Name: evaluating the immune response of a nanoemulsion adjuvant vaccine against methicillin-resistant staphylococcus aureus (mrsa) infection
Uploaded: 2023-09-01T12:40:00
Description: Watch this Scientific Journal Video about Evaluating the Immune Response of a Nanoemulsion Adjuvant Vaccine Against Methicillin-Resistant Staphylococcus aureus MRSA Infection at JoVE.com

This research was supported by No. 2021YFC2302603 of the National Key Research and Development Program of China, No. 32070924 and 32000651 of the NSFC, and No. 2019jcyjA-msxmx0159 of the Natural Science Foundation Project Program of Chongqing.

The animal experiments were conducted based on the manual on the use and care of experimental animals and were approved by the Laboratory Animal Welfare and Ethics Committee of the Third Military Medical University. Female Balb/c mice, 6-8 weeks old, were used for the present study. The animals were obtained from commercial sources (see Table of Materials).
1. Preparation of the MRSA HI antigen protein
<ol>
	<li>Obtain IsdB and Hla clones f...

<ol>
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S., Otto, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogenicity+and+virulence+of+Staphylococcus+aureus.">Pathogenicity and virulence of Staphylococcus aureus.</a> Virulence. 12 (1), 547-569 (2021).</li><li>Lakhundi, S., Zhang, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methicillin-resistant+Staphylococcus+aureus:+molecular+characterization,+evolution,+and+epidemiology.">Methicillin-resistant Staphylococcus aureus: molecular characterization, evolution, and epidemiology.</a> Clinical Microbiology Reviews. 31 (4), e00020 (2018).</li><li>Mancuso, G., Midiri, A., Gerace, E., Biondo, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacterial+antibiotic+resistance:+the+most+critical+pathogens.">Bacterial antibiotic resistance: the most critical pathogens.</a> Pathogens. 10 (10), 1310 (2021).</li><li>Goull&#233;, J. 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V., Stylianou, A., Malamou, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+force+microscopy+nanoindentation+method+on+collagen+fibrils.">Atomic force microscopy nanoindentation method on collagen fibrils.</a> Materials. 15 (7), 2477 (2022).</li><li>Zeng, H., 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=An+immunodominant+epitope-specific+monoclonal+antibody+cocktail+improves+survival+in+a+mouse+model+of+Staphylococcus+aureus+bacteremia.">An immunodominant epitope-specific monoclonal antibody cocktail improves survival in a mouse model of Staphylococcus aureus bacteremia.</a> The Journal of Infectious Diseases. 223 (10), 1743-1752 (2021).</li><li>Roy, U., Kornitzer, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heme-iron+acquisition+in+fungi.">Heme-iron acquisition in fungi.</a> Current Opinion in Microbiology. 52, 77-83 (2019).</li><li>Saeed, K., 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=Bacterial+toxins+in+musculoskeletal+infections.">Bacterial toxins in musculoskeletal infections.</a> Journal of Orthopaedic Research. 39 (2), 240-250 (2021).</li><li>Xu, Q., Zhou, A., Wu, H., Bi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+in+vivo+evaluation+of+baicalin-loaded+W/O+nanoemulsion+for+lymphatic+absorption.">Development and in vivo evaluation of baicalin-loaded W/O nanoemulsion for lymphatic absorption.</a> Pharmaceutical Development and Technology. 24 (9), 1155-1163 (2019).</li><li>Singh, Y., 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=Nanoemulsion:+Concepts,+development+and+applications+in+drug+delivery.">Nanoemulsion: Concepts, development and applications in drug delivery.</a> Journal of Controlled Release. 252, 28-49 (2017).</li><li>Kadakia, E., Shah, L., Amiji, M. 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IsdB, a bacterial cell wall-anchored and iron-regulated surface protein, plays an important role in the process of obtaining heme iron15. Hla, alpha toxin, is among the most effective bacterial toxins known in MRSA, and can form pores in eukaryotic cells and interfere with adhesion and epithelial cells16. In our study, a novel recombination MRSA antigen protein (HI) was constructed and expressed with gene engineering technology based on the antigen genes o...

