Name: production of high-titer recombinant newcastle disease virus from allantoic fluid
Uploaded: 2022-05-25T14:00:00
Description: Watch this Scientific Journal Video about Production of High-Titer Recombinant Newcastle Disease Virus from Allantoic Fluid at JoVE.com

J.G.E.Y was the recipient of an Ontario Veterinary College PhD Scholarship and an Ontario Graduate Scholarship. This work was funded by Natural Sciences and Engineering Research Council of Canada Discovery Grants to SKW (grant #304737) and LS (grant #401127).

All work involving the use of animals was approved by the University of Guelph Animal Care Committee in accordance with the Canadian Council on Animal Care. All work is performed in a BioSafety Level 2 (BSL2) laboratory in Canada where mesogenic NDV is a Risk Group 2 Pathogen. All steps involved in the amplification and purification of NDV should be performed in a Type IIA biological safety cabinet for safety and sterility purposes.
1. Amplification of NDV using specified pathogen-free e...

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Viruses used as therapeutic agents in preclinical studies must be highly purified to avoid toxicity when administered in vivo15. If adventitious agents or contaminants are not removed, this can lead to severe adverse reactions negating the therapeutic effect of the viral agent28. As NDV is produced in embryonated chicken eggs, there are several contaminating egg proteins, such as ovalbumin, that must be removed prior to its use in vivo in preclinical or cl...

