The authors have no acknowledgements to make.

1. Sample Collection
<ol>
	<li>Collect 70 samples from different environments and regions. In this case, use the following: 5 dirty water samples from the village of Saint Pierre de Meyzoargues (France), 15 samples from the lake in Parc Bor&#233;ly in Marseille (France); 15 sea water samples with sediment from the rocky inlets at Samena in Marseille (France), 25 river water samples from the Alps (France), and finally, 10 samples from sewage in La Ciotat (France).</li>
	<li>Vortex samples for homogenization before inocu...

<ol>
	<li>Raoult, 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=The+1.2-megabase+genome+sequence+of+Mimivirus.">The 1.2-megabase genome sequence of Mimivirus.</a> Science. 306 (5700), 1344-1350 (2004).</li><li>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=Giant+viruses+in+the+oceans:+the+4th+Algal+Virus+Workshop.">Giant viruses in the oceans: the 4th Algal Virus Workshop.</a> Virol J. 2, 52-52 (2004).</li><li>Monier, A. 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=Marine+mimivirus+relatives+are+probably+large+algal+viruses.">Marine mimivirus relatives are probably large algal viruses.</a> Audio, Transactions of the IRE Professional Group on. 5, 12-12 (2007).</li><li>Monier, A., Claverie, J. M., Ogata, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Taxonomic+distribution+of+large+DNA+viruses+in+the+sea.">Taxonomic distribution of large DNA viruses in the sea.</a> Genome Biol. , (2008).</li><li>Claverie, J. -. 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=Mimivirus+and+Mimiviridae:+Giant+viruses+with+an+increasing+number+of+potential+hosts,+including+corals+and+sponges.">Mimivirus and Mimiviridae: Giant viruses with an increasing number of potential hosts, including corals and sponges.</a> J Invertebr Pathol. 101 (3), 9-9 (2009).</li><li>Colson, 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=Evidence+of+the+megavirome+in+humans.">Evidence of the megavirome in humans.</a> J Clin Virol. 57 (3), 191-200 (2013).</li><li>La Scola, B., 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=Tentative+characterization+of+new+environmental+giant+viruses+by+MALDI-TOF+mass+spectrometry.">Tentative characterization of new environmental giant viruses by MALDI-TOF mass spectrometry.</a> Intervirology. 53 (5), 344-353 (2010).</li><li>Boughalmi, 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=High-throughput+isolation+of+giant+viruses+of+the+Mimiviridae+and+Marseilleviridae+families+in+the+Tunisian+environment.">High-throughput isolation of giant viruses of the Mimiviridae and Marseilleviridae families in the Tunisian environment.</a> Environ Microbiol. , (2012).</li><li>Pagnier, I., 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+decade+of+improvements+in+mimiviridae+and+marseilleviridae+isolation+from+amoeba.">A decade of improvements in mimiviridae and marseilleviridae isolation from amoeba.</a> Intervirology. 56 (6), 354-363 (2012).</li><li>Philippe, N., 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=Pandoraviruses:+Amoeba+Viruses+with+Genomes+Up+to+2.5+Mb+Reaching+That+of+Parasitic+Eukaryotes.">Pandoraviruses: Amoeba Viruses with Genomes Up to 2.5 Mb Reaching That of Parasitic Eukaryotes.</a> Science. 341 (6143), 281-286 (2013).</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> PNAS. , (2014).</li><li>Saadi, 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=First+Isolation+of+Mimivirus+in+a+Patient+With+Pneumonia.">First Isolation of Mimivirus in a Patient With Pneumonia.</a> Clin Infect Dis. , (2013).</li><li>Saadi, 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=Shan+virus:+a+new+mimivirus+isolated+from+the+stool+of+a+Tunisian+patient+with+pneumonia.">Shan virus: a new mimivirus isolated from the stool of a Tunisian patient with pneumonia.</a> Intervirology. 56 (6), 424-429 (2013).</li><li>Claverie, J. -. M., Abergel, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mimivirus:+the+emerging+paradox+of+quasi-autonomous+viruses.">Mimivirus: the emerging paradox of quasi-autonomous viruses.</a> Trends Genet : TIG. 26 (10), 431-437 (2010).</li><li>Colson, 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=Viruses+with+more+than+1,000+genes:+Mamavirus,+a+new+Acanthamoeba+polyphaga+mimivirus+strain,+and+reannotation+of+Mimivirus+genes.">Viruses with more than 1,000 genes: Mamavirus, a new Acanthamoeba polyphaga mimivirus strain, and reannotation of Mimivirus genes.</a> Genome Biol Evol. 3, 737-742 (2010).</li><li>Claverie, J. -. M., Abergel, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Open+questions+about+giant+viruses.">Open questions about giant viruses.</a> Adv Virus Res. 85, 25-56 (2013).</li><li>Fischer, M. G. M., Allen, M. J. M., Wilson, W. H. W., Suttle, C. A. C. <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> PNAS. 107 (45), 19508-19513 (2010).</li><li>Van Etten, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Another+really,+really+big+virus.">Another really, really big virus.</a> Viruses. 3 (1), 32-46 (2011).</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> J.Virol. , (2015).</li><li>Co&#351;kun, K. A., Oz&#231;elik, S., Tutar, L., Elald&#305;, N., Tutar, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+identification+of+free-living+amoebae+from+tap+water+in+Sivas,+Turkey.">Isolation and identification of free-living amoebae from tap water in Sivas, Turkey.</a> Biomed res Int. 2013, 675145 (2013).</li><li>Bradbury, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Free-living+amoebae+recovered+from+human+stool+samples+in+Strongyloides+agar+culture.">Free-living amoebae recovered from human stool samples in Strongyloides agar culture.</a> J Clin microbiol. 52 (2), 699-700 (2014).</li><li>Pagnier, I., Valles, C., Raoult, D., La Scola, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+Vermamoeba+vermiformis+and+associated+bacteria+in+hospital+water.">Isolation of Vermamoeba vermiformis and associated bacteria in hospital water.</a> Microb Pathog. 80, 14-20 (2015).</li><li>Ogata, H., Toyoda, 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=Remarkable+sequence+similarity+between+the+dinoflagellate-infecting+marine+girus+and+the+terrestrial+pathogen+African+swine+fever+virus.">Remarkable sequence similarity between the dinoflagellate-infecting marine girus and the terrestrial pathogen African swine fever virus.</a> Virol J. 6, 178-178 (2008).</li><li>Tarutani, K., Nagasaki, K., Itakura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+a+virus+infecting+the+novel+shellfish-killing+dinoflagellate+Heterocapsa+circularisquama.">Isolation of a virus infecting the novel shellfish-killing dinoflagellate Heterocapsa circularisquama.</a> Aquat Microb Ecol. 23, 103-111 (2001).</li></ol>

