody, and fusing antibody-producing mouse spleen cells with myeloma B cells; and selecting a monoclonal antibody showing high specificity and affinity for Shigella flexneri.

The produced YhdP antibody is further sequenced to find that the produced antibody has a heavy chain including a region shown in SEQ ID NO: 9 and a light chain including a region shown in SEQ

ID NO: 10 or a portion thereof.

The present invention is further explained in the following specific embodiments which are intended to be illustrative only and should not be construed as limiting the scope of the present invention.

Embodiment

Embodiment 1 Bacterial strain

Shigella flexneri 2a strain 301, isolated from fecal specimens from patients with diarrhea in

Changping District, Beijing, designated as S. flexneri 2a str. 301 (abbreviated as Sf301). This strain was always used as a standard strain for a Shigella flexneri serotype 2a in China, and was provided by the Institute of Infectious Disease Prevention and Control of the Chinese Center for Disease

Control and Prevention.

Embodiment 2 Preparation of anti-Shigella flexneri YhdP monoclonal antibody (a) Preparation of YhdP antigen

The harvested Sf2a301 was resuspended in sterile water, treated with lysozyme at a final mass concentration of 20 g/L, and lysed by shaking with a lysis solution, followed by extraction of DNA.

A PCR reaction was performed by using the DNA a template to amplify genes of YhdP, wherein the reaction conditions were as follows: pre-denaturation at 94°C for 3 min, at 94°C for 30s, at 55°C for 30s, and at 72°C for 30s; and extension at 72°C for 3 min for a total of 30 cycles. The amplification 6 products were correctly sequenced and cloned into pcDNA3.1. A recombinant plasmid was‘ 0203901 transformed into host bacteria E. coli DH5a, positive clones were inoculated into a LB medium, isopropylthiogalactoside (IPTG) at a final concentration of 1 mmol/L was added for induction, and a sample was subjected to SDS-PAGE electrophoresis after induction. After SDS-PAGE was completed, electrotransfer was conducted to a nitrocellulose membrane, and identification was conducted by an anti-His monoclonal antibody. After an expression product was identified correctly, 200 ml of the induced bacteria were centrifuged to collect thalli, and after ultrasonic lysis, a supernatant was collected, and a target protein YhdP was subjected to affinity purification by using a

Ni?*-NTA protein purification kit from Invitrogen. (b) Immunization of mice

BALB/c mice (6 weeks old, male) were intramuscularly immunized with 50 pg of the purified target protein YhdP mixed with 50 pg of a Freund's complete adjuvant (Sigma, India). Then booster immunization was conducted twice.

The antibody reactivity in serums of the immunized mice was determined by ELISA, and mice with the highest titer value of 1:16000 were picked. (c) Production of monoclonal antibody by hybridoma technology

Mice with the highest antibody specificity were selected for a fusion reaction.

Preparation of feeder cells: macrophages were prepared and fed 1-2 days prior to cell fusion. A layer of feeder cells was plated on a 96-well plate, with 2x10* cells per well. The 96-well plate was then placed in a 37°C, 6% CO: incubator for incubation.

Spleen cells were aseptically taken, and suspended in a 5 ml HAT medium, 1x10%/ml of spleen cells were mixed with 2x107/ml of myeloma cells SP2/0, 30 ml of an incomplete medium was added, and uniform mixing was performed. The mixture was centrifuged at 1000 r/min for 5-10 min, a supernatant was sucked as much as possible to be thoroughly removed, 1 ml of 50% PEG (pH=8.0) 7 pre-heated to 40°C was added while gentle stirring, then an incomplete medium was added, the 7503801 mixture was allowed to stand for 10 min, and centrifuged at 1000 r/min for 5 min, a supernatant was discarded, resuspending was conducted with an HAT medium, and the resuspended material was separatedly put into a 96-well plate, and incubated in a 37°C, 6% CO: incubator. Hybridoma cells were screened after fusion for two weeks.

Wells containing positive cells were cloned into a 96-well tissue culture plate by a limiting dilution method. Hybridoma cells were screened by ELISA, with only 8 clones giving a strong positive signal in indirect ELISA; wherein, a clone YhdP-C3-8 exhibited the highest affinity for YhdP. This clone was selected for further large-scale production of antibodies.

