Research in the Ghanim lab was supported by research grant no. 908-42.12/2006 from the German-Israeli Foundation (GIF), grant no. IS-4062-07 from the United States-Israel Binational Agricultural Research and Development Fund (BARD), and research grant no. 884/07 from Israel Science Foundation (ISF) to M.G.

1. General Whitefly, Plant, and Virus Preparations for FISH Analysis
<ol>
	<li>Rear B and Q biotype whiteflies on cotton seedlings (Gossypium hirsutum L. cv. Acala) and maintain inside insect-proof cages and growth rooms under standard conditions of 25&#177;2 &#176;C, 60% relative humidity, and a 14-hr light/10-hr dark photoperiod.</li>
	<li>Perform PCR to test infection with endosymbionts using endosymbiont-specific primers as previously described15-19.</li>
	<li>Purchase Tomato seedlings (Solanum esculentum cv. Beefsteak) from a commercial nursery or plant tomato seeds.</li>
	<li>Maintain under the same rearing conditions described above until the plants reach the four true-leaf stage, the age most suitable for whitefly-mediated inoculation of TYLCV15 (see section 4.1 below).</li>
</ol>
2. Insect Handling, Fixation, Probe Design, Hybridization, and Visualization for Endosymbiont FISH
<ol>
	<li>Collect 10 adult whiteflies by aspiration from cotton plants, or pick 10 3rd or 4th instar nymphs from cotton leaves.</li>
	<li>Immediately immerse in Carnoy&#8217;s fixative (chloroform-ethanol-glacial acetic acid, 6:3:1, vol/vol) inside Eppendorf tubes. Fix for 2 hr to overnight (preferably overnight).</li>
	<li>Completely remove the fixative and decolorize in 6% H2O2 in ethanol for 2 hr.</li>
	<li>Preserve the samples in absolute ethanol for several days to several weeks at room temperature, or proceed to the next step.</li>
	<li>Design probes as complementary reverse DNA primers based on the 16s ribosomal RNA genes of each bacterium. For designing the probes, take into the account the same considerations for designing PCR primers. Use the oligonucleotide probes BTP1 5&#39;-Cy5-TGTCAGTGTCAGCCCAGAAG-3&#39;, Rb1 5&#39;-Cy3-TCCACGTCGCCGTCTTGC-3&#39;, BTH 5&#39;-Cy3-CCAGATTCCCAGACTTTACTCA-3&#39; and Ars2 5&#39;-cy3-TCATGACCACAACCTCCAAA-3&#39; for specific targeting of Portiera, Rickettsia, Hamilonella,&#160;and Arsenophonus, respectively.</li>
	<li>Hybridize samples overnight in the dark in hybridization buffer (20 mM Tris-HCl, pH 8.0, 0.9 M NaCl, 0.01% [wt/vol] sodium dodecyl sulfate, 30% [vol/vol] formamide) containing 10 pmol fluorescent probe per ml. Combine more than one probe with different fluorescent dyes if necessary. Use noninfected whiteflies with the targeted bacterium and no-probe samples as negative controls.</li>
	<li>Mount the samples whole, on a microscope slide, in hybridization buffer contained with a liquid blocker, cover with a cover slip, seal with nail polish, and view under a fluorescence or confocal microscope.</li>
</ol>
3. Whitefly Organ Dissection, Fixation, Hybridization, and Visualization for TYLCV FISH
<ol>
	<li>Collect adult whiteflies&#160;continuously reared on TYLCV-infected tomato plants by aspiration and anesthetize by exposure to paper towel impregnated with acetone. Expose whiteflies only for 1-2 min as too long exposure to acetone can fix whiteflies tissues. Use nonviruliferous whiteflies reared on noninfected tomato plants and no probe samples for controls to confirm specific hybridization.</li>
	<li>Mount whiteflies on depression microscope slides for organ dissection using a stereo microscope.</li>
	<li>Pull away the insect head from the prothorax and dissect salivary glands in 1x PBS supplemented with 1% toluidine blue stain for better visualization, due to their small size. Allow absorption of the stain for 2-3 min.</li>
	<li>Pull the insect apart at the juncture between the thorax and the abdomen to observe and expel out the midgut. Expel the contents of the abdomen by pushing with forceps on the abdomen tip.</li>
	<li>Gently remove the PBS and toluidine blue from successful dissections and gently add 300 &#181;l of Carnoy&#8217;s fixative to fix the organs for 5 min.</li>
	<li>Add the fixative from one side of the depressed well and not from the top to prevent uncontrolled movement of the dissected organs. Once touching the fixative, the organs will adhere to the glass, and throughout the process they will not move.</li>
	<li>Remove fixative and add 500 &#181;l of hybridization buffer supplemented with 10 pmol of the fluorescent DNA probe Cy5-5&#39;-GGAACATCAGGGCTTCGATA-3&#39;, which is complementary to a sequence in TYLCV coat protein gene.</li>
	<li>Hybridize overnight at room temperature in the dark by incubating the slide with the specimen inside a small humid chamber composed of small plastic box with wet towel paper at the bottom.</li>
	<li>Following the hybridization, pick up the organs with a fine dissection tool and rapidly move them to a fresh microscope slide containing 30 &#181;l of new hybridization buffer supplemented with DAPI (0.1 mg/ml&#160;in 1x PBS) and contained with liquid blocker.</li>
	<li>Cover the specimens with a cover slip, seal with nail polish and view under a fluorescence or confocal microscope.&#160;</li>
</ol>
4. Plant Handling, Hand-sectioning, Fixation, and Hybridization for TYLCV FISH
<ol>
	<li>Inoculate tomato seedlings with TYLCV using viruliferous whitefly-mediated inoculation. The virus can be detected using this FISH method in symptomless plants one week after inoculation. Typical disease symptoms are visible three weeks post inoculation. Use noninfected tomato plants and no probe samples for controls to confirm specific hybridization.</li>
	<li>Use a sharp histological razor blade for preparing hand-cut 2-4 cm long longitudinal or cross sections of tomato stems and leaves.</li>
	<li>In Eppendorf tubes, fix the sections in Carnoy&#8217;s fixative for 2 hr&#160;to overnight at room temperature.</li>
	<li>Remove fixative and preserve the sections in absolute ethanol for several days to several weeks at room temperature, or proceed to the next step.</li>
	<li>Wash the sections three times, 1 min each, in hybridization buffer.</li>
	<li>Hybridize the sections with 500 &#181;l of hybridization buffer supplemented with 10 pmol of the fluorescent oligonucleotide probe Cy3-5&#39;-GGAACATCAGGGCTTCGATA-3&#39; which is complementary to a sequence in TYLCV coat protein gene.</li>
	<li>Wash the sections three times, 1 min each, in hybridization buffer.</li>
	<li>Mount sections whole in hybridization buffer supplemented with DAPI (0.1 mg/ml&#160;in 1x PBS) and contained with liquid blocker, cover with a coverslip, seal with nail polish and view under a fluorescence or confocal microscope.</li>
</ol>

