We are grateful to Suzanne Emerson for the hepatitis E virus p6 clone. HEV-specific rabbit hyperimmune serum was kindly provided by Rainer Ulrich, Friedrich Loeffler Institute, Germany. Moreover, we thank all members of the Department of Molecular and Medical Virology at the Ruhr University Bochum for their support and discussion. Figures 1-7 were generated with BioRender.com.

The authors have nothing to disclose.

Starting with the plasmid preparation, DNA yields should exceed 150 ng/&#181;L to be able to perform&#160;multiple linearization from the same plasmid stock, which minimizes the risk of bacteria-induced mutagenesis of crucial genome sequences. Furthermore, it is important to check the restriction digest for the complete plasmid linearization by gel electrophoresis (Figure 8b). A lack of linearized plasmid DNA would induce rolling circle amplification causing the in vitro transcription to be ...

Hepatitis E is a fairly&#160;underestimated disease with increasing prevalence worldwide. About 20 million infections result in more than 70,000 deaths per year1. The underlying agent, the Hepatitis E virus (HEV), was reassigned recently and is now classified within the family Hepeviridae including the genera Orthohepevirus and Piscihepevirus. HEV of various origins are classed within the species Orthohepevirus A-D including isolates from humans, swine, rabbits, rats, birds and other mammals2. At present, eight different genotypes (GT) of the positive-orientated, single-stranded RNA virus have been identified2. Although they differ in their sequence identity, routes of transmission and geographical distribution, their genomic structure is highly conserved. More specific, the 7.2 kbp HEV genome is divided into 3 major open reading frames (ORF1-3). While ORF1 encodes all enzymes needed for a successful replication within the host cell, ORF2 encodes the capsid protein, and the ORF3 protein operates as a functional ion channel required for assembly and release of infectious particles3. Once released into the basal or apical lumen HEV exists in both, quasienveloped and non-enveloped/naked species depending on whether the virus originates from blood or feces, respectively4,5.
While GT1 and GT2 are mainly found in developing countries solely infecting humans6 via the fecal-oral route, GT3, GT4 and GT7 predominantly occur in developed countries1,7 with a variety of species serving as reservoirs, e.g., swine8, rat9, chicken10,11, deer12, mongoose13, bat14, rabbit15,16, wild boar17 and many more7,18,19, providing evidence of zoonosis7,20,21,22. In addition to inadequate sanitary conditions23 and contaminated food products12,24,25,26, transmission via blood transfusion and organ transplantations is also possible27,28. HEV is a common cause of liver cirrhosis and liver failure29 especially in patients with pre-existing liver disease, immunocompromised individuals (genotype 3, 4 and 7) and pregnant women (genotype 1). Of note, there are also extrahepatic manifestations such as hematopoietic disease30,31,32, neurological disorders33 and renal injury34.
To date, the off-label drug ribavirin (RBV) is the treatment of choice for many infected patients35,36. However, cases of treatment failure and poor clinical long-term outcomes have been reported. Treatment failure has been linked to viral mutagenesis and increased viral heterogeneity in chronically infected patients37,38,39. On the contrary, a recent European retrospective multicenter study was not able to correlate polymerase mutations to RBV treatment failure40. In clinical observations and in vitro experiments, interferon41,42,43, sofosbuvir44,45, zinc salts46 and silvestrol47,48 have also shown antiviral effects. Nonetheless, a specific HEV treatment remains to be found, hampered by the lack of knowledge about the HEV life cycle and its pathogenesis. Therefore, a robust cell culture system for virological studies and the development of new antiviral drugs is urgently needed49.
Unfortunately, like other hepatitis viruses, HEV is difficult to propagate in conventional cell lines and usually progresses very slowly leading to low viral loads. Nevertheless, some groups were able to boost viral loads by the generation of cell line subclones50 or the adjustment of media supplements51. Recently the generation of cDNA clones52 and the adaption of primary patient isolates by passaging53,54 further improved HEV propagation in cell culture55. In this protocol, we used the genome of a cell culture adapted Kernow-C1 strain (referred to as p6_WT)54&#160;and a mutant strain harboring a replication-enhancing mutation (referred to as p6_G1634R)37. Kernow-C1 is the most frequently used strain in HEV cell culture and is capable to produce high viral loads. By assessing viral RNA copy numbers, HEV replication can be monitored in vitro. Nevertheless, these techniques do not allow assessment of the number of infectious particles being produced. Therefore, we have established an immunofluorescence staining to determine Focus Forming Units (FFU/mL).
The here described method56 can be used to produce full-length infectious viral particles that are capable to infect a variety of cell types from diverse origins including primary cells and mammalian cell lines. This is a fundamental prerequisite to decipher important aspects of HEV infection and tropism. There is no need for inoculation with usually limited patient isolates. The production of infectious HEV particles from plasmids poses an infinite source, which makes this protocol comparably efficient. In addition, this system can be used for reverse genetics enabling the study of in vivo identified genome alteration and their impact on HEV replication and fitness. This technique overcomes many limitations and, can path the way for drug development, mutagenesis studies and the evaluation of virus-host interactions such as restriction or entry factors.

