Name: reverse transcription-loop-mediated isothermal amplification (rt-lamp) assay for zika virus and housekeeping genes in urine, serum, and mosquito samples
Uploaded: 2018-09-14T15:00:00
Description: Watch this Scientific Journal Video about Reverse Transcription-Loop-mediated Isothermal Amplification RT-LAMP Assay for Zika Virus and Housekeeping Genes in Urine, Serum, and Mosquito Samples at JoVE

This work was supported by the Maureen and Ronald Hirsch family philanthropic contribution and Field Neurosciences Institute, St. Mary&#39;s of Michigan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We also thank Dr. Bernadette Zwaans and Elijah Ward for their critical review of the manuscript.

All methods described here have been approved by the Institutional Review Board (IRB) of Beaumont Health. All experiments were performed in accordance with relevant guidelines and regulations.
CAUTION: All potentially infectious materials should be handled according to Biosafety Level 2 standards including the use of personal protective equipment. Any procedures which may produce aerosol should be performed in a biosafety cabinet. Additionally, work with live mosquitoes should be performed in ...

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P., Pocock, R. L., Vrba, V., Blake, D. P. <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)+assays+for+the+species-specific+detection+of+Eimeria+that+infect+chickens.">Loop-mediated isothermal amplification (LAMP) assays for the species-specific detection of Eimeria that infect chickens.</a> The Journal of Visualized Experiments. (96), (2015).</li><li>Lamb, L. 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=Rapid+Detection+of+Zika+Virus+in+Urine+Samples+and+Infected+Mosquitos+by+Reverse+Transcription-Loop-Mediated+Isothermal+Amplification.">Rapid Detection of Zika Virus in Urine Samples and Infected Mosquitos by Reverse Transcription-Loop-Mediated Isothermal Amplification.</a> Scientific Reports. 8 (1), 3803 (2018).</li><li>Faye, O., 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=One-step+RT-PCR+for+detection+of+Zika+virus.">One-step RT-PCR for detection of Zika virus.</a> Journal of Clinical Virology. 43 (1), 96-101 (2008).</li><li>Schrader, C., Schielke, A., Ellerbroek, L., Johne, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PCR+inhibitors+-+occurrence,+properties+and+removal.">PCR inhibitors - occurrence, properties and removal.</a> Journal of Applied Microbiology. 113 (5), 1014-1026 (2012).</li><li>Poole, C. B., Tanner, N. A., Zhang, Y., Evans, T. C., Carlow, C. K. <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+brugian+filariasis+by+loop-mediated+isothermal+amplification.">Diagnosis of brugian filariasis by loop-mediated isothermal amplification.</a> Public Library of Science Neglected Tropical Diseases. 6 (12), 1948 (2012).</li><li>Tanner, N. A., Zhang, Y., Evans, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+multiple+target+detection+in+real-time+loop-mediated+isothermal+amplification.">Simultaneous multiple target detection in real-time loop-mediated isothermal amplification.</a> Biotechniques. 53 (2), 81-89 (2012).</li><li>Chan, 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=Rapid,+Affordable+and+Portable+Medium-Throughput+Molecular+Device+for+Zika+Virus.">Rapid, Affordable and Portable Medium-Throughput Molecular Device for Zika Virus.</a> Scientific Reports. 6, 38223 (2016).</li><li>Lee, 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=Simple+and+Highly+Sensitive+Molecular+Diagnosis+of+Zika+Virus+by+Lateral+Flow+Assays.">Simple and Highly Sensitive Molecular Diagnosis of Zika Virus by Lateral Flow Assays.</a> Analytical Chemistry. 88 (24), 12272-12278 (2016).</li><li>Pardee, 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=Low-Cost+Detection+of+Zika+Virus+Using+Programmable+Biomolecular+Components.">Low-Cost Detection of Zika Virus Using Programmable Biomolecular Components.</a> Cell. 165 (5), 1255-1266 (2016).</li><li>Song, 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=Instrument-Free+Point-of-Care+Molecular+Detection+of+Zika+Virus.">Instrument-Free Point-of-Care Molecular Detection of Zika Virus.</a> Analytical Chemistry. 88 (14), 7289-7294 (2016).</li><li>Yaren, O., 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=Point+of+sampling+detection+of+Zika+virus+within+a+multiplexed+kit+capable+of+detecting+dengue+and+chikungunya.">Point of sampling detection of Zika virus within a multiplexed kit capable of detecting dengue and chikungunya.</a> BioMed Central Infectious Diseases. 17 (1), 293 (2017).</li><li>Wang, X., 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=Rapid+and+sensitive+detection+of+Zika+virus+by+reverse+transcription+loop-mediated+isothermal+amplification.">Rapid and sensitive detection of Zika virus by reverse transcription loop-mediated isothermal amplification.</a> Journal of Virological Methods. 238, 86-93 (2016).</li><li>Priye, 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=A+smartphone-based+diagnostic+platform+for+rapid+detection+of+Zika,+chikungunya,+and+dengue+viruses.">A smartphone-based diagnostic platform for rapid detection of Zika, chikungunya, and dengue viruses.</a> Scientific Reports. 7, 44778 (2017).</li></ol>

