Name: single cell micro-aspiration as an alternative strategy to fluorescence-activated cell sorting for giant virus mixture separation
Uploaded: 2019-10-27T13:00:00
Description: Watch this Scientific Journal Video about Single Cell Micro-aspiration as an Alternative Strategy to Fluorescence-activated Cell Sorting for Giant Virus Mixture Separation at JoVE.com

The authors would like to thank both Jean-Pierre Baudoin and Olivier Mbarek for their advice and Claire Andr&#233;ani for her help in English corrections and modifications. This work was supported by a grant from the French State managed by the National Research Agency under the &#34;Investissements d&#8217;avenir (Investments for the Future)&#34; program with the reference ANR-10-IAHU-03 (M&#233;diterran&#233;e Infection) and by R&#233;gion Provence Alpes C&#244;te d&#8217;Azur and European funding FEDER PRIMI.

1. Amoeba Culture
<ol>
	<li>Use Vermamoeba vermiformis (strain CDC19) as a cell support.</li>
	<li>Add 30 mL of protease-peptone-yeast extract-glucose medium (PYG) (Table 1) and 3 mL of the amoebae at a concentration of 1 x 106 cells/mL in a 75 cm2 cell culture flask.</li>
	<li>Maintain the culture at 28 &#176;C.</li>
	<li>After 48 h, quantify the amoebae using counting slides.</li>
	<li>To rinse, harvest the cells at a concentration of 1 x 106 cells/mL and pel...