Embodiment 3 Sequencing of monoclonal antibody (a) mRNA isolation

Hybridoma cells YhdP-C3-8 producing an anti-YhdP antibody were cultured in a 5% CO» humidification chamber in an Eagle's medium containing 10% (vol/vol) fetal bovine serum supplemented with 100 U/mL of penicillin and 100 mg/mL of streptomycin.

After the cells grew to a density of 10° cells/ml, the cells were harvested by centrifugation at 1000xg for 5 min.

For total RNA isolation, the cells were homogenized in a RNA lysis solution (Sigma, USA) containing 5x10° cells/ml, followed by RNA extraction according to manufacturer's instructions. (b) cDNA synthesis, and PCR amplification of immunoglobulin variable region

A first strand cDNA was synthesized from an mRNA template with a random hexadeoxyribonucleotide primer. Variable regions of a heavy chain (VH) and a light chain (VL) were amplified from the first strand cDNA with Taq DNA polymerase, and PCR was performed for 30 cycles (1 cycle at 94°C for 1 min, at 55°C for 1 min, and at 72°C for 1 min). Primers Yh-H-1 and Yh-

H-2 were used to amplify the VH; and primers Yh-L-1 and Yh-L-2 were used to amplify the VL. The 8 amplified variable heavy chain (SEQ ID NO: 9) and light chain (SEQ ID NO: 10) products were" 503901 sequenced, and a homology search for immunoglobulins was performed by using a Kabat database.

Embodiment 4 Study on the therapeutic effect of anti-YhdP antibody and a combination of the antibody and antibiotics

A cell model was employed to study the pathogenicity of Shigella affected by the anti-YhdP antibody in vitro. Hela cells were infected by Shigella flexneri 2a 301 (Sf301), and plaque formation was observed under a high power microscope to determine the extent to which the pathogenicity of Sf301 was affected by the anti-YhdP antibody.

The concentration of the Hela cells was adjusted to 5x107/L, the Hela cells were added to a 24-well plate, and incubated overnight in a CO: incubator, and after the Hela cells grew into a monolayer, the

Hela cells were washed twice with a 1640 medium without antibiotics.

Sf301 in a logarithmic growth phase was taken, a serum-free 1640 medium was added to a centrifuge tube, and Sf301 (10-10%) was diluted step by step in the centrifuge tube according to a 10-fold gradient.

Sf301 with different dilutions was mixed with the anti-YhdP antibody (1:500 dilution), the anti-YhdP antibody (1:500 dilution)+ampicillin (1%), and ampicillin (1%) in a 1640 medium, and Sf301 in a control group was mixed with a 1640 medium without an antibody, the above mixtures were added to 24-well plates, with 3 parallel wells per dilution, and 300 ul per well, and one well was left for normal cell control, the 24-well plates were placed in a 37°C incubator for 2h with shaking once every min to evenly distribute bacteria, and after 2h, a supernatant was discarded, and washing was conducted for 3 times with PBS to remove residual liquid as much as possible. 30 2% low melting point agarose (prepared with ultrapure water) was heated and melted in a water bath at 75°C. After cooling to about 50°C, the melted agarose was mixed with a phenol red-free 1640 9 medium pre-heated at 37°C (containing 20 pg/ml of gentamicin, and 5% calf serum in 1640) in a ratio 7905801 of 1:1, and after uniform mixing, the mixture was quickly added to the 24-well plates, 500 ul per well.

The 24-well plates were incubated at room temperature for half an hour, and then the 24-well plates were turned upside down for inverted culture after the agarose was coagulated, and cytopathy was observed under a microscope every day. On day 2-3 of culture, the 24-well plates were taken out, 2 ml of 4% paraformaldehyde was added for fixation overnight, covering agarose was removed, staining was conducted with 0.1% crystal violet, and the number of plaques was counted against light.

The results are shown in Fig. 1.

