Name: the development of lyophilized loop-mediated isothermal amplification reagents for the detection of coxiella burnetii
Uploaded: 2016-04-18T14:00:00
Description: Watch this Scientific Journal Video about The Development of Lyophilized Loop-mediated Isothermal Amplification Reagents for the Detection of Coxiella burnetii at JoVE.com

This research was supported by Naval Medical Research Center, research work unit 6000.RAD1.J.A0310. The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the U.S. Government. Wei-Mei Ching is an employee of the U.S. Government. This work was prepared as part of her official duties. Title 17 U.S.C. &#167;105 provides that &#39;Copyright protection under this title is not available for any work of the United States Government.&#39; Title 17 U.S.C. &#167;101 defines a U.S. Government work as a work prepared by military service member or employee of the U.S. Government as part of that person&#39;s official duties.

1. Prepare Plasmid DNA Dilutions as Standard for LAMP Reaction
<ol>
	<li>Use a spectrophotometer to measure the optical density (O.D.) at 260 nm to determine the plasmid (containing target gene IS1111a of C. burnetii RSA 493) DNA concentration. An O.D.260 of 1 equates to 50 &#181;g/&#181;l of DNA.</li>
	<li>Convert the amount of plasmid DNA into the copy number. Since the size of the plasmid is 6,330 bp, the molecular weight of this plasmid is 4.1 x 106 g (6,330 bp x 649 g/bp). T...