<ol>
	<li>Czosnek, H., Laterrot, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+worldwide+survey+of+Tomato+yellow+leaf+curl+viruses.">A worldwide survey of Tomato yellow leaf curl viruses.</a> Arch. Virol. 142, 1391-1406 (1997).</li><li>Ling, K. S., Simmons, A. M., Hassell, R. L., Keinath, A. P., Polston, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=First+report+of+Tomato+Yellow+Leaf+Curl+Virus+in+South+Carolina.">First report of Tomato Yellow Leaf Curl Virus in South Carolina.</a> Plant Dis. 90, 379 (2006).</li><li>Polston, J. E., McGovern, R. J., Brown, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Introduction+of+Tomato+yellow+leaf+curl+virus+in+Florida+and+implications+for+the+spread+of+this+and+other+geminiviruses+of+tomato.">Introduction of Tomato yellow leaf curl virus in Florida and implications for the spread of this and other geminiviruses of tomato.</a> Plant Dis. 83, 984-988 (1999).</li><li>Polston, J. E., Rosebrock, T. R., Sherwood, T., Creswell, T., Shoemaker, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Appearance+of+Tomato+yellow+leaf+curl+virus+in+North+Carolina.">Appearance of Tomato yellow leaf curl virus in North Carolina.</a> Plant Dis. 86, 73 (2002).</li><li>Frohlich, D. R., Torres-Jerez, I., Bedford, I. D., Markham, P. G., Brown, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+phylogeographical+analysis+of+the+Bemisia+tabaci+species+complex+based+on+mitochondrial+DNA+markers.">A phylogeographical analysis of the Bemisia tabaci species complex based on mitochondrial DNA markers.</a> Mol. Ecol. 8, 1683-1691 (2002).</li><li>Ghanim, M., Morin, S., Czosnek, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rate+of+Tomato+yellow+leaf+curl+virus+translocation+in+the+circulative+transmission+pathway+of+its+vector,+the+whitefly+Bemisia+tabaci.">Rate of Tomato yellow leaf curl virus translocation in the circulative transmission pathway of its vector, the whitefly Bemisia tabaci.</a> Phytopathology. 91, 188-196 (2001).</li><li>Ghanim, M., Rosell, R. C., Campbell, L. R., Czosnek, H., Brown, J. K., Ullman, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Digestive++salivary+and+reproductive+organs+of+Bemisia+tabaci+(Gennadius)+Hemiptera:+Aleyrodidae)+B+type.">Digestive salivary and reproductive organs of Bemisia tabaci (Gennadius) Hemiptera: Aleyrodidae) B type.</a> J. Morphol. 248, 22-40 (2001).</li><li>Hunter, W. B., Hiebert, E., Webb, S. E., Tsai, J. K., Polston, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Location+of+geminiviruses+in+the+whitefly+Bemisia+tabaci+(Homoptera:+Aleyrodidae).">Location of geminiviruses in the whitefly Bemisia tabaci (Homoptera: Aleyrodidae).</a> Plant Dis. 82, 1147-1151 (1998).</li><li>Rosell, R. C., Torres-Jerez, I., Brown, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+pathway+of+geminivirus+in+whitefly+extracts,+saliva,+hemolymph+and+honeydew.">Temporal pathway of geminivirus in whitefly extracts, saliva, hemolymph and honeydew.</a> Phytopathology. 89, 239-246 (1999).</li><li>Czosnek, H., Ghanim, M., Ghanim, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+circulative+pathway+of+begomoviruses+in+the+whitefly+vector+Bemisia+tabaci&#8212;insights+from+studies+with+Tomato+yellow+leaf+curl+virus.">The circulative pathway of begomoviruses in the whitefly vector Bemisia tabaci&#8212;insights from studies with Tomato yellow leaf curl virus.