Staphylococcal Protein A

Example 3

Recombinant Protein Purification

FIG. 5 shows the steps of one of the purifications carried out on the chimera. In the case of GRNLY, this process was shown in an earlier paper [Ibáñez, R., University of Zaragoza. 2015]. It can be seen in FIG. 5A that the P. Pastoris supernatant obtained after induction (lane 1) contains rather diluted proteins. After concentrating same with Pellicom, protein bands are not seen in the permeate (lane 3), but proteins that are much more concentrated than in the supernatant are seen in the concentrate (lane 2). After dialysis (lane 4), the band profile remains similar to the concentrate. Furthermore, protein bands are not seen in the buffer in which the dialysis bag (lane 5) was introduced. Upon addition of the nickel resin, the chimera binds to said resin as it has a histidine tag. After adding the resin (lane 6), the intensity of a band corresponding to a protein of about 40 kDa decreases with respect to the concentrate and dialysate. This band may correspond to the chimera. The fact that this band does not altogether disappear may indicate that the nickel resin was saturated. In the washes performed on the resin, particularly in the first wash (lane 7), it can be seen how the residues of other proteins are removed. Finally, after the elution of the nickel column, a major protein with a molecular weight of about 40 kDa corresponding to the molecular weight of the chimera (lane 11) is clearly observed. As shown in FIG. 5B, it was confirmed by means of immunoblot that this band of about 40 kDa corresponds to the chimera (lane 11). It is also confirmed that the resin was saturated because a band appears in the post-resin dialysis phase (lane 6).

FIG. 6 shows different elution fractions and the pooling of all of them with the exception of elution fraction 1. FIG. 6A shows several bands in the different elution fractions and in the total eluate. The band with the highest intensity has a molecular weight corresponding to the chimera. Furthermore, other bands having intermediate molecular weights are observed, which means that the chimera undergoes partial proteolysis. The band with the second highest intensity has a molecular weight of about 10 kDa, which corresponds to 9-kDa GRNLY, as its molecular weight increases since it is bound to a histidine tag. In FIG. 6B, it was confirmed by means of immunoblot that these bands of about 40 and 10 kDa correspond to the chimeric recombinant protein and to recombinant GRNLY, respectively.

Once the chimera is generated, its functionality must be assured, that is, on one hand the scFv still recognizes the CEA antigen, and on the other hand GRNLY is still cytotoxic.

Example 1

The sequence coding for the light chain variable region of the antibody was inserted into vector pFUSE2ss-CLIg-hK (Invivogen, Catalog Number: pfuse2ss-hclk) using EcoRI and BsiWI restriction sites to construct a light chain expression vector. The sequence coding for the heavy chain variable region of the antibody was inserted into vector pFUSEss-CHIg-hG2 (Invivogen, Catalog Number: pfusess-hchg2) or vector pFUSEss-CHIg-hG4 (Invivogen, Catalog Number: pfusess-hchg4) using EcoRI and NheI restriction sites to construct a heavy chain expression vector.

The culture and transfection of Expi293 cells were performed in accordance with the handbook of Expi293™ Expression System Kit from Invitrogen (Catalog Number: A14635). The density of the cells was adjusted to 2×10⁶ cells/ml for transfection, and 0.6 μg of the light chain expression vector as described above and 0.4 μg of the heavy chain expression vector as described above were added to each ml of cell culture, and the supernatant of the culture was collected four days later.

The culture supernatant was subjected to non-reduced SDS-PAGE gel electrophoresis in accordance with the protocol described in Appendix 8, the Third edition of the “Molecular Cloning: A Laboratory Manual”.

Pictures were taken with a gel scanning imaging system from BEIJING JUNYI Electrophoresis Co., LTD and in-gel quantification was performed using Gel-PRO ANALYZER software to determine the expression levels of the antibodies after transient transfection. Results were expressed relative to the expression level of control antibody 1 (control antibody 1 was constructed according to U.S. Pat. No. 7,186,809, which comprises a light chain variable region as set forth in SEQ ID NO: 10 of U.S. Pat. No. 7,186,809 and a heavy chain variable region as set forth in SEQ ID NO: 12 of U.S. Pat. No. 7,186,809, the same below) (control antibody 2 was constructed according to U.S. Pat. No. 7,638,606, which comprises a light chain variable region as set forth in SEQ ID NO: 6 of U.S. Pat. No. 7,638,606 and a variable region as set forth in SEQ ID NO: 42 of U.S. Pat. No. 7,638,606, the same below). See Tables 2a-2c below for the results.

Example 4

6-8 week-old SPF Balb/c mice were selected and injected subcutaneously with antibodies (the antibodies of the present invention or control antibody 2) in a dose of 5 mg/kg (weight of the mouse). Blood samples were collected at the time points before administration (0 h) and at 2, 8, 24, 48, 72, 120, 168, 216, 264, 336 h after administration. For blood sampling, the animals were anesthetized by inhaling isoflurane, blood samples were taken from the orbital venous plexus, and the sampling volume for each animal was about 0.1 ml; 336 h after administration, the animals were anesthetized by inhaling isoflurane and then euthanized after taking blood in the inferior vena cava.