Embodiment 5 Immunofluorescence detection of localization after infection with Shigella flexneri 2a strain 301

Hela cells with good growth were transferred to a well plate, on the next day, a Shigella flexneri 2a strain 301 was added to each well, and the cells after infection with the Shigella flexneri 2a strain 301 for 6h, 8h, 12h and 24h were respectively fixed with paraformaldehyde for 20 min at room temperature. Paraformaldehyde was discarded, the cells were washed for 3 times with PBS, each washing being conducted for 5 min, 0.1% Triton-X-100/PBS was added, the cells were permeabilized for 10 min at room temperature, the permeabilized cells were washed with PBS, BSA was added for blocking for 2h at room temperature, a YhdP monoclonal antibody was diluted at a ratio of 1:200, and added into a culture dish, incubation was conducted for 1h, and the culture dish was put at 4°C overnight, on the next day, washing was conducted for 3 times with PBST, a 1:400 goat anti-mouse

IgG/Dylight secondary antibody was added, incubation was conducted for 1h at room temperature in the dark, washing was conducted twice with PBST, and observation is conducted by a fluorescence microscope (see Fig. 2). The results show that the YhdP monoclonal antibody can locate the position of the Shigella flexneri 2a strain 301 in cells.

Embodiment 6 Western blot analysis

Hela cells with good growth were transferred to a well plate, on the next day, a Shigella flexneri 2a strain 301 was added to each well, cells were harvested after 6h, 12h, 24h, 36h, 48h of infection, the 10 cells were washed twice with PBS, 100 ul of a PIPA lysis buffer was added to a cell pellet to be mixed /508901 gently and uniformly, the cells were lysed in an ice bath for 30 min, a supernatant was collected after centrifugation, a protein concentration of a cell lysate was quantified by a BCA protein quantification method, the protein concentration was adjusted to be consistent, a protein sample was prepared with a loading buffer, heating was conducted at 100°C for denaturation, and the protein sample was separated by 10% polyacrylamide gel electrophoresis, and then electrotransferred onto a nitrocellulose membrane. After completion of transferring onto the membrane, blocking was conducted by skim milk, a YhdP antibody was added, the mixture was put overnight, then washing was conducted for three times with PBST, an anti-mouse IgG Dy800 secondary antibody was added, incubation was conducted for 40 min at room temperature in the dark, washing was conducted for three times with with PBST, and then scanning was conducted by Odyssey for identification. The results show that the YhdP antibody can recognize protein lysates after infection with the Shigella flexneri 2a strain 301 (see Fig. 3).

Embodiment 7 Indirect plate enzyme-linked immunosorbent assay 100 pI of a Shigella flexneri 2a strain 301 or a Salmonella typhimurium preparation was added to microtiter wells, and blocked with 5% bovine serum albumin (BSA) in phosphate buffered saline (PBS). After washing with PBS, a YhdP antibody produced by mice was added, and the antibody was diluted in a 10-fold gradient, and a plate was incubated at 37°C for 60 min. The wells were washed, a secondary antibody (goat anti-mouse IgG-HRP, 1:1000) was then added, and incubation was conducted at 37°C for 60 min. After washing again with PBS, 100 ul of a TMB/H20> substrate was added to the wells, and incubation was conducted at room temperature for about 10 min. The results clearly show that the monoclonal antibody can specifically recognize Shigella flexneri, but not

Salmonella typhimurium, with an antibody titer of 1:6400.

Partial nucleotide and amino acid sequences involved in the present invention are as follows:

HCDR1: GRFTISRDGGG (SEQ ID NO: 1)

HCDR2: CKSLGQDT (SEQ ID NO: 2)

HCDR3: YGDSQSIW (SEQ ID NO: 3) 11 s LCDR1: VIVLDKLSRLGAGK (SEQ ID NO: 4) LU503901

LCDR2: WLVNTR (SEQ ID NO: 5)

LCDR3: GYGMHWVRQ (SEQ ID NO: 6)

Heavy chain variable region

GLLEGYLMTPYAKMYSKQIEGSSSVKGRFTISRDGGGWTSRQLFRGCRQACKSLGQDTYT

ELRLAGKDPFVIQSRLGSSCPTGTTSNGLITIQYGDSQSIWDGCRPASLDHVWLVNTRKLFS

(SEQ ID NO: 7)

Light chain variable region

TYTGQELRLPTGGEGFVIQYPQTVTVLDKLSRLGAGKDSSCPVLISGKQYGDWLVNTRDG

CRETIQVTGTSASLSQSIDHVWVVQPLVESGYGMHWVRQGGGRSLRLSCTQS (SEQ ID NO: 8)

