Application of DCD protein in preparation of preparation for promoting platelet anti-MRSA

Abstract

The invention discloses application of DCD protein to preparation of a preparation for promoting platelet anti-MRSA (Methicillin Resistant Staphylococcus Aureus). The research finds that after the platelets and the MRSA are co-cultured, the platelets secrete a large amount of novel antibacterial peptide DCD; then establishing a platelet and MRSA co-culture system in vitro, and counting by using a bacterial colony coating plate to verify that the novel antibacterial peptide DCD can inhibit MRSA proliferation in a concentration-dependent manner, and the antibacterial peptide DCD promotes the inhibiting effect of the platelet on MRSA in vitro.

Description

Technical Field

[0001] The present invention relates to a novel platelet antibacterial peptide, and particularly to a novel antibacterial peptide Dermcidin derived from platelets and its application against MRSA. Background Art

[0002] Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common and difficult-to-treat drug-resistant bacteria causing hospital and community infections. Due to the widespread use of antibiotics, MRSA has developed resistance to a variety of antibiotics, and even "superbugs" with multidrug resistance have emerged, which poses a severe challenge to the treatment of MRSA infections in clinical practice.

[0003] In clinical practice, many patients undergoing radiotherapy or chemotherapy are infected with MRSA due to bone marrow suppression. Compared with ordinary MRSA-infected patients, MRSA-infected patients with hematological malignancies have lower platelet counts and need to receive platelet transfusions and use more advanced antibiotics to treat bacterial infections. Summary of the Invention

[0004] In recent years, studies have found that in addition to the classical hemostatic function, platelets also play an important role in the body's inflammatory and immune responses. Especially in antibacterial infections, platelets play an important immune defense function. Through preliminary proteomic screening, the present invention discovered a platelet-derived protein DCD; subsequently, immunofluorescence and fluorescence confocal experiments were used to co-localize platelets and DCD protein, and the results showed that DCD protein was contained in platelets; Western blot also detected the presence of DCD protein in platelet lysates. Immunoelectron microscopy results further showed that DCD protein was present in platelet α-granules.

[0005] Furthermore, the inventors conducted an enzyme-linked immunosorbent assay (ELISA) and found that compared with the control platelet group (DCD content was 0.0024 μg / mL), the DCD content in the supernatant reached 3.5107 μg / mL after platelets were co-cultured with MRSA. The results indicated that after co-culture with MRSA, platelets secreted a large amount of the novel antibacterial peptide DCD. Then, a co-culture system of platelets and MRSA was established in vitro, and colony plate counting was used to verify that the antibacterial peptide DCD could inhibit the proliferation of MRSA, and the antibacterial peptide DCD promoted the antibacterial effect of platelets against MRSA.

[0006] Based on the above research findings, the present invention provides the use of DCD protein for preparing a preparation for promoting platelets to resist MRSA. Further provided is the use of DCD-1L protein for preparing a preparation for promoting platelets to resist MRSA. An alternative scheme is that the concentration of the DCD-1L protein in platelets is 25-30 μg / mL. Another alternative scheme is that the amino acid sequence of the DCD-1L is: SSLLEKGLDGAKKAVGGLGKLGKDAVEDLESVGKGAVHDVKDVLDSVL. Brief Description of the Drawings

[0007] Figure 1The results of proteomics showed that the expression of platelet activation-related proteins and DCD proteins was upregulated after co-culture with MRSA; the figure showed that the proteins in the platelet supernatant after co-culture with MRSA for 10 hours were collected for quantitative proteomics analysis. In the figure, P represents platelets cultured alone; P-M represents platelets co-cultured with MRSA; (A) KEGG pathway enrichment analysis of differentially expressed proteins in the P-M_vs_P group (top 20). The vertical Y-axis represents the pathway, and the X-axis represents the number of differentially expressed proteins related to the corresponding pathway. The numbers on the right side of each bar represent the enrichment factor of the corresponding pathway, and the color of the bar represents the P value calculated by Fisher's exact test; (B) Cluster analysis of 31 differentially expressed proteins related to platelet activation in the P-M_vs_P group. In the figure, the rows represent proteins, and the columns represent groups. The relative expression level is represented by the depth of color, with red indicating high expression and blue indicating low expression; (C) Analysis of collagen expression. COL1A1: Collagen alpha-1(I)chain, collagen alpha-1(I) chain; COL1A2: Collagen alpha-2(I)chain, collagen alpha-2(I) chain; (D) Analysis of fibrinogen expression, FGA: Fibrinogen alpha chain, fibrinogen alpha chain; FGB: Fibrinogen beta chain, fibrinogen beta chain; FGG: Fibrinogen gamma chain, fibrinogen gamma chain; (E) Analysis of platelet glycoprotein expression, GPV: Platelet glycoprotein V, platelet glycoprotein V; GPIV: Platelet glycoprotein IV, platelet glycoprotein IV; (F) Analysis of von Willebrand factor expression, vWF, von Willebrand factor: von Willebrand factor; (G) Analysis of integrin family protein expression, ITGA2: Integrin alpha-2, integrin alpha 2; ITGA2B: Integrin alpha-IIb, integrin alpha IIb; ITGB1: Integrin beta-1, integrin beta 1; ITGB3: Integrin beta-3, integrin beta 3; (H) Analysis of DCD protein expression.