</a> Ann. Appl. Biol. 140, 215-231 (2002).</li><li>Gottlieb, 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=The+transmission+efficiency+of+Tomato+yellow+leaf+curl+virusby+the+whitefly+Bemisiatabaciis+correlated+with+the+presence+of+aspecificsymbiotic+bacterium+species.">The transmission efficiency of Tomato yellow leaf curl virusby the whitefly Bemisiatabaciis correlated with the presence of aspecificsymbiotic bacterium species.</a> J. Virol. 84, 9310-9317 (2010).</li><li>Brumin, M., Levy, M., Ghanim, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transovarial+transmission+of+Rickettsia+spp.+and+organ-specific+infection+of+the+whitefly+Bemisia+tabaci.">Transovarial transmission of Rickettsia spp. and organ-specific infection of the whitefly Bemisia tabaci.</a> Appl. Environ. Microbiol. 78, 5565-5574 (2012).</li><li>Ghanim, M., Medina, V., Czosnek, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Localization of Tomato yellow leaf curl virus in its whitefly vector Bemisia tabaci. In Tomato Yellow Leaf Curl Virus Disease, Management, Molecular Biology, Breeding for Resistance. , 175-187 (2007).</li><li>Ghanim, M., Brumin, M., Popovski, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple,+rapid+and+inexpensive+method+for+localization+of+Tomato+yellow+leaf+curl+virus+and+Potato+leafroll+virus+in+plant+and+insect+vectors.">A simple, rapid and inexpensive method for localization of Tomato yellow leaf curl virus and Potato leafroll virus in plant and insect vectors.</a> J. Virol. Methods. 159, 311-314 (2009).</li><li>Gotz, 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=Implication+of+Bemisia+tabaci+heat+shock+protein+70+in+Begomovirus-whitefly+interactions.">Implication of Bemisia tabaci heat shock protein 70 in Begomovirus-whitefly interactions.</a> J. Virol. 86, 13241-13252 (2012).</li><li>Nirgianaki, 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=Wolbachia+infections+of+the+whitefly+Bemisia+tabaci.">Wolbachia infections of the whitefly Bemisia tabaci.</a> Curr. Microbiol. 47, 93-101 (2003).</li><li>Baumann, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biology+of+bacteriocyte-associated+endosymbionts+of+plant+sap-sucking+insects.">Biology of bacteriocyte-associated endosymbionts of plant sap-sucking insects.</a> Ann. Rev. Microbiol. 59, 155-189 (2005).</li><li>Gottlieb, 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=Identification+and+localization+of+a+Rickettsia+sp.+in+Bemisia+tabaci+(Homoptera)+Aleyrodidae).">Identification and localization of a Rickettsia sp. in Bemisia tabaci (Homoptera) Aleyrodidae).</a> App. Environ. Microbiol. 72, 3646-3652 (2006).</li><li>Li, Z. X., Lin, H. Z., Guo, X. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+of+Wolbachia+infection+in+Bemisia+tabaci.">Prevalence of Wolbachia infection in Bemisia tabaci.</a> Curr. Microbiol. 54, 467-471 (2007).</li><li>Skaljac, M., Zanic, K., Hrncic, S., Radonjic, S., Perovic, T., Ghanim, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diversity+and+localization+of+bacterial+symbionts+in+three+whitefly+species+(Hemiptera:+Aleyrodidae)+from+the+east+coast+of+the+Adriatic.">Diversity and localization of bacterial symbionts in three whitefly species (Hemiptera: Aleyrodidae) from the east coast of the Adriatic.</a> Bull. Entomol. Res. 103, 48-59 (2013).</li></ol>