Newcastle Disease Virus, also known as Avian Orthoavulavirus-1, is an enveloped avian paramyxovirus with the potential to be used both as an oncolytic virus or a viral-vectored vaccine1,2,3,4,5,6,7. Most recently, NDV engineered to express the spike protein of SARS-CoV-2 has been characterized as an effective intranasal vaccine in mouse and hamster challenge models7,8,9. When used as a cancer immunotherapy, it results in the recruitment of innate immune cells, specifically natural killer cells, production of type I interferon, and the generation of antitumor-specific T cells10,11,12,13. In addition to these potent immunostimulatory properties, NDV has a strong safety profile and a well-established reverse genetics system14,15. These desirable characteristics have prompted the evaluation of NDV in numerous preclinical and human clinical trials (NCT04871737, NCT01926028, NCT04764422)16,17. To further advance this highly promising, immune-stimulatory viral vector, detailed methods are needed for producing and purifying high-titer, ultra-pure NDV that can be safely administered in vivo.
As NDV is an avian paramyxovirus, it is most frequently amplified in embryonated chicken eggs. While there are cell-based systems available for propagating NDV, most have been unable to produce titers similar to that achieved in embryonated chicken eggs18. Nevertheless, there are some drawbacks to producing NDV in eggs, including the fact that egg-based production is lengthy and not easily scalable, sourcing large quantities of SPF chicken eggs can be problematic, and there exists the potential for contamination with egg allergens13,18,19,20. Recently, one group has shown that Vero cells grown in suspension in serum-free medium can support the replication of NDV to titers comparable to those achieved in eggs, prior to purification21. However, this required serial passaging of the virus to adapt the virus to Vero cells, and the optimization of a method to purify NDV from suspension Vero cells is still required21.
As highlighted previously, methods used for purifying high-titer, in vivo-grade virus vary depending on the virus in question22. There is a well-established reverse genetics system available for the generation of recombinant NDV. This process, involving the use of a cDNA clone, helper plasmids, and a helper virus expressing T7 RNA polymerase, has been previously described in detail15,23. This protocol can be applied to either lentogenic or mesogenic NDV. The virus described in this protocol is a recombinant mesogenic NDV encoding the green fluorescent protein (GFP) from the jellyfish Aequorea victoria inserted between viral P and M genes as an individual transcription unit, as this has previously been described as the optimal site for foreign transgene insertion24.
Enclosed methods outline the purification of NDV based on its size, ranging from 100 to 500 nm, and its density15. This has allowed for the generation of in vivo-grade, high-titer NDV stocks in approximately 3 weeks, starting from when the eggs are received to having a final titer. Techniques frequently used in the large-scale production of egg-based viruses such as tangential flow filtration, depth filtration, and density gradient ultracentrifugation are described, enabling the translation of these methods to larger-scale production. Previously described techniques for the purification of NDV have been improved by the incorporation of a virus-stabilizing buffer, use of iodixanol during density gradient ultracentrifugation, and the description of various quality control measures to ensure in vivo-grade quality15. This has allowed for the purification of in vivo-grade NDV reaching titers as high as 3 &#215; 1010 PFU/mL from 0.8 to 1.0 L of allantoic fluid.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.25% Trypsin</td>
			<td>HyClone</td>
			<td>SH30042.02</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL Slip-Tip Syringe</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr>
			<td>10 mL Luer-Lok Syringe</td>
			<td>BD</td>
			<td>302995</td>
			<td></td>
		</tr>
		<tr>
			<td>10% Povidone Iodine Solution</td>
			<td>LORIS</td>
			<td>109-08</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Conical Tubes</td>
			<td>Thermo-Fisher</td>
			<td>14955240</td>
			<td></td>
		</tr>
		<tr>
			<td>18G x 1 1/2 in Blunt Fill Needle</td>
			<td>BD</td>
			<td>305180</td>
			<td></td>
		</tr>
		<tr>
			<td>18G x 1 1/2 in Precision Glide Needle</td>
			<td>BD</td>
			<td>305196</td>
			<td></td>
		</tr>
		<tr>
			<td>25 G x 5/8 in Needle</td>
			<td>BD</td>
			<td>305122</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Mercaptoethanol</td>
			<td>Thermo-Fisher</td>
			<td>03446I-100</td>
			<td></td>
		</tr>
		<tr>
			<td>30% Acrylamide/Bis Solution 37.5:1</td>
			<td>BioRad</td>
			<td>1610158</td>
			<td></td>
		</tr>
		<tr>
			<td>4% Paraformaldehyde-PBS</td>
			<td>Thermo-Fisher</td>
			<td>J19943-K2</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL Luer-Lok Syringe</td>
			<td>BD</td>
			<td>309646</td>
			<td></td>
		</tr>
		<tr>
			<td>96 Well Tissue Culture Plate - Flat Bottom</td>
			<td>Greiner Bio One</td>
			<td>655180</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic Acid, Glacial</td>
			<td>Thermo-Fisher</td>
			<td>A38-212</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>Froggabio</td>
			<td>A87-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa-Fluor 488 Goat-Anti-Mouse</td>
			<td>Invitrogen</td>
			<td>A11001</td>
			<td></td>
		</tr>
		<tr>
			<td>Allegra X-14 Centrifuge</td>
			<td>Beckman Coulter</td>
			<td>B08861</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium Persulfate</td>
			<td>BioRad</td>
			<td>161-0700</td>
			<td></td>
		</tr>
		<tr>
			<td>Bleach (5%)</td>
			<td>Thermo-Fisher</td>
			<td>36-102-0599</td>
			<td></td>
		</tr>
		<tr>
			<td>Broad, unserrated tipped forceps</td>
			<td>Thermo-Fisher</td>
			<td>09-753-50</td>
			<td></td>
		</tr>
		<tr>
			<td>Bromophenol Blue</td>
			<td>Sigma-Aldrich</td>
			<td>114405-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Centramate Cassette Holder</td>
			<td>PALL</td>
			<td>CM018V</td>
			<td></td>
		</tr>
		<tr>
			<td>ChemiDoc XRS+</td>
			<td>BioRad</td>
			<td>1708265</td>
			<td></td>
		</tr>
		<tr>
			<td>CO2 Incubator</td>
			<td>Thermo-Fisher</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Coomassie Brilliant Blue R-259</td>
			<td>Thermo-Fisher</td>
			<td>BP101-50</td>
			<td></td>
		</tr>
		<tr>
			<td>DF1 Cells</td>