<ol>
	<li>Anderson, 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=Diagnosis+and+management+of+Q+fever+United+States,+2013:+recommendations+from+CDC+and+the+Q+Fever+Working+Group.">Diagnosis and management of Q fever United States, 2013: recommendations from CDC and the Q Fever Working Group.</a> MMWR Recomm. Rep. 62 (3), 1-30 (2013).</li><li>Rolain, J. M., Boulos, A., Mallet, M. N., Raoult, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlation+between+ratio+of+serum+doxycycline+concentration+to+MIC+and+rapid+decline+of+antibody+levels+during+treatment+of+Q+fever+endocarditis.">Correlation between ratio of serum doxycycline concentration to MIC and rapid decline of antibody levels during treatment of Q fever endocarditis.</a> Antimicrob. Agents and Chemother. 49 (7), 2673-2676 (2005).</li><li>Fournier, P. E., Raoult, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+PCR+and+serology+assays+for+early+diagnosis+of+acute+Q+fever.">Comparison of PCR and serology assays for early diagnosis of acute Q fever.</a> J. Clin. Microbiol. 41 (11), 5094-5098 (2003).</li><li>Schneeberger, P. 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=Real-time+PCR+with+serum+samples+is+indispensable+for+early+diagnosis+of+acute+Q+fever.">Real-time PCR with serum samples is indispensable for early diagnosis of acute Q fever.</a> Clin. Vaccine Immunol. 17 (2), 286-290 (2010).</li><li>Turra, M., Chang, G., Whybrow, D., Higgins, G., Qiao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+of+acute+Q+fever+by+PCR+on+sera+during+a+recent+outbreak+in+rural+South+Australia.">Diagnosis of acute Q fever by PCR on sera during a recent outbreak in rural South Australia.</a> Ann. N Y Acad. Sci. 1078, 566-569 (2006).</li><li>Notomi, T., 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=Loop-mediated+isothermal+amplification+of+DNA.">Loop-mediated isothermal amplification of DNA.</a> Nucleic Acids Res. 28 (12), (2000).</li><li>Paris, D. H., Blacksell, S. D., Newton, P. N., Day, N. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple,+rapid+and+sensitive+detection+of+Orientia+tsutsugamushi.+by+loo-isothermal+DNA+amplification.">Simple, rapid and sensitive detection of Orientia tsutsugamushi. by loo-isothermal DNA amplification.</a> Trans. R. Soc. Trop. Med. Hyg. 102 (12), 1239-1246 (2008).</li><li>Huber, 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=Loop-mediated+isothermal+amplification+assay+targeting+the+47-kDa+gene+of+Orientia+tsutsugamushi.:+A+rapid+and+sensitive+alternative+to+real-time+PCR.">Loop-mediated isothermal amplification assay targeting the 47-kDa gene of Orientia tsutsugamushi.: A rapid and sensitive alternative to real-time PCR.</a> J. Med. Microb. Diagn. 1 (112), (2012).</li><li>Pan, L., Zhang, L., Wang, G., Liu, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid,+sensitive+detection+of+the+ompB+gene+of+spotted+fever+group+rickettsiae+by+loop-mediated+isothermal+amplification.">Rapid, sensitive detection of the ompB gene of spotted fever group rickettsiae by loop-mediated isothermal amplification.</a> BMC Infect. Dis. 12 (254), (2012).</li><li>Mori, Y., Nagamine, K., Tomita, N., Notomi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+loop-mediated+isothermal+amplification+reaction+by+turbidity+derived+from+magnesium+pyrophosphate+formation.">Detection of loop-mediated isothermal amplification reaction by turbidity derived from magnesium pyrophosphate formation.</a> Biochem. Biophys. Res. Commun. 289 (1), 150-154 (2001).</li><li>Qiao, Y. 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=Loop-mediated+isothermal+amplification+for+rapid+detection+of+Bacillus+anthracis.spores.">Loop-mediated isothermal amplification for rapid detection of Bacillus anthracis.spores.</a> Biotechnol. Lett. 29 (12), 1939-1946 (2007).</li><li>Tomita, N., Mori, Y., Kanda, H., Notomi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loop-mediated+isothermal+amplification+(LAMP)+of+gene+sequences+and+simple+visual+detection+of+products.">Loop-mediated isothermal amplification (LAMP) of gene sequences and simple visual detection of products.</a> Nat. Protoc. 3 (5), 877-882 (2008).</li><li>Thekisoe, O. 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=Stability+of+Loop-Mediated+Isothermal+Amplification+(LAMP)+reagents+and+its+amplification+efficiency+on+crude+trypanosome+DNA+templates.">Stability of Loop-Mediated Isothermal Amplification (LAMP) reagents and its amplification efficiency on crude trypanosome DNA templates.</a> J. Vet. Med. Sci. 71 (4), 471-475 (2009).</li><li>Chen, H. W., Ching, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+loop-mediated+isothermal+amplification+assays+for+rapid+and+easy+detection+of+Coxiella+Burnetii.">Development of loop-mediated isothermal amplification assays for rapid and easy detection of Coxiella Burnetii.</a> J. Microbiol Methods. 107, 176-181 (2014).</li><li>Wang, 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=A+Comparison+of+In-House+Real-Time+LAMP+Assays+with+a+Commercial+Assay+for+the+Detection+of+Pathogenic+Bacteria.">A Comparison of In-House Real-Time LAMP Assays with a Commercial Assay for the Detection of Pathogenic Bacteria.</a> Molecules. 20 (6), 9487-9495 (2015).</li></ol>

Previously, we developed a sensitive and specific LAMP assay targeting the insertion element IS1111a14. The IS1111 element was selected because it is highly conserved among the different strains of C. burnetii and its high number of copies (7 to 110) in the bacteria (Klee 2006). Our results showed that LAMP can detect about 25 copies of the IS1111 element, which may correlate to as little as one chromosomal copy of Coxiella DNA. In this study, Bst DNA polym...