The authors have nothing to disclose.

The protocol described here for the localization of a plant virus in its plant host and insect vector, and endosymbiotic bacteria in their specific whitefly host, can be adapted for the localization of other viruses in plants and even in animal tissues. Furthermore, the protocol can be used to localize endosymbiotic and pathogenic bacteria and other microorganisms in plant and animal systems. The described methods rely on simple concept of hybridization between a short, fluorescently-labeled oligonucleotide DNA probe&#16...

When studying the interactions between plant viruses and other pathogens with their infected plant hosts, it is important to visualize the pathogens and their respective nucleic acids in situ, regardless whether they cause negative effects on their hosts. This is most important when studying pathogen movement within and between plant cells. In situ localization of gene products of the pathogen is an essential step that complements other approaches for studying the pathogenicity process. Many plant pathogens, especially viruses, are transmitted by insects, having complex and intimate interactions with their vectors. Localization of these viruses in their vectors is important for studying the path for transmission, and the possible interaction sites inside the vector. The transmission of some insect-vectored plant viruses is aided by endosymbiotic bacteria that reside within these insects. To better study the transmission of these plant viruses by their vectors, it is also essential to visualize the endosymbiotic bacteria in general, and those involved in virus transmission, in particular. Colocalization of the virus and endosymbiotic bacteria is thus desired for investigating the possible relationships between these organisms within their insect host. Aside from virus transmission, endosymbiotic bacteria influence several aspects of the biology of insect vectors, thus spatial localization of these bacteria within insects is of high interest and importance.
Tomato yellow leaf curl virus (TYLCV) (Begomovirus, Geminiviridae) is the most important viral disease complex of cultivated tomato worldwide1-4. TYLCV is a phloem-limited virus and is exclusively vectored by the whitefly Bemisia tabaci 5,6. A model describing the translocation of begomoviruses in their whitefly vectors has been proposed6-9. Two specific barriers are actively crossed during this circulative transmission: the midgut/hemolymph and the hemolymph/salivary gland barriers. This transmission process is hypothesized to be mediated by unknown receptors which recognize the virus capsid. TYLCV is thought to cross B. tabaci midgut6,10, and is absorbed through the primary salivary gland6&#160;before it is injected into the plant. In the whitefly hemolymph, TYLCV interacts with a GroEL protein produced by the insect secondary endosymbiotic bacterium Hamiltonella. This interaction ensures safe transport of TYLCV in the hemolymph, and protects it from attack by the insect immune system11. Hamiltonella and Portiera, the primary endosymbiont of whiteflies, are housed in bacteriocytes, insect cells found in the hemolymph and house endosymbiotic bacteria11. B. tabaci harbors additional endosymbiotic bacteria including Rickettsia, Arsenophonus, Wolbachia,&#160;and Fritschea, which can be localized inside or outside the bacteriocytes, and have diverse effects on the insect&#8217;s biology12.
Several reports have attempted to study the localization of TYLCV in plants and whiteflies by using time-consuming and costly protocols such as Transmission Electron Microscopy (TEM), antibodies and RNA in situ on microscopic thick section10,13, a recent study described the localization of plant viruses inside their plant and vector hosts by using a simple protocol14. Here we describe a simple protocol for the localization of TYLCV in B. tabaci dissected midguts and salivary glands, and in sections prepared from TYLCV-infected plants. We further describe the localization of Portiera, the primary endosymbiont of B. tabaci, and its secondary endosymbionts Hamitonella, Rickettsia and Arsenophonus. This protocol is based on using short DNA probes, that are fluorescently labeled on their 5&#39;&#160;end, and specifically hybridize to complementary sequences in viral or bacterial gene sequences. The sample processing is relatively easy and the signal obtained is highly specific. The described protocol can be used to localize viruses, bacteria and other pathogens in their plant, animal and insect hosts, and can further be used to localize mRNA in any given tissue.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Fluorescently labeled&#160; Probes</td>
			<td style="width:95px;">Metabion</td>
			<td style="width:129px;">20 bp HPLC purified</td>
			<td style="width:212px;">Sequence designed by customer</td>
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			<td height="21" style="height:21px;width:219px;">Toluidine blue</td>
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			<td height="21" style="height:21px;width:219px;">sodium dodecyl sulfate</td>
			<td style="width:95px;">Sigma-Aldrich</td>
			<td style="width:129px;">L3771</td>
			<td style="width:212px;">Molecular Biology Grade</td>
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			<td height="21" style="height:21px;width:219px;">Formamide</td>
			<td style="width:95px;">Sigma-Aldrich</td>
			<td style="width:129px;">F9037</td>
			<td style="width:212px;">Molecular Biology Grade</td>
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			<td height="21" style="height:21px;width:219px;">Tris-HCl</td>
			<td style="width:95px;">Sigma-Aldrich</td>
			<td style="width:129px;">T5941</td>
			<td style="width:212px;">Molecular Biology Grade</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Glacial Acetic Acid</td>
			<td style="width:95px;">Sigma-Aldrich</td>
			<td style="width:129px;">320099</td>
			<td style="width:212px;">Molecular Biology Grade</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Liquid Blocker</td>
			<td>Ted Pella Inc.</td>
			<td>22309</td>
			<td></td>
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fluorescence in situ hybridizations (fish) for the localization of viruses and endosymbiotic bacteria in plant and insect tissues