Heavy chain

GLLEGYLMTPYAKMYSKQIEGSSSVKGRFTISRDGGGWTSRQLFRGCRQACKSLGQDTYT

ELRLAGKDPFVIQSRLGSSCPTGTTSNGLITIQYGDSQSIWDGCRPASLDHVWLVNTRKLFS

WGQGTMVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNTQALTSG

VHTFPAVLQSSGLYSLSSVVTVPSSCVGTQTYICNVNHKPSNTKVDKKVEPKSCDKTPECPP

CPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDLHHEDPEVKFNWYVDGVEVHNAKT

KPREEQYNSTYRVVSVLTVLHQVFLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPLMYT

LPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTMIVLDSDGSFFLYSKLTV

DKSRWQQGNVFSCSVSNEALHNHYTQKSLSLSPGK (SEQ ID NO: 9)

Light chain

TYTGQELRLPTGGEGFVIQYPQTVTVLDKLSRLGAGKDSSCPVLISGKQYGDWLVNTRDG

CRETIQVTGTSASLSQSIDHVWVVQPLVESGYGMHWVRQGGGRSLRLSCTQSSWDQPEDF

ATYYCQQLNSFPSPAVLQSSTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVVSVLTVLFYPR

12

EQVAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSAVEWESANNDYEKHKVYACEVT" 4503901

HQGLSSPVTVDNEKSRGEC (SEQ ID NO: 10)

Yh-H-1: GTGTGTGCTTGAAGCCAGTG (SEQ ID NO: 11)

Yh-H-2: GTCTTGGAGCGGAGTCAACTCC (SEQ ID NO: 12)

Yh-L-1: GAAGAGATTGTTGCAGCTGGACC (SEQ ID NO: 13)

Yh-L-2: AATAAGTGATGCCATTACTAT (SEQ ID NO: 14) 13

Claims (12)

1. Claims i. An isolated antibody or antigen binding portion thereof, which binds to protein YhdP of Shigella flexneri, wherein the antibody or antigen binding portion thereof comprises a heavy chain variable region comprising HCDRI1 as shown in SEQ ID NO: 1, HCDR2 as shown in SEQ ID NO: 2, and HCDR3 as shown in SEQ ID NO: 3, and a light chain variable region comprising LCDR1 as shown in SEQ ID NO: 4, LCDR2 as shown in SEQ ID NO: 5, and LCDR3 as shown in SEQ ID NO: 6.
2. 2. The isolated antibody or antigen binding portion thereof according to claim 1, comprising a heavy chain variable region (VH) as shown in SEQ ID NO: 7 and a light chain variable region (VL) as shown in SEQ ID NO: 8.
3. 3. The isolated antibody or antigen binding portion thereof according to claim 1 or 2, comprising a heavy chain as shown in SEQ ID NO: 9 and a light chain as shown in SEQ ID NO: 10.
4. 4. A nucleotide encoding the isolated antibody or antigen binding portion thereof according to any one of claims 1 to 3.
5. 5. A vector, comprising a nucleic acid molecule capable of encoding the antibody or antigen binding portion thereof according to any one of claims 1 to 3.
6. &. A cell, comprising the vector according to claim 5.
7. 7. A pharmaceutical composition, comprising the antibody or antigen binding portion thereof according to any one of claims 1 to 3. 14
8. 8. The pharmaceutical composition according to claim 7, wherein the pharmaceutical composition js 7503901 used for the treatment of Shigella infection.
9. 9. The pharmaceutical composition according to claim 7 or 8, wherein the pharmaceutical composition is in combination with antibiotics.
10. 10. Use of the isolated antibody or antigen binding portion thereof according to any one of claims 1 to 3 in the manufacture of a medicament for the treatment of Shigella infection.
11. 11. Use of the isolated antibody or antigen binding portion thereof according to any one of claims 1 to 3 in the preparation of a kit for detecting Shigella flexneri in foods and clinical samples.
12. 12. The use according to claim 11, wherein a detection method comprises immunofluorescence, western blot, indirect plate ELISA or dot-ELISA. 15