The ZIKV RT-LAMP assay described in this paper works using both human and mosquito samples6. The limit of detection was approximately 1 genome equivalent6, which should be sufficient since the typical viral load of a symptomatic ZIKV infected patient is 103 to&#160;106 PFU/mL7. Additionally, this method can detect ZIKV in samples without first isolating RNA and without virus amplification in cell culture. This signifi...

In 2015, Zika virus (ZIKV) gained prominent global attention as an infectious disease of concern because infection during pregnancy was linked to miscarriage, stillbirth, severe neurological birth defects including microcephaly, as well as other congenital birth defects1. In rare cases, ZIKV has been associated with Guillain-Barr&#233; syndrome. ZIKV is primarily transmitted by Aedes mosquitoes; however, it can also be spread through sexual contact1. Given that the infection with ZIKV is asymptomatic in most people or presents with mild flu-like symptoms that overlap with the symptoms of infection of other arborviruses1, there was a need for improved methods for rapid and cost-effective detection of ZIKV to screen both people as well as local mosquito populations.
Quantitative reverse transcription PCR (qRT-PCR) is a reliable assay for ZIKV detection; however, this technique requires expensive specialized equipment, trained personnel, and RNA isolation from the sample of interest. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) is a one-step nucleic acid amplification method based on PCR technology that only requires one incubation temperature due to the use of a thermophilic DNA polymerase with strand displacement properties. This circumvents the need for a thermocycler and decreases the length of time needed to complete the assay. Additional advantages of RT-LAMP include its high specificity and sensitivity, robustness at a range of pH levels and temperatures, and resistance to many PCR inhibitors2. It has a relatively low cost and reagents are stable at room temperature. Given these characteristics, RT-LAMP can be deployed in a laboratory or in the field. As such, LAMP reactions have been developed to detect a range of pathogens and other types of infection3,4,5. The goal of the RT-LAMP protocol described in this paper is to detect ZIKV without RNA isolation in human serum and urine samples as well as in a single infected mosquito within 30 min through RT-LAMP. This method can be used to replace qRT-PCR as it is a sensitive, rapid diagnostic tool that works quickly and in settings outside of the laboratory.