Fluorescence in situ hybridization (FISH) is a name given to a variety of techniques commonly used for visualizing gene transcripts in eukaryotic cells and can be further modified to visualize other components in the cell such as infection with viruses and bacteria. Spatial localization and visualization of viruses and bacteria during the infection process is an essential step that complements expression profiling experiments such as microarrays and RNAseq in response to different stimuli. Understanding the spatiotemporal infections with these agents complements biological experiments aimed at understanding their interaction with cellular components. Several techniques for visualizing viruses and bacteria such as reporter gene systems or immunohistochemical methods are time-consuming, and some are limited to work with model organisms&#160;and involve complex methodologies. FISH that targets RNA or DNA species in the cell is a relatively easy and fast method for studying spatiotemporal localization of genes and for diagnostic purposes. This method can be robust and relatively easy to implement when the protocols employ short hybridizing, commercially-purchased probes, which are not expensive. This is particularly robust when sample preparation, fixation, hybridization, and microscopic visualization do not involve complex steps. Here we describe a protocol for localization of bacteria and viruses in insect and plant tissues. The method is based on simple preparation, fixation, and hybridization of insect whole mounts and dissected organs or hand-made plant sections, with 20 base pairs short DNA probes conjugated to fluorescent dyes on their 5&#39; or 3&#39; ends. This protocol has been successfully applied to a number of insect and plant tissues, and can be used to analyze expression of mRNAs or other RNA or DNA species in the cell.

The system studied in this manuscript is shown in Figure 1 and includes an infected plant with TYLCV, an adult and a nymph of the whitefly B. tabaci, and the internal anatomy of the whitefly showing the path for TYLCV translocation in the insect. Figure 2 shows double FISH in an adult whitefly for the primary symbiont Portiera and the secondary symbiont Arsenophonus. Figure 3 shows double FISH for Portiera and Hamiltonella, an...

Watch this Scientific Journal Video about Fluorescence in situ Hybridizations FISH for the Localization of Viruses and Endosymbiotic Bacteria in Plant and Insect Tissues at JoVE.com

Fluorescence in situ Hybridizations FISH for the Localization of Viruses and Endosymbiotic Bacteria in Plant and Insect Tissues

We describe here a simple fluorescence in situ hybridization (FISH) method for the localization of viruses and bacteria in insect and plant tissues. This protocol can be extended for the visualization of mRNA in whole mount and microscopic sections.

Fluorescence in situ Hybridizations (FISH) for the Localization of Viruses and Endosymbiotic Bacteria in Plant and Insect Tissues

Fluorescence in situ hybridization (FISH) is a name given to a variety of techniques commonly used for visualizing gene transcripts in eukaryotic cells ...

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23.2K Views.  Volcani Center. We describe here a simple fluorescence in situ hybridization (FISH) method for the localization of viruses and bacteria in insect and plant tissues. This protocol can be extended for the visualization of mRNA in whole mount and microscopic sections.

Video: Fluorescence in situ Hybridizations FISH for the Localization of Viruses and Endosymbiotic Bacteria in Plant and Insect Tissues

Locked Nucleic Acid Flow Cytometry-fluorescence in situ Hybridization (LNA flow-FISH): a Method for Bacterial Small RNA Detection

Fluorescence in situ hybridization (FISH) is a powerful technique that is used to detect and localize specific nucleic acid sequences in the cellular environment. In order to increase throughput, FISH can be combined with flow cytometry (flow-FISH) to enable the detection of targeted nucleic acid sequences in thousands of individual cells. As a result, flow-FISH offers a distinct advantage over lysate/ensemble-based nucleic acid detection methods because each cell is treated as an independent observation, thereby permitting stronger statistical and variance analyses. These attributes have prompted the use of FISH and flow-FISH methods in a number of different applications and the utility of these methods has been successfully demonstrated in telomere length determination1,2, cellular identification and gene expression3,4, monitoring viral multiplication in infected cells5, and bacterial community analysis and enumeration6.
Traditionally, the specificity of FISH and flow-FISH methods has been imparted by DNA oligonucleotide probes. Recently however, the replacement of DNA oligonucleotide probes with nucleic acid analogs as FISH and flow-FISH probes has increased both the sensitivity and specificity of each technique due to the higher melting temperatures (Tm) of these analogs for natural nucleic acids7,8. Locked nucleic acid (LNA) probes are a type of nucleic acid analog that contain LNA nucleotides spiked throughout a DNA or RNA sequence9,10. When coupled with flow-FISH, LNA probes have previously been shown to outperform conventional DNA probes7,11 and have been successfully used to detect eukaryotic mRNA12 and viral RNA in mammalian cells5.
Here we expand this capability and describe a LNA flow-FISH method which permits the specific detection of RNA in bacterial cells (Figure 1). Specifically, we are interested in the detection of small non-coding regulatory RNA (sRNA) which have garnered considerable interest in the past few years as they have been found to serve as key regulatory elements in many critical cellular processes13. However, there are limited tools to study sRNAs and the challenges of detecting sRNA in bacterial cells is due in part to the relatively small size (typically 50-300 nucleotides in length) and low abundance of sRNA molecules as well as the general difficulty in working with smaller biological cells with varying cellular membranes. In this method, we describe fixation and permeabilzation conditions that preserve the structure of bacterial cells and permit the penetration of LNA probes as well as signal amplification steps which enable the specific detection of low abundance sRNA (Figure 2).

