We would like to acknowledge support from the College of Veterinary Medicine and Biomedical Sciences Experiential Award and College Research Council Shared Research Program to NKG and funding by ATCC (award # 2016-0550-0002) to KMD. We would also like to acknowledge Anne Simpson for technical support and BEI Resources, NIAID, NIH for the following reagents: Monoclonal Anti-Mycobacterium tuberculosis LpqH (Gene Rv3763), IT-54 (produced in vitro), NR-13792, Monoclonal Anti-Mycobacterium tuberculosis GroES (Gene Rv3418c), Clone IT-3 (SA-12) (produced in vitro), NR-49223, and Monoclonal Anti-Mycobacterium tuberculosis LAM, Clone CS-35 (produced in vitro), NR-13811.

The Colorado State University Institutional Biosafety Committee approved the present study (19-046B). Cultivation of Mycobacterium tuberculosis and harvesting of EV-rich culture supernatants were performed by trained personnel in a high-containment laboratory. The materials were moved out of the high-containment area after a valid inactivation method was performed, confirmed, and approved by institutional biosafety policies. While replicating the protocol, if validated inactivation or sterile filtration method i...

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	<li>Gill, S., Catchpole, R., Forterre, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+membrane+vesicles+in+the+three+domains+of+life+and+beyond.">Extracellular membrane vesicles in the three domains of life and beyond.</a> FEMS Microbiology Reviews. 43 (3), 273-303 (2019).</li><li>World Health Organization. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GLOBAL+TUBERCULOSIS+REPORT+2021.">GLOBAL TUBERCULOSIS REPORT 2021.</a> World Health Organization. , (2021).</li><li>Prados-Rosales, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mycobacteria+release+active+membrane+vesicles+that+modulate+immune+responses+in+a+TLR2-dependent+manner+in+mice.">Mycobacteria release active membrane vesicles that modulate immune responses in a TLR2-dependent manner in mice.</a> Journal of Clinical Investigation. 121 (4), 1471-1483 (2011).</li><li>Prados-Rosales, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mycobacterial+membrane+vesicles+administered+systemically+in+mice+induce+a+protective+immune+response+to+surface+compartments+of+mycobacterium+tuberculosis.">Mycobacterial membrane vesicles administered systemically in mice induce a protective immune response to surface compartments of mycobacterium tuberculosis.</a> mBio. 5 (5), 01921 (2014).</li><li>Prados-Rosales, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+for+mycobacterium+tuberculosis+membrane+vesicles+in+iron+acquisition.">Role for mycobacterium tuberculosis membrane vesicles in iron acquisition.</a> Journal of Bacteriology. 196 (6), 1250-1256 (2014).</li><li>Lee, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteomic+analysis+of+extracellular+vesicles+derived+from+Mycobacterium+tuberculosis.">Proteomic analysis of extracellular vesicles derived from Mycobacterium tuberculosis.</a> Proteomics. 15 (19), 3331-3337 (2015).</li><li>Athman, J. 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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+identification+of+membrane+vesicle-associated+proteins+in+Gram-positive+bacteria+and+mycobacteria.">Isolation and identification of membrane vesicle-associated proteins in Gram-positive bacteria and mycobacteria.</a> MethodsX. 1, 124-129 (2014).</li><li>Cvjetkovic, A., L&#246;tvall, J., L&#228;sser, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+rotor+type+and+centrifugation+time+on+the+yield+and+purity+of+extracellular+vesicles.">The influence of rotor type and centrifugation time on the yield and purity of extracellular vesicles.</a> Journal of Extracellular Vesicles. 3 (1), 23111 (2014).</li><li>Dauros Singorenko, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+membrane+vesicles+from+prokaryotes:+a+technical+and+biological+comparison+reveals+heterogeneity.">Isolation of membrane vesicles from prokaryotes: a technical and biological comparison reveals heterogeneity.