No anticoagulant was added to the blood samples, and serum was isolated from each sample by centrifugation at 1500 g for 10 min at room temperature within 2 h after blood sampling. The collected supernatants were immediately transferred to new labeled centrifuge tubes and then stored at −70° C. for temporary storage. The concentrations of the antibodies in the mice were determined by ELISA:

1. Preparation of Reagents

sIL-4Rα (PEPRO TECH, Catalog Number: 200-04R) solution: sIL-4Rα was taken and 1 ml ddH2O was added therein, mixed up and down, and then a solution of 100 μg/ml was obtained. The solution was stored in a refrigerator at −20° C. after being subpacked.

Sample to be tested: 1 μl of serum collected at different time points was added to 999 μl of PBS containing 1% BSA to prepare a serum sample to be tested of 1:1000 dilution.

Standard sample: The antibody to be tested was diluted to 0.1 μg/ml with PBS containing 1% BSA and 0.1% normal animal serum (Beyotime, Catalog Number: ST023). Afterwards, 200, 400, 600, 800, 900, 950, 990 and 1000 μl of PBS containing 1% BSA and 0.1% normal animal serum were respectively added to 800, 600, 400, 200, 100, 50, 10 and 0 μl of 0.1 μg/ml antibodies to be tested, and thus standard samples of the antibodies of the present invention were prepared with a final concentration of 80, 60, 40, 20, 10, 5, 1, or 0 ng/ml respectively.

2. Detection by ELISA

250 μl of 100 μg/ml sIL-4Rα solution was added to 9.75 ml of PBS, mixed up and down, and then an antigen coating buffer of 2.5 μg/ml was obtained. The prepared antigen coating buffer was added to a 96-well ELISA plate (Corning) with a volume of 100 μl per well. The 96-well ELISA plate was incubated overnight in a refrigerator at 4° C. after being wrapped with preservative film (or covered). On the next day, the 96-well ELISA plate was taken out and the solution therein was discarded, and PBS containing 2% BSA was added thereto with a volume of 300 μl per well. The 96-well ELISA plate was incubated for 2 hours in a refrigerator at 4° C. after being wrapped with preservative film (or covered). Then the 96-well ELISA plate was taken out and the solution therein was discarded, and the plate was washed 3 times with PBST. The diluted standard antibodies and the sera to be detected were sequentially added to the corresponding wells, and three duplicate wells were made for each sample with a volume of 100 μl per well. The ELISA plate was wrapped with preservative film (or covered) and incubated for 1 h at room temperature. Subsequently, the solution in the 96-well ELISA plate was discarded and then the plate was washed with PBST for 3 times. Later, TMB solution (Solarbio, Catalog Number: PR1200) was added to the 96-well ELISA plate row by row with a volume of 100 μl per well. The 96-well ELISA plate was placed at room temperature for 5 minutes, and 2 M H2SO4 solution was added in immediately to terminate the reaction. The 96-well ELISA plate was then placed in flexstation 3 (Molecular Devices), the values of OD450 were read, the data were collected and the results were calculated with Winnonlin software. The pharmacokinetic results were shown in FIG. 1 and Table 6 below.

Example 5

A series of pharmacokinetic experiments were carried out in Macaca fascicularises to further screen antibodies.

3-5 year-old Macaca fascicularises each weighting 2-5 Kg were selected and injected subcutaneously with antibodies (the antibodies of the present invention or control antibody 2) in a dose of 5 mg/kg (weight of the Macaca fascicularis). The antibody or control antibody 2 to be administered was accurately extracted with a disposable aseptic injector, and multi-point injections were made subcutaneously on the inner side of the thigh of the animal, and the injection volume per point was not more than 2 ml. Whole blood samples were collected from the subcutaneous vein of the hind limb of the animal at the time points before administration (0 h) and at 0.5, 2, 4, 8, 24, 48, 72, 120, 168, 240, 336 h, 432 h, 504 h, 600 h, 672 h after administration. The blood volume collected from each animal was about 0.1 ml each time.

No anticoagulant was added to the blood samples, and serum was isolated from each sample by centrifugation at 1500 g for 10 min at room temperature within 2 h after blood sampling. The collected supernatants were immediately transferred to new labeled centrifuge tubes and then stored at −70° C. for temporary storage. The concentrations of the antibodies in the Macaca fascicularises were determined according the method as described in Example 4. The pharmacokinetic results are shown in FIG. 2 and Table 7 below.