The small Gram-negative bacterium Coxiella burnetii is the causative agent of Q fever, which is a worldwide zoonosis. Due to Q fever&#39;s worldwide distribution and the high infectivity of C. burnetii, US military and civilian personnel deployed overseas are at risk of being infected in the endemic areas.
Q fever manifests in two forms: acute and chronic infections. Acute Q-fever presents itself with flu-like symptoms, hepatitis, or pneumonia, and is usually a self-limiting disease with a low mortality rate. Chronic Q-fever, while less prevalent, often results in endocarditis, which has a much higher mortality rate if left untreated1,2. Therefore, early diagnosis to guide an appropriate treatment is critical for patient care. Polymerase chain reaction (PCR) and quantitative real time PCR (qPCR) assays have been developed for detecting C. burnetii DNA in cell cultures and clinical samples3-5. Both PCR and qPCR are costly and often not readily available in resource-constrained areas for routine work.
Originally described by Notomi6, loop-mediated isothermal amplification (LAMP) offers an alternative DNA amplification method. LAMP uses Bst DNA polymerase for strand displacement DNA synthesis along with specially designed primer sets that recognize at least six independent regions of the target gene. The most significant advantage of LAMP is that amplification occurs under isothermal conditions. Therefore, only a water bath, heating block or an incubator is required. This method has been used to detect several rickettsial pathogens7-9. Visualization of amplified DNA products by gel electrophoresis is the most accurate method which can differentiate true positives from false positives due to nonspecific amplification. However the procedures involved in gel electrophoresis are not practical for resource-limited areas. Several alternative methods were developed to detect the reaction products. These alternative, such as turbidity derived from magnesium pyrophosphate formation10 or using a fluorescent intercalating dye to be visualized under UV light11,12 are more favorable than running a gel. The LAMP reagents were stable for one month when stored at 25 &#176;C and 37 &#176;C, which are ambient temperatures in tropical and sub-tropical countries where Q fever is endemic13.
A LAMP assay was developed in our laboratory to detect the presence of C. burnetii in plasma samples14. Here we describe a simple protocol for the preparation of the LAMP reaction mixture from the lyophilized reagents. The lyophilized reagents are stable for one month when stored at RT. When combined with an easy visualization method, this is an ideal method to use for detecting C. burnetii in a resource-limited setting.

<table border="0" cellpadding="0" cellspacing="0" width="773">
	<tbody>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">LAMP primers</td>
			<td style="width:188px;">Eurofins MWG operon</td>
			<td style="width:131px;">10 nmol, salt free</td>
			<td style="width:240px;">Sequence designed by customer</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">Bst DNA polymerase</td>
			<td style="width:188px;">New England Biolabs</td>
			<td style="width:131px;">M0275L</td>
			<td style="width:240px;">8 units/ml</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">10X Thermo pol buffer</td>
			<td style="width:188px;">New England Biolabs</td>
			<td style="width:131px;">B9004S</td>
			<td style="width:240px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">dNTP mixture</td>
			<td style="width:188px;">New England Biolabs</td>
			<td style="width:131px;">N0447L</td>
			<td style="width:240px;">10 mM each</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">Betaine</td>
			<td style="width:188px;">Sigma-Aldrich</td>
			<td style="width:131px;">B0300</td>
			<td style="width:240px;">5 M, Trimethylglycine</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">Magnesium Sulfate</td>
			<td style="width:188px;">Sigma-Aldrich</td>
			<td style="width:131px;">M3409-1ML</td>
			<td style="width:240px;">1 M</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">10X Bluejuice</td>
			<td style="width:188px;">Invitrogen</td>
			<td style="width:131px;">10816-015</td>
			<td style="width:240px;">gel loading buffer</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">SYBR green</td>
			<td style="width:188px;">Invitrogen</td>
			<td style="width:131px;">S7585</td>
			<td style="width:240px;">10,000X, visualize products in tubes</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">GelRed</td>
			<td style="width:188px;">Phenix Research Products</td>
			<td style="width:131px;">RGB-4103</td>
			<td style="width:240px;">10,000X, visualize products in gels</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">Lyophilized reagents</td>
			<td style="width:188px;">Gene Reach</td>
			<td style="width:131px;"></td>
			<td style="width:240px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">Hydroxynaphthol blue</td>
			<td style="width:188px;">Fluka</td>
			<td style="width:131px;">33936-10G</td>
			<td style="width:240px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:215px;">ESEQuant tube scanner</td>
			<td style="width:188px;">Qiagen</td>
			<td style="width:131px;"></td>
			<td style="width:240px;">real-time detection</td>
		</tr>
	</tbody>
</table>

the development of lyophilized loop-mediated isothermal amplification reagents for the detection of coxiella burnetii