</a> Journal of Extracellular Vesicles. 6 (1), 1324731 (2017).</li><li>Wallace, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culturing+mycobacteria.">Culturing mycobacteria.</a> Methods in Molecular Biology. 2314, 1-58 (2021).</li><li>Lucas, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extraction+and+separation+of+mycobacterial+proteins.">Extraction and separation of mycobacterial proteins.</a> Methods in Molecular Biology. 2314, 77-107 (2021).</li><li>Walker, S. A., Kennedy, M. T., Zasadzinski, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encapsulation+of+bilayer+vesicles+by+self-assembly.">Encapsulation of bilayer vesicles by self-assembly.</a> Nature. 387 (6628), 61-64 (1997).</li><li>Edwards, D. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+vesicle+formation+at+lipid+bilayer+membranes.">Spontaneous vesicle formation at lipid bilayer membranes.</a> Biophysical Journal. 71 (3), 1208 (1996).</li><li>. Production Manuals &amp; SOPs. SP007: Running of polyacrylamide gels, SP011: Western blot, and SP0012: Silver staining protocols Available from: <a target="_blank" href="https://labs.vetmebiosci.colostate.edu/dobos/bei-resources/">https://labs.vetmebiosci.colostate.edu/dobos/bei-resources/</a> (2022)</li><li>Engers, H. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Results+of+a+World+Health+Organization-sponsored+workshop+to+characterize+antigens+recognized+by+mycobacterium-specific+monoclonal+antibodies.">Results of a World Health Organization-sponsored workshop to characterize antigens recognized by mycobacterium-specific monoclonal antibodies.</a> Infection and Immunity. 51 (2), 718-720 (1986).</li><li>Chatterjee, D., Lowell, K., Rivoire, B., McNeil, M. R., Brennan, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipoarabinomannan+of+Mycobacterium+tuberculosis.+Capping+with+mannosyl+residues+in+some+strains.">Lipoarabinomannan of Mycobacterium tuberculosis. Capping with mannosyl residues in some strains.</a> Journal of Biological Chemistry. 267 (9), 6234-6239 (1992).</li><li>Th&#233;ry, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimal+information+for+studies+of+extracellular+vesicles+2018+(MISEV2018):+a+position+statement+of+the+International+Society+for+Extracellular+Vesicles+and+update+of+the+MISEV2014+guidelines.">Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines.</a> Journal of Extracellular Vesicles. 7 (1), 1535750 (2018).</li><li>Palacios, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mycobacterium+tuberculosis+extracellular+vesicle-associated+lipoprotein+LpqH+as+a+potential+biomarker+to+distinguish+paratuberculosis+infection+or+vaccination+from+tuberculosis+infection.">Mycobacterium tuberculosis extracellular vesicle-associated lipoprotein LpqH as a potential biomarker to distinguish paratuberculosis infection or vaccination from tuberculosis infection.</a> BMC Veterinary Research. 15 (1), 1-9 (2019).</li><li>Ziegenbalg, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunogenicity+of+mycobacterial+vesicles+in+humans:+Identification+of+a+new+tuberculosis+antibody+biomarker.">Immunogenicity of mycobacterial vesicles in humans: Identification of a new tuberculosis antibody biomarker.</a> Tuberculosis. 93 (4), 448-455 (2013).</li><li>Chiplunkar, S. S., Silva, C. A., Bermudez, L. E., Danelishvili, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+membrane+vesicles+released+by+Mycobacterium+avium+in+response+to+environment+mimicking+the+macrophage+phagosome.">Characterization of membrane vesicles released by Mycobacterium avium in response to environment mimicking the macrophage phagosome.</a> Future Microbiology. 14 (4), 293-313 (2019).</li></ol>

The authors have nothing to disclose.

Mycobacterium tuberculosis extracellular vesicles are highly antigenic reservoirs, which present them as an attractive avenue for developing diagnostic tools and future vaccines4,19,20. Historically, density gradient ultracentrifugation has been used to separate Mtb EVs from other soluble, secreted material8. While this process is effective, it is also time-consuming, technically challenging, and...

