Name: a rapid strategy for the isolation of new faustoviruses from environmental samples using vermamoeba vermiformis
Uploaded: 2016-06-04T15:00:00
Description: Watch this Scientific Journal Video about A Rapid Strategy for the Isolation of New Faustoviruses from Environmental Samples Using Vermamoeba vermiformis at JoVE.com

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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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

Separation of Single-stranded DNA, Double-stranded DNA and RNA from an Environmental Viral Community Using Hydroxyapatite Chromatography

Viruses, particularly bacteriophages (phages), are the most numerous biological entities on Earth1,2. Viruses modulate host cell abundance and diversity, contribute to the cycling of nutrients, alter host cell phenotype, and influence the evolution of both host cell and viral communities through the lateral transfer of genes 3. Numerous studies have highlighted the staggering genetic diversity of viruses and their functional potential in a variety of natural environments. 
Metagenomic techniques have been used to study the taxonomic diversity and functional potential of complex viral assemblages whose members contain single-stranded DNA (ssDNA), double-stranded DNA (dsDNA) and RNA genotypes 4-9. Current library construction protocols used to study environmental DNA-containing or RNA-containing viruses require an initial nuclease treatment in order to remove nontargeted templates 10. However, a comprehensive understanding of the collective gene complement of the virus community and virus diversity requires knowledge of all members regardless of genome composition. Fractionation of purified nucleic acid subtypes provides an effective mechanism by which to study viral assemblages without sacrificing a subset of the community&#x2019;s genetic signature. 
Hydroxyapatite, a crystalline form of calcium phosphate, has been employed in the separation of nucleic acids, as well as proteins and microbes, since the 1960s11. By exploiting the charge interaction between the positively-charged Ca2+ ions of the hydroxyapatite and the negatively charged phosphate backbone of the nucleic acid subtypes, it is possible to preferentially elute each nucleic acid subtype independent of the others. We recently employed this strategy to independently fractionate the genomes of ssDNA, dsDNA and RNA-containing viruses in preparation of DNA sequencing 12. Here, we present a method for the fractionation and recovery of ssDNA, dsDNA and RNA viral nucleic acids from mixed viral assemblages using hydroxyapatite chromotography.

We describe an efficient method to separate single-stranded DNA, double-stranded DNA and RNA molecules from environmental viral communities. Nucleic acids are fractionated using hydroxyapatite chromatography with increasing concentrations of phosphate-containing buffers. This method permits the isolation of all viral nucleic acid types from environmental samples.

Viruses, particularly bacteriophages (phages), are the most numerous biological entities on Earth1,2.  Viruses modulate host cell abundance and diversity, ...

Multiplex Detection of Bacteria in Complex Clinical and Environmental Samples using Oligonucleotide-coupled Fluorescent Microspheres

Bacterial vaginosis (BV) is a recurring polymicrobial syndrome that is characterized by a change in the "normal" microbiota from Lactobacillus-dominated to a microbiota dominated by a number of bacterial species, including Gardnerella vaginalis, Atopobium vaginae, and others1-3. This condition is associated with a range of negative health outcomes, including HIV acquisition4, and it can be difficult to manage clinically5. Furthermore, diagnosis of BV has relied on the use of Gram stains of vaginal swab smears that are scored on various numerical criteria6,7. While this diagnostic is simple, inexpensive, and well suited to resource-limited settings, it can suffer from problems related to subjective interpretations and it does not give a detailed profile of the composition of the vaginal microbiota8. Recent deep sequencing efforts have revealed a rich, diverse vaginal microbiota with clear differences between samples taken from individuals that are diagnosed with BV compared to those individuals that are considered normal9,10, which has resulted in the identification of a number of potential targets for molecular diagnosis of BV11,12. These studies have provided a wealth of useful information, but deep sequencing is not yet practical as a diagnostic method in a clinical setting. We have recently described a method for rapidly profiling the vaginal microbiota in a multiplex format using oligonucleotide-coupled fluorescent beads with detection on a Luminex platform13. This method, like current Gram stain-based methods, is rapid and simple but adds the additional advantage of exploiting molecular knowledge arising from sequencing studies in probe design. This method therefore provides a way to profile the major microorganisms that are present in a vaginal swab that can be used to diagnose BV with high specificity and sensitivity compared to Gram stain while providing additional information on species presence and abundance in a semi-quantitative and rapid manner. This multiplex method is expandable well beyond the range of current quantitative PCR assays for particular organisms, which is currently limited to 5 or 6 different assays in a single sample14. Importantly, the method is not limited to the detection of bacteria in vaginal swabs and can be easily adapted to rapidly profile nearly any microbial community of interest. For example, we have recently begun to apply this methodology to the development of diagnostic tools for use in wastewater treatment plants.