Coxiella burnetii, the agent causing Q fever, is an obligate intracellular bacterium. PCR based diagnostic assays have been developed for detecting C. burnetii DNA in cell cultures and clinical samples. PCR requires specialized equipment and extensive end user training, and therefore, it is not suitable for routine work especially in a resource-constrained area. We have developed a loop-mediated isothermal amplification (LAMP) assay to detect the presence of C. burnetii in patient samples. This method is performed at a single temperature around 60 &#176;C in a water bath or heating block. The sensitivity of this LAMP assay is very similar to PCR with a detection limit of about 25 copies per reaction. This report describes the preparation of the reaction using lyophilized reagents and visualization of results using hydroxynaphthol blue (HNB) or a UV lamp with fluorescent intercalating dye in the reaction. The LAMP reagents were lyophilized and stored at room temperature (RT) for one month without loss of detection sensitivity. This LAMP assay is particularly robust because the reaction mixture preparation does not involve complex steps. This method is ideal for use in resource-limited settings where Q fever is endemic.

The lyophilized LAMP reagents inside the 0.2 ml tube contains Bst DNA polymerase, primers, and dNTPs. 20 &#181;l of reconstitution buffer is used to re-suspend the lyophilized reagents. Figure 1 shows the LAMP reaction results on agarose gels with freshly prepared reagents and lyophilized reagents. The lyophilized reagent does not reduce its activity. LAMP reactions prepared by both reagents can detect 25 copies of DNA template. Figure 2 shows th...

Watch this Scientific Journal Video about The Development of Lyophilized Loop-mediated Isothermal Amplification Reagents for the Detection of Coxiella burnetii at JoVE.com

The Development of Lyophilized Loop-mediated Isothermal Amplification Reagents for the Detection of Coxiella burnetii

We described here a simple loop-mediated isothermal amplification (LAMP) method using lyophilized reagents for the detection of C. burnetii in patient samples.

The Development of Lyophilized Loop-mediated Isothermal Amplification Reagents for the Detection of Coxiella burnetii

Coxiella burnetii, the agent causing Q fever, is an obligate intracellular bacterium. PCR based diagnostic assays have been developed for detecting C. ...