			<td>ATCC</td>
			<td>CRL-12203</td>
			<td></td>
		</tr>
		<tr>
			<td>Diet Gel Recovery</td>
			<td>ClearH2O, INC</td>
			<td>72-01-1062</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital 1502 Sportsman Egg Incubator</td>
			<td>Berry Hill</td>
			<td>1502W</td>
			<td></td>
		</tr>
		<tr>
			<td>D-Mannitol</td>
			<td>Sigma-Aldrich</td>
			<td>M4125-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Egg Candler</td>
			<td>Berry Hill</td>
			<td>A46</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol (70%)</td>
			<td>Thermo-Fisher</td>
			<td>BP82031GAL</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid (EDTA) solution, pH 8.0, 0.5 M in H2O</td>
			<td>Thermo-Fisher</td>
			<td>BP2482-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Female Threaded Tee fittings, nylon, 1/8 in NPT(F)</td>
			<td>Cole-Parmer</td>
			<td>06349-50</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Gibco</td>
			<td>12483-020</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Point High Precision Forceps</td>
			<td>Thermo-Fisher</td>
			<td>22-327379</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent Microscope</td>
			<td>ZEISS AXIO</td>
			<td></td>
			<td>Not necessary if not performing IFA or if NDV does not encode a fluorescent protein</td>
		</tr>
		<tr>
			<td>Freeze Dry System Freezone 4.5</td>
			<td>LABCONCO</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GiBOX Gel Imager</td>
			<td>Syngene</td>
			<td></td>
			<td>Imaging of Agarose Gels</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Thermo-Fisher</td>
			<td>G33-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Thermo-Fisher</td>
			<td>BP381-5</td>
			<td></td>
		</tr>
		<tr>
			<td>High Capacity cDNA Reverse Transcriptase Kit</td>
			<td>Thermo-Fisher</td>
			<td>4368814</td>
			<td></td>
		</tr>
		<tr>
			<td>High Glucose Dulbecco&#39;s Modified Essential Medium</td>
			<td>Cytiva</td>
			<td>SH30022.01</td>
			<td></td>
		</tr>
		<tr>
			<td>Humidity Kit</td>
			<td>Berry Hill</td>
			<td>3030</td>
			<td></td>
		</tr>
		<tr>
			<td>Iodixanol</td>
			<td>Sigma-Aldrich</td>
			<td>D1556</td>
			<td>60% (w/v) solution of iodixanol in water (sterile)</td>
		</tr>
		<tr>
			<td>L-Lysine Monohydrochloride</td>
			<td>Sigma-Aldrich</td>
			<td>62929-100G-F</td>
			<td></td>
		</tr>
		<tr>
			<td>Male and Female Luer-Lok a 1/8 in national pipe thread, NPT</td>
			<td>Cole-Parmer</td>
			<td>41507-44</td>
			<td></td>
		</tr>
		<tr>
			<td>Masterflex L/S Digital Drive</td>
			<td>Cole-Parmer</td>
			<td>RK-07522-20</td>
			<td>Peristaltic Pump with digital display</td>
		</tr>
		<tr>
			<td>Masterflex L/S Easy Load Pump Head for Precision Tubing</td>
			<td>Cole-Parmer</td>
			<td>RK-07514-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Masterflex Silicon tubing (Platinum) L/S 16</td>
			<td>Cole-Parmer</td>
			<td>96420-16</td>
			<td>BioPharm Platinum-Cured Silicone</td>
		</tr>
		<tr>
			<td>MC Pro 5 Thermocycler</td>
			<td>Eppendorf</td>
			<td>EP950040025</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Thermo-Fisher</td>
			<td>A412-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini Protean Tetra Cell</td>
			<td>BioRad</td>
			<td>1658000EDU</td>
			<td>SDS-PAGE cast and running appartus</td>
		</tr>
		<tr>
			<td>Mouse-Anti-NDV</td>
			<td>Novus Biologicals</td>
			<td>NBP2-11633</td>
			<td>Clone 6H12</td>
		</tr>
		<tr>
			<td>Normal Goat Serum</td>
			<td>Abcam</td>
			<td>AB7481</td>
			<td></td>
		</tr>
		<tr>
			<td>NP-40</td>
			<td>Thermo-Fisher</td>
			<td>85124</td>
			<td></td>
		</tr>
		<tr>
			<td>Omega Membrane LV Centramate Cassette, 100K</td>
			<td>PALL</td>
			<td>OS100T02</td>
			<td></td>
		</tr>
		<tr>
			<td>Optima XE-90 Ultracentrifuge</td>
			<td>Beckman Coulter</td>
			<td>A94471</td>
			<td></td>
		</tr>
		<tr>
			<td>OWL Easycast B1A Mini Gel Electrophoresis System</td>
			<td>Thermo-Fisher</td>
			<td>B1A</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS 10X Solution</td>
			<td>Thermo-Fisher</td>
			<td>BP399-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(Ethylene Glycol) Average Mn 20,000</td>
			<td>Sigma-Aldrich</td>
			<td>81300-1KG</td>
			<td></td>
		</tr>
		<tr>
			<td>PowePac 300</td>
			<td>BioRad</td>
			<td></td>
			<td>Model 1655050 - for Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>Q5 High Fidelity 2X Master Mix</td>
			<td>New England Biolabs</td>
			<td>M0492S</td>
			<td></td>
		</tr>
		<tr>
			<td>QIA Amp Viral RNA Mini Kit</td>
			<td>Qiagen</td>
			<td>52904</td>
			<td></td>
		</tr>
		<tr>
			<td>RedSafe</td>
			<td>Thermo-Fisher</td>
			<td>50999562</td>
			<td></td>
		</tr>
		<tr>
			<td>Slide-a-lyzer Dialysis Cassette (Extra Strength), 10,000 MWCO 0.5-3 mL</td>
			<td>Thermo-Fisher</td>
			<td>66380</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Dodecyl Sulfate</td>
			<td>Thermo-Fisher</td>
			<td>BP166-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide (Pellets)</td>
			<td>Thermo-Fisher</td>
			<td>S318-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Specific pathogen free eggs</td>
			<td>CFIA</td>
			<td>NA</td>
			<td>Supplier will vary depending on location</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Thermo-Fisher</td>
			<td>S5-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Supracap 50 Depth Filter</td>
			<td>PALL</td>
			<td>SC050V100P</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Scissors</td>
			<td>Thermo-Fisher</td>
			<td>08-951-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Sw41Ti Rotor</td>
			<td>Beckman Coulter</td>
			<td>331362</td>
			<td>Used in protocol step 2.3.1, 2.3.6, 2.3.7</td>
		</tr>
		<tr>
			<td>SX4750 Rotor</td>
			<td>Beckman Coulter</td>
			<td>369702</td>
			<td></td>
		</tr>
		<tr>
			<td>SxX4750 Adaptor for Concial-Bottom Tubes</td>
			<td>Beckman Coulter</td>
			<td>359472</td>
			<td></td>
		</tr>
		<tr>
			<td>TEMED</td>
			<td>Invitrogen</td>
			<td>15524-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Thin-Wall Ultraclear centrifuge tubes (9/16 in x 3 1/2 in)</td>
			<td>Beckman Coulter</td>
			<td>344059</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Thermo-Fisher</td>
			<td>BP152-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubing Screw Clamp</td>
			<td>PALL</td>
			<td>88216</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>Sigma-Aldrich</td>
			<td>P1379-1L</td>
			<td></td>
		</tr>
		<tr>
			<td>Utility Pressure Gauges</td>
			<td>Cole-Parmer</td>
			<td>68355-06</td>
			<td></td>
		</tr>
	</tbody>
</table>