Methicillin-resistant Staphylococcus aureus (MRSA) is an opportunistic pathogen with one of the highest infection rates in an intensive care unit (ICU) wards1, cardiology departments, and burn departments worldwide. MRSA exhibits high rates of infection, mortality, and broad drug resistance, presenting great difficulties in clinical treatment2. In the Global Priority List of Antibiotic-Resistant Bacteria released by the World Health Organisation (WHO) in 2017, MRSA was listed in the most critical category3. A vaccine against MRSA infection is therefore urgently needed.
Aluminum adjuvant has been used for a long time, and the adjuvant auxiliary mechanism is relatively clear, safe, effective, and well tolerated4. Aluminum adjuvants are currently a widely used type of adjuvant. It is generally believed that antigens adsorbed on aluminum salt particles can improve the stability and enhance the ability of the injection site to uptake antigens, providing good absorption and slow release5. Currently, the main disadvantage of aluminum adjuvants is that they lack an adjuvant effect or exhibit only a weak adjuvant effect on some vaccine candidate antigens6. In addition, aluminum adjuvants induce IgE-mediated hypersensitivity reactions5. Therefore, it is necessary to develop novel adjuvants to stimulate a stronger immune response.
Nanoemulsion adjuvants are colloidal dispersion systems composed of oil, water, surfactants, and cosurfactants7. In addition, the adjuvants are thermodynamically stable and isotropic, can be autoclaved or stabilized by high-speed centrifugation, and can be formed spontaneously under mild preparation conditions. Several emulsion adjuvants (such as MF59, NB001-002 series, AS01-04 series, etc.) are currently on the market or in the clinical research stage, but their particle sizes are greater than&#160;160 nm8. Therefore, the advantages of nanoscale (1-100 nm) medicinal preparations (i.e., large specific surface area, small particle size, surface effect, high surface energy, small size effect, and macro quantum tunneling effect) cannot be fully exploited. In the present protocol, a novel adjuvant based on nanoemulsion technology with a diameter size of 1-100 nm has been reported to exhibit good adjuvant activity9. We tested the recombination subunit vaccine antigen protein HI (&#945;-hemolysin mutant [Hla] and Fe ion surface determining factor B [IsdB] subunit N2 active fragment fusion protein); a series of procedures were established to examine the physical properties and stability, evaluate its specific antibody response after intramuscular administration, and test the protective effect of the vaccine using a mouse systemic infection model.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>5424-Small high speed centrifugeFA-45-24-11</td>
			<td>Eppendorf, Germany&#160;</td>
			<td>5424000495</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well plates</td>
			<td>Corning Incorporated, USA</td>
			<td>CLS3922</td>
			<td></td>
		</tr>
		<tr>
			<td>AFM Dimension FastScan</td>
			<td>BRUKER, Germany&#160;</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol lamp</td>
			<td>Shenzhen Yibaxun Technology Co.,China</td>
			<td>YBS-AA-11408</td>
			<td></td>
		</tr>
		<tr>
			<td>Balb/c mice&#160;</td>
			<td>Beijing HFK Bioscience Co. Ltd.&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BCIP/NBT</td>
			<td>Fuzhou Maixin Biotechnology Development Company,China</td>
			<td>BCIP/NBT</td>
			<td></td>
		</tr>
		<tr>
			<td>Bio-Rad 6.0 microplate reader</td>
			<td>Bio-Rad Laboratories Incorporated Limited Co., CA, USA</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>BL21 Competent Cell</td>
			<td>Merck millipore,Germany</td>
			<td>70232-3CN</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA-100G</td>
			<td>Sigma-Aldrich, USA</td>
			<td>B2064-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge 5810 R</td>
			<td>Eppendorf, Germany&#160;</td>
			<td>5811000398</td>
			<td></td>
		</tr>
		<tr>
			<td>Coomassie bright blue G-250 staining solution</td>
			<td>MIKX,China</td>
			<td>DB236</td>
			<td></td>
		</tr>
		<tr>
			<td>Decolorization solution</td>
			<td>BOSTER,China</td>
			<td>AR0163-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Electro-heating standing-temperature cultivator HH-B11-420</td>
			<td>Shanghai Yuejin Medical Device Factory, China</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>Electrophoresis apparatus</td>
			<td>Beijing Liuyi Instrument Factory, China</td>
			<td>DYCZ-25D</td>
			<td></td>
		</tr>
		<tr>
			<td>Gel image</td>
			<td>Tanon, USA</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutathione-Sepharose Resin GST</td>
			<td>Mei5bio,China</td>
			<td>affinity chromatography resin</td>