<table border="0" cellpadding="0" cellspacing="0" style="width:901px;" width="902">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Bst 2.0 WarmStart DNA polymerase</td>
			<td style="width:223px;">New England Biolabs</td>
			<td style="width:223px;">M0537S</td>
			<td style="width:207px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Isothermal Amplification Buffer&#160;</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">B0537S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">WarmStart RTx Reverse Transcriptase</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">M0380S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Antarctic Thermolabile UDG</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">M0372S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MgSO4</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">B1003S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">100mM dATP Solution</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">N0440S</td>
			<td>Deoxynucleotide Set N0446S</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">100mM dCTP Solution</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">N0441S</td>
			<td>Deoxynucleotide Set N0446S</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">100mM dTTP Solution</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">N0443S</td>
			<td>Deoxynucleotide Set N0446S</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">100mM dGTP Solution</td>
			<td>New England Biolabs</td>
			<td style="width:223px;">N0442S</td>
			<td>Deoxynucleotide Set N0446S</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">100mM dUTP Solution</td>
			<td style="width:223px;">Thermo Fisher Scientific</td>
			<td style="width:223px;">R0133</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SYBR Green I Nucleic Acid Gel Stain</td>
			<td style="width:223px;">Invitrogen</td>
			<td style="width:223px;">S7563</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nancy-520</td>
			<td style="width:223px;">Sigma Aldrich</td>
			<td style="width:223px;">01494</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Low DNA Mass Ladder</td>
			<td style="width:223px;">Invitrogen</td>
			<td style="width:223px;">10-068-013</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Zika Postive Control</td>
			<td style="width:223px;">Robert Koch Institute, Germany</td>
			<td style="width:223px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Agarose</td>
			<td style="width:223px;">Thermo Fisher Scientific</td>
			<td style="width:223px;">BP1600</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">BlueJuice Gel Loading Buffer</td>
			<td style="width:223px;">Invitrogen</td>
			<td style="width:223px;">10816015</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Primers</td>
			<td style="width:223px;">Integrated DNA Technologies</td>
			<td style="width:223px;">Custom Oligo</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Nuclease-Free Water</td>
			<td style="width:223px;">Ambion</td>
			<td style="width:223px;">AM9938</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Urine Preservative</td>
			<td style="width:223px;">Norgen Biotek</td>
			<td style="width:223px;">18126</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">ZIKV PCR Standard</td>
			<td>Robert Koch Institute</td>
			<td style="width:223px;">N/A</td>
			<td>Vero E6 cell supernatants</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">DENV2 New Guinea C Control</td>
			<td style="width:223px;">Connecticut Agricultural Experiment Station</td>
			<td style="width:223px;">N/A</td>
			<td></td>
		</tr>
	</tbody>
</table>

reverse transcription-loop-mediated isothermal amplification (rt-lamp) assay for zika virus and housekeeping genes in urine, serum, and mosquito samples

Infection with Zika virus (ZIKV) can be asymptomatic in adults, however, infection during pregnancy can lead to miscarriage and severe neurological birth defects. The goal of this protocol is to quickly detect ZIKV in both human and mosquito samples. The current gold standard for ZIKV detection is quantitative reverse transcription PCR (qRT-PCR); reverse transcription loop-mediated isothermal amplification (RT-LAMP) may allow for a more efficient and low-cost testing without the need for expensive equipment. In this study, RT-LAMP is used for ZIKV detection in various biological samples within 30 min, without first isolating the RNA from the sample. This technique is demonstrated using ZIKV infected patient urine and serum, and infected mosquito samples. 18S ribosomal ribonucleic acid and actin are used as controls in human and mosquito samples, respectively.

RT-LAMP reactions can be analyzed using three different methods. First, with the addition of a fluorescent nucleic acid dye, positive reactions will be yellow/green in color where negative reactions will appear orange in color to the naked eye. Second, the addition of the fluorescent nucleic acid dye to RT-LAMP reaction results in a fluorescent signal when the samples are excited by UV light. Negative reactions will not have a detectable fluorescent signal over any background fluorescence...

Watch this Scientific Journal Video about Reverse Transcription-Loop-mediated Isothermal Amplification RT-LAMP Assay for Zika Virus and Housekeeping Genes in Urine, Serum, and Mosquito Samples at JoVE

Reverse Transcription-Loop-mediated Isothermal Amplification RT-LAMP Assay for Zika Virus and Housekeeping Genes in Urine, Serum, and Mosquito Samples

This protocol provides an efficient and low-cost method to detect Zika virus or control targets in human urine and serum samples or in mosquitoes by reverse transcription loop-mediated isothermal amplification (RT-LAMP). This method does not require RNA isolation and can be done within 30 min.

Reverse Transcription-Loop-mediated Isothermal Amplification (RT-LAMP) Assay for Zika Virus and Housekeeping Genes in Urine, Serum, and Mosquito Samples

Infection with Zika virus (ZIKV) can be asymptomatic in adults, however, infection during pregnancy can lead to miscarriage and severe neurological birth ...