Locked Nucleic Acid Flow Cytometry-fluorescence in situ Hybridization LNA flow-FISH: a Method for Bacterial Small RNA Detection

A novel high-throughput method is described that enables the detection and relative quantitation of small RNA and mRNA expression from single bacterial cells using locked nucleic acid probes and flow cytometry-fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) is a powerful technique that is used to detect and localize specific nucleic acid sequences in the cellular ...

Fluorescence Microscopy Methods for Determining the Viability of Bacteria in Association with Mammalian Cells

Central to the field of bacterial pathogenesis is the ability to define if and how microbes survive after exposure to eukaryotic cells. Current protocols to address these questions include colony count assays, gentamicin protection assays, and electron microscopy. Colony count and gentamicin protection assays only assess the viability of the entire bacterial population and are unable to determine individual bacterial viability. Electron microscopy can be used to determine the viability of individual bacteria and provide information regarding their localization in host cells. However, bacteria often display a range of electron densities, making assessment of viability difficult. This article outlines protocols for the use of fluorescent dyes that reveal the viability of individual bacteria inside and associated with host cells. These assays were developed originally to assess survival of Neisseria gonorrhoeae in primary human neutrophils, but should be applicable to any bacterium-host cell interaction. These protocols combine membrane-permeable fluorescent dyes (SYTO9 and 4&#39;,6-diamidino-2-phenylindole [DAPI]), which stain all bacteria, with membrane-impermeable fluorescent dyes (propidium iodide and SYTOX Green), which are only accessible to nonviable bacteria. Prior to eukaryotic cell permeabilization, an antibody or fluorescent reagent is added to identify extracellular bacteria. Thus these assays discriminate the viability of bacteria adherent to and inside eukaryotic cells. A protocol is also provided for using the viability dyes in combination with fluorescent antibodies to eukaryotic cell markers, in order to determine the subcellular localization of individual bacteria. The bacterial viability dyes discussed in this article are a sensitive complement and/or alternative to traditional microbiology techniques to evaluate the viability of individual bacteria and provide information regarding where bacteria survive in host cells.

Central to the field of bacterial pathogenesis is the ability to define if and how microbes survive after exposure to eukaryotic cells. This article outlines protocols for the use of fluorescent dyes that reveal the viability of individual bacteria inside and associated with host cells.

Central to the field of bacterial pathogenesis is the ability to define if and how microbes survive after exposure to eukaryotic cells. Current protocols ...

Intranasal Administration of Recombinant Influenza Vaccines in Chimeric Mouse Models to Study Mucosal Immunity

Vaccines are one of the greatest achievements of mankind, and have saved millions of lives over the last century. Paradoxically, little is known about the physiological mechanisms that mediate immune responses to vaccines perhaps due to the overall success of vaccination, which has reduced interest into the molecular and physiological mechanisms of vaccine immunity. However, several important human pathogens including influenza virus still pose a challenge for vaccination, and may benefit from immune-based strategies. 
Although influenza reverse genetics has been successfully applied to the generation of live-attenuated influenza vaccines (LAIVs), the addition of molecular tools in vaccine preparations such as tracer components to follow up the kinetics of vaccination in vivo, has not been addressed. In addition, the recent generation of mouse models that allow specific depletion of leukocytes during kinetic studies has opened a window of opportunity to understand the basic immune mechanisms underlying vaccine-elicited protection. Here, we describe how the combination of reverse genetics and chimeric mouse models may help to provide new insights into how vaccines work at physiological and molecular levels, using as example a recombinant, cold-adapted, live-attenuated influenza vaccine (LAIV). We utilized laboratory-generated LAIVs harboring cell tracers as well as competitive bone marrow chimeras (BMCs) to determine the early kinetics of vaccine immunity and the main physiological mechanisms responsible for the initiation of vaccine-specific adaptive immunity. In addition, we show how this technique may facilitate gene function studies in single animals during immune responses to vaccines. We propose that this technique can be applied to improve current prophylactic strategies against pathogens for which urgent medical countermeasures are needed, for example influenza, HIV, Plasmodium, and hemorrhagic fever viruses such as Ebola virus.

There is an overall lack of knowledge about how vaccines work. Here we propose the combined use of reverse genetics and bone marrow chimeric mice to gain insight into the early host immune responses to vaccines with a special focus on dendritic cells and T cell immunity.

Vaccines are one of the greatest achievements of mankind, and have saved millions of lives over the last century. Paradoxically, little is known about the ...

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

The presence of bacteria within the pocket epithelium and underlying connective tissue in gingival biopsies from patients with periodontitis has been reported using various methods, including electron microscopy, immunohistochemistry or immunofluorescence using bacteria-specific antibodies, and fluorescent in situ hybridization (FISH) using a fluorescence-labeled oligonucleotide probe. Nevertheless, these methods are not widely used due to technical limitation or difficulties. Here a method to localize bacteria within paraffin-embedded tissues using DIG-labeled DNA probes has been introduced. The paraffin-embedded tissues are the most common form of biopsy tissues available from pathology banks. Bacteria can be detected either in a species-specific or universal manner. Bacterial signals are detected as either discrete forms (coccus, rod, fusiform, and hairy form) of bacteria or dispersed forms. The technique allows other histological information to be obtained: the epithelia, connective tissue, inflammatory infiltrates, and blood vessels are well distinguished. This method can be used to study the role of bacteria in various diseases, such as periodontitis, cancers, and inflammatory immune diseases.