The overall goal of this experiment is to develop a simple LAMP method using lyophilized reagents for the detection of C.burnetii in patient samples. The main advantage of this protocol is that no coaching is required for the storage of the reagents. This method is ideal for use in resource-limited settings where Q fever is endemic.Demonstrating the procedure will be Tatiana, a technician from our laboratory. Beginning with DNA for the target gene IS1111a from C.burnetii RSA493, determine the plasmid concentration with a spectrophotometer at 260 nanometers. Convert the plasmid DNA concentration into copy number using the following calculations, where 6330 equals the length and base pairs of the plasmid, and 34.2 nanograms per microliter is the concentration of the plasmid, as just determined using the spectrophotometer.Then prepare 8-to 10-fold serial dilutions of the plasmid to arrive at the following number of copies per microliter. To prepare the DNA template for the LAMP reaction, begin with 200 microliters of human plasma samples, and with the DNA miniprep kit, extract the DNA according to the manufacturer's protocol. Dilute the final sample into a 20-microliter volume.Prepare 1 mililiter of 2x LAMP reaction buffer by combining the following reagents. Mix by pulse-vortexing for 10 seconds. To perform the standard LAMP reaction, in a 0.2 milliliter PCR tube, mix 12.5 microliters of 2x LAMP buffer, 1.2 microliters of primer mix, 1 microliter of Bst DNA polymerase, and 5.3 microliters of water.Next, add 5 microliters of DNA to the 20 microliter reaction and mix well, then incubate at 60 degrees Celsius in a water bath or heating block for 60 minutes. After the incubation, terminate the reaction by adding 5 microliters of 10x gel loading buffer to the tube. Then load 5 microliters of the reaction products onto a 2%agarose gel stained with intercalating nucleic acid stain.Run the gel in 1x TBE at 100 volts for 35 minutes, then use UV light to visualize the results. To perform the LAMP reaction with reconstituted reagents, prepare 1 milliliter of reconstitution buffer by combining the following reagents. Mix by pulse-vortexing for 10 seconds.Next, remove the tubes that contained the lyophilized reagents from the sealed aluminium foil bag. For Step 4.2, it is very important to make sure the aluminium foil bag is properly sealed before opening it. Do not use the tubes if the aluminum bag is not sealed or is damaged.Add 20 microliters of reconstitution buffer to each tube of reagents and mix by pipetting up and down five times. Ensure that the lyophilized reagents are completely re-suspended. Then, add 5 microliters of DNA template to the reconstituted reagents and mix well.Incubate at 60 degrees Celsius in a water bath or heating block for 60 minutes. To terminate the reaction after the incubation, add 5 microliters of 10x gel loading buffer, then add 5 microliters of the reaction products onto a 2%agarose gel stained with intercalating nucleic acid stain. Run the gel in 1x TBE buffer at 100 volts for 35 minutes, then visualize the results by UV light.To perform the LAMP reaction with hydroxynaphthol blue, or HNB, or intercalating dye, prepare 1 milliliter of reconstitution buffer by combining the following reagents that include HNB or a fluorescent intercalating dye. Mix by pulse-vortexing for 10 seconds. Carry out the LAMP reaction as just described and use UV light or the naked eye to visualize the results.To perform the LAMP reaction with a tube scanner, add 5 microliters of DNA to the reconstituted reagents containing the fluorescent intercalating dye, then insert the closed tube into the tube scanner. Set the incubation temperature to 60 degrees Celsius and measure the fluorescence at 520 nanometers for 60 minutes. This figure shows the LAMP reaction results on agarose gels with freshly-prepared reagents and lyophilized reagents.Observe the lyophilized reagent maintains its activity. LAMP reactions prepared by both reagents detected 25 copies of DNA template. In this figure, the detection of the reaction's products with HNB or fluorescent intercalating dye in the reaction is shown.The addition of HNB to the reaction produces a visual color change, from purple to blue, with 25, 50, and 100 copies of DNA template present in the reactions. In addition, the inclusion of fluorescent intercalating dye in the reaction shows a strong fluorescent signal with UV light when similar DNA copy numbers are present. Shown here are the results from using the tube scanner to monitor the fluorescent signals in real-time with fluorescent intercalating dye.The fluorescent signals are above baseline after 14, 18, 21, and 23 minutes, with 10^6, 10^4, 10^3, and 100 copies of DNA template in the reactions. Once mastered, this procedure can be done in 90 minutes. After its development, this assay paved the way for quick diagnosis of Coxiella burnetii infection in resource-limited areas.After watching this video, you should have a good understanding of how to reconstitute lyophilized LAMP reagents. Don't forget that patient samples can be infectious and safety precautions should always be taken while performing this procedure.

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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 ...