This method can quickly determine if samples contain Zika virus. This is useful for pregnant women, couples trying to conceive, or surveillance of local mosquito populations that are at risk for Zika infection. The main advantage of this technique is that it's fast, easy, does not require expensive equipment, and can be done without an RNA isolation step.The implications of this technique extend towards diagnosis of Zika infection, because infection during pregnancy is linked to miscarriage, stillbirth, and other severe congenital, neurological birth defects. Though this method can provide insight into Zika, it can also be applied to other infectious diseases such as dengue, chikungunya, or West Nile virus by using virus-specific primers. To begin, reconstitute each RT-LAMP primer in molecular grade water to a final concentration of 100 micromolar.Briefly vortex the primer solution to ensure the solution is homogeneous. Centrifuge for about five seconds at maximum speed to collect the primer solution. Then prepare a 10x RT-LAMP primer mix as outlined in table two of the tech's protocol.Vortex briefly to ensure homogeneity. And centrifuge briefly at maximum speed to avoid any loss. Store the primers at minus 20 degrees Celsius, between uses, avoiding any freeze-thaw cycles.For human urine samples, use either fresh urine, frozen urine or urine in preservative. Thaw any frozen samples on ice before use. Human serum samples should be either fresh or frozen, while ZIKV infected cell lines should contain either conditioned media or cell lysates.Finally, for Aedes aegypti mosquitoes, use whole carcasses, either fresh or frozen. Thaw any frozen mosquito carcasses on ice. Place an individual mosquito in 100 microliters of PBS.Using a P10 pipette tip crush the mosquito 10 times, and homogenize it to create a crude mosquito lysate. Briefly centrifuge the crude lysate to pellet any debris and use the supernatant for downstream RT-LAMP analysis. To begin, prepare an RT-LAMP master mix reaction on ice for each primer set to be used, as outline by table three in the tech's protocol.Vortex each sample to ensure it is well mixed. Then briefly spin them down to prevent volume loss. For each reaction, pipette 23.0 microliters of the RT-LAMP master mix into a 200 microliter PCR tube.Then, add two microliters of sample to bring the total volume to 25.0 microliters. Use molecular grade water for the negative control, and make sure to include a positive control. Optionally, include a specificity control reaction of a related arbovirus such as dengue virus, as outlined in tech's protocol.Using a heat block, water bath, or a thermocycler, heat the samples at 61 degrees Celsius for 30 minutes. After this, increase the heat to 80 degree Celsius for 10 minutes to heat deactivate the polymerase. Perform the RT-LAMP analysis in a separate enclosed space.Dilute the fluorescent nucleic acid dye one to ten in TAE buffer. Add two micorliters of the fluorescent nucleic acid dye solution to 12 micorliters of the RT-LAMP reaction. Assess the RT-LAMP reactions visually by looking for the presence of a color change.Optionally use a camera to take pictures of RT-LAMP reactions on a white background. Next, place the samples under a 302 nanometer UV light to confirm the presence of RT-LAMP products by fluorescence. Use a camera to take a picture of the result.To begin performing electrophoresis pour 2%agarose gel in 1x TAE buffer with a nucleic acid stain for visualization. Add five microliters of a DNA ladder in the first lane to compare the molecular weights. For each RT-LAMP reaction, mix 13 microliters of RT-LAMP reaction mixture with two microliters of DNA loading dye.Load this 15 microliter mixture. Run the gel at 90 volts for 90 minutes or until the bands are separated. An image with 302 nanometer UV light.When finished, dispose of RT-LAMP reactions in double sealed bags. In this study, three different methods are utilized to analyze RT-LAMP reactions. When using fluorescent nucleic acid dye positive reactions become yellow-green in color, while negative reactions appear orange.This dye also results in a fluorescent signal when samples are excited by UV light. Lastly, RT-LAMP reactions can be run out on an agarose gel. Positive RT-LAMP reactions will have a banding pattern, whereas negative reactions will have no DNA bands.These methods are used to demonstrate the specificity of the ZIKV RT-LAMP reaction. Only the ZIKV molecular control has a positive RT-LAMP reaction. Furthermore, while ZIKV is detected in both the urine and serum of a patient with known ZIKV infection, it is not seen in the asymptomatic control patient without ZIKV infection.The samples are then tested for human 18S rRNA. Only the samples taken from patients are seen to be positive for 18S rRNA. Mosquito samples can be similarly tested for ZIKV or the RT-LAMP quality control AEDAE.Only the positive molecular control for ZIKV and the mosquito infected with ZIKV are seen to be positive for ZIKV. However all the mosquitoes are positive for AEDAE by RT-LAMP. Once mastered, this technique can be done in under 30 minutes if it is performed properly.It's important to remember that RT-LAMP reactions are prone to false positive reactions. Prevention steps include using a thermolabile uracil DNA glycosylase in reactions, using a lateral workflow, performing analysis in a separate space, and reducing time post amplification tubes are open. Following this procedure other methods like QPCR can be performed in order to answer additional questions, like how many copies the virus, or other targets, are present in the sample.After watching this video, you should have a a good understanding of how to use RT-LAMP to detect Zika virus and target controls in human urine and serum, as well as mosquitos. Don't forget that working with Zika virus and nucleic acid stain can be extremely hazardous, and precautions such as wearing gloves should always be taken while performing this procedure. Given the association of Zika virus infection with congenital abnormalities, women who are pregnant, trying to conceive, or partners of these women, should significantly minimize their laboratory exposure to Zika virus.