Example 10

In vivo pharmacokinetics of the antibodies of the invention are further detected and compared in this Example, in order to investigate the possible effects of specific amino acids at specific positions on the pharmacokinetics of the antibodies in animals. The specific experimental method was the same as that described in Example 4, and the results are shown in Table 9 below.

From the specific sequence, the amino acid at position 103 in the sequence of the heavy chain H1031 (SEQ ID NO. 91) of the antibody (in CDR3) is Asp (103Asp), and the amino acid at position 104 is Tyr (104Tyr). Compared with antibodies that have no 103Asp and 104Tyr in heavy chain, the present antibodies which have 103Asp and 104Tyr have a 2- to 4-fold higher area under the drug-time curve and an about 70% reduced clearance rate.

The expression levels of the antibodies of the present invention are also detected and compared, in order to investigate the possible effects of specific amino acids at specific positions on the expression of the antibodies. Culture and transfection of Expi293 cells were conducted according to Example 1, and the collected culture supernatant was then passed through a 0.22 μm filter and then purified by GE MabSelect Sure (Catalog Number: 11003494) Protein A affinity chromatography column in the purification system GE AKTA purifier 10. The purified antibody was collected and concentrated using Amicon ultrafiltration concentrating tube (Catalog Number: UFC903096) and then quantified. The quantitative results are shown in Table 10 below.

From the specific sequence, the amino acid at position 31 in the sequence of the light chain L1012 (SEQ ID NO. 44), L1020 (SEQ ID NO. 55) or L1023 (SEQ ID NO. 51) of the antibody (in CDR1) is Ser (31Ser). Compared with antibodies that have no 31Ser in light chain, the present antibodies which have 31Ser have a 2- to 5-fold higher expression level.

The above description for the embodiments of the present invention is not intended to limit the present invention, and those skilled in the art can make various changes and variations according to the present invention, which are within the protection scope of the claims of the present invention without departing from the spirit of the same.

Example 8

In selecting genomes for a given bacterial species where a SLAM homolog was identified, preference was given to reference genomes that contained fully sequenced genomes. SLAM homologs were identified using iterative Blast searches into closely related species to Neisseria to more distantly related species. For each of the SLAM homologs identified in these species, the corresponding genomic record (NCBI genome) was used to identify genes upstream and downstream along with their corresponding functional annotations (NCBI protein database, Ensembl bacteria). In a few cases, no genes were predicted upstream or downstream of the SLAM gene as they were too close to the beginning or end of the contig, respectively, and thus these sequences were ignored.

Neighbouring genes were analyzed for 1) an N-terminal lipobox motif (predicted using LipoP, SignalP), and 2) a solute binding protein, Tbp-like (InterPro signature: IPR or IPR011250), or pagP-beta barrel (InterPro signature: IPR011250) fold. If they contained these elements, we identified the adjacent genes as potential SLAM-dependent surface lipoproteins.

A putative SLAM (PM1515, SEQ ID NO: 1087) was identified in Pasteurella multocida using the Neisseria SLAM as a search. The putative SLAM (PM1515, SEQ ID NO: 1087) was adjacent to a newly predicted lipoprotein gene with unknown function (PM1514, SEQ ID NO: 1083) (FIG. 11A). The putative SLAM displayed 32% identity to N. meningitidis SLAM1 while the SLP showed no sequence similarity to known SLAM-dependent neisserial SLPs.

The putative SLAM (PM1515, SEQ ID NO: 1087) and its adjacent lipoprotein (PM1514, SEQ ID NO: 1083) were cloned into pET26b and pET52b, respectively, as previously described and transformed into E. coli C43 and grown overnight on LB agar supplemented with kanamycin (50 ug/ml) and ampicillin (100 ug/ml).

Cells were grown in auto-induction media for 18 hours at 37 C and then harvested, washed twice in PBS containing 1 mM MgCl2, and labeled with α-Flag (1:200, Sigma) for 1 hr at 4 C. The cells were then washed twice with PBS containing 1 mM MgCl2 and then labeled with R-PE conjugated α-mouse IgG (25 ug/mL, Thermo Fisher Scientific) for 1 hr at 4 C. following straining, cells were fixed in 2% formaldehyde for 20 minutes and further washed with PBS containing 1 mM MgCl2. Flow Cytometry was performed with a Becton Dickinson FACSCalibur and the results were analyzed using FLOWJO software. Mean fluorescence intensity (MFI) was calculated using at least three replicates was used to compare surface exposure the lipoprotein in strains either containing or lacking the putative SLAM (PM1515) and are shown in FIG. 11C and FIG. 11D. PM1514 could be detected on the surface of E. coli illustrating i) that SLAM can be used to identify SLPs and ii) that SLAM is required to translocate these SLPs to the surface of the cell—thus identifying a class of proteins call “SLAM-dependent surface lipoproteins”. Antibodies were raised against purified PmSLP (PM1514) and the protein was shown to be on the surface of Pasteurella multocida via PK shaving assays.