Extracellular vesicle (EV) release by pathogens may be the key to unlocking new technologies to control infectious diseases1. Mycobacterium tuberculosis (Mtb) is a pathogen of high consequence, infecting approximately one-third of the world&#39;s population and claiming the lives of millions of people each year2. EV production by Mtb is well documented yet elusive in the biogenesis and varied roles (i.e., immunostimulatory, immunosuppressive, iron and nutrient acquisition) of these EVs in the context of infection3,4,5. Efforts to understand the composition of Mtb EVs revealed 50-150 nm lipid membrane-enclosed spheres derived from the plasma membrane containing lipids and proteins of immunological significance3,6. Investigation of the role of Mtb EVs in bacterial physiology has revealed the importance of bacterial EV modulation in response to environmental stress for survival5. Host-pathogen interaction studies have been more complicated to interpret, but evidence indicates that Mtb EVs can influence the immune response of the host and may potentially serve as an effective vaccination component3,4,7.
Most studies of Mtb EVs thus far have relied on density gradient ultracentrifugation for vesicle enrichment8. This has been effective for small-scale studies; however, this technique has several technical and logistical challenges. Alternate workflows couple multistep centrifugation, for the removal of whole cells and large debris, with a final ultracentrifugation step to pellet EVs. This methodology can vary in efficiency, and often results in low yield and co-purification of soluble non-vesicle associated biomolecules while also impacting vesicle integrity9. Additionally, this process is time-consuming, manually intensive, and very limited in throughput due to equipment constraints.
The present protocol describes an alternative technique to density gradient ultracentrifugation: size exclusion chromatography (SEC). This method has been demonstrated for environmental mycobacteria, and in the current work, it has been extrapolated to Mtb10. A commercially available column and automatic fraction collector can improve consistency in vesical preparation and reduce the necessity for specific, expensive equipment. It is also possible to complete this protocol in a fraction of the time compared to density gradient ultracentrifugation, increasing the throughput. This technique is less technically challenging, making it easier to master, and can increase inter/intra-laboratory reproducibility. Finally, SEC has high separation efficiency and is gentle, preserving the integrity of the vesicles.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>20x MES SDS Running Buffer</td>
			<td>ThermoFisher Scientific</td>
			<td>NP0002</td>
			<td></td>
		</tr>
		<tr>
			<td>96 well plate</td>
			<td>Corning</td>
			<td>15705-066</td>
			<td></td>
		</tr>
		<tr>
			<td>Automatic Fraction Collector</td>
			<td>IZON Science</td>
			<td>AFC-V1-USD</td>
			<td></td>
		</tr>
		<tr>
			<td>BenchMark Pre-stained Protein Ladder</td>
			<td>Invitrogen</td>
			<td>10748010</td>
			<td></td>
		</tr>
		<tr>
			<td>Benchtop centrifuge</td>
			<td>Beckman Coulter</td>
			<td>Allegra 6R</td>
			<td></td>
		</tr>
		<tr>
			<td>Centricon Plus - 70 Centrifugal filter, 100 kDa cutoff</td>