production of high-titer recombinant newcastle disease virus from allantoic fluid

Newcastle disease virus (NDV), also known as avian orthoavulavirus serotype-1, is a negative sense, single-stranded RNA virus that has been developed both as an oncolytic virus and a viral-vectored vaccine. NDV is an attractive therapeutic and prophylactic agent due to its well-established reverse genetics system, potent immunostimulatory properties, and excellent safety profile. When administered as an oncolytic virus or a viral-vectored vaccine, NDV elicits a robust antitumor or antigen-specific immune response, activating both the innate and adaptive arms of the immune system. 
Given these desirable characteristics, NDV has been evaluated in numerous clinical trials and is one of the most well-studied oncolytic viruses. Currently, there are two registered clinical trials involving NDV: one evaluating a recombinant NDV-vectored vaccine for SARS-CoV-2 (NCT04871737), and a second evaluating a recombinant NDV encoding Interleukin-12 in combination with Durvalumab, an antiPD-L1 antibody (NCT04613492). To facilitate further advancement of this highly promising viral vector, simplified methods for generating high-titer, in vivo-grade, recombinant NDV (rNDV) are needed. 
This paper describes a detailed procedure for amplifying rNDV in specified pathogen-free (SPF) embryonated chicken eggs and purifying rNDV from allantoic fluid, with improvements to reduce loss during purification. Also included are descriptions of the recommended quality control assays, which should be performed to confirm lack of contaminants and virus integrity. Overall, this detailed procedure enables the synthesis, purification, and storage of high-titer, in vivo-grade, recombinant, lentogenic, and mesogenic NDV for use in preclinical studies.

Harvesting allantoic fluid 
As allantoic fluid is harvested from embryonated chicken eggs, it should appear clear and transparent. If the fluid appears opaque and yellow, this indicates the presence of contaminants. Inclusion of this allantoic fluid during purification will impede the purification process, as the pressure will quickly rise and surpass 10 psi, resulting in the shearing of the virus and loss of infectious virus. Allantoic fluid that appears bloody suggests that the eggs were inoculate...

Watch this Scientific Journal Video about Production of High-Titer Recombinant Newcastle Disease Virus from Allantoic Fluid at JoVE.com

Production of High-Titer Recombinant Newcastle Disease Virus from Allantoic Fluid

Here we provide a detailed procedure for production, purification, and quantification of high-titer recombinant Newcastle disease virus. This protocol consistently yields &#62; 6 &#215; 109 plaque-forming units/mL, providing virus quantities appropriate for in vivo animal studies. Additional quality control assays to ensure safety in vivo are described.

Newcastle disease virus (NDV), also known as avian orthoavulavirus serotype-1, is a negative sense, single-stranded RNA virus that has been developed both ...