			<td></td>
		</tr>
		<tr>
			<td>H2SO4</td>
			<td>Chengdu KESHI Chemical Co., LTD,China</td>
			<td>7664-93-9</td>
			<td></td>
		</tr>
		<tr>
			<td>HI recombinant protein</td>
			<td>Third Military Medical University,China</td>
			<td>110-27-0</td>
			<td></td>
		</tr>
		<tr>
			<td>HRP -Goat Anti-Mouse IgG</td>
			<td>Biodragon, China</td>
			<td>BF03001</td>
			<td></td>
		</tr>
		<tr>
			<td>HRP- Goat anti-mouse IgG1</td>
			<td>Biodragon, China</td>
			<td>BF03002R</td>
			<td></td>
		</tr>
		<tr>
			<td>HRP- Goat anti-mouse IgG2a</td>
			<td>Biodragon, China</td>
			<td>BF03003R</td>
			<td></td>
		</tr>
		<tr>
			<td>HRP- Goat anti-mouse IgG2b</td>
			<td>Biodragon, China</td>
			<td>BF03004R</td>
			<td></td>
		</tr>
		<tr>
			<td>Inoculation loop</td>
			<td>Haimen Feiyue Co.,LTD,China</td>
			<td>YR-JZH-1UL</td>
			<td></td>
		</tr>
		<tr>
			<td>IsdB and Hla clones</td>
			<td>Shanghai Jereh Biotechnology Co,China</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl nutmeg (pharmaceutic adjuvant)</td>
			<td>SEPPIC, France</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>isopropyl- &#946;-D-1-mercaptogalactopyranoside</td>
			<td>fdbio,China</td>
			<td>FD3278-1</td>
			<td></td>
		</tr>
		<tr>
			<td>LB bouillon culture-medium</td>
			<td>Beijing AOBOX Biotechnology Co., LTD,China</td>
			<td>02-136</td>
			<td></td>
		</tr>
		<tr>
			<td>Lnfrared physiotherapy lamp</td>
			<td>Guangzhou Runman Medical Equipment Co.,China</td>
			<td>7600</td>
			<td></td>
		</tr>
		<tr>
			<td>Low temperature refrigerated centrifuge</td>
			<td>Eppendorf, Germany&#160;</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>Malvern NANO ZS</td>
			<td>Malvern Instruments Ltd., UK</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>MH(A) medium</td>
			<td>Beijing AOBOX Biotechnology Co., LTD,China</td>
			<td>02-051</td>
			<td></td>
		</tr>
		<tr>
			<td>MH(B) medium</td>
			<td>Beijing AOBOX Biotechnology Co., LTD,China</td>
			<td>02-052</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro plate washing machine 405 LSRS</td>
			<td>Bio Tek Instruments,Inc Highland&#160; Park,USA</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini-TBC Compact Film Transfer Instrument</td>
			<td>BeiJingDongFangRuiLi Co.,LTD,China</td>
			<td>1658030</td>
			<td></td>
		</tr>
		<tr>
			<td>MMC packing</td>
			<td>TOSOH(SHANGHAI)CO.,LTD</td>
			<td>0022818</td>
			<td></td>
		</tr>
		<tr>
			<td>MRSA252</td>
			<td>USA, ATCC</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>Nanodrop ultraviolet spectrophotometer</td>
			<td>Thermo Scientific, USA</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>New FlashTM Protein any KD PAGE Protein electrophoresis gel kit</td>
			<td>DAKEWE, China</td>
			<td>8012011</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>biosharp, China</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>PCR, Amplifier</td>
			<td>Thermal Cycler, USA</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>pGEX-target gene recombinant plasmid</td>
			<td>Shanghai Jereh Biotechnology Co,China</td>
			<td>B3528G</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphotungstic acid</td>
			<td>G-CLONE, China</td>
			<td>CS1231-25g</td>
			<td></td>
		</tr>
		<tr>
			<td>pipette</td>
			<td>Eppendorf, Germany&#160;</td>
			<td>3120000844</td>
			<td></td>
		</tr>
		<tr>
			<td>polyoxyethylated castor oil (pharmaceutic adjuvant)</td>
			<td>Aladdin, China</td>
			<td>K400327-1kg</td>
			<td></td>
		</tr>
		<tr>
			<td>Primary antibody</td>
			<td>Laboratory homemade:from immunized mice with positive sera</td>
			<td>null</td>
			<td>See Reference 11 for details</td>
		</tr>
		<tr>
			<td>propylene glycol (pharmaceutic adjuvant)</td>
			<td>Sigma-Aldrich, USA</td>
			<td>P4347-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein Marker</td>
			<td>Thermo Scientufuc, USA</td>
			<td>26616</td>
			<td></td>
		</tr>
		<tr>
			<td>PVDF TRANSFER MEMBRANE</td>
			<td>Invitrogen,USA</td>
			<td>88518</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning Electron Microscope</td>
			<td>JEOL,Japan</td>
			<td>JSM-IT800</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium pentobarbital</td>
			<td>Merck,Germany</td>
			<td>Tc-P8411</td>
			<td></td>
		</tr>
		<tr>
			<td>Talos L120C TEM</td>
			<td>Thermo Fisher, USA</td>
			<td>null</td>
			<td></td>
		</tr>
		<tr>
			<td>TMB color solution</td>
			<td>TIAN GEN, China</td>
			<td>PA107-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Turtle kits</td>
			<td>Xiamen Bioendo Technology Co.,LTD</td>
			<td>ES80545</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Macklin, China</td>
			<td>9005-64-5</td>
			<td></td>
		</tr>
	</tbody>
</table>