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

Here a method to localize bacteria within paraffin-embedded tissues using DIG-labeled 16S rRNA-targeting DNA probes has been described. This protocol can be applied to study the role of bacteria in various diseases such as periodontitis, cancers, and inflammatory immune diseases.

The presence of bacteria within the pocket epithelium and underlying connective tissue in gingival biopsies from patients with periodontitis has been ...

Identification of Plasmodesmal Localization Sequences in Proteins In Planta

Plasmodesmata (Pd) are cell-to-cell connections that function as gateways through which small and large molecules are transported between plant cells. Whereas Pd transport of small molecules, such as ions and water, is presumed to occur passively, cell-to-cell transport of biological macromolecules, such proteins, most likely occurs via an active mechanism that involves specific targeting signals on the transported molecule. The scarcity of identified plasmodesmata (Pd) localization signals (PLSs) has severely restricted the understanding of protein-sorting pathways involved in plant cell-to-cell macromolecular transport and communication. From a wealth of plant endogenous and viral proteins known to traffic through Pd, only three PLSs have been reported to date, all of them from endogenous plant proteins. Thus, it is important to develop a reliable and systematic experimental strategy to identify a functional PLS sequence, that is both necessary and sufficient for Pd targeting, directly in the living plant cells. Here, we describe one such strategy using as a paradigm the cell-to-cell movement protein (MP) of the Tobacco mosaic virus (TMV). These experiments, that identified and characterized the first plant viral PLS, can be adapted for discovery of PLS sequences in most Pd-targeted proteins.

Identification of Plasmodesmal Localization Sequences in Proteins In Planta

Plant intercellular connections, the plasmodesmata (Pd), play central roles in plant physiology and plant-virus interactions. Critical to Pd transport are sorting signals that direct proteins to Pd. However, our knowledge about these sequences is still in its infancy. We describe a strategy to identify Pd localization signals in Pd-targeted proteins.

Plasmodesmata (Pd) are cell-to-cell connections that function as gateways through which small and large molecules are transported between plant cells. ...

Protocols for Investigating the Host-tissue Distribution, Transmission-mode, and Effect on the Host Fitness of a Densovirus in the Cotton Bollworm

Many novel viruses have been discovered in animal hosts using next-generation sequencing technologies. Previously, we reported a mutualistic virus, Helicoverpa armigera densovirus (HaDV2), in a lepidopteran species, the cotton bollworm, Helicoverpa armigera (Hubner). Here, we describe the protocols that are currently used to study the effect of HaDV2 on its host. First, we establish a HaDV2-free cotton bollworm colony from a single breeding pair. Then, we orally inoculate some neonate larval offspring with HaDV2-containing filtered liquid to produce two colonies with the same genetic background: one HaDV2-infected, the other uninfected. A protocol to compare life table parameters (e.g., larval, pupal, and adult periods and fecundity) between the HaDV2-infected and -uninfected individuals is also presented, as are the protocols for determining the host-tissue distribution and transmission efficiency of HaDV2. These protocols would also be suitable for investigating the effects of other orally transmitted viruses on their insect hosts, lepidopteran hosts in particular.

Here, we present a protocol to investigate the host-tissue distribution, transmission mode, and effect on the host fitness of a densovirus within a lepidopteran species, the cotton bollworm. This protocol can also be used for studying the interaction between other orally-transmitted viruses and their insect hosts.

Many novel viruses have been discovered in animal hosts using next-generation sequencing technologies. Previously, we reported a mutualistic virus, ...

Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals

The neuraminidase (NA) inhibitors are the only class of antivirals approved for the treatment and prophylaxis of influenza that are effective against currently circulating strains. In addition to their use in treating seasonal influenza, the NA inhibitors have been stockpiled by a number of countries for use in the event of a pandemic. It is therefore important to monitor the susceptibility of circulating influenza viruses to this class of antivirals. There are different types of assays that can be used to assess the susceptibility of influenza viruses to the NA inhibitors, but the enzyme inhibition assays using either a fluorescent substrate or a chemiluminescent substrate are the most widely used and recommended. This protocol describes the use of a fluorescence-based assay to assess influenza virus susceptibility to NA inhibitors. The assay is based on the NA enzyme cleaving the 2&#8242;-(4-Methylumbelliferyl)-&#945;-D-N-acetylneuraminic acid (MUNANA) substrate to release the fluorescent product 4-methylumbelliferone (4-MU). Therefore, the inhibitory effect of an NA inhibitor on the influenza virus NA is determined based on the concentration of the NA inhibitor that is required to reduce 50% of the NA activity, given as an IC50 value.