<table>
	<tbody>
		<tr>
			<td>0.45 &#181;m mesh</td>
			<td>Sarstedt</td>
			<td>83.1826</td>
			<td>Harvest extracellular Virus</td>
		</tr>
		<tr>
			<td>4 % Histofix</td>
			<td>CarlRoth</td>
			<td>P087.4</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>Acetic acid</td>
			<td>CarlRoth</td>
			<td>6755.1</td>
			<td>Collagen working solution</td>
		</tr>
		<tr>
			<td>Amicon Ultra-15</td>
			<td>Merck Millipore</td>
			<td>UFC910024</td>
			<td>Virus harvesting</td>
		</tr>
		<tr>
			<td>Ampicillin</td>
			<td>Sigma-Aldrich</td>
			<td>A1593</td>
			<td>Selection of transformed bacteria</td>
		</tr>
		<tr>
			<td>ATP</td>
			<td>Roche</td>
			<td>11140965001</td>
			<td>in vitro transcription and electroporation</td>
		</tr>
		<tr>
			<td>BioRender</td>
			<td>BioRender</td>
			<td></td>
			<td>Figure Generation</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Roth</td>
			<td>5239.2</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>Collagen R solution 0.4 % sterile</td>
			<td>Serva</td>
			<td>47256.01</td>
			<td>Collagen working solution</td>
		</tr>
		<tr>
			<td>CTP</td>
			<td>Roche</td>
			<td>11140922001</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>Cuvette</td>
			<td>Biorad</td>
			<td>165-2088</td>
			<td>Electroporation</td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Invitrogen</td>
			<td>D21490</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>gibco</td>
			<td>41965-039</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>DNAse</td>
			<td>Promega</td>
			<td>M6101</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>DTT</td>
			<td>Promega</td>
			<td>included in P2077</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Roth</td>
			<td>3054.3</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>Escherichia coli JM109</td>
			<td>Promega</td>
			<td>L2005</td>
			<td>Transformation</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>gibco</td>
			<td>10270106</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Fluoromount</td>
			<td>SouthernBiotech</td>
			<td>0100-01</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>GenePulser Xcell Electroporation System</td>
			<td>BioRad</td>
			<td>1652660</td>
			<td>Electroporation</td>
		</tr>
		<tr>
			<td>Gentamycin</td>
			<td>gibco</td>
			<td>15710049</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>GTP</td>
			<td>Roche</td>
			<td>11140957001</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>H2O</td>
			<td>Braun</td>
			<td>184238001</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>Hepes</td>
			<td>Invitrogen</td>
			<td>15630-03</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>Horse serum</td>
			<td>gibco</td>
			<td>16050122</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>K2HPO4</td>
			<td>Roth</td>
			<td>P749.1</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>KCL</td>
			<td>Roth</td>
			<td>6781.3</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Roth</td>
			<td>3904.2</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>L-Glutamin</td>
			<td>gibco</td>
			<td>25030081</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>L-Glutathione reduced</td>
			<td>Sigma-Aldrich</td>
			<td>G4251-5G</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>MEM</td>
			<td>gibco</td>
			<td>31095-029</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>MEM NEAA (100&#215;)</td>
			<td>gibco</td>
			<td>11140-035</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Roth</td>