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Research

JoVE Journal

Genetics

The Use of Induced Somatic Sector Analysis (ISSA) for Studying Genes and Promoters Involved in Wood Formation and Secondary Stem Development

Secondary stem growth in trees and associated wood formation are significant both from biological and commercial perspectives. However, relatively little is known about the molecular control that governs their development. This is in part due to physical, resource and time limitations often associated with the study of secondary growth processes. A number of in vitro techniques have been used involving either plant part or whole plant system in both woody and non-woody plant species. However, questions about their applicability for the study of secondary stem growth processes, the recalcitrance of certain species and labor intensity are often prohibitive for medium to high throughput applications. Also, when looking at secondary stem development and wood formation the specific traits under investigation might only become measurable late in a tree&#39;s lifecycle after several years of growth. In addressing these challenges alternative in vivo protocols have been developed, named Induced Somatic Sector Analysis, which involve the creation of transgenic somatic tissue sectors directly in the plant&#39;s secondary stem. The aim of this protocol is to provide an efficient, easy and relatively fast means to create transgenic secondary plant tissue for gene and promoter functional characterization that can be utilized in a range of tree species. Results presented here show that transgenic secondary stem sectors can be created in all live tissues and cell types in secondary stems of a variety of tree species and that wood morphological traits as well as promoter expression patterns in secondary stems can be readily assessed facilitating medium to high throughput functional characterization.

The Use of Induced Somatic Sector Analysis ISSA for Studying Genes and Promoters Involved in Wood Formation and Secondary Stem Development

Here we present a protocol that facilitates the medium to high throughput functional characterization of gene and promoter constructs in tree secondary stem tissue within comparatively short time frames. It is efficient, easy to use and widely applicable to a range of tree species.

Secondary stem growth in trees and associated wood formation are significant both from biological and commercial perspectives. However, relatively little ...

Peptide-derived Method to Transport Genes and Proteins Across Cellular and Organellar Barriers in Plants

The capacity to introduce exogenous proteins and express (or down-regulate) specific genes in plants provides a powerful tool for fundamental research as well as new applications in the field of plant biotechnology. Viable methods that currently exist for protein or gene transfer into plant cells, namely Agrobacterium and microprojectile bombardment, have disadvantages of low transformation frequency, limited host range, or a high cost of equipment and microcarriers. The following protocol outlines a simple and versatile method, which employs rationally-designed peptides as delivery agents for a variety of nucleic acid- and protein-based cargoes into plants. Peptides are selected as tools for development of the system due to their biodegradability, reduced size, diverse and tunable properties as well as the ability to gain intracellular/organellar access. The preparation, characterization and application of optimized formulations for each type of the wide range of delivered cargoes (plasmid DNA, double-stranded DNA or RNA, and protein) are described. Critical steps within the protocol, possible modifications and existing limitations of the method are also discussed.

Existing methods for the modification of plants have limited applicability. The novel peptide-derived technology proposed here promises both simplicity and efficiency in the introduction of exogenous protein or genes into the desired intracellular compartments of intact plants.

The capacity to introduce exogenous proteins and express (or down-regulate) specific genes in plants provides a powerful tool for fundamental research as ...

Determination of the Optimal Chromosomal Location(s) for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach

The optimal chromosomal position(s) of a given DNA element was/were determined by transposon-mediated random insertion followed by fitness selection. In bacteria, the impact of the genetic context on the function of a genetic element can be difficult to assess. Several mechanisms, including topological effects, transcriptional interference from neighboring genes, and/or replication-associated gene dosage, may affect the function of a given genetic element. Here, we describe a method that permits the random integration of a DNA element into the chromosome of Escherichia coli and select the most favorable locations using a simple growth competition experiment. The method takes advantage of a well-described transposon-based system of random insertion, coupled with a selection of the fittest clone(s) by growth advantage, a procedure that is easily adjustable to experimental needs. The nature of the fittest clone(s) can be determined by whole-genome sequencing on a complex multi-clonal population or by easy gene walking for the rapid identification of selected clones. Here, the non-coding DNA region DARS2, which controls the initiation of chromosome replication in E. coli, was used as an example. The function of DARS2 is known to be affected by replication-associated gene dosage; the closer DARS2 gets to the origin of DNA replication, the more active it becomes. DARS2 was randomly inserted into the chromosome of a DARS2-deleted strain. The resultant clones containing individual insertions were pooled and competed against one another for hundreds of generations. Finally, the fittest clones were characterized and found to contain DARS2 inserted in close proximity to the original DARS2 location.

Determination of the Optimal Chromosomal Locations for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach

Here, the power of a transposon-mediated random insertion of a non-coding DNA element was used to resolve its optimal chromosomal position.

The optimal chromosomal position(s) of a given DNA element was/were determined by transposon-mediated random insertion followed by fitness selection. In ...

Chromatin Immunoprecipitation (ChIP) Protocol for Low-abundance Embryonic Samples

Chromatin immunoprecipitation (ChIP) is a widely-used technique for mapping the localization of post-translationally modified histones, histone variants, transcription factors, or chromatin-modifying enzymes at a given locus or on a genome-wide scale. The combination of ChIP assays with next-generation sequencing (i.e., ChIP-Seq) is a powerful approach to globally uncover gene regulatory networks and to improve the functional annotation of genomes, especially of non-coding regulatory sequences. ChIP protocols normally require large amounts of cellular material, thus precluding the applicability of this method to investigating rare cell types or small tissue biopsies. In order to make the ChIP assay compatible with the amount of biological material that can typically be obtained in vivo during early vertebrate embryogenesis, we describe here a simplified ChIP protocol in which the number of steps required to complete the assay were reduced to minimize sample loss. This ChIP protocol has been successfully used to investigate different histone modifications in various embryonic chicken and adult mouse tissues using low to medium cell numbers (5 x 104 - 5 x 105 cells). Importantly, this protocol is compatible with ChIP-seq technology using standard library preparation methods, thus providing global epigenomic maps in highly relevant embryonic tissues.

Chromatin Immunoprecipitation ChIP Protocol for Low-abundance Embryonic Samples

Here, we describe a chromatin immunoprecipitation (ChIP) and ChIP-seq library preparation protocol to generate global epigenomic profiles from low-abundance chicken embryonic samples.

Chromatin immunoprecipitation (ChIP) is a widely-used technique for mapping the localization of post-translationally modified histones, histone variants, ...

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

In our efforts to determine the patterns of expression and subcellular localization of Drosophila RNAs on a genome-wide basis, and in a variety of tissues, we have developed numerous modifications and improvements to our original fluorescent in situ hybridization (FISH) protocol. To facilitate throughput and cost effectiveness, all steps, from probe generation to signal detection, are performed using exon 96-well microtiter plates. Digoxygenin (DIG)-labelled antisense RNA probes are produced using either cDNA clones or genomic DNA as templates. After tissue fixation and permeabilization, probes are hybridized to transcripts of interest and then detected using a succession of anti-DIG antibody conjugated to biotin, streptavidin conjugated to horseradish peroxidase (HRP) and fluorescently conjugated tyramide, which in the presence of HRP, produces a highly reactive intermediate that binds to electron dense regions of immediately adjacent proteins. These amplification and localization steps produce a robust and highly localized signal that facilitates both cellular and subcellular transcript localization. The protocols provided have been optimized to produce highly specific signals in a variety of tissues and developmental stages. References are also provided for additional variations that allow the simultaneous detection of multiple transcripts, or transcripts and proteins, at the same time.

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

The described RNA in situ hybridization protocol allows the detection of RNA in whole Drosophila embryos or dissected tissues. Using 96-well microtiter plates and tyramide signal amplification, transcripts can be detected at high resolution, sensitivity, and throughput, and at a relatively low cost.

In our efforts to determine the patterns of expression and subcellular localization of Drosophila RNAs on a genome-wide basis, and in a variety of ...