[0008] Figure 2 Results of DCD protein secretion after co-culture of platelets with MRSA; (A) Immunofluorescence detection of DCD in platelets, Phalloidin (green): Phalloidin (green): 488 phalloidin was used as a control counterstain at a dilution ratio of 1:100; DCD (red): Dermcidin. Scale bar = 500 μm. The images are representative results of three independent experiments; (B) Western blot was used to detect the expression of DCD in platelet lysates. 10 μg, 15 μg, and 20 μg represent the protein content of platelet lysates added to each well; (C) ELISA was used to measure the content of DCD in the supernatant after co-culture with MRSA. All results were tested at least three times, and the data are presented as mean ± standard error. Student's t-test was used for comparison between the two groups of results.

[0009] Figure 3 Results of the localization of DCD in platelets; (A) DCD in platelets was observed by fluorescence confocal microscopy. Phalloidin (green): Phalloidin (green): 488 phalloidin was used as a control counterstain at a dilution ratio of 1:100; DCD (red): Dermcidin. Scale bar = 10 μm; (B) Immunoelectron microscopy was used to observe the location of DCD in platelets. DCD was labeled with black gold particles (indicated by red arrows). Scale bar = 1.0 μm (left panel), 500 nm (right panel and lower panel). The original magnification was 70,000 times (left panel) and 210,000 times (right panel and lower panel). These images are representative results of three independent experiments.

[0010] Figure 4 Antibacterial activity of DCD-1L against MRSA; The results were obtained by plating and counting the number of bacterial colonies in each group after co-culturing MRSA (10 6 CFU / mL) with different concentrations of DCD-1L (0, 5, 10, 15, 20, 25, 30, 35, and 40 μg / mL) for 4 hours; (A) Plating and counting of bacterial colonies in each group. The images are representative results of three independent experiments; (B) Bacterial death curve plotted based on the statistical results in (A). DCD-1L, dermcidin-1L. All results were independently repeated and tested at least three times, and the data are presented as mean ± standard error.

[0011] Figure 5DCD enhanced the antibacterial effect of platelets against MRSA; (A) Plate count of bacterial colonies in each group. After co - culturing platelets with MRSA for 10 hours, different concentrations of DCD - 1L were added to the bacterial suspension, and then the DCD - 1L and the bacterial suspension were incubated together for 4 hours. Then, the number of bacterial colonies in each group was counted by plate counting of colonies. The image represents the results of three independent experiments; (B) Bacterial death curve drawn according to the results of (A), P: platelets; P - M: co - culture of platelets and MRSA; P - M+DCD - 1L(20, 25, 30 μg / mL): After co - culturing platelets with MRSA for 10 hours, 20, 25, and 30 μg / mL concentrations of DCD - 1L were added to the bacterial suspension respectively; (C) Comparison of turbidity of bacterial suspensions in each group. DCD - 1L with a concentration of 30 μg / mL was added to the co - culture system of platelets and MRSA. After co - culturing for 10 hours, the turbidity of the bacterial suspension was compared, and the number of bacterial colonies in each group was counted. The image represents the results of three independent experiments; (D) Statistical results of bacterial colony counts in each group in (C), MRSA: culture of MRSA alone; P - M: co - culture of platelets and MRSA; P - M+DCD - 1L: DCD - 1L (30 μg / mL) was added to the co - culture system of platelets and MRSA, and then co - cultured for 10 hours. All results were repeated and tested at least three times. The data were presented in the form of mean ± standard error. Student's t - test was used for comparison between two groups. Detailed implementation mode

[0012] Unless otherwise specified, scientific and technical terms in this article are understood according to the knowledge of ordinary technical personnel in the relevant field.