This protocol outlines the techniques used to produce Newcastle Disease Virus so that it can be administered safely to mice and other animals such as hamsters and sheep. The use of tangential flow filtration allows for large starting volumes to be processed more efficiently compared to existing procedures that use only centrifugation processes. This is a lengthy procedure involving several intricate steps, meaning time management may be an issue.I would recommend identifying all potential pause steps so that the technique can be split up appropriately, minimizing stress. Demonstrating this procedure will be Alex, a research assistant from my laboratory. For the purification of Newcastle Disease Virus or NDV, first, prime the previously set experimental system by running 50 milliliters of PBS through it.Stop the pump when approximately five milliliters of PBS are left in the tube. Next, attach a depth filter with a one to three micromolar retention rating to the tubing. To vent the filter, remove the second cap on the epical side of the depth filter then start running an additional 50 milliliters of PBS through the system.Once the PBS begins to flow through the vent at the top of the filter, close the port and continue to flow PBS through the lines. After that replace the waste vessel with a new sterile collection vessel and begin to run Allantoic Fluid through the depth filter. Next, set up the tangential flow filtration or TFF system in an open confirmation and run as described in the manuscript.When there are about five milliliters of fluid left in the reservoir, pause the pump and add depth filtered Allantoic Fluid to the reservoir. Then resume the pump flow. To prevent shearing of the virus, it's important to ensure that the pressure of the system does not exceed 10 pound force per square inch.To increase the illusion, a combination of the speed of the peristaltic pump and C-clamp should be used. 150 to 100 milliliters of Allantoic Fluid are left in the reservoir, pause the pump and exchange the buffer by adding 150 to 200 milliliters of ML buffer. Again, pause the pump when five to 10 milliliters of fluid are left in the reservoir, then using two C-clamps close the waistline.Uncouple the retented line feeding the reservoir and insert it into a 50 milliliter conical tube. Then resume the flow and pause when there are few drops of fluid left in the reservoir tank. Next, remove the C-clamps from the waste lines and reattach the retented feed line to the reservoir tank.Meanwhile, to prepare for iodixanol density gradient ultracentrifugation, first add a 0.5 milliliters of 40%iodixanol to a 13.2 milliliter open top thin wall ultra centrifuge tube. Then make the column ready with successive additions of 2.5 milliliters of 20%iodixanol, and 2.5 milliliters of 10%iodixanol. Before ultracentrifugation, carefully add six to 6.5 milliliters of the virus solution alluded from the TFF system to the iodixanol column without disturbing the gradient.After ultracentrifugation, remove the tubes with a pair of sterile forceps. The target band should be a large band between the 10 and 20%gradients. Next, suspend the tube over the top of a beaker using a retort stand.After that, attach a 1.5 inch needle of 18 gauge to a five milliliter syringe then puncture the side of the ultracentrifuge tube with the needle and remove the target band by slowly extending the plunger. After removing iodixanol from the virus solution as described in the manuscript, use a syringe to carefully inject the virus into a dialysis cassette. To concentrate the virus solution, remove the dialysis cassette from the dialysis buffer and place it in a small sealable plastic bag.Then add a 15 to 25 milliliters of 40%polyethylene glycol to the bag so that the dialysis cassette is completely submerged. After dialysis briefly rinse the dialysis cassette with PBS. Next, fill a syringe fitted with a 1.5 inch needle of 18 gauge with air, insert the syringe into the dialysis cassette and push the plunger.Rotate the apparatus for removing the virus without removing any of the introduced air. To dislodge residual virus adhering to the membrane, carefully massage the membrane with gloved fingers without damaging it. To ease the dislodging process, remove some of the excess air in the dialysis cassette.For quality control assays, first, dilute the virus solution 100 times by adding 10 microliters of it to 990 microliters of PBS in a 1.5 milliliter tube. Then continue serial dilution by adding 100 microliters of the previous dilution to 900 microliters of PBS. For infection assays, add 20 microliters of each delusion to each well of a 96 well plate.Before examining the cytopathic effect of green fluorescence protein, or performing an indirect immunofluorescence assay, incubate the plate at 37 degrees Celsius with 5%carbon dioxide for at least 48 hours. By using this protocol, highly purified NDV was obtained as demonstrated by sodium do sulfate polyacrylamide gel electrophoresis of the viral proteins. The infectivity of the virus purified by this method was also verified by the 50%tissue culture infection dose or TCID50 assay done in 96 well plates.The TCID50 was determined from the number of positive wells for each dilution by using the Spearman-Karber calculator. The infection assay revealed the difference between the cytopathic effects of lentogenic and mesogenic NDV on DF one cells under different conditions after 10 and 24 hours of incubation. The immuno florence assay was also effective in studying the infection of Vero cells by lentogenic NDV.When priming the experimental system, ensure that the lines are primed effectively as any residual sodium hydroxide will inactivate the virus. Also is important to maintain membrane integrity as compromising this will significantly impair virus purification and yield.

production-high-titer-recombinant-newcastle-disease-virus-from

Research

JoVE Journal

Cancer Research

Genome-wide RNAi Screening to Identify Host Factors That Modulate Oncolytic Virus Therapy

High-throughput genome-wide RNAi (RNA interference) screening technology has been widely used for discovering host factors that impact&#160;virus replication. Here we present the application of this technology to uncovering host targets that specifically modulate the replication of Maraba virus, an oncolytic rhabdovirus, and vaccinia virus with the goal of enhancing therapy. While the protocol has been tested for use with oncolytic Maraba virus and oncolytic vaccinia virus, this approach is applicable to other oncolytic viruses and can also be utilized for identifying host targets that modulate virus replication in mammalian cells in general. This protocol describes the development and validation of an assay for high-throughput RNAi screening in mammalian cells, the key considerations and preparation steps important for conducting a primary high-throughput RNAi screen, and a step-by-step guide for conducting a primary high-throughput RNAi screen; in addition, it broadly outlines the methods for conducting secondary screen validation and tertiary validation studies. The benefit of high-throughput RNAi screening is that it allows one to catalogue, in an extensive and unbiased fashion, host factors that modulate any aspect of virus replication for which one can develop an in vitro assay such as infectivity, burst size, and cytotoxicity. It has the power to uncover biotherapeutic targets unforeseen based on current knowledge.

Here we describe a protocol for employing high-throughput RNAi screening to uncover host targets that can be manipulated to enhance oncolytic virus therapy, specifically rhabodvirus and vaccinia virus therapy, but it can be readily adapted to other oncolytic virus platforms or for discovering host genes that modulate virus replication generally.

High-throughput genome-wide RNAi (RNA interference) screening technology has been widely used for discovering host factors that impact&#160;virus ...

Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration

With an increasing incidence of prostate cancer, identification of new tumor drivers or modulators is crucial. Genetically engineered mouse models (GEMM) for prostate cancer are hampered by tumor heterogeneity and its complex microevolution dynamics. Traditional prostate cancer mouse models include, amongst others, germline and conditional knockouts, transgenic expression of oncogenes, and xenograft models. Generation of de novo mutations in these models is complex, time-consuming, and costly. In addition, most of traditional models target the majority of the prostate epithelium, whereas human prostate cancer is well known to evolve as an isolated event in only a small subset of cells. Valuable models need to simulate not only prostate cancer initiation, but also progression to advanced disease.
Here we describe a method to target a few cells in the prostate epithelium by transducing cells by viral particles. The delivery of an engineered virus to the murine prostate allows alteration of gene expression in the prostate epithelia. Virus type and quantity will hereby define the number of targeted cells for gene alteration by transducing a few cells for cancer initiation and many cells for gene therapy. Through surgery-based injection in the anterior lobe, distal from the urinary track, the tumor in this model can expand without impairing the urinary function of the animal. Furthermore, by targeting only a subset of prostate epithelial cells the technique enables clonal expansion of the tumor, and therefore mimics human tumor initiation, progression, as well as invasion through the basal membrane.
This novel technique provides a powerful prostate cancer model with improved physiological relevance. Animal suffering is limited, and since no additional breeding is required, overall animal count is reduced. At the same time, analysis of new candidate genes and pathways is accelerated, which in turn is more cost efficient.

This protocol describes a newly established method for virus delivery to the murine prostate. Using either CRISPR/Cas9 technology, gene overexpression, or Cre recombinase delivery, the technique allows orthotopic alteration of gene expression and implements a novel mouse model for prostate cancer.

With an increasing incidence of prostate cancer, identification of new tumor drivers or modulators is crucial. Genetically engineered mouse models (GEMM) ...

Methods for Evaluating the Role of c-Fos and Dusp1 in Oncogene Dependence

The demonstration of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) has heralded a new era in cancer therapeutics. However, a small population of cells does not respond to TKI treatment, resulting in minimal residual disease (MRD); even the most potent TKIs fail to eradicate these cells. These MRD cells serve as a reservoir to develop resistance to therapy. Why TKI treatment is ineffective against MRD cells is not known. Growth factor signaling is implicated in supporting the survival of MRD cells during TKI treatment, but a mechanistic understanding is lacking. Recent studies demonstrated that an elevated c-Fos and Dusp1 expression as a result of convergent oncogenic and growth factor signaling in MRD cells mediate TKI resistance. The genetic and chemical inhibition of c-Fos and Dusp1 renders CML exquisitely sensitive to TKIs and cures CML in both genetic and humanized mouse models. We identified these target genes using multiple microarrays from TKI-sensitive and -resistant cells. Here, we provide methods for target validation using in vitro and in vivo mouse models. These methods can easily be applied to any target for genetic validation and therapeutic development.

Here, we describe protocols for the genetic and chemical validation of c-Fos and Dusp1 as a drug target in leukemia using in vitro and in vivo genetic and humanized mouse models. This method can be applied to any target for genetic validation and therapeutic development.

The demonstration of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) has heralded a new era in cancer therapeutics. However, ...

Neutrophil Extracellular Traps Generated by Low Density Neutrophils Obtained from Peritoneal Lavage Fluid Mediate Tumor Cell Growth and Attachment

Activated neutrophils release neutrophil extracellular traps (NETs), which can capture and destroy microbes. Recent studies suggest that NETs are involved in various disease processes, such as autoimmune disease, thrombosis, and tumor metastases. Here, we show a detailed in vitro technique to detect NET activity during the trapping of free tumor cells, which grow after attachment to NETs. First, we collected low density neutrophils (LDN) from postoperative peritoneal lavage fluid from patients who underwent laparotomies. Short-term culturing of LDN resulted in massive NET formation that was visualized with green fluorescent nuclear and chromosome counterstain. After co-incubation of human gastric cancer cell lines MKN45, OCUM-1, and NUGC-4 with the NETs, many tumor cells were trapped by the NETs. Subsequently, the attachment was completely abrogated by the degradation of NETs with DNase I. Time-lapse video revealed that tumor cells trapped by the NETs did not die but instead grew vigorously in a continuous culture. These methods may be applied to the detection of adhesive interactions between NETs and various types of cells and materials.

Here, we present a method in which human low-density neutrophils (LDN), recovered from postoperative peritoneal lavage fluid, produce massive neutrophil extracellular traps (NETs) and efficiently trap free tumor cells that subsequently grow.

Activated neutrophils release neutrophil extracellular traps (NETs), which can capture and destroy microbes. Recent studies suggest that NETs are involved ...