<ol>
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H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole-genome+sequencing+of+a+pandoravirus+isolated+from+keratitis-inducing+acanthamoeba.">Whole-genome sequencing of a pandoravirus isolated from keratitis-inducing acanthamoeba.</a> Genome Announcements. 3 (2), 00136-00215 (2015).</li><li>Legendre, 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=Thirty-thousand-year-old+distant+relative+of+giant+icosahedral+DNA+viruses+with+a+pandoravirus+morphology.">Thirty-thousand-year-old distant relative of giant icosahedral DNA viruses with a pandoravirus morphology.</a> Proceedings of the National Academy of Sciences of the United States of America. 111 (11), 4274-4279 (2014).</li><li>Legendre, 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=In-depth+study+of+Mollivirus+sibericum,+a+new+30,000-y-old+giant+virus+infecting+Acanthamoeba.">In-depth study of Mollivirus sibericum, a new 30,000-y-old giant virus infecting Acanthamoeba.</a> Proceedings of the National Academy of Sciences of the United States of America. 112 (38), 5327-5335 (2015).</li><li>Legendre, 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=Diversity+and+evolution+of+the+emerging+Pandoraviridae+family.">Diversity and evolution of the emerging Pandoraviridae family.</a> Nature Communications. 9 (1), 2285 (2018).</li><li>Aherfi, S., 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+Large+Open+Pangenome+and+a+Small+Core+Genome+for+Giant+Pandoraviruses.">A Large Open Pangenome and a Small Core Genome for Giant Pandoraviruses.</a> Frontiers in Microbiology. 9, 166 (2018).</li><li>Andreani, 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=Cedratvirus,+a+Double-Cork+Structured+Giant+Virus,+is+a+Distant+Relative+of+Pithoviruses.">Cedratvirus, a Double-Cork Structured Giant Virus, is a Distant Relative of Pithoviruses.</a> Viruses. 8 (11), 300 (2016).</li><li>Rodrigues, R. A. L., 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=Morphologic+and+genomic+analyses+of+new+isolates+reveal+a+second+lineage+of+cedratviruses.">Morphologic and genomic analyses of new isolates reveal a second lineage of cedratviruses.</a> Journal of Virology. , 00372 (2018).</li><li>Bertelli, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cedratvirus+lausannensis-+digging+into+Pithoviridaediversity.">Cedratvirus lausannensis- digging into Pithoviridaediversity.</a> Environmental Microbiology. , (2017).</li><li>Levasseur, 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=Comparison+of+a+modern+and+fossil+Pithovirus+reveals+its+genetic+conservation+and+evolution.">Comparison of a modern and fossil Pithovirus reveals its genetic conservation and evolution.</a> Genome Biology and Evolution. , (2016).</li><li>Dornas, F. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Brazilian+Marseillevirus+Is+the+Founding+Member+of+a+Lineage+in+Family+Marseilleviridae.">A Brazilian Marseillevirus Is the Founding Member of a Lineage in Family Marseilleviridae.</a> Viruses. 8 (3), 76 (2016).</li><li>Yoshikawa, G., Blanc-Mathieu, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Medusavirus,+a+novel+large+DNA+virus+discovered+from+hot+spring+water.">Medusavirus, a novel large DNA virus discovered from hot spring water.</a> Journal of Virology. , (2019).</li><li>Legendre, 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=Pandoravirus+Celtis+Illustrates+the+Microevolution+Processes+at+Work+in+the+Giant+Pandoraviridae+Genomes.">Pandoravirus Celtis Illustrates the Microevolution Processes at Work in the Giant Pandoraviridae Genomes.</a> Frontiers in Microbiology. 10, 430 (2019).</li><li>Abrah&#227;o, 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=Tailed+giant+Tupanvirus+possesses+the+most+complete+translational+apparatus+of+the+known+virosphere.">Tailed giant Tupanvirus possesses the most complete translational apparatus of the known virosphere.</a> Nature Communications. 9 (1), 749 (2018).</li><li>Reteno, D. G., 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=Faustovirus,+an+asfarvirus-related+new+lineage+of+giant+viruses+infecting+amoebae.">Faustovirus, an asfarvirus-related new lineage of giant viruses infecting amoebae.</a> Journal of Virology. 89 (13), 6585-6594 (2015).</li><li>Bajrai, L., 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=Kaumoebavirus,+a+New+Virus+That+Clusters+with+Faustoviruses+and+Asfarviridae.">Kaumoebavirus, a New Virus That Clusters with Faustoviruses and Asfarviridae.</a> Viruses. 8 (12), 278 (2016).</li><li>Andreani, 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=Orpheovirus+IHUMI-LCC2:+A+New+Virus+among+the+Giant+Viruses.">Orpheovirus IHUMI-LCC2: A New Virus among the Giant Viruses.</a> Frontiers in Microbiology. 8, 779 (2018).</li><li>Fischer, M. G., Allen, M. J., Wilson, W. H., Suttle, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Giant+virus+with+a+remarkable+complement+of+genes+infects+marine+zooplankton.">Giant virus with a remarkable complement of genes infects marine zooplankton.</a> Proceedings of the National Academy of Sciences of the United States of America. 107 (45), 19508-19513 (2010).</li><li>Moniruzzaman, 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=Genome+of+brown+tide+virus+(AaV),+the+little+giant+of+the+Megaviridae,+elucidates+NCLDV+genome+expansion+and+host-virus+coevolution.">Genome of brown tide virus (AaV), the little giant of the Megaviridae, elucidates NCLDV genome expansion and host-virus coevolution.</a> Virology. 466-467, 60-70 (2014).</li><li>Gallot-Lavall&#233;e, L., Blanc, G., Claverie, J. -. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+genomics+of+Chrysochromulina+Ericina+Virus+(CeV)+and+other+microalgae-infecting+large+DNA+viruses+highlight+their+intricate+evolutionary+relationship+with+the+established+Mimiviridae+family.">Comparative genomics of Chrysochromulina Ericina Virus (CeV) and other microalgae-infecting large DNA viruses highlight their intricate evolutionary relationship with the established Mimiviridae family.</a> Journal of Virology. , (2017).</li><li>Deeg, C. M., Chow, C. -. E. T., Suttle, C. 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The duration of the single cell micro-aspiration handling and its good functioning is operator-dependent. The different steps of the experiment require precision. The use of the micromanipulation components of the workstation must be under constant control by observing the process of micro-aspiration and the release of the cell. The follow-up by microscopic observation is necessary for capture and transfer of a cell. An experienced operator can take 1 to 2 h to isolate 10 cells and retransfer them one by one depending on...