The possibility that Faustovirus could be the first member of a new Megavirales family close to ASFV was first suggested by Reteno et al.,19 but some differences can still be distinguished. It appears unclear whether Faustovirus should join the Asfarviridae family or whether it should instead form a new putative viral family. This issue will require further investigation, in particular a more comprehensive characterization of its morphology, host range, replication cycle and gene repertoire. More Faus...

The discovery of giant viruses, especially those belonging to the Megavirales order, completely changed the world of viruses in terms of particle size and genome complexity. Viruses were previously thought to be small entities, and the Mimivirus appeared to break all the rules.1 Metagenomic data suggests the ubiquity of giant viruses not only in the environment, 2-5 but also in humans.6 Therefore, there is still a need to search for these viruses on a large scale. The diversity of these giant viruses was assessed by sampling not only a variety of aquatic environments and their associated sediments worldwide,7-11 but also by screening a variety of human samples12,13 and environmental samples.7,9 The Acanthamoeba polyphaga mimivirus was isolated by co-culture using phagocytic protists, primarily Acanthamoeba spp.14-16 An entire collection of giant viruses were then also isolated from this specified protist host, which made the scientific community restrict its research and isolation procedure for Acanthamoeba spp. Clearly this reliance on a single host species has resulted in a large fraction of viruses being overlooked. The fact that the giant virus, CroV, was isolated with the highly motile marine protozoa Cafeteria roenbergensis,17,18 demonstrates the need to use a wider range of protozoa in order to discover new lineages or families of giant viruses. Reteno et al. managed to select other protozoa as cell hosts which had never previously been used, and isolated the new Asfar-related lineage of giant viruses (the newly named Faustovirus).19
In an attempt to isolate new Faustovirus genotypes in order to expand the members of this viral lineage, we modified our isolation procedures and used them to screen environmental samples capable of harvesting new Faustoviruses. We then described the entire protocol to characterize the new isolates. We assessed Vermamoeba vermiformis, the most common free-living protist found in human environments,20-22 which is already used in the isolation of the first Faustovirus prototype E12.19 This protist is currently still host-specific for Faustovirus. We knew that none of the known giant viruses was pathogenic for this amoeba, because no attempts to grow other giant viruses in our lab showed amoeba lysis or viral growth. For this reason, we believe that V. vermiformis is the best and most unique cell support known to isolate new Faustoviruses.