We describe a multiplex method for the detection of microorganisms within a sample using oligonucleotide-coupled fluorescent beads. Amplicon from all organisms within a sample is hybridized to a panel of probe-coupled beads. A Luminex or Bio-Plex instrument is used to query each bead for bead type and hybridization signal.

Bacterial vaginosis (BV) is a recurring polymicrobial syndrome that is characterized by a change in the "normal" microbiota from Lactobacillus-dominated ...

Isolation and Genome Analysis of Single Virions using 'Single Virus Genomics'

Whole genome amplification and sequencing of single microbial cells enables genomic characterization without the need of cultivation 1-3. Viruses, which are ubiquitous and the most numerous entities on our planet 4 and important in all environments 5, have yet to be revealed via similar approaches. Here we describe an approach for isolating and characterizing the genomes of single virions called 'Single Virus Genomics' (SVG). SVG utilizes flow cytometry to isolate individual viruses and whole genome amplification to obtain high molecular weight genomic DNA (gDNA) that can be used in subsequent sequencing reactions.

Single Virus Genomics (SVG) is a method to isolate and amplify the genomes of single virons. Viral suspensions of a mixed assemblage are sorted using flow cytometry onto a microscope slide with discrete wells containing agarose, thereby capturing the virion and reducing genome shearing during downstream processing. Whole genome amplification is achieved using multiple displacement amplification (MDA) resulting in genomic material that is suitable for sequencing.

Whole genome amplification and sequencing of single microbial cells enables genomic characterization without the need of cultivation 1-3. Viruses, which ...

Right Ventricular Systolic Pressure Measurements in Combination with Harvest of Lung and Immune Tissue Samples in Mice

The function of the right heart is to pump blood through the lungs, thus linking right heart physiology and pulmonary vascular physiology. Inflammation is a common modifier of heart and lung function, by elaborating cellular infiltration, production of cytokines and growth factors, and by initiating remodeling processes 1.
Compared to the left ventricle, the right ventricle is a low-pressure pump that operates in a relatively narrow zone of pressure changes. Increased pulmonary artery pressures are associated with increased pressure in the lung vascular bed and pulmonary hypertension 2. Pulmonary hypertension is often associated with inflammatory lung diseases, for example chronic obstructive pulmonary disease, or autoimmune diseases 3. Because pulmonary hypertension confers a bad prognosis for quality of life and life expectancy, much research is directed towards understanding the mechanisms that might be targets for pharmaceutical intervention 4. The main challenge for the development of effective management tools for pulmonary hypertension remains the complexity of the simultaneous understanding of molecular and cellular changes in the right heart, the lungs and the immune system.
Here, we present a procedural workflow for the rapid and precise measurement of pressure changes in the right heart of mice and the simultaneous harvest of samples from heart, lungs and immune tissues. The method is based on the direct catheterization of the right ventricle via the jugular vein in close-chested mice, first developed in the late 1990s as surrogate measure of pressures in the pulmonary artery5-13. The organized team-approach facilitates a very rapid right heart catheterization technique. This makes it possible to perform the measurements in mice that spontaneously breathe room air. The organization of the work-flow in distinct work-areas reduces time delay and opens the possibility to simultaneously perform physiology experiments and harvest immune, heart and lung tissues.
The procedural workflow outlined here can be adapted for a wide variety of laboratory settings and study designs, from small, targeted experiments, to large drug screening assays. The simultaneous acquisition of cardiac physiology data that can be expanded to include echocardiography5,14-17 and harvest of heart, lung and immune tissues reduces the number of animals needed to obtain data that move the scientific knowledge basis forward. The procedural workflow presented here also provides an ideal basis for gaining knowledge of the networks that link immune, lung and heart function. The same principles outlined here can be adapted to study other or additional organs as needed.

A specific and rapid protocol to simultaneously investigate right heart function, lung inflammation, and the immune response is described as a learning tool. Video and figures describe physiology and microdissection techniques in an organized team-approach that is adaptable to be used for small to large sized studies.

The function of the right heart is to pump blood through the lungs, thus linking right heart physiology and pulmonary vascular physiology. Inflammation is ...