Development of an in vitro model system for studying the interaction of Equus caballus IgE with its high-affinity receptor Fc&#949;RI

The interaction of IgE with its high-affinity Fc receptor (Fc&#949;RI) followed by an antigenic challenge is the principal pathway in IgE mediated allergic reactions. As a consequence of the high affinity binding between IgE and Fc&#949;RI, along with the continuous production of IgE by B cells, allergies usually persist throughout life, with currently no permanent cure available. Horses, especially race horses, which are commonly inbred, are a species of mammals that are very prone to the development of hypersensitivity responses, which can seriously affect their performance. Physiological responses to allergic sensitization in horses mirror that observed in humans and dogs. In this paper we describe the development of an in situ assay system for the quantitative assessment of the release of mediators of the allergic response pertaining to the equine system. To this end, the gene encoding equine Fc&#949;RI&#945; was transfected into and expressed onto the surface of parental Rat Basophil Leukemia (RBL-2H3.1) cells. The gene product of the transfected equine &#945;-chain formed a functional receptor complex with the endogenous rat &#946;- and &#947;-chains 1. The resultant assay system facilitated an assessment of the quantity of mediator secreted from equine Fc&#949;RI&#945; transfected RBL-2H3.1 cells following sensitization with equine IgE and antigenic challenge using &#946;-hexosaminidase release as a readout 2, 3. Mediator release peaked at 36.68% &#177; 4.88% at 100 ng ml-1 of antigen. This assay was modified from previous assays used to study human and canine allergic responses 4, 5. We have also shown that this type of assay system has multiple applications for the development of diagnostic tools and the safety assessment of potential therapeutic intervention strategies in allergic disease 6, 2, 3.

Development of an &lt;em&gt;in vitro&lt;/em&gt; model system for studying the interaction of &lt;em&gt;Equus&lt;/em&gt; &lt;em&gt;caballus&lt;/em&gt; IgE with its high-affinity receptor Fc&amp;#949;RI

The current study describes the development and applications of a genetically engineered assay system based on the transfection of rat basophilic leukemia cells with the equine Fc&#949;RI&#945; gene. Transfected cells express a functional receptor where the release of mediators of the allergic response can be activated by IgE and antigen.

The interaction of IgE with its high-affinity Fc receptor (Fc&#949;RI) followed by an antigenic challenge is the principal pathway in IgE mediated ...

Loop-mediated Isothermal Amplification (LAMP) Assays for the Species-specific Detection of Eimeria that Infect Chickens

Eimeria species parasites, protozoa which cause the enteric disease coccidiosis, pose a serious threat to the production and welfare of chickens. In the absence of effective control clinical coccidiosis can be devastating. Resistance to the chemoprophylactics frequently used to control Eimeria is common and sub-clinical infection is widespread, influencing feed conversion ratios and susceptibility to other pathogens such as Clostridium perfringens. Despite the availability of polymerase chain reaction (PCR)-based tools, diagnosis of Eimeria infection still relies almost entirely on traditional approaches such as lesion scoring and oocyst morphology, but neither is straightforward. Limitations of the existing molecular tools include the requirement for specialist equipment and difficulties accessing DNA as template. In response a simple field DNA preparation protocol and a panel of species-specific loop-mediated isothermal amplification (LAMP) assays have been developed for the seven Eimeria recognised to infect the chicken. We now provide a detailed protocol describing the preparation of genomic DNA from intestinal tissue collected post-mortem, followed by setup and readout of the LAMP assays. Eimeria species-specific LAMP can be used to monitor parasite occurrence, assessing the efficacy of a farm&#8217;s anticoccidial strategy, and to diagnose sub-clinical infection or clinical disease with particular value when expert surveillance is unavailable.

Loop-mediated Isothermal Amplification LAMP Assays for the Species-specific Detection of Eimeria that Infect Chickens

Diagnosis of Eimeria infection in chickens remains demanding. Parasite morphology- and host pathology-led approaches are commonly inconclusive, while molecular approaches based on PCR have proven demanding in cost and expertise. The aim of this protocol is to establish loop-mediated isothermal amplification (LAMP) as a straightforward molecular diagnostic for eimerian infection.

Eimeria species parasites, protozoa which cause the enteric disease coccidiosis, pose a serious threat to the production and welfare of chickens. In the ...

Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants

Invasion and colonization of host cells by bacterial pathogens depend on the activity of a large number of prokaryotic proteins, defined as virulence factors, which can subvert and manipulate key host functions. The study of host/pathogen interactions is therefore extremely important to understand bacterial infections and develop alternative strategies to counter infectious diseases. This approach however, requires the development of new high-throughput assays for the unbiased, automated identification and characterization of bacterial virulence determinants. Here, we describe a method for the generation of a GFP-tagged mutant library by transposon mutagenesis and the development of high-content screening approaches for the simultaneous identification of multiple transposon-associated phenotypes. Our working model is the intracellular bacterial pathogen Coxiellaburnetii, the etiological agent of the zoonosis Q fever, which is associated with severe outbreaks with a consequent health and economic burden. The obligate intracellular nature of this pathogen has, until recently, severely hampered the identification of bacterial factors involved in host pathogen interactions, making of Coxiella the ideal model for the implementation of high-throughput/high-content approaches.

Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants

Coxiella burnetii is an obligate intracellular Gram-negative bacterium responsible for the zoonotic disease Q fever. Here we describe methods for the generation of Coxiella fluorescent transposon mutants as well as the automated identification and analysis of the resulting internalization, replication and cytotoxic phenotypes.

Invasion and colonization of host cells by bacterial pathogens depend on the activity of a large number of prokaryotic proteins, defined as virulence ...

Qualitative and Quantitative Assays for Detection and Characterization of Protein Antimicrobials

Initial evaluations of large microbial libraries for potential producers of novel antimicrobial proteins require both qualitative and quantitative methods to screen for target enzymes prior to investing greater research effort and resources. The goal of this protocol is to demonstrate two complementary assays for conducting these initial evaluations. The microslide diffusion assay provides an initial or simple detection screen to enable the qualitative and rapid assessment of proteolytic activity against an array of both viable and heat-killed bacterial target substrates. As a counterpart, the increased sensitivity and reproducibility of the dye-release assay provides a quantitative platform for evaluating and comparing environmental influences affecting the hydrolytic activity of protein antimicrobials. The ability to label specific heat-killed cell culture substrates with Remazol brilliant blue R dye expands this capability to tailor the dye-release assay to characterize enzymatic activity of interest.

Here, we present protocols to rapidly screen and characterize enzymes for antimicrobial activity. The microslide diffusion assay and the dye-release assay utilize target bacterial substrates for qualitative and quantitative enzymatic activity evaluation.

Initial evaluations of large microbial libraries for potential producers of novel antimicrobial proteins require both qualitative and quantitative methods ...

Applying Fluorescence Resonance Energy Transfer (FRET) to Examine Effector Translocation Efficiency by Coxiella burnetii during siRNA Silencing

Coxiella burnetii, the causative agent of Q fever, is an intracellular pathogen that relies on a Type IV Dot/Icm Secretion System to establish a replicative niche. A cohort of effectors are translocated through this system into the host cell to manipulate host processes and allow the establishment of a unique lysosome-derived vacuole for replication. The method presented here involves the combination of two well-established techniques: specific gene silencing using siRNA and measurement of effector translocation using a FRET-based substrate that relies on &#946;-lactamase activity. Applying these two approaches, we can begin to understand the role of host factors in bacterial secretion system function and effector translocation. In this study we examined the role of Rab5A and Rab7A, both important regulators of the endocytic trafficking pathway. We demonstrate that silencing the expression of either protein results in a decrease in effector translocation efficiency. These methods can be easily modified to examine other intracellular and extracellular pathogens that also utilize secretion systems. In this way, a global picture of host factors involved in bacterial effector translocation may be revealed.

Applying Fluorescence Resonance Energy Transfer FRET to Examine Effector Translocation Efficiency by Coxiella burnetii during siRNA Silencing

Investigating the interactions between bacterial pathogens and their hosts is an important area of biological research. Here, we describe the necessary techniques to measure effector translocation by Coxiella burnetii during siRNA gene silencing using BlaM substrate.