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			<td height="21" style="height:21px;width:235px;">Single cytology tunnel</td>
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a rapid strategy for the isolation of new faustoviruses from environmental samples using vermamoeba vermiformis

The isolation of giant viruses is of great interest in this new era of virology, especially since these giant viruses are related to protists. Giant viruses may be potentially pathogenic for many species of protists. They belong to the recently described order of Megavirales. The new lineage Faustovirus that has been isolated from sewage samples is distantly related to the mammalian pathogen African swine fever virus. This virus is also specific to its amoebal host, Vermamoeba vermiformis, a protist common in health care water systems. It is crucial to continue isolating new Faustovirus genotypes in order to enlarge its genotype collection and study its pan-genome. We developed new strategies for the isolation of additional strains by improving the use of antibiotic and antifungal combinations in order to avoid bacterial and fungal contaminations of the amoeba co-culture and favoring the virus multiplication. We also implemented a new starvation medium to maintain V. vermiformis in optimal conditions for viruses co-culture. Finally, we used flow cytometry rather than microscopic observation, which is time-consuming, to detect the cytopathogenic effect. We obtained two isolates from sewage samples, proving the efficiency of this method and thus widening the collection of Faustoviruses, to better understand their environment, host specificity and genetic content.

The system studied in this manuscript validated its proof of concept by isolating two new Faustoviruses. Of the 70 samples tested, two episodes of lysis were detected, in contrast to our reliable negative controls. The negative control for lysis contained an 86% amoeba population. By contrast, the positive samples (ST1 for Saint Pierre de Meyzoargues), and (LC9 for the La Ciotat Sample 9) showed a dramatic decline in gated amoebae; more than 60% of amoebae were lysed with the highest perc...

Watch this Scientific Journal Video about A Rapid Strategy for the Isolation of New Faustoviruses from Environmental Samples Using Vermamoeba vermiformis at JoVE.com

A Rapid Strategy for the Isolation of New Faustoviruses from Environmental Samples Using Vermamoeba vermiformis

We describe here the latest advances in viral isolation for the characterization of new genotypes of Faustovirus, a new asfarvirus-related lineage of giant viruses. This protocol can be applied to the high throughput isolation of viruses, especially giant viruses infecting amoeba.

A Rapid Strategy for the Isolation of New Faustoviruses from Environmental Samples Using Vermamoeba vermiformis

The isolation of giant viruses is of great interest in this new era of virology, especially since these giant viruses are related to protists. Giant ...