[0013] The following are specific embodiments of the present invention to further explain and illustrate the present invention. Reagents, research materials, etc. used in the following examples are all commercially available products.

[0014] Example 1: Screening and identification of DCD antibacterial peptide

[0015] This example screened and identified a novel antibacterial peptide DCD in human platelets.

[0016] 1 Materials and methods

[0017] 1.1 MRSA strains, culture and counting

[0018] MRSA (ATCC BAA-1717) was sourced from the Clinical Laboratory of the First Affiliated Hospital of Air Force Medical University. Cultivation and counting of MRSA: The preserved MRSA strain was inoculated onto Luria-Bertani (LB) solid medium and cultured at 37 °C for 24 hours; then, single colonies of MRSA were picked and inoculated into LB liquid medium and cultured for 6 to 8 hours until the logarithmic growth phase was reached; the absorbance value of the bacteria was measured at a wavelength of 600 nm using an ultraviolet spectrophotometer (UV-2550; Shimadzu Corporation, Kyoto, Japan). According to the plate colony counting results, an absorbance value of 1.0 corresponded to 10 9 colony-forming units (CFU) / mL of MRSA. The MRSA concentration was diluted to 10 6 CFU / mL with LB medium and then set aside; after serial dilution of the bacterial suspensions of each group, 100 μL of the bacterial suspension was inoculated onto LB plates for cultivation; after cultivation at 37 °C for 18 to 24 hours, the bacterial colonies were counted.

[0019] 1.2 Preparation of human washed platelets

[0020] Human apheresis platelets were centrifuged (382×g, 5 minutes) and washed with phosphate-buffered saline (PBS) (containing 10% acid citrate dextrose [ACD] blood preservative); after washing twice, the platelets were resuspended in LB medium, and the concentration of the platelet suspension was adjusted to 1.8×10 8 per mL and set aside. The human platelets used in the experiment had obtained informed consent from voluntary blood donors and were carried out after approval by the Medical Ethics Committee of the First Affiliated Hospital of Air Force Medical University.

[0021] 1.3 Proteomics analysis

[0022] The method for establishing a co-culture system of platelets and MRSA was as follows: 600 μL of MRSA and 5 mL of platelets were taken in LB medium and cultured with shaking at 37 °C and 180 revolutions per minute for 10 hours (the total volume of the culture system was 6 mL, in which the final concentration of platelets was 150×10 9 per L, and the final concentration of MRSA was 10 5 CFU / mL).

[0023] Cold methanol was used to enrich the proteins in the supernatant of platelets co-cultured with or without MRSA. The specific method is as follows: the supernatant sample was mixed with cold methanol (100% concentration, 4°C) at a ratio of 1:5 and stored at -20°C for 2 hours; then the protein was collected by centrifugation at 4°C and 10,000×g for 15 minutes and washed with methanol (90% concentration); after centrifugation at 4°C and 10,000×g for 15 minutes, the protein precipitate was air-dried for 15 minutes; finally, the protein precipitate was dissolved in 8M urea protein solution and stored at -80°C; the obtained protein sample was sent to Shanghai Zhongke New Life Biotechnology Co., Ltd. for quantitative proteomics analysis using tandem mass spectrometry tag (TMT) technology.

[0024] 1.4 ELISA determination of DCD content

[0025] The co-culture system of platelets and MRSA was established as described in 1.3 above. After 10 hours of co-culture, the supernatant was collected and the DCD concentration in the supernatant was determined using a human Dermcidin ELISA kit (orb406184, Biorbyt, UK) according to the instructions of the kit.