Coxiella burnetii, the causative agent of Q fever, is an intracellular pathogen that relies on a Type IV Dot/Icm Secretion System to establish a ...

Development of a More Sensitive and Specific Chromogenic Agar Medium for the Detection of Vibrio parahaemolyticus and Other Vibrio Species

Foodborne infections in the US caused by Vibrio species have shown an upward trend. In the genus Vibrio, V. parahaemolyticus is responsible for the majority of Vibrio-associated infections. Thus, accurate differentiation among Vibrio spp. and detection of V. parahaemolyticus is critically important to ensure the safety of our food supply. Although molecular techniques are increasingly common, culture-depending methods are still routinely done and they are considered standard methods in certain circumstances. Hence, a novel chromogenic agar medium was tested with the goal of providing a better method for isolation and differentiation of clinically relevant Vibrio spp. The protocol compared the sensitivity, specificity and detection limit for the detection of V. parahaemolyticus between the new chromogenic medium and a conventional medium. Various V. parahaemolyticus strains (n=22) representing diverse serotypes and source of origins were used. They were previously identified by Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC), and further verified in our laboratory by tlh-PCR. In at least four separate trials, these strains were inoculated on the chromogenic agar and thiosulfate-citrate-bile salts-sucrose (TCBS) agar, which is the recommended medium for culturing this species, followed by incubation at 35-37 &#176;C for 24-96 hr. Three V. parahaemolyticus strains (13.6%) did not grow optimally on TCBS, nonetheless exhibited green colonies if there was growth. Two strains (9.1%) did not yield the expected cyan colonies on the chromogenic agar. Non-V. parahaemolyticus strains (n=32) were also tested to determine the specificity of the chromogenic agar. Among these strains, 31 did not grow or exhibited other colony morphologies. The mean recovery of V. parahaemolyticus on the chromogenic agar was ~96.4% relative to tryptic soy agar supplemented with 2% NaCl. In conclusion, the new chromogenic agar is an effective medium to detect V. parahaemolyticus and to differentiate it from other vibrios.

Development of a More Sensitive and Specific Chromogenic Agar Medium for the Detection of Vibrio parahaemolyticus and Other Vibrio Species

Detection and isolation of clinically relevant Vibrio species require selective and differential culture media. This study evaluated the ability of a new chromogenic medium to detect and identify V. parahaemolyticus and other related species. The new medium was found to have better sensitivity and specificity than the conventional medium.

Foodborne infections in the US caused by Vibrio species have shown an upward trend. In the genus Vibrio, V. parahaemolyticus is responsible for the ...

Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), that carry foreign genes such as a reporter or marker protein in their genomes. These recombinant viruses usually faithfully mimic the life cycle of the original virus in infected cells and exhibit the same host range dependence. The development of a recombinant virus enables the efficient screening of inhibitors and the identification of specific host factors. However, to date the construction of recombinant hepatitis B virus (HBV) has been difficult because of various experimental limitations. The main limitation is the compact genome size of HBV, and a fairly strict genome size that does not exceed 1.3 genome sizes, that must be packaged into virions. Thus, the size of a foreign gene to be inserted should be smaller than 0.4 kb if no deletion of the genome DNA is to be performed. Therefore, to overcome this size limitation, the deletion of some HBV DNA is required. Here, we report the construction of recombinant HBV encoding a reporter gene to monitor the early stage of the HBV replication cycle by replacing part of the HBV core-coding region with the reporter gene by deleting part of the HBV pol coding region. Detection of recombinant HBV infection, monitored by the reporter activity, was highly sensitive and less expensive than detection using the currently available conventional methods to evaluate HBV infection. This system will be useful for a number of applications including high-throughput screening for the identification of anti-HBV inhibitors, host factors and virus-susceptible cells.

Here we describe a newly developed hepatitis B virus (HBV) reporter system to monitor the early stages of the HBV life cycle. This simplified in vitro system will aid in the screening of anti-HBV agents using a high-throughput strategy.

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), ...