A Simple Migration/Invasion Workflow Using an Automated Live-cell Imager

Cancer cell mobility is crucial for the initiation of metastasis. Therefore, investigation of the cell movement and invasive capacity is of great significance. Migration assays provide basic insight of cell movement at a 2D level, whereas invasion assays are more physiologically relevant, mimicking in vivo cancer cell dislodgment from the original site and invading through the extracellular matrix. The current protocol provides a single workflow for migration and invasion assays. Together with the integrated automated microscopic camera for real-time HD images and built-in analysis module, it gives researchers a time-efficient, simple and reproducible experimental option. This protocol also includes substitutions for the consumables and alternative analysis methods for users to choose from.

The current protocol describes an integrated method investigating cancer cell migration and invasion on a single platform in real-time, providing an easily reproducible and time-efficient option to study cell mobility and morphology.

Cancer cell mobility is crucial for the initiation of metastasis. Therefore, investigation of the cell movement and invasive capacity is of great ...

Evaluating Cell Death Using Cell-Free Supernatant of Probiotics in Three-Dimensional Spheroid Cultures of Colorectal Cancer Cells

This manuscript describes a protocol to evaluate cancer cell deaths in three dimensional (3D) spheroids of multicellular types of cancer cells using supernatants from Lactobacillus fermentum cell culture, considered as probiotics cultures. The use of 3D cultures to test Lactobacillus cell-free supernatant (LCFS) are a better option than testing in 2D monolayers, especially as L. fermentum can produce anti-cancer effects within the gut. L. fermentum supernatant was identified to possess increased anti-proliferative effects against several colorectal cancer (CRC) cells in 3D culture conditions. Interestingly, these effects were strongly related to the culture model, demonstrating the notable ability of L. fermentum to induce cancer cell death. Stable spheroids were generated from diverse CRCs (colorectal cancer cells) using the protocol presented below. This protocol of generating 3D spheroid is time saving and cost effective. This system was developed to easily investigate the anti-cancer effects of LCFS in multiple types of CRC spheroids. As expected, CRC spheroids treated with LCFS strongly induced cell death during the experiment and expressed specific apoptosis molecular markers as analyzed by qRT-PCR, western blotting, and FACS analysis. Therefore, this method is valuable for exploring cell viability and evaluating the efficacy of anti-cancer drugs.

Here methods are presented to understand anti-cancer effects of Lactobacillus cell-free supernatant (LCFS). Colorectal cancer cell lines show cell deaths when treated with LCFS in 3D cultures. The process of generating spheroids can be optimized depending on the scaffold and the analysis methods presented are useful for evaluating the involved signaling pathways.

This manuscript describes a protocol to evaluate cancer cell deaths in three dimensional (3D) spheroids of multicellular types of cancer cells using ...

A Murine Ommaya Xenograft Model to Study Direct-Targeted Therapy of Leptomeningeal Disease

Leptomeningeal disease (LMD) is an uncommon type of central nervous system (CNS) metastasis to the cerebral spinal fluid (CSF). The most common cancers that cause LMD are breast and lung cancers and melanoma. Patients diagnosed with LMD have a very poor prognosis and generally survive for only a few weeks or months. One possible reason for the lack of efficacy of systemic therapy against LMD is the failure to achieve therapeutically effective concentrations of drug in the CSF because of an intact and relatively impermeable blood-brain barrier (BBB) or blood-CSF barrier across the choroid plexus. Therefore, directly administering drugs intrathecally or intraventricularly may overcome these barriers. This group has developed a model that allows for the effective delivery of therapeutics (i.e., drugs, antibodies, and cellular therapies) chronically and the repeated sampling of CSF to determine drug concentrations and target modulation in the CSF (when the tumor microenvironment is targeted in mice). The model is the murine equivalent of a magnetic resonance imaging-compatible Ommaya reservoir, which is used clinically. This model, which is affixed to the skull, has been designated as the &#34;Murine Ommaya.&#34; As a therapeutic proof of concept, human epidermal growth factor receptor 2 antibodies (clone 7.16.4) were delivered into the CSF via the Murine Ommaya to treat mice with LMD from human epidermal growth factor receptor 2-positive breast cancer. The Murine Ommaya increases the efficiency of drug delivery using a miniature access port and prevents the wastage of excess drug; it does not interfere with CSF sampling for molecular and immunological studies. The Murine Ommaya is useful for testing novel therapeutics in experimental models of LMD.

Here, we describe a murine xenograft model that functionally resembles an Ommaya reservoir in patients. We developed the Murine Ommaya to study novel therapeutics for the universally fatal leptomeningeal disease.

Leptomeningeal disease (LMD) is an uncommon type of central nervous system (CNS) metastasis to the cerebral spinal fluid (CSF). The most common cancers ...