We describe the use of a phenotypic fluorescence-based neuraminidase inhibition assay to assess the susceptibility of influenza A and B viruses to the neuraminidase inhibitor class of antivirals.

The neuraminidase (NA) inhibitors are the only class of antivirals approved for the treatment and prophylaxis of influenza that are effective against ...

Quantitative Fluorescence In Situ Hybridization (FISH) and Immunofluorescence (IF) of Specific Gene Products in KSHV-Infected Cells

Mechanistic insight arrives from careful study and quantification of specific RNAs and proteins. The relative locations of these biomolecules throughout the cell at specific times can be captured with fluorescence in situ hybridization (FISH) and immunofluorescence (IF). During lytic herpesvirus infection, the virus hijacks the host cell to preferentially express viral genes, causing changes in cell morphology and behavior of biomolecules. Lytic activities are centered in nuclear factories, termed viral replication compartments, which are discernable only with FISH and IF. Here we describe an adaptable protocol of RNA FISH and IF techniques for Kaposi's sarcoma-associated herpesvirus (KSHV)-infected cells, both adherent and in suspension. The method includes steps for the development of specific anti-sense oligonucleotides, double RNA FISH, RNA FISH with IF, and quantitative calculations of fluorescence intensities. This protocol has been successfully applied to multiple cell types, uninfected cells, latent cells, lytic cells, time-courses, and cells treated with inhibitors to analyze the spatiotemporal activities of specific RNAs and proteins from both the human host and KSHV.

Quantitative Fluorescence In Situ Hybridization FISH and Immunofluorescence IF of Specific Gene Products in KSHV-Infected Cells

We describe a protocol utilizing fluorescence in situ hybridization (FISH) to visualize multiple herpesviral RNAs within lytically infected human cells, either in suspension or adherent. This protocol includes quantification of fluorescence producing a nucleocytoplasmic ratio and can be extended for simultaneous visualization of host and viral proteins with immunofluorescence (IF).

Mechanistic insight arrives from careful study and quantification of specific RNAs and proteins. The relative locations of these biomolecules throughout ...

Live-Cell Fluorescence Microscopy to Investigate Subcellular Protein Localization and Cell Morphology Changes in Bacteria

Investigations of factors influencing cell division and cell shape in bacteria are commonly performed in conjunction with high-resolution fluorescence microscopy as observations made at a population level may not truly reflect what occurs at a single cell level. Live-cell timelapse microscopy allows investigators to monitor the changes in cell division or cell morphology which provide valuable insights regarding subcellular localization of proteins and timing of gene expression, as it happens, to potentially aid in answering important biological questions. Here, we describe our protocol to monitor phenotypic changes in Bacillus subtilis and Staphylococcus aureus using a high-resolution deconvolution microscope. The objective of this report is to provide a simple and clear protocol that can be adopted by other investigators interested in conducting fluorescence microscopy experiments to study different biological processes in bacteria as well as other organisms.

This article provides a step-by-step guide to investigate protein subcellular localization dynamics and to monitor morphological changes using high-resolution fluorescence microscopy in Bacillus subtilis and Staphylococcus aureus.

Investigations of factors influencing cell division and cell shape in bacteria are commonly performed in conjunction with high-resolution fluorescence ...

Localization and Quantification of Begomoviruses in Whitefly Tissues by Immunofluorescence and Quantitative PCR

Begomoviruses (genus Begomovirus, family Geminiviridae) are transmitted by whiteflies of the Bemisia tabaci complex in a persistent, circulative manner. Considering the extensive damage caused by begomoviruses to crop production worldwide, it is imperative to understand the interaction between begomoviruses and their whitefly vector. To do so, localization and quantification of the virus in the vector tissues is crucial. Here, using tomato yellow leaf curl virus (TYLCV) as an example, we describe a detailed protocol to localize begomoviruses in whitefly midguts, primary salivary glands, and ovaries by immunofluorescence. The method is based on the use of specific antibodies against a virus coat protein, dye-labeled secondary antibodies, and a confocal microscope. The protocol can also be used to colocalize begomoviral and whitefly proteins. We further describe a protocol for the quantification of TYLCV in whitefly midguts, primary salivary glands, hemolymph, and ovaries by quantitative PCR (qPCR). Using primers specifically designed for TYLCV, the protocols for quantification allow the comparison of the amount of TYLCV in different tissues of the whitefly. The described protocol is potentially useful for the quantification of begomoviruses in the body of a whitefly and a virus-infected plant. These protocols can be used to analyze the circulation pathway of begomoviruses in the whitefly or as a complement to other methods to study whitefly-begomovirus interactions.

We describe an immunofluorescence and quantitative PCR method for the localization and quantification of begomoviruses in insect tissues. The immunofluorescence protocol can be used to colocalize viral and vector proteins. The quantitative PCR protocol can be extended to quantify viruses in whole whitefly bodies and virus-infected plants.

Begomoviruses (genus Begomovirus, family Geminiviridae) are transmitted by whiteflies of the Bemisia tabaci complex in a persistent, circulative manner. ...