evaluating the immune response of a nanoemulsion adjuvant vaccine against methicillin-resistant staphylococcus aureus (mrsa) infection

Nanoemulsion adjuvant vaccines have attracted extensive attention because of their small particle size, high thermal stability, and ability to induce validly immune responses. However, establishing a series of comprehensive protocols to evaluate the immune response of a novel nanoemulsion adjuvant vaccine is vital. Therefore, this article features a rigorous procedure to determine the physicochemical characteristics of a vaccine (by transmission electron microscopy [TEM], atomic force microscopy [AFM], and dynamic light scattering [DLS]), the stability of the vaccine antigen and system (by a high-speed centrifuge test, a thermodynamic stability test, SDS-PAGE, and western blot), and the specific immune response (IgG1, IgG2a, and IgG2b). Using this approach, researchers can evaluate accurately&#160;the protective effect of a novel nanoemulsion adjuvant vaccine in a lethal MRSA252 mouse model. With these protocols, the most promising nanoemulsion vaccine adjuvant in terms of effective adjuvant potential can be identified. In addition, the methods can help optimize novel vaccines for future development.

The protocol for preparing the nanoemulsion adjuvant vaccine and in vitro and in vivo&#160;tests of this vaccine was evaluated. TEM, AFM, and DLS&#160;were used to determine the important characteristics of the zeta potential and particle size on the surface of this sample (Figure 1). SDS-PAGE and western blotting showed that the amount of antigen in the precipitate and supernatant did not significantly degrade after centrifugation, which indicated that the vaccine was stru...

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Evaluating the Immune Response of a Nanoemulsion Adjuvant Vaccine Against Methicillin-Resistant Staphylococcus aureus MRSA Infection

The present protocol prepares and evaluates the physical properties, immune response, and in vivo protective effect of a novel nanoemulsion adjuvant vaccine.

Evaluating the Immune Response of a Nanoemulsion Adjuvant Vaccine Against Methicillin-Resistant Staphylococcus aureus (MRSA) Infection

Nanoemulsion adjuvant vaccines have attracted extensive attention because of their small particle size, high thermal stability, and ability to induce ...