The overall goal of this new isolation strategy is to widen the number of new virus isolates in order to study the pan-genome of this new viral family, and to better understand their ecosystems and potential pathogenicity to humans. This method can answer key questions in the virology field, to help virologists world wide interested in prospecting giant viruses and faustoviruses in particular. The main advantage of this technique is that it show new improvement to many stage like the antibiotic and antifungal mixture.The new starvation medium adapted for the amoeba and the use of floss-cytometry for faster and more sensitive lysis detection. After collecting dirty water samples according to the text protocol, prepare the host cell, V.vermiformis by adding the amoebae to a 75 square centimeter cell culture flask with 30 milliliters of protease peptone yeast extract glucose, or PYG medium and incubate at 28 degrees Celsius for 48 hours. Use counting slides to count the amoebae and when they reach a concentration of five times 10 to the 5th, to 10 to the 6th cells per milliliter, harvest the cells by centrifugation at 720 times g for 10 minutes.Aspirate the supernatant, and use 30 milliliters of sterile pages amoebal saline or PAS to resuspend the amoebae pellet. After rinsing the pellet a second time, use 30 milliliters of starvation medium, containing an antibiotic and an antifungal to resuspend the cells to approximately 10 to the 6th amoeba per milliliter. Starvation medium enables the amoebae to stay alive without encystment or multiplication.Next, seed 200 microliters of amoeba in the wells of a 96 well flat bottom plate and incubate at 30 degrees Celsius for 30 minutes. Then, after vortexing the water samples for one minute at room temperature, innoculate 25 microliters of each sample onto the amoebae cells, leaving two wells without sample as negative controls. To avoid evaporation, place the plate containing the primo culture into a bag with a wet compress, and place the humidified chamber with plate into an incubator at 30 degrees Celsius.Three days after the first innoculation, sub-culture the primo culture plate onto a fresh 96 well plate of amoebae as just demonstrated, without any microscopic observation. Incubate at 30 degrees Celsius for three days. Then, using the subculture, innoculate a third plate as just described, and incubate for two days.To detect lysis in the final cocultured plate, turn on the cytometer and run a clean and rinse according to the manufacturer's protocol to reduce the background noise. To carry out a 40 minute completely automated acquisition, launch the high throughput sampler or HTS to automatically load samples from the 96 well plate according to the manufacturer's protocol. Program the HTS settings as listed here.That include a sample volume of 150 microliters, a mixing volume of 50 microliters, a mixing speed of 180, the number of mixes as 5, a washing volume between samples of 400 microliters, a flow rate of 2.5 microliters per second, and the number of recorded events as 10, 000. Click on home to allow the HTS to spot or locate the plate. Then assess the negative control wells containing the host amoeba cells first.In order to gate the amoeba population, and to determine the cell percentage according to their physical characteristics. Be sure to have a homogeneous amoeba population and a second population of lower events corresponding to debris and noise. Next, start the gating by clicking acquire sample.Then, using the arrow, which defines the gates, localize the amoeba population of interest. After gating at least 10, 000 events, click on run to allow the HTS to automatically run the entire plate. Perform data acquisition and analysis according to the size parameter forward scatter and the structure parameter side scatter.Refer to the text for additional details. Following licence detection by flow-cytometry, pipette the lysed cocultures to suspend the remaining amoebae. After pipetting 50 microliters of each sample onto slides, directly cytocentrifuge the suspension at 800 times g for 10 minutes.Next, use pure methanol to fix the slides, then leave the slides to dry at room temperature. After fixation, plunge the slides into ESN solution three times for four seconds each before placing the slides into blue azur for six seconds. Finally, plunge the slides into PBS for 45 seconds.Leave the slides to dry at room temperature before proceeding to observation. To stain new fixed slides with DAPI, pipette 15 microliters of DAPI into the dry slides. Observe the slides under a light microscope at 1000x magnification in order to check for the presence of virus factories.To carry out electron microscopy, deposit five microliters of the positive sample onto a glow-discharged grid, and incubate at room temperature for approximately 20 minutes. Carefully dry the grid, then add a small amount of 1%ammonium molybdate and incubate for 10 seconds. After carefully removing the drop, allow the grid to dry for five minutes.Next, set the electron microscope to 200 kiloelectron volts. Then, place the grid on the holder and introduce the holder into the microscope. Click on the vacuum overview icon and check the vacuum.Then, close the valves, and set a spot size of five, and a magnification of 25, 000 before beginning observation. After locating a giant virus on the acquisition screen, use the measure tool to measure the virus. Carry out molecular biology and viral genome sequencing according to the text protocol.This figure shows results from the detection of two faustoviruses compared to the reliable negative controls. The negative control for lysis contained an 86%amoeba population. By contrast, more than 60%of the amoebae were lysed with the highest percentage of debris in the positive samples.As seen here, Eus and blue azur stains the nuclei of uninfected and infected amoebae cells, and the presence of virus factories inside the infected cells. DAPI staining also confirms the presence of virus factories inside amoebae. In these images, electron microscopy reveals the presence of faustovirus with the typical appearance of megavirals composed of an icosadedral capsid that lacks fibrils and a size of 200 nanometers.Once mastered and after the coculture, this technique of lysis detection and virus characterization can be done in an hour, if it's performed properly. While attempting this procedure, it is important to remember to control the amoebal viability and to check any probable contaminations. Following this procedure, other methods like molecular biology targeting giant viruses can be performed in order to answer additional questions like the virus family and or genotype.After its development, this technique paved the way for researchers in the field of virology to explore this viral family, their specific host, and their potential pathogenicity. After watching this video, you should have a good understanding of how to easily isolate giant viruses by widening the number and types of samples and by choosing the best host cell and the best control conditions. Don't forget that working with viruses potentially pathogenic for humans can be extremely hazardous, specially with huge samples.So precautions such as working in an SB2 labs with secure conditions should always be taken while performing this procedure.

a-rapid-strategy-for-isolation-new-faustoviruses-from-environmental

Research

JoVE Journal

Immunology and Infection

7.6K 조회수.  Aix Marseille University. The overall goal of this new isolation strategy is to widen the number of new virus isolates in order to study the pan-genome of this new viral family, and to better understand their ecosystems and potential pathogenicity to humans. This method can answer key questions in the virology field, to help virologists world wide interested in prospecting giant viruses and faustoviruses in particular. The main advantage of this technique is that it show new improvement to many stage like the antibiot...