Transient Expression of Foreign Genes in Insect Cells (sf9) for Protein Functional Assay

The transient gene expression system is one of the most important technologies for performing protein functional analysis in the baculovirus in vitro cell culture system. This system was developed to express foreign genes under the control of the baculoviral promoter in transient expression plasmids. Furthermore, this system can be applied to a functional assay of either the baculovirus itself or foreign proteins. The most widely and commercially available transient gene expression system is developed based on the immediate-early gene (IE) promoter of Orgyia pseudotsugata multicapsid nucleopolyhedrovirus (OpMNPV). However, a low expression level of foreign genes in insect cells was observed. Therefore, a transient gene expression system was constructed for improving protein expression. In this system, recombinant plasmids were constructed to contain the target sequence under the control of the Drosophila heat shock 70 (Dhsp70) promoter. This protocol presents the application of this heat shock-based pDHsp/V5-His (V5 epitope with 6 histidine)/Spodoptera frugiperda cell (sf9 cell) system; this system is available not only for gene expression but also for evaluating the anti-apoptotic activity of candidate proteins in insect cells. Furthermore, this system can be either transfected with one recombinant plasmid or co-transfected two potentially functionally antagonistic recombinant plasmids in insect cells. The protocol demonstrates the efficiency of this system and provides a practical case of this technique.

Transient Expression of Foreign Genes in Insect Cells sf9 for Protein Functional Assay

This protocol describes a heat shock-induced protein expression system (pDHsp/V5-His/sf9 cell system), which can be used for either expressing foreign proteins or evaluating the anti-apoptotic activity of potential foreign proteins and their truncated amino acids in insect cells.

The transient gene expression system is one of the most important technologies for performing protein functional analysis in the baculovirus in vitro cell ...

Adapting 3' Rapid Amplification of CDNA Ends to Map Transcripts in Cancer

Maturation of eukaryotic mRNAs involves 3&#39; end formation, which involves the addition of a poly(A) tail. In order to map the 3&#39; end of a gene, the traditional method of choice is 3&#39; rapid amplification of cDNA ends (3&#39; RACE). Protocols for 3&#39; RACE require the careful design and selection of nested primers within the 3&#39; untranslated region (3&#39; UTR) of the target gene of interest. However, with a few modifications the protocol can be used to include the entire 3&#39; UTR and sequences within the open reading frame (ORF), providing a more comprehensive picture of the relationship between the ORF and the 3&#39; UTR. This is in addition to identification of the polyadenylation signal (PAS), as well as the cleavage and polyadenylation site provided by conventional 3&#39; RACE. Expanded 3&#39; RACE can detect unusual 3&#39; UTRs, including gene fusions within the 3&#39; UTR, and the sequence information can be used to predict potential miRNA binding sites as well as AU rich destabilizing elements that may affect the stability of the transcript.

The two different 3&#39; rapid amplification of cDNA ends (3&#39; RACE) protocols described here make use of two different DNA polymerases to map sequences that include a segment of the open reading frame (ORF), the stop codon, and the entire 3&#39; UTR of a transcript using RNA obtained from different cancer cell lines.

Maturation of eukaryotic mRNAs involves 3&#39; end formation, which involves the addition of a poly(A) tail. In order to map the 3&#39; end of a gene, the ...

Amplification of Near Full-length HIV-1 Proviruses for Next-Generation Sequencing

The Full-Length Individual Proviral Sequencing (FLIPS) assay is an efficient and high-throughput method designed to amplify and sequence single, near full-length (intact and defective), HIV-1 proviruses. FLIPS allows determination of the genetic composition of integrated HIV-1 within a cell population. Through identifying defects within HIV-1 proviral sequences that arise during reverse transcription, such as large internal deletions, deleterious stop codons/hypermutation, frameshift mutations, and mutations/deletions in cis acting elements required for virion maturation, FLIPS can identify integrated proviruses incapable of replication. The FLIPS assay can be utilized to identify HIV-1 proviruses that lack these defects and are&#160;therefore potentially replication-competent. The FLIPS protocol involves: lysis of HIV-1 infected cells, nested PCR of near full-length HIV-1 proviruses (using primers targeted to the HIV-1 5&#39; and 3&#39; LTR), DNA purification and quantification, library preparation for Next-generation Sequencing (NGS), NGS, de novo assembly of proviral contigs, and a simple process of elimination for identifying replication-competent proviruses. FLIPS provides advantages over traditional methods designed to sequence integrated HIV-1 proviruses, such as single-proviral sequencing. FLIPS amplifies and sequences near full-length proviruses enabling replication competency to be determined, and also uses fewer amplification primers, preventing the consequences of primer mismatches. FLIPS is a useful tool for understanding the genetic landscape of integrated HIV-1 proviruses, especially within the latent reservoir, however, its utilization can extend to any application in which the genetic composition of integrated HIV-1 is required.