Nucleocytoplasmic large DNA viruses (NCLDV) are extremely diverse, defined by four families that infect eukaryotes1. The first described viruses with genomes above 300 kbp were Phydcodnaviridae, including Paramecium bursaria Chlorella virus 1 PBCV12. The isolation and the first description of Mimivirus, showed that the size of viruses doubled in terms of both the size of the particle (450 nm) and the length of the genome (1.2 Mb)3. Since then, many giant viruses have been described, usually isolated using an amoeba co-culture procedure. Several giant viruses with different morphologies and genetic contents can be isolated from Acanthamoeba sp. cells, including Marseilleviruses, Pandoraviruses, Pithoviruses, Mollivirus, Cedratviruses, Pacmanvirus, Tupanvirus, and recently Medusavirus4,5,6,7,8,9,10,11,12,13,14,15,16,17. In parallel, the isolation of Vermamoeba vermiformis allowed the isolation and description of the giant viruses Faustovirus, Kaumoebavirus, and Orpheovirus18,19,20. Other giant viruses were isolated with their host protists, such as Cafeteria roenbergensis21, Aureococcus anophagefferens22, Chrysochromulina ericina23, and Bodo saltans24. All of these isolations were the result of an increasing number of teams working on isolation and the introduction of high throughput strategy updates25,26,27,28, such as the improvement of the co-culture system with the use of flow cytometry.
In 2016, we used a strategy associating co-culture and flow cytometry to isolate giant viruses27. This strategy was developed to increase the number of samples inoculated, to diversify protists used as cell supports, and to quickly detect the lysis of the cell support. The system was updated by adding a supplemental step to avoid preliminary molecular biology identification and quick detection of an unknown viral population as in the case of Pacmanvirus29. Coupling flow cytometry to cell sorting allowed for separation of a mixture of Mimivirus and Cedratvirus A1130. However, we later encountered the limitations of the separation and detection of these viral subpopulations by flow cytometry. After sequencing, when we assembled the genomes of Faustovirus ST125 and Faustovirus LCD7 (unpublished data), we surprisingly found in each assembly two supplemental genomes of two novel viruses not identified in public genome databases. However, neither flow cytometry nor transmission electronic microscopy (TEM) showed that the amoebaes were infected by two different viruses, Clandestinovirus ST1 and Usurpativirus LCD7. We designed specific PCR systems to amplify Faustovirus, Usurpativirus, and Clandestinovirus markers respectively based on their genomes; our purpose was to have PCR-based systems that enable verification of the purity of the viruses being separated. However, end-point dilution and flow cytometry failed to separate them. The isolation of this single viral population was difficult because neither the morphology nor replicative elements of Clandestinovirus and Usurpativirus populations have been characterized. We detected only one viral population by flow cytometry due to the overlapping of the two populations (tested after the effective separation). We tried to separate them using single particle sorting on 96-well plates, but we did not observe any cytopathic effects, and we detected neither Clandestinovirus nor Usurpativirus by PCR amplification. Finally, it was only the combination of end point dilution followed by single amoeba micro-aspiration that enabled separation of these two low-abundance giant viruses from Faustoviruses. This method of separation is the object of this article.