[0026] 1.5 Immunofluorescence and fluorescence confocal microscopy to detect DCD in platelets

[0027] Platelets were fixed with 200 μL 0.05% glutaraldehyde solution for 15 minutes; after centrifugation and washing, platelets were treated with 400 μL 0.1% Triton-X100 at room temperature for 15 minutes; after centrifugation, platelets were blocked with 3% bovine serum albumin (BSA) in PBS at room temperature for 30 minutes; then, platelets were incubated with anti-DCD monoclonal antibody (H-12, sc-398429, Santa Cruz, USA) (1:100) at 4°C overnight, centrifuged and washed, platelets were incubated with anti-mouse IgG goat polyclonal antibody (BA1031, Boster Biotechnology, China) as secondary antibody (1:100) in the dark for 1 hour, washed twice, and platelets were incubated with PBS at room temperature for 30 minutes. 488 phalloidin working solution (PF00001, Proteintech, USA) was incubated in PBS (1:100) for 20 min; after washing, the platelets were suspended in 200 μL PBS, and 10 μL was placed on a slide, covered with a coverslip, and observed using a fluorescence microscope (Ni-U, Nikon, Japan) and a confocal microscope (LSM 900, Carl Zeiss, Germany), respectively.

[0028] 1.6 Immunoelectron microscopy for localization of DCD in platelets

[0029] Fix the platelet samples with 200 μL of 3% glutaraldehyde solution (4 °C, 24 hours). The fixed platelet samples were sent to the electron microscopy room of the Department of Pathology, Air Force Medical University for embedding and sectioning. The ultra-thin sections of the platelet samples were fixed with nickel grids, dispersed on polyester blocks, rinsed with pure water, soaked for 5 minutes, and after drying the sections with filter paper, the sections were immersed in 1% H2O2 (filtered) for 10 minutes. Next, rinse the sections, dry them, incubate them with blocking solution (3% BSA in pure water) at room temperature for 30 minutes, and after drying, incubate the sections with anti-DCD primary antibody (1:100) overnight at 4 °C. After rinsing and soaking, dry the sections with PBSA (1% BSA in PBS) for 7 minutes, and after drying, incubate the secondary antibody (10 nm gold-labeled, goat anti-mouse, ab39619, Abcam, UK) in PBSA (1:250) in the dark for 1 hour; after rinsing and drying, stain the sections with uranyl acetate for 8 minutes. Stain with lead citrate for 8 minutes after washing, and then rinse and dry the sections; finally, observe using a transmission electron microscope (TEM) (HT-7800, Hitachi, Japan).

[0030] 1.7 Detection of DCD protein in platelet lysate by Western blot

[0031] Approximately 10 6 platelets were lysed with RIPA lysis buffer (P0013C, Beyotime Biotechnology Co., Ltd., China) on ice for 30 minutes, and then the platelet lysate was centrifuged at 10000×g for 20 minutes at 4 °C to collect the supernatant; the protein concentration in the supernatant was measured using a BCA protein assay kit (P0012S, Beyotime Biotechnology Co., Ltd., China); next, protein samples with total protein contents of 10, 15, and 20 μg were taken respectively for sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by transfer membrane (1200 mA / h), and then blocked at room temperature for 30 minutes; then incubated with anti-DCD primary antibody (1:1000) overnight at 4 °C, and then incubated with sheep polyclonal antibody (horseradish peroxidase-conjugated, BA1050, Boster Biotechnology Co., Ltd., China) as the secondary antibody (1:1000) for 1 hour, block the membrane, then wash the membrane with PBST, and then use a chemiluminescent imaging system (ChemiDoc XRS+, Bio-Rad, USA) to perform imaging analysis on it.

[0032] 2 Results

[0033] 2.1 Upregulation of platelet activation-related protein expression after co-culture with MRSA

[0034] The results of proteomic analysis were subjected to KEGG pathway enrichment analysis, and it was found that the differentially expressed proteins were located in important pathways such as platelet activation, regulation of the actin cytoskeleton, and extracellular matrix receptor interaction. Among them, the platelet activation pathway (marked by the red box in the figure) had the most differentially expressed proteins enriched ( Figure 1 A).

[0035] The results of cluster analysis showed that compared with the control platelet group, 31 differentially expressed proteins related to platelet activation were up-regulated in the group of platelets co-cultured with MRSA ( Figure 1 B).

[0036] The proteomics of important differentially expressed proteins related to platelet activation and aggregation in the platelet activation pathway showed that compared with the control platelet group, multiple important differentially expressed proteins after co-culturing platelets with MRSA: collagen (COL1A1, COL1A2, Figure 1 C), fibrinogen (FGA, FGB, FGG, Figure 1 D), platelet glycoprotein (GPV, GPIV, Figure 1 E), von Willebrand factor (vWF, Figure 1 F), integrin family proteins (α2, αIIb, β1, β3, Figure 1 G) and DCD protein ( Figure 1 H) were all up-regulated (P values were all < 0.05), and they are all important proteins involved in the regulation of platelet activation and aggregation.