Rapid Identification of Gram Negative Bacteria from Blood Culture Broth Using MALDI-TOF Mass Spectrometry

An important role of the clinical microbiology laboratory is to provide rapid identification of bacteria causing bloodstream infection. Traditional identification requires the sub-culture of signaled blood culture broth with identification available only after colonies on solid agar have matured. MALDI-TOF MS is a reliable, rapid method for identification of the majority of clinically relevant bacteria when applied to colonies on solid media. The application of MALDI-TOF MS directly to blood culture broth is an attractive approach as it has potential to accelerate species identification of bacteria and improve clinical management. However, an important problem to overcome is the pre-analysis removal of interfering resins, proteins and hemoglobin&#160;contained in blood culture specimens which, if not removed, interfere with the MS spectra and can result in insufficient or low discrimination identification scores. In addition it is necessary to concentrate bacteria to develop spectra of sufficient quality. The presented method describes the concentration, purification, and extraction of Gram negative bacteria allowing for the early identification of bacteria from a signaled blood culture broth.

The application of matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) directly to blood culture broth expedites the identification of bacteria. The presented method is a rapid and reliable method for identification of Gram negative bacteria directly from blood culture broth.

An important role of the clinical microbiology laboratory is to provide rapid identification of bacteria causing bloodstream infection. Traditional ...

Rapid Analysis of Chromosome Aberrations in Mouse B Lymphocytes by PNA-FISH

Defective DNA repair leads to increased genomic instability, which is the root cause of mutations that lead to tumorigenesis. Analysis of the frequency and type of chromosome aberrations in different cell types allows defects in DNA repair pathways to be elucidated. Understanding mammalian DNA repair biology has been greatly helped by the production of mice with knockouts in specific genes. The goal of this protocol is to quantify genomic instability in mouse B lymphocytes. Labeling of the telomeres using PNA-FISH probes (peptide nucleic acid - fluorescent in situ hybridization) facilitates the rapid analysis of genomic instability in metaphase chromosome spreads. B cells have specific advantages relative to fibroblasts, because they have normal ploidy and a higher mitotic index. Short-term culture of B cells therefore enables precise measurement of genomic instability in a primary cell population which is likely to have fewer secondary genetic mutations than what is typically found in transformed fibroblasts or patient cell lines.

DNA repair pathways are essential for maintenance of genomic integrity and preventing mutation and cancer. The goal of this protocol is to quantify genomic instability by direct observation of chromosome aberrations in metaphase spreads from mouse B cells using fluorescent in situ hybridization (FISH) for telomeric DNA repeats.

Defective DNA repair leads to increased genomic instability, which is the root cause of mutations that lead to tumorigenesis. Analysis of the frequency ...

Isolation of Leukocytes from the Murine Tissues at the Maternal-Fetal Interface

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing fetus. This tolerance is initiated during coitus, established during fecundation and implantation, and maintained throughout pregnancy. Active cellular and molecular mediators of maternal-fetal tolerance are enriched at the site of contact between fetal and maternal tissues, known as the maternal-fetal interface, which includes the placenta and the uterine and decidual tissues. This interface is comprised of stromal cells and infiltrating leukocytes, and their abundance and phenotypic characteristics change over the course of pregnancy. Infiltrating leukocytes at the maternal-fetal interface include neutrophils, macrophages, dendritic cells, mast cells, T cells, B cells, NK cells, and NKT cells that together create the local micro-environment that sustains pregnancy. An imbalance among these cells or any inappropriate alteration in their phenotypes is considered a mechanism of disease in pregnancy. Therefore, the study of leukocytes that infiltrate the maternal-fetal interface is essential in order to elucidate the immune mechanisms that lead to pregnancy-related complications. Described herein is a protocol that uses a combination of gentle mechanical dissociation followed by a robust enzymatic disaggregation with a proteolytic and collagenolytic enzymatic cocktail to isolate the infiltrating leukocytes from the murine tissues at the maternal-fetal interface. This protocol allows for the isolation of high numbers of viable leukocytes (&#62;70%) with sufficiently conserved antigenic and functional properties. Isolated leukocytes can then be analyzed by several techniques, including immunophenotyping, cell sorting, imaging, immunoblotting, mRNA expression, cell culture, and in vitro functional assays such as mixed leukocyte reactions, proliferation, or cytotoxicity assays.

Described herein is a protocol to isolate and analyze the infiltrating leukocytes of tissues at the maternal-fetal interface (uterus, decidua, and placenta) of mice. This protocol maintains the integrity of most cell surface markers and yields enough viable cells for downstream applications including flow cytometry analysis.