			<td>Millipore Sigma</td>
			<td>UFC710008</td>
			<td>Ultrafiltration device used in step 1.1</td>
		</tr>
		<tr>
			<td>Electroblotting System</td>
			<td>ThermoFisher Scientific</td>
			<td>09-528-135</td>
			<td></td>
		</tr>
		<tr>
			<td>EM Grade Paraformaldehyde</td>
			<td>Electron Microscopy Sciences</td>
			<td>15714-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Formvar/Carbon 200 mesh Cu Grids</td>
			<td>Electron Microscopy Sciences</td>
			<td>FCF200H-Cu-TA</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat Anti-Mouse IgG H&#38;L (Alkaline Phosphatase), whole molecule, 1 mL</td>
			<td>AbCam</td>
			<td>ab6790</td>
			<td>Secondary antibody</td>
		</tr>
		<tr>
			<td>JEM-1400 Transmission Electron Microscope</td>
			<td>JOEL</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Micro BCA Protein Assay Kit</td>
			<td>ThermoFisher Scientific</td>
			<td>23235</td>
			<td></td>
		</tr>
		<tr>
			<td>Microplate reader</td>
			<td>BIOTEK</td>
			<td>Epoch</td>
			<td></td>
		</tr>
		<tr>
			<td>Monoclonal Anti-Mycobacterium tuberculosis GroES (Gene Rv3814c)</td>
			<td>BEI Resources</td>
			<td>NR-49223</td>
			<td>Primary antibody</td>
		</tr>
		<tr>
			<td>Monoclonal Anti-Mycobacterium tuberculosis LpqH (Gene Rv3763)</td>
			<td>BEI Resources</td>
			<td>NR-13792</td>
			<td>Primary antibody</td>
		</tr>
		<tr>
			<td>Monocolonal Anti-Mycobacterium tuberculosis LAM, Clone CS-35</td>
			<td>BEI Resources</td>
			<td>NR-13811</td>
			<td>Primary antibody</td>
		</tr>
		<tr>
			<td>NanoClean 1070</td>
			<td>Fischione Instruments</td>
			<td></td>
			<td>For plasma cleaning of the TEM grid</td>
		</tr>
		<tr>
			<td>Nanosight equipped with syringe pump and computer with NanoSight NTA software</td>
			<td>Malvern Panalytical</td>
			<td>NS300</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitrocellulose membrane, Roll, 0.2 &#956;m</td>
			<td>BioRad</td>
			<td>1620112</td>
			<td></td>
		</tr>
		<tr>
			<td>NuPAGE 4-12% Bis-Tris Protein Gels</td>
			<td>ThermoFisher Scientific</td>
			<td>NP0323BOX</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-buffered Saline, 1X without calcium and magnesium</td>
			<td>Corning</td>
			<td>21-040-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Pierce BCA Protein Assay Kit</td>
			<td>ThermoFisher Scientific</td>
			<td>23225</td>
			<td></td>
		</tr>
		<tr>
			<td>PowerPac Basic Power Supply</td>
			<td>BioRad</td>
			<td>1645050</td>
			<td></td>
		</tr>
		<tr>
			<td>qEV Original 35 nm 5/pk</td>
			<td>IZON Science</td>
			<td>SP5-USD</td>
			<td>SEC column</td>
		</tr>
		<tr>
			<td>SDS sample buffer</td>
			<td>Boster</td>
			<td>AR1112</td>
			<td>In-house recipe used in this procedure, however this product is equivalent</td>
		</tr>
		<tr>
			<td>SDS-PAGE gel chamber</td>
			<td>ThermoFisher Scientific</td>
			<td>EI0001</td>
			<td></td>
		</tr>
		<tr>
			<td>Sigmafast BCIP/NBT</td>
			<td>Millipore Sigma</td>
			<td>B5655</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver Stain Plus Kit</td>
			<td>BioRad</td>
			<td>1610449</td>
			<td>In-house protocol used in this procedure, however this kit is equivalent</td>
		</tr>
		<tr>
			<td>Uranyl Acetate</td>
			<td>Electron Microscopy Sciences</td>
			<td>22400</td>
			<td></td>
		</tr>
	</tbody>
</table>