The demonstrated protocol underlined the direct and effective experimental approach and the detailed steps to immune response effects of novel viral adjuvants. This protocol provides the research with not only a basically immune evaluation method for adjuvant vaccine but can also determines their mass stability. To begin, take the 10 milligrams per milliliter working solution of the MRSA HI antigen protein, and to it, sequentially add the three excipients, isopropyl myristate, polyoxyethylene castor oil, and propylene glycol, maintaining a mass ratio of one is to six is to three.Stir the mixture well, then gradually add sterilized pure water to reach a system volume of 10 milliliters. To prepare the nanoemulsion vaccine by low energy emulsification method, stir it at 500 rotations per minute and 25 degrees Celsius for approximately 20 minutes. Subsequently, the nanoemulsion vaccine containing one milligram per milliliter protein is obtained as a clear transparent liquid.For antigen coating of the enzyme linked immunosorbent assay or ELISA plate, dilute HI protein antigen to 10 micrograms per milliliter with coating solution, and add 100 microliters of the diluted antigen per well in the ELISA plate. Incubate the plate at four degrees Celsius overnight. After incubation, wash the plate with 300 microliters of PBST per well.Seal the wells with 300 microliters of the sealing solution per well for two hours at 37 degrees Celsius, then dilute three microliters of the mice serum from each experimental group 100 times by adding 297 microliters of PBST, and vortex the diluted serum. Add 100 microliters of diluted serum per well in the coated ELISA plate for each serum sample. Similarly, dilute the positive and negative control serums 100 times with PBST by adding four microliters of positive or negative control serum to 396 microliters of PBST, followed by vortex mixing.To perform double ratio dilution, add 200 microliters of the previously diluted experimental serum to the first row of the coated ELISA plate, then add 100 microliters of PBST to all wells, except those in rows one and 12. Next, adjust the pipette gun to 100 microliters and transfer 100 microliters of serum from the first row to the second row containing PBST. Mix the content in the second row 10 times using the pipette gun.Similarly, perform one is to two successive dilutions of the serum til row 11. Once done, discard 100 microliters of liquid from row 11. Add 100 microliters of diluted negative and positive serum to each corresponding well in row 12 following the sample template.Seal the ELISA plate with plastic wrap and incubate at 37 degrees Celsius for one hour. Meanwhile, dilute secondary antibody anti-mouse IgG HRP 10, 000 times by adding PBST. After the one-hour incubation, wash the ELISA plate with 300 microliters of PBST per well to clean the unbound antibodies, then add 100 microliters of the diluted secondary antibody to each well and incubate the plate at 37 degrees Celsius for 40 minutes.Wash the plate with 300 microliters of PBST per well, then add 100 microliters of TMB color development solution to each well. Place the plates at 37 degrees Celsius and away from light for 10 minutes. After which, terminate the reaction immediately with 50 microliters of two molar sulfuric acid.Detect the optical density or OD values at 415 nanometers using an enzyme marker within 15 minutes after termination. The physical characteristics of novel nanoemulsion vaccine were analyzed using transmission electron microscopy and atomic force microscopy. Dynamic light scattering was used to determine the particle size distribution and the zeta potential of the sample.SDS-PAGE and western blotting showed that the amount of antigen in the precipitate and supernatant did not significantly defer after centrifugation, indicating the vaccine was structurally intact, specific, and immunogenic. The nanoemulsion adjuvant vaccine significantly increased the total IgG, IgG1, and IgG2a antibody titers of the mice. The immunogenicity of the protein vaccine was significantly improved.The serum IgG2b OD values at 450 nanometers were highest when PBS was used at a one is to 5, 000 dilution. The lethal model of MRSA 252 mice reflected that the nanoemulsion vaccine showed a good protective effect and effectively inhibited bacterial infection with MRS A 252, improving the survival rate of infected mice. The preparation of nanoemulssion and the addition of serum to the plant are the most important.Also, where detection the antibody titer, one should pay attention to correct to a wider and liquid-based out. Besides adjuvants, this method can also be used for the immune evolution of other math arrays, such as plastics or delivery systems.

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Research

JoVE Journal

Immunology and Infection

The Use of Drip Flow and Rotating Disk Reactors for Staphylococcus aureus Biofilm Analysis

Most microbes in nature are thought to exist as surface-associated communities in biofilms.1 Bacterial biofilms are encased within a matrix and attached to a surface.2 Biofilm formation and development are commonly studied in the laboratory using batch systems such as microtiter plates or flow systems, such as flow-cells. These methodologies are useful for screening mutant and chemical libraries (microtiter plates)3 or growing biofilms for visualization (flow cells)4. Here we present detailed protocols for growing Staphylococcus aureus in two additional types of flow system biofilms: the drip flow biofilm reactor and the rotating disk biofilm reactor.
Drip flow biofilm reactors are designed for the study of biofilms grown under low shear conditions.5 The drip flow reactor consists of four parallel test channels, each capable of holding one standard glass microscope slide sized coupon, or a length of catheter or stint. The drip flow reactor is ideal for microsensor monitoring, general biofilm studies, biofilm cryosectioning samples, high biomass production, medical material evaluations, and indwelling medical device testing.6,7,8,9
The rotating disk reactor consists of a teflon disk containing recesses for removable coupons.10 The removable coupons can by made from any machinable material. The bottom of the rotating disk contains a bar magnet to allow disk rotation to create liquid surface shear across surface-flush coupons. The entire disk containing 18 coupons is placed in a 1000 mL glass side-arm reactor vessel. A liquid growth media is circulated through the vessel while the disk is rotated by a magnetic stirrer. The coupons are removed from the reactor vessel and then scraped to collect the biofilm sample for further study or microscopy imaging. Rotating disc reactors are designed for laboratory evaluations of biocide efficacy, biofilm removal, and performance of anti-fouling materials.9,11,12,13

The Use of Drip Flow and Rotating Disk Reactors for Staphylococcus aureus Biofilm Analysis

Protocols for utilizing open system flow biofilms with drip flow reactors and rotating disk reactors are presented in detail.

Most microbes in nature are thought to exist as surface-associated communities in biofilms.1  Bacterial biofilms are encased within a matrix and attached ...

Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)

MRSA is a worldwide threat to public health, and MRSA skin and soft-tissue infections now account for more than half of all soft-tissue infections in the United States. Among soft-tissue infections, myositis, pyomyositis, and necrotizing fasciitis have been increasingly reported in association with MRSA arising from the community. To understand the interplay between MRSA and host immunity leading to more severe infection, the availability of animal models is critical, permitting the study of host and bacterial factors. Several infection models have been introduced to assess the pathogenesis of S. aureus during superficial skin infection. Here, we describe a subcutaneous infection model that examines the skin, subcutaneous, and muscle pathologies.

Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA

Murine skin and soft tissue infection model is utilized for assessing the virulence function of methicillin resistant Staphylococcus aureus (MRSA) and the host immunological responses. Here, we presented a subcutaneous infection model for skin and soft tissue infection.

MRSA is a worldwide threat to public health, and MRSA skin and soft-tissue infections now account for more than half of all soft-tissue infections in the ...

Experimental Endocarditis Model of Methicillin Resistant Staphylococcus aureus (MRSA) in Rat

Endovascular infections, including endocarditis, are life-threatening infectious syndromes1-3. Staphylococcus aureus is the most common world-wide cause of such syndromes with unacceptably high morbidity and mortality even with appropriate antimicrobial agent treatments4-6. The increase in infections due to methicillin-resistant S. aureus (MRSA), the high rates of vancomycin clinical treatment failures and growing problems of linezolid and daptomycin resistance have all further complicated the management of patients with such infections, and led to high healthcare costs7, 8. In addition, it should be emphasized that most recent studies with antibiotic treatment outcomes have been based in clinical settings, and thus might well be influenced by host factors varying from patient-to-patient. Therefore, a relevant animal model of endovascular infection in which host factors are similar from animal-to-animal is more crucial to investigate microbial pathogenesis, as well as the efficacy of novel antimicrobial agents. Endocarditis in rat is a well-established experimental animal model that closely approximates human native valve endocarditis. This model has been used to examine the role of particular staphylococcal virulence factors and the efficacy of antibiotic treatment regimens for staphylococcal endocarditis. In this report, we describe the experimental endocarditis model due to MRSA that could be used to investigate bacterial pathogenesis and response to antibiotic treatment.

Experimental Endocarditis Model of Methicillin Resistant Staphylococcus aureus MRSA in Rat

Experimental rat endocarditis model due to methicillin-resistant S. aureus.

Endovascular infections, including endocarditis, are life-threatening infectious syndromes1-3. Staphylococcus aureus is the most common world-wide cause ...

Quantitative Measurement of the Immune Response and Sleep in Drosophila

A complex interaction between the immune response and host behavior has been described in a wide range of species. Excess sleep, in particular, is known to occur as a response to infection in mammals 1 and has also recently been described in Drosophila melanogaster2. It is generally accepted that sleep is beneficial to the host during an infection and that it is important for the maintenance of a robust immune system3,4. However, experimental evidence that supports this hypothesis is limited4, and the function of excess sleep during an immune response remains unclear. We have used a multidisciplinary approach to address this complex problem, and have conducted studies in the simple genetic model system, the fruitfly Drosophila melanogaster. We use a standard assay for measuring locomotor behavior and sleep in flies, and demonstrate how this assay is used to measure behavior in flies infected with a pathogenic strain of bacteria. This assay is also useful for monitoring the duration of survival in individual flies during an infection. Additional measures of immune function include the ability of flies to clear an infection and the activation of NF&kappa;B, a key transcription factor that is central to the innate immune response in Drosophila. Both survival outcome and bacterial clearance during infection together are indicators of resistance and tolerance to infection. Resistance refers to the ability of flies to clear an infection, while tolerance is defined as the ability of the host to limit damage from an infection and thereby survive despite high levels of pathogen within the system5. Real-time monitoring of NF&kappa;B activity during infection provides insight into a molecular mechanism of survival during infection. The use of Drosophila in these straightforward assays facilitates the genetic and molecular analyses of sleep and the immune response and how these two complex systems are reciprocally influenced.

Quantitative Measurement of the Immune Response and Sleep in Drosophila

To understand a link between the immune response and behavior, we describe a method to measure locomotor behavior in Drosophila during bacterial infection as well as the ability of flies to mount an immune response by monitoring survival, bacterial load, and real-time activity of a key regulator of innate immunity, NF&kappa;B.

A complex interaction between the immune response and  host behavior has been described in a wide range of species. Excess sleep, in  particular, is known ...