Immune tolerance in pregnancy requires that the immune system of the mother undergoes distinctive changes in order to accept and nurture the developing ...

Nasal Wipes for Influenza A Virus Detection and Isolation from Swine

Surveillance for influenza A viruses in swine is critical to human and animal health because influenza A virus rapidly evolves in swine populations and new strains are continually emerging. Swine are able to be infected by diverse lineages of influenza A virus making them important hosts for the emergence and maintenance of novel influenza A virus strains. Sampling pigs in diverse settings such as commercial swine farms, agricultural fairs, and live animal markets is important to provide a comprehensive view of currently circulating IAV strains. The current gold-standard ante-mortem sampling technique (i.e. collection of nasal swabs) is labor intensive because it requires physical restraint of the pigs. Nasal wipes involve rubbing a piece of fabric across the snout of the pig with minimal to no restraint of the animal. The nasal wipe procedure is simple to perform and does not require personnel with professional veterinary or animal handling training. While slightly less sensitive than nasal swabs, virus detection and isolation rates are adequate to make nasal wipes a viable alternative for sampling individual pigs when low stress sampling methods are required. The proceeding protocol outlines the steps needed to collect a viable nasal wipe from an individual pig.

The authors present a protocol to collect swine nasal wipes to detect and isolate influenza A viruses.

Surveillance for influenza A viruses in swine is critical to human and animal health because influenza A virus rapidly evolves in swine populations and ...

Isolation and Characterization of Extracellular Vesicles Produced by Iron-limited Mycobacteria

Mycobacteria, including Mycobacterium tuberculosis (Mtb), the causative agent of human tuberculosis, naturally release extracellular vesicles (EVs) containing immunologically active molecules. Knowledge regarding the molecular mechanisms of vesicle biogenesis, the content of the vesicles, and their functions at the pathogen-host interface is very limited. Addressing these questions requires rigorous procedures for isolation, purification, and validation of EVs. Previously, vesicle production was found to be enhanced when M. tuberculosis was exposed to iron restriction, a condition encountered by Mtb in the host environment. Presented here is a complete and detailed protocol to isolate and purify EVs from iron-deficient mycobacteria. Quantitative and qualitative methods are applied to validate purified EVs.

Mycobacterium tuberculosis shows increased production and release of extracellular vesicles in response to low iron conditions. This work details a protocol for generating low iron conditions and methods for the purification and characterization of mycobacterial extracellular vesicles released in response to iron deficiency.

Mycobacteria, including Mycobacterium tuberculosis (Mtb), the causative agent of human tuberculosis, naturally release extracellular vesicles (EVs) ...

Isolation and Quantification of Epstein-Barr Virus from the P3HR1 Cell Line

The Epstein-Barr virus (EBV), formally designated as Human herpesvirus 4 (HHV-4), is the first isolated human tumor virus. Nearly 90-95% of the world&#39;s adult population is infected by EBV. With the recent advancements in molecular biology and immunology, the application of both in vitro and in vivo experimental models has provided deep and meaningful insight into the pathogenesis of EBV in many diseases as well as into EBV-associated tumorigenesis. The aim of this visualized experiment paper is to provide an overview of the isolation of EBV viral particles from cells of the P3HR1 cell line, followed by quantification of the viral preparation. P3HR1 cells, originally isolated from a human Burkitt lymphoma, can produce a P3HR1 virus, which is a type 2 EBV strain. The EBV lytic cycle can be induced in these P3HR1 cells by treatment with phorbol 12-myristate 13-acetate (PMA), yielding EBV viral particles.
Using this protocol for the isolation of EBV particles, P3HR1 cells are cultured for 5 days at 37 &#176;C and 5% CO2 in complete RPMI-1640 medium containing 35 ng/mL PMA. Subsequently, the culture medium is centrifuged at a speed of 120 x g for 8 min to pellet the cells. The virus-containing supernatant is then collected and spun down at a speed of 16,000 x g for 90 min to pellet the EBV particles. The viral pellet is then resuspended in a complete RPMI-1640 medium. This is followed by DNA extraction and quantitative real-time PCR to assess the concentration of EBV particles in the preparation.

This protocol permits the isolation of Epstein-Barr virus particles from the human P3HR1 cell line upon inducing the viral lytic cycle with phorbol 12-myristate 13-acetate. DNA is subsequently extracted from the viral preparation and subjected to real-time PCR to quantify the viral particle concentration.