<table border="0" cellpadding="0" cellspacing="0" style="width:1068px;" width="1067">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Agarose Standard</td>
			<td style="width:185px;">Euromedex</td>
			<td style="width:161px;">Unkown</td>
			<td style="width:391px;">Standard PCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">AmpliTaq Gold 360 Master Mix</td>
			<td style="width:185px;">Applied Biosystems</td>
			<td style="width:161px;">4398876</td>
			<td>Standard PCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">CellTram 4r Oil</td>
			<td style="width:185px;">Eppendorf</td>
			<td style="width:161px;">5196000030</td>
			<td>Control the cells during the microaspiration process</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Corning cell culture flasks 150 cm2</td>
			<td style="width:185px;">Sigma-aldrich</td>
			<td style="width:161px;">CLS430825</td>
			<td>Culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Corning cell culture flasks 25 cm2</td>
			<td style="width:185px;">Sigma-aldrich</td>
			<td style="width:161px;">CLS430639</td>
			<td>Culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Corning cell culture flasks 75 cm2</td>
			<td style="width:185px;">Sigma-aldrich</td>
			<td style="width:161px;">CLS430641</td>
			<td>Culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">DFC 425C camera</td>
			<td style="width:185px;">LEICA</td>
			<td style="width:161px;">Unkown</td>
			<td>Observation/Monitoring</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Eclipse TE2000-S Inverted Microscope</td>
			<td style="width:185px;">Nikon</td>
			<td style="width:161px;">Unkown</td>
			<td>Observation/Monitoring</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">EZ1 advanced XL</td>
			<td style="width:185px;">Quiagen</td>
			<td style="width:161px;">9001874</td>
			<td>DNA extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Glasstic Slide 10 With Counting Grids</td>
			<td style="width:185px;">Kova International</td>
			<td style="width:161px;">87144E</td>
			<td>Cell count</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Mastercycler nexus</td>
			<td style="width:185px;">Eppendorf</td>
			<td style="width:161px;">6331000017</td>
			<td>Standard PCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Microcapillary 20 &#181;m</td>
			<td style="width:185px;">Eppendorf</td>
			<td style="width:161px;">5175 107.004</td>
			<td>Microaspiration and release of cells</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Micromanipulator InjectMan NI2</td>
			<td style="width:185px;">Eppendorf</td>
			<td style="width:161px;">631-0210</td>
			<td>Microcapillary positioning</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Nuclease-Free Water</td>
			<td style="width:185px;">ThermoFischer</td>
			<td style="width:161px;">AM9920</td>
			<td>Standard PCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Optima XPN Ultracentrifuge</td>
			<td style="width:185px;">BECKMAN COULTER</td>
			<td style="width:161px;">A94469</td>
			<td>Virus purification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Petri dish 35 mm</td>
			<td style="width:185px;">Ibidi</td>
			<td style="width:161px;">81158</td>
			<td>Culture/observation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Sterile syringe filters 5 &#181;m</td>
			<td style="width:185px;">Sigma-aldrich</td>
			<td style="width:161px;">SLSV025LS</td>
			<td>Filtration</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">SYBR green Type I</td>
			<td style="width:185px;">Invitrogen</td>
			<td style="width:161px;">unknown</td>
			<td>Fluorescent molecular probes/ flow cytometry</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">SYBR Safe</td>
			<td style="width:185px;">Invitrogen</td>
			<td style="width:161px;">S33102</td>
			<td>Standard PCR; DNA gel stain</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Tecnai G20</td>
			<td style="width:185px;">FEI</td>
			<td style="width:161px;">Unkown</td>
			<td>Electron microscopy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Type 70 Ti Fixed-Angle Titanium Rotor</td>
			<td style="width:185px;">BECKMAN COULTER</td>
			<td style="width:161px;">337922</td>
			<td>Virus purification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Ultra-Clear Tube, 25 x 89 mm</td>
			<td style="width:185px;">BECKMAN COULTER</td>
			<td style="width:161px;">344058</td>
			<td>Virus purification</td>
		</tr>
	</tbody>
</table>

single cell micro-aspiration as an alternative strategy to fluorescence-activated cell sorting for giant virus mixture separation

During the amoeba co-culture process, more than one virus may be isolated in a single well. We previously solved this issue by end point dilution and/or fluorescence activated cell sorting (FACS) applied to the viral population. However, when the viruses in the mixture have similar morphologic properties and one of the viruses multiplies slowly, the presence of two viruses is discovered at the stage of genome assembly and the viruses cannot be separated for further characterization. To solve this problem, we developed a single cell micro-aspiration procedure that allows for separation and cloning of highly similar viruses. In the present work, we present how this alternative strategy allowed us to separate the small viral subpopulations of Clandestinovirus ST1 and Usurpativirus LCD7, giant viruses that grow slowly and do not lead to amoebal lysis compared to the lytic and fast-growing Faustovirus. Purity control was assessed by specific gene amplification and viruses were produced for further characterization.

Single cell micro-aspiration is a micromanipulation process optimized in this manuscript (Figure 1). This technique enables capture of a rounded, infected amoeba (Figure 2A) and its release in a novel plate containing uninfected amoebae (Figure 2). It is a functional prototype that applies to the co-culture system and has successfully isolated non-lytic giant viruses. This approach was used for the first time in the...

Watch this Scientific Journal Video about Single Cell Micro-aspiration as an Alternative Strategy to Fluorescence-activated Cell Sorting for Giant Virus Mixture Separation at JoVE.com

Single Cell Micro-aspiration as an Alternative Strategy to Fluorescence-activated Cell Sorting for Giant Virus Mixture Separation

Here, we describe a single cell micro-aspiration method for the separation of infected amoebae. In order to separate viral subpopulations in Vermamoeba vermiformis infected by Faustoviruses and unknown giant viruses, we developed the protocol detailed below and demonstrated its ability to separate two low-abundance novel giant viruses.

During the amoeba co-culture process, more than one virus may be isolated in a single well. We previously solved this issue by end point dilution and/or ...

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