[0037] The above results indicate that platelets co-cultured with MRSA may be activated, and the expression of platelet-derived DCD protein is up-regulated.

[0038] 2.2 Platelets will release a novel antimicrobial peptide DCD in large amounts after co-culturing with MRSA

[0039] The above experimental results show that the expression of platelet-derived DCD protein is up-regulated after co-culturing with MRSA.

[0040] Furthermore, the present invention used a DCD-specific monoclonal antibody to immunofluorescently label human platelets and observed by fluorescence microscopy. The results showed that DCD protein was present in platelets ( Figure 2 A).

[0041] The results of Western blot experiments showed that DCD protein was present in platelet lysates ( Figure 2 B). In addition, the ELISA detection results showed that compared with the control single platelet group, after co-culturing with MRSA, the content of DCD secreted by platelets increased significantly, and its concentration reached 3.58 μg / ml ( Figure 2C). These results indicate that DCD protein is present in platelets and that platelets secrete a large amount of DCD after co - culturing with MRSA.

[0042] 2.3 DCD is present in the α - granules of platelets

[0043] To determine the location of DCD in platelets, the present invention first observed the co - localization of DCD and platelets by fluorescence confocal microscopy, and the results confirmed that DCD was present in platelets ( Figure 3 A), and then labeled DCD in platelets with a specific DCD monoclonal antibody and a gold - labeled secondary antibody, and observed using a transmission electron microscope. The immunoelectron microscopy results showed that DCD was present in the α - granules of platelets ( Figure 3 B). These results indicate that the novel platelet antibacterial peptide DCD is present in the α - granules of platelets.

[0044] The full - length DCD protein (protein number: P81605; gene ID: 117159) consists of 110 amino acid residues. In vivo, DCD is hydrolyzed by a protease and processed into C - terminal peptides, namely 48 - amino - acid - residue (DCD - 1L), 47 - amino - acid - residue (DCD - 1) and other shorter fragments. Therefore, the following examples determined the in vitro antibacterial activity of synthetic DCD - 1L against MRSA.

[0045] Example 2: Verification of the anti - MRSA effect of DCD antibacterial peptide

[0046] This example further verified the antibacterial effect of the novel human platelet antibacterial peptide DCD against MRSA.

[0047] 1 Materials and methods

[0048] 1.1 Determination of the antibacterial activity of DCD - 1L against MRSA

[0049] DCD - 1L was synthesized by Wuhan Haode Biotechnology Co., Ltd., and its amino acid sequence is as follows: SSLLEKGLDGAKKAVGGLGKLGKDAVEDLESVGKGAVHDVKDVLDSVL.

[0050] Antibacterial activity determination method: MRSA was diluted to 10 6 CFU / ml in PBS; 20 μl of the diluted MRSA suspension was incubated with different concentrations of DCD - 1L in PBS (total volume 60 μl) at 37 °C for 4 hours; after incubation, the bacterial suspension was diluted with PBS at a ratio of 1:100, and 100 μL of the diluted bacterial suspension was spread on three LB plates three times. The plates were cultured in an incubator at 37 °C for 24 hours, and then the colonies were counted.

[0051] The antibacterial activity was calculated according to the following formula: [1 - (the number of surviving bacteria after incubation with the antibacterial peptide) / (the number of surviving cells in the buffer without the antibacterial peptide)] × 100.

[0052] IC 95 represents the lethal concentration (μg / mL) of the antibacterial peptide, which results in a 95% reduction in the colony-forming units (CFU) compared to the buffer control.

[0053] 1.2 Analysis of antibacterial activity after adding DCD-1L to the co-culture system of platelets and MRSA

[0054] To further explore whether adding DCD-1L to the co-culture system of platelets and MRSA can promote the inhibitory effect of platelets on MRSA, two experiments were conducted in this invention:

[0055] (1) A co-culture system of platelets and MRSA was established. After shaking and co-culturing for 10 hours in a constant temperature shaker at 37°C (180 revolutions per minute), 20 μL of the co-cultured bacterial suspension was taken and incubated with different concentrations of DCD-1L in the co-culture supernatant (total volume 60 μL) at 37°C for 4 hours. After incubation, the bacterial suspension was diluted and inoculated onto three LB plates in three aliquots and cultured at 37°C for 24 hours. Then, the bacterial colonies on the plates were counted. The calculation method of antibacterial activity was the same as above.