Full-length individual proviral sequencing (FLIPS) provides an efficient and high-throughput method for the amplification and sequencing of single, near full-length (intact and defective) HIV-1 proviruses and allows for determination of their potential replication-competency. FLIPS overcomes limitations of previous assays designed to sequence the latent HIV-1 reservoir.

The Full-Length Individual Proviral Sequencing (FLIPS) assay is an efficient and high-throughput method designed to amplify and sequence single, near ...

qKAT: Quantitative Semi-automated Typing of Killer-cell Immunoglobulin-like Receptor Genes

Killer cell immunoglobulin-like receptors (KIRs) are a set of inhibitory and activating immune receptors, on natural killer (NK) and T cells, encoded by a polymorphic cluster of genes on chromosome 19. Their best-characterized ligands are the human leukocyte antigen (HLA) molecules that are encoded within the major histocompatibility complex (MHC) locus on chromosome 6. There is substantial evidence that they play a significant role in immunity, reproduction, and transplantation, making it crucial to have techniques that can accurately genotype them. However, high-sequence homology, as well as allelic and copy number variation, make it difficult to design methods that can accurately and efficiently genotype all KIR genes. Traditional methods are usually limited in the resolution of data obtained, throughput, cost-effectiveness, and the time taken for setting up and running the experiments. We describe a method called quantitative KIR semi-automated typing (qKAT), which is a high-throughput multiplex real-time polymerase chain reaction method that can determine the gene copy numbers for all genes in the KIR locus. qKAT is a simple high-throughput method that can provide high-resolution KIR copy number data, which can be further used to infer the variations in the structurally polymorphic haplotypes that encompass them. This copy number and haplotype data can be beneficial for studies on large-scale disease associations, population genetics, as well as investigations on expression and functional interactions between KIR and HLA.

Quantitative killer cell immunoglobulin-like receptor (KIR) semi-automated typing (qKAT) is a simple, high-throughput, and cost-effective method to copy number type KIR genes for their application in population and disease association studies.

Killer cell immunoglobulin-like receptors (KIRs) are a set of inhibitory and activating immune receptors, on natural killer (NK) and T cells, encoded by a ...

Evaluation of a Universal Nested Reverse Transcription Polymerase Chain Reaction for the Detection of Lyssaviruses

To detect rabies virus and other member species of the genus Lyssavirus within the family Rhabdoviridae, the pan-lyssavirus nested reverse transcription polymerase chain reaction (nested RT-PCR) was developed to detect the conserved region of the nucleoprotein (N) gene of lyssaviruses. The method applies reverse transcription (RT) using viral RNA as template and oligo (dT)15 and random hexamers as primers to synthesize the viral complementary DNA (cDNA). Then, the viral cDNA is used as a template to amplify an 845 bp N gene fragment in first-round PCR using outer primers, followed by second-round nested PCR to amplify the final 371 bp fragment using inner primers. This method can detect different genetic clades of rabies viruses (RABV). The validation, using 9,624 brain specimens from eight domestic animal species in 10 years of clinical rabies diagnoses and surveillance in China, showed that the method has 100% sensitivity and 99.97% specificity in comparison with the direct fluorescent antibody test (FAT), the gold standard method recommended by the World Health Organization (WHO) and the World Organization for Animal Health (OIE). In addition, the method could also specifically amplify the targeted N gene fragment of 15 other approved and two novel lyssavirus species in the 10th Report of the International Committee on Taxonomy of Viruses (ICTV) as evaluated by a mimic detection of synthesized N gene plasmids of all lyssaviruses. The method provides a convenient alternative to FAT for rabies diagnosis and has been approved as a National Standard (GB/T36789-2018) of China.

A pan-lyssavirus nested reverse transcription polymerase chain reaction has been developed to detect specifically all known lyssaviruses. Validation using rabies brain samples of different animal species showed that this method has a sensitivity and specificity equivalent to the gold standard fluorescent antibody test and could be used for routine rabies diagnosis.

To detect rabies virus and other member species of the genus Lyssavirus within the family Rhabdoviridae, the pan-lyssavirus nested reverse transcription ...