mycobacterium tuberculosis extracellular vesicle enrichment through size exclusion chromatography

The role of extracellular vesicles (EVs) in the context of bacterial infection has emerged as a new avenue for understanding microbial physiology. Specifically, Mycobacterium tuberculosis (Mtb) EVs play a role in the host-pathogen interaction and response to environmental stress. Mtb EVs are also highly antigenic and show potential as vaccine components. The most common method for purifying Mtb EVs is density gradient ultracentrifugation. This process has several limitations, including low throughput, low yield, reliance on expensive equipment, technical challenges, and it can negatively impact the resulting preparation. Size exclusion chromatography (SEC) is a gentler alternative method that combats many of the limitations of ultracentrifugation. This protocol demonstrates that SEC is effective for Mtb EV enrichment and produces high-quality Mtb EV preparations of increased yield in a rapid and scalable manner. Additionally, a comparison to density gradient ultracentrifugation by quantification and qualification procedures demonstrates the benefits of SEC. While the evaluation of EV quantity (nanoparticle tracking analysis), phenotype (transmission electron microscopy), and content (Western blotting) is tailored to Mtb EVs, the workflow provided can be applied to other mycobacteria.

Culture filtrate protein (CFP) from Mycobacterium tuberculosis (Mtb) was concentrated, quantified, and then 3 mg of material was applied to a size exclusion chromatography (SEC) column. The protein and particle concentrations were enumerated by BCA and NTA, respectively. Expected ranges for protein and particle recovery plus the exact values obtained for these results are reported in Table 1. Values much higher than these ranges may indicate contamination or column integrity issues. Values signi...

Watch this Scientific Journal Video about Mycobacterium tuberculosis Extracellular Vesicle Enrichment through Size Exclusion Chromatography at JoVE.com

Mycobacterium tuberculosis Extracellular Vesicle Enrichment through Size Exclusion Chromatography

This protocol describes size exclusion chromatography, a facile and reproducible technique for enriching Mycobacterium tuberculosis extracellular vesicles from culture supernatants.

Mycobacterium tuberculosis Extracellular Vesicle Enrichment through Size Exclusion Chromatography

The role of extracellular vesicles (EVs) in the context of bacterial infection has emerged as a new avenue for understanding microbial physiology. ...