Portal Vein Injection of Colorectal Cancer Organoids to Study the Liver Metastasis Stroma

Hepatic metastasis of colorectal cancer (CRC) is a leading cause of cancer-related death. Cancer-associated fibroblasts (CAFs), a major component of the tumor microenvironment, play a crucial role in metastatic CRC progression and predict poor patient prognosis. However, there is a lack of satisfactory mouse models to study the crosstalk between metastatic cancer cells and CAFs. Here, we present a method to investigate how liver metastasis progression is regulated by the metastatic niche and possibly could be restrained by stroma-directed therapy. Portal vein injection of CRC organoids generated a desmoplastic reaction, which faithfully recapitulated the fibroblast-rich histology of human CRC liver metastases. This model was tissue-specific with a higher tumor burden in the liver when compared to an intra-splenic injection model, simplifying mouse survival analyses. By injecting luciferase-expressing tumor organoids, tumor growth kinetics could be monitored by in vivo imaging. Moreover, this preclinical model provides a useful platform to assess the efficacy of therapeutics targeting the tumor mesenchyme. We describe methods to examine whether adeno-associated virus-mediated delivery of a tumor-inhibiting stromal gene to hepatocytes could remodel the tumor microenvironment and improve mouse survival. This approach enables the development and assessment of novel therapeutic strategies to inhibit hepatic metastasis of CRC.

Portal vein injection of colorectal cancer (CRC) organoids generates stroma-rich liver metastasis. This mouse model of CRC hepatic metastasis represents a useful tool to study tumor-stroma interactions and develop novel stroma-directed therapeutics such as adeno-associated virus-mediated gene therapies.

Hepatic metastasis of colorectal cancer (CRC) is a leading cause of cancer-related death. Cancer-associated fibroblasts (CAFs), a major component of the ...

A Three-Dimensional Spheroid Model to Investigate the Tumor-Stromal Interaction in Hepatocellular Carcinoma

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver cancer, rationalize its rank as the second most common cause of cancer-related death. Preclinical models need to be adapted to recapitulate the human conditions to select the best therapeutic candidates for clinical development and aid the delivery of personalized medicine. Three-dimensional (3D) cellular spheroid models show promise as an emerging in vitro alternative to two-dimensional (2D) monolayer cultures. Here, we describe a 3D tumor spheroid&#160;model which exploits the ability of individual cells to aggregate when maintained in hanging droplets, and is more representative of an in vivo environment than standard monolayers. Furthermore, 3D spheroids can be produced by combining homotypic or heterotypic cells, more reflective of the cellular heterogeneity in vivo, potentially enabling the study of environmental interactions that can influence progression and treatment responses. The current research optimized the cell density to form 3D homotypic and heterotypic tumor spheroids by immobilizing cell suspensions on the lids of standard 10 cm3 Petri dishes. Longitudinal analysis was performed to generate growth curves for homotypic versus heterotypic tumor/fibroblasts spheroids. Finally, the proliferative impact of fibroblasts (COS7 cells) and liver myofibroblasts (LX2) on homotypic tumor (Hep3B) spheroids was investigated. A seeding density of 3,000 cells (in 20 &#181;L media) successfully yielded Huh7/COS7 heterotypic spheroids, which displayed a steady increase in size up to culture day 8, followed by growth retardation. This finding was corroborated using Hep3B homotypic spheroids cultured in LX2 (human hepatic stellate cell line) conditioned medium (CM). LX2 CM triggered the proliferation of Hep3B spheroids compared to control tumor spheroids. In conclusion, this protocol has shown that 3D tumor spheroids can be used as a simple, economical, and prescreen in vitro tool to study tumor-stromal interactions more comprehensively.

Comprehensive in vitro models that faithfully recapitulate the relevant human disease are lacking. The current study presents three-dimensional (3D) tumor spheroid creation and culture, a reliable in vitro tool to study the tumor-stromal interaction in human hepatocellular carcinoma.

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver ...

Microfluidic Shear Apparatus Setup for Single-Cell Fluid Shear Assay

Begin the protocol by preparing the shear assay viscous flow media. To do so, preheat the base culture media for about 10 to 20 minutes at 60 to 70 degrees Celsius using a magnetic stir or hot plate. While continuously stirring the media, gently add methylcellulose into it to help the methylcellulose particles disperse quickly without coagulating.Allow this process to continue for approximately 15 to 24 hours to ensure a clear homogenous mix of media and cellulose. To set up the shear apparatus, attach a rubber gasket to the flow path to fasten the connection between the flow chamber and the Petri dish, and ensure a controlled uniform flow of single cells. The rubber gasket comes in different sizes depending on the desired flow profile and area of observation.Next, set up the shear assay system comprising of 60 or 100 milliliter dual syringes connected to a programmable syringe pump for infusion and withdrawal of the viscous culture media. Fill a syringe with the prepared viscous flow media and attach the filled syringe to its respective location on the syringe pump. Then, attach an empty syringe to the other syringe location on the syringe pump.Using 1/16th inch tubing and tubing connectors, connect both syringes to the flow chamber. Program the pump to infuse and withdraw a certain volume of fluid at a designated rate, and select the corresponding syringes. An example program is shown on the screen.Aspirate the cell culture media from the Petri dish to prepare for shear. Next, insert and fix the flow chamber with the rubber gasket onto the Petri dish containing the attached cells. Place the fitted microfluidic flow chamber with the cells in the dish onto an inverted microscope connected to a display monitor.The setup is now ready for applying fluid shear stress onto a single cell and optically monitoring the resulting cellular deformation.