[0056] (2) A co-culture system of platelets and MRSA was established, and DCD-1L with a final concentration of 30 μg / mL was added to the co-culture system simultaneously. Then, after shaking and co-culturing for 10 hours in a constant temperature shaker at 37°C (180 revolutions per minute), the turbidity of each group of bacterial solutions was observed, and the number of bacterial colonies was counted by the plate counting method.

[0057] 1.3 Statistical analysis method

[0058] Student's t-test (GraphPad Prism v.5.01) was used to evaluate the statistical differences between the means of the two groups. The results were expressed in the form of mean ± standard error. The statistical significance was set at P < 0.05.

[0059] 2 Results

[0060] 2.1 DCD inhibits the proliferation of MRSA in a concentration-dependent manner

[0061] As described above, the present invention has demonstrated that activated platelets secrete a large amount of DCD after co-culture with MRSA. Further determination of the in vitro antibacterial activity of DCD-1L against MRSA showed that lower concentrations of DCD-1L (5, 10, 15, and 20 μg / mL) had no antibacterial effect on MRSA; DCD-1L began to exhibit partial antibacterial activity at a concentration of 25 μg / mL, with an antibacterial activity (i.e., the mortality rate of MRSA) of approximately 26%, and its antibacterial activity exceeded 95% at a concentration of 30 μg / mL; when the concentration reached 35 μg / mL, DCD-1L showed 100% antibacterial activity against MRSA. Subsequently, as the concentration of DCD-1L increased, its antibacterial activity remained unchanged ( Figure 4 A and 4B).

[0062] These results indicate that the 95% inhibitory concentration (IC 95 ) of DCD-1L against MRSA is 30 μg / mL, and its 100% inhibitory concentration is 35 μg / mL. The antibacterial effect of DCD-1L against MRSA in vitro is concentration-dependent.

[0063] 2.2 DCD promoted the antibacterial effect of platelets against MRSA

[0064] The above experimental results have confirmed that DCD-1L can inhibit the proliferation of MRSA in vitro. To further explore whether DCD-1L can promote the antibacterial effect of platelets against MRSA, two experiments were conducted in the present invention: (1) After co-culturing platelets and MRSA for 10 hours, different concentrations of DCD-1L were added to the bacterial suspension for co-incubation, and then the bacterial colonies were counted. The results showed that when the added concentration of DCD-1L was 20 μg / mL, the mortality rate (i.e., antibacterial activity) of MRSA was 68%; when the concentration of DCD-1L was 25 μg / mL, the mortality rate of MRSA exceeded 95%; when the added concentration of DCD-1L was 30 μg / mL, the mortality rate of MRSA reached 100% ( Figure 5 A and 5B). These results indicate that the higher the concentration of DCD-1L added to the bacterial suspension after co-culturing platelets and MRSA, the higher the mortality rate of MRSA.

[0065] (2) To compare the different inhibitory effects of platelets alone and platelets + DCD-1L on MRSA, DCD-1L with a final concentration of 30 μg / mL was added to the co-culture system of platelets and MRSA. After 10 hours of co-culture, the turbidity of the bacterial suspension in each group was compared, and the number of bacterial colonies in each group was counted. The results showed that compared with the partial antibacterial effect of platelets alone, adding DCD-1L to the co-culture system of platelets and MRSA further enhanced the anti-MRSA effect of platelets, and this antibacterial effect was better than that of using DCD-1L alone.Figure 5 C and 5D). These results indicate that DCD-1L can promote the antibacterial effect of platelets against MRSA.

[0066]

Claims

1. Use of DCD protein for preparing a preparation for promoting platelets to resist MRSA.

2. Use of DCD-1L protein for preparing a preparation for promoting platelets to resist MRSA.

3. The application according to claim 2, characterized in that, The concentration of the DCD-1L protein in platelets is 25-30 μg / mL.

4. The application according to claim 2, wherein The amino acid sequence of the DCD-1L is as follows: SSLLEKGLDGAKKAVGGLGKLGKDAVEDLESVGKGAVHDVKDVLD SVL.

Images