			<td>2189.2</td>
			<td>Cytomix</td>
		</tr>
		<tr>
			<td>Microvolume UV-Vis spectrophotometer NanoDrop One</td>
			<td>Thermo Fisher</td>
			<td>ND-ONE-W</td>
			<td>DNA/RNA concentration</td>
		</tr>
		<tr>
			<td>MluI enzyme</td>
			<td>NEB</td>
			<td>R0198L</td>
			<td>Linearization</td>
		</tr>
		<tr>
			<td>NEB buffer</td>
			<td>NEB</td>
			<td>included in R0198L</td>
			<td>Linearization</td>
		</tr>
		<tr>
			<td>NucleoSpin Plasmid kit</td>
			<td>Macherey &#38; Nagel</td>
			<td>740588.250</td>
			<td>Plasmid preparation</td>
		</tr>
		<tr>
			<td>NucleoSpin RNA Clean-up Kit</td>
			<td>Macherey &#38; Nagel</td>
			<td>740948.250</td>
			<td>RNA purification</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>gibco</td>
			<td>70011051</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Pen/Strep</td>
			<td>Thermo Fisher</td>
			<td>15140122</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Plasmid encoding full-length HEV genome (p6_G1634R)</td>
			<td>Todt et.al</td>
			<td></td>
			<td>Virus production</td>
		</tr>
		<tr>
			<td>Plasmid encoding full-length HEV genome (p6_WT)</td>
			<td>Shukla et al.</td>
			<td>GenBank accession no. JQ679013</td>
			<td>Virus production</td>
		</tr>
		<tr>
			<td>Primary antibody 1E6</td>
			<td>LS-Bio</td>
			<td>C67675</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>Primary antibody 8282</td>
			<td></td>
			<td></td>
			<td>Rainer Ulrich, Friedrich Loeffler Institute, Germany</td>
		</tr>
		<tr>
			<td>QIAprep Spin Miniprep Kit</td>
			<td>Qiagen</td>
			<td>27106</td>
			<td>DNA extraction</td>
		</tr>
		<tr>
			<td>Ribo m7G Cap Analog</td>
			<td>Promega</td>
			<td>P1711</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>RNase away</td>
			<td>CarlRoth</td>
			<td>A998.3</td>
			<td>RNA purification</td>
		</tr>
		<tr>
			<td>RNasin (RNase inhibitor)</td>
			<td>Promega</td>
			<td>N2515</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>Secondary antibody donkey anti-mouse 488</td>
			<td>Thermo Fisher</td>
			<td>A-21202</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>Secondary antibody goat anti-rabbit 488</td>
			<td>Thermo Fisher</td>
			<td>A-11008</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>Sodium Pyruvat</td>
			<td>gibco</td>
			<td>11360070</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>T7 RNA polymerase</td>
			<td>Promega</td>
			<td>P2077</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>Transcription Buffer</td>
			<td>Promega</td>
			<td>included in P2077</td>
			<td>in vitro transcription</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>CarlRoth</td>
			<td>3051.3</td>
			<td>Immunofluorescence</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.5 %)</td>
			<td>gibco</td>
			<td>15400054</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>ultra-low IgG</td>
			<td>gibco</td>
			<td>1921005PJ</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>UTP</td>
			<td>Roche</td>
			<td>11140949001</td>
			<td>in vitro transcription</td>
		</tr>
	</tbody>
</table>

a cell culture model for producing high titer hepatitis e virus stocks

Hepatitis E virus is the leading cause of liver cirrhosis and liver failure with increasing prevalence worldwide. The single-stranded RNA virus is predominantly transmitted by blood transfusions, inadequate sanitary conditions and contaminated food products. To date the off-label drug ribavirin (RBV) is the treatment of choice for many patients. Nonetheless, a specific HEV treatment