Staphylococcus aureus Growth using Human Hemoglobin as an Iron Source

S. aureus is a pathogenic bacterium that requires iron to carry out vital metabolic functions and cause disease. The most abundant reservoir of iron inside the human host is heme, which is the cofactor of hemoglobin. To acquire iron from hemoglobin, S. aureus utilizes an elaborate system known as the iron-regulated surface determinant (Isd) system1. Components of the Isd system first bind host hemoglobin, then extract and import heme, and finally liberate iron from heme in the bacterial cytoplasm2,3. This pathway has been dissected through numerous in vitro studies4-9. Further, the contribution of the Isd system to infection has been repeatedly demonstrated in mouse models8,10-14. Establishing the contribution of the Isd system to hemoglobin-derived iron acquisition and growth has proven to be more challenging. Growth assays using hemoglobin as a sole iron source are complicated by the instability of commercially available hemoglobin, contaminating free iron in the growth medium, and toxicity associated with iron chelators. Here we present a method that overcomes these limitations. High quality hemoglobin is prepared from fresh blood and is stored in liquid nitrogen. Purified hemoglobin is supplemented into iron-deplete medium mimicking the iron-poor environment encountered by pathogens inside the vertebrate host. By starving S. aureus of free iron and supplementing with a minimally manipulated form of hemoglobin we induce growth in a manner that is entirely dependent on the ability to bind hemoglobin, extract heme, pass heme through the bacterial cell envelope and degrade heme in the cytoplasm. This assay will be useful for researchers seeking to elucidate the mechanisms of hemoglobin-/heme-derived iron acquisition in S. aureus and possibly other bacterial pathogens.

Staphylococcus aureus Growth using Human Hemoglobin as an Iron Source

Here we describe a growth assay for Staphylococcus aureus using hemoglobin as the sole source of available nutrient iron. This assay establishes the role of bacterial factors involved in hemoglobin-derived iron acquisition.

S. aureus is a pathogenic bacterium that requires iron to  carry out vital metabolic functions and cause disease. The most abundant  reservoir of iron ...

Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus

Staphylococcal Cassette Chromosome mec (SCCmec) typing is a very important molecular tool for understanding the epidemiology and clonal strain relatedness of methicillin-resistant Staphylococcus aureus (MRSA), particularly with the emerging outbreaks of community-associated MRSA (CA-MRSA) occurring on a worldwide basis. Traditional PCR typing schemes classify SCCmec by targeting and identifying the individual mec and ccr gene complex types, but require the use of many primer sets and multiple individual PCR experiments. We designed and published a simple multiplex PCR assay for quick-screening of major SCCmec types and subtypes I to V, and later updated it as new sequence information became available. This simple assay targets individual SCCmec types in a single reaction, is easy to interpret and has been extensively used worldwide. However, due to the sophisticated nature of the assay and the large number of primers present in the reaction, there is the potential for difficulties while adapting this assay to individual laboratories. To facilitate the process of establishing a MRSA SCCmec assay, here we demonstrate how to set up our multiplex PCR assay, and discuss some of the vital steps and procedural nuances that make it successful.

Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus

We demonstrate a simple multiplex PCR assay for quick-screening and typing of Staphylococcal Cassette Chromosome mec (SCCmec) types I-V for methicillin-resistant Staphylococcus aureus, and provide some of the vital steps and procedural nuances that make it successful for adapting this assay to individual laboratories.

Staphylococcal Cassette Chromosome mec (SCCmec) typing  is a very important molecular tool for understanding the epidemiology and  clonal strain ...

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in mice. Recently, myeloid differentiation factor 88 (MyD88) signaling was shown to be important for initial T cell priming and memory T cell development during WNV NS4B-P38G mutant infection. In this study, two flow cytometry-based methods &#8211; an in vitro T cell priming assay and an intracellular cytokine staining (ICS) &#8211; were utilized to assess dendritic cells (DCs) and T cell functions. In the T cell priming assay, cell proliferation was analyzed by flow cytometry following co-culture of DCs from both groups of mice with carboxyfluorescein succinimidyl ester (CFSE) - labeled CD4+ T cells of OTII transgenic mice. This approach provided an accurate determination of the percentage of proliferating CD4+ T cells with significantly improved overall sensitivity than the traditional assays with radioactive reagents. A microcentrifuge tube system was used in both cell culture and cytokine staining procedures of the ICS protocol. Compared to the traditional tissue culture plate-based system, this modified procedure was easier to perform at biosafety level (BL) 3 facilities. Moreover, WNV- infected cells were treated with paraformaldehyde in both assays, which enabled further analysis outside BL3 facilities. Overall, these in vitro immunological assays can be used to efficiently assess cell-mediated immune responses during WNV infection.

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

Two flow cytometry-based methods &#8211; an in vitro T cell priming assay and intracellular cytokine staining were utilized to measure antigen presenting capacity of dendritic cells and antigen-specific T cell responses to a West Nile virus mutant infection in mice.

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in ...

Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR (RS-PCR)

The ribosomal spacer PCR (RS-PCR) is a highly resolving and robust genotyping method for S. aureus that allows a high throughput at moderate costs and is, therefore, suitable to be used for routine purposes. For best resolution, data evaluation and data management, a miniaturized electrophoresis system is required. Together with such an electrophoresis system and the in-house developed software (freely available here) assignment of the pattern of bands to a genotype is standardized and straight forward. DNA extraction is simple (boiling prep), setting-up of the reactions is easy and they can be run on any standard PCR machine. PCR cycling is common except prolonged ramping and elongation times. Compared to spa typing and Multi Locus Sequence Typing (MLST), RS-PCR does not require DNA sequencing what simplifies the analysis considerably and allows a high throughput. Furthermore, the resolution for bovine strains of S. aureus is at least as good as spa typing and better than MLST or pulsed-field gel electrophoresis (PFGE). The RS-PCR data base includes presently a total of 141 genotypes and variants. The method is highly associated with the virulence gene pattern, contagiosity and pathogenicity of S. aureus strains involved in bovine mastitis. S. aureus genotype B (GTB) is contagious and causes herds problems causing large costs in the Switzerland and other European countries. All the other genotypes observed in Switzerland infect individual cows and quarters. Genotyping by RS-PCR allows the reliable prediction of the epidemiological and the pathogenic potential of S. aureus involved in bovine intramammary infection (IMI), two key factors for clinical veterinary medicine. Because of these beneficial properties together with moderate costs and a high sample throughput the goal of this publication is to give a detailed, step-by-step protocol for easily establishing and running RS-PCR for genotyping S. aureus in other laboratories.

Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR RS-PCR

Here, ribosomal spacer PCR (RS-PCR) is used together with a miniaturized electrophoresis system as a fast and high resolution method for genotyping S. aureus at moderate costs allowing a high throughput.

The ribosomal spacer PCR (RS-PCR) is a highly resolving and robust genotyping method for S. aureus that allows a high throughput at moderate costs and is, ...

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus

One important feature of the major opportunistic human pathogen Staphylococcus aureus is its extraordinary ability to rapidly acquire resistance to antibiotics. Genomic studies reveal that S. aureus carries many virulence and resistance genes located in mobile genetic elements, suggesting that horizontal gene transfer (HGT) plays a critical role in S. aureus evolution. However, a full and detailed description of the methodology used to study HGT in S. aureus is still lacking, especially regarding natural transformation, which has been recently reported in this bacterium. This work describes three protocols that are useful for the in vitro investigation of HGT in S. aureus: conjugation, phage transduction, and natural transformation. To this aim, the cfr gene (chloramphenicol/florfenicol resistance), which confers the Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A (PhLOPSA)-resistance phenotype, was used. Understanding the mechanisms through which S. aureus transfers genetic materials to other strains is essential to comprehending the rapid acquisition of resistance and helps to clarify the modes of dissemination reported in surveillance programs or to further predict the spreading mode in the future.

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus

We describe here three different protocols for the in vitro investigation of conjugation, transduction, and natural transformation in Staphylococcus aureus.

One important feature of the major opportunistic human pathogen Staphylococcus aureus is its extraordinary ability to rapidly acquire resistance to ...

Evaluation of Host-Pathogen Responses and Vaccine Efficacy in Mice

Vaccines are a 20th century medical marvel. They have dramatically reduced the morbidity and mortality caused by infectious diseases and contributed to a striking increase in life expectancy around the globe. Nonetheless, determining vaccine efficacy remains a challenge. Emerging evidence suggests that the current acellular vaccine (aPV) for Bordetella pertussis (B. pertussis) induces suboptimal immunity. Therefore, a major challenge is designing a next-generation vaccine that induces protective immunity without the adverse side effects of a whole-cell vaccine (wPV). Here we describe a protocol that we used to test the efficacy of a promising, novel adjuvant that skews immune responses to a protective Th1/Th17 phenotype and promotes a better clearance of a B. pertussis challenge from the murine respiratory tract. This article describes the protocol for mouse immunization, bacterial inoculation, tissue harvesting, and analysis of immune responses. Using this method, within our model, we have successfully elucidated crucial mechanisms elicited by a promising, next-generation acellular pertussis vaccine. This method can be applied to any infectious disease model in order to determine vaccine efficacy.

Here we present an elegant protocol for in vivo evaluation of vaccine effectiveness and host immune responses. This protocol can be adapted for vaccine models that study viral, bacterial, or parasitic pathogens.

Vaccines are a 20th century medical marvel. They have dramatically reduced the morbidity and mortality caused by infectious diseases and contributed to a ...