This protocol reduces the technical complexity and time required for the enrichment of extracellular vesicles from Mycobacterium tuberculosis, Mtb EVs. It provides a gentle alternative to traditional ultracentrifugation and density-based techniques. The main advantage of this technique is that it is easy to perform, making it more reproducible.It provides a high yield of Mtb EVs with minimal non-EV protein co-enrichment. Demonstrating the procedure will be Joanie Ryan, a former graduate student of our lab. To begin, prepare a 100-kilodalton molecular weight cutoff centrifugal filter by adding the full volume capacity of PBS.Centrifuge for five minutes at 2, 800 times G at 4 degrees Celsius. Discard the flowthrough and any remaining PBS, and fill the sample chamber with Mtb CFP to its maximum capacity. Centrifuge at 2, 800 times G at 4 degrees Celsius until the volume has reduced to the minimum volume of the ultrafiltration device.Repeat as necessary until the entire sample has been reduced sufficiently. Add 1X PBS to the filter unit containing the concentrate up to the total device capacity. Reduce the volume as described before and repeat this step five times to ensure complete washing and buffer exchange.Then, recover the 100-kilodalton concentrated CFP retentate or 100R, according to the ultrafiltration device specifications. Wash the filter with a minimal volume of 1X PBS at least three times, and pull the wash with the 100R to maximize the recovery. Use several dilution of samples in PBS and quantitate the 100R material with a bicinchoninic assay.Test the sample in triplicate. Allow the size exclusion chromatography, or SEC column, to equilibrate to room temperature. Turn on the AFC using the power switch on the back of the tower unit and press Setup on the main menu touch screen if necessary to adjust the settings for the load cell.From the setup screen, align the carousel by selecting Carousel followed by Calibrate. Insert the carousel with the 13 small holes facing up into the AFC tower and adjust the carousel by pressing the minus or plus buttons so that the fluid nozzle is directly above the flush position. Remove the caps from the equilibrated SEC column and slide the SEC column into the appropriate column mount.Carefully install it on the AFC tower. Ensure that the radio frequency identification tag on the column faces the AFC, and check that the connection between the column and the valve is secure. Place the waste outlet tubing in a collection container.From the setup screen, select Collection Schedule and set the count to 13 and the size to 0.5 milliliters by pressing the minus or plus buttons. Leave the buffer volume setting as the default of 2.7 milliliters and then close the collection schedule window. Select Start Collection from the home screen and confirm the collection parameters by selecting Yes.Load 13 labeled 1.7 milliliter microcentrifuge tubes with the lids open and pointing toward the carousel center. Advance the AFC by selecting OK, then mount the column reservoir and advance again by pressing OK.Select the option to flush the column by pressing Yes, and add one column volume of 0.2 micrometer filtered PBS to remove any storage buffer. Once the flush is complete, advance the AFC by pressing OK.Place the carousel cover over the AFC and press OK.Use a pipette to remove any excess buffer from the column.Bring three milligrams of 100R sample to 500 microliters with 1X PBS and add the sample to the top of the column. Prepare one column volume of 0.2 micrometer filtered PBS. Advance the AFC and allow the sample to run into the fret.Once the sample has fully entered the column, add the PBS prepared earlier to the reservoir. Monitor the run of the AFC while it collects first the void volume and then the specified fractions. After the run completes and the carousel returns to the waste position, remove the cover and the fraction tubes from the carousel.For 0.5 millimeters fractions collected from three milligrams of 100R Mtb CFP, measure the protein concentration using the micro-BCA with a 1:3 dilution for fractions numbered 1 to 7 of each sample in triplicate. For 0.5 milliliters fractions numbered 5 to 13, use the BCA with no dilution for each sample in triplicate. Add SDS sample buffer to 10 microliters of each fraction and five micrograms of CFP and 100R.Boil for five minutes at 100 degrees Celsius. Then load on a 4 to 12%Bis-Tris gel with a molecular weight ladder for polyacrylamide gel electrophoresis, or PAGE. Run an SDS-PAGE gel using 1X MES running buffer and a 200-volt current for 35 minutes.Remove the gel from the cassette and apply a 50-volt current for a minimum of one hour to transfer the resolved proteins to a 0.2 micrometer nitrocellulose membrane. Finally, perform the Western blot analysis to evaluate the proteins. An SDS-PAGE gel stained with silver demonstrates the overall protein profile for each fraction.The data shows that the later fractions contain more protein and resemble the 100R material. Western blots detecting LAM, LpqH and GroES demonstrate that protein marker changes across the fractions. Transmission electron microscopy, or TEM images, of SEC fractions 1 to 3 pulled prior to fixation are shown here.The density gradient ultracentrifugation of Mtb EVs was negatively stained for TEM imaging. The nanoparticle tracking analysis, or NTA distribution, of SEC fractions 1 to 3 is shown here. The density gradient ultracentrifugation Mtb EVs were analyzed with nanoparticle tracking analysis, and the size distribution is displayed here.This protocol has been optimized for EV purification from three milligrams of 100R. If the protein load is varied, the recommended dilution and BCA strategy on resulting fractions may require adjustment. Mtb EVs prepared with this technique can be used for downstream compositional and omics-based studies.They are also suitable for in vitro and in vivo experiments. This technique provides a facile and efficient way to produce high-quality Mtb EV preparations, paving the way for increased reproducibility in future Mtb EV experiments.

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Research

JoVE Journal

Immunology and Infection

2.2K 조회수.  Colorado State University. 이 프로토콜은 결핵균, Mtb EV에서 세포 외 소포를 농축하는 데 필요한 기술적 복잡성과 시간을 줄입니다. 전통적인 초원심분리 및 밀도 기반 기술에 대한 부드러운 대안을 제공합니다. 이 기술의 가장 큰 장점은 수행하기 쉽고 재현성이 높다는 것입니다.최소한의 비 EV 단백질 공동 농축으로 높은 수율의 Mtb EV를 제공합니다. 절차를 시연하는 것은 우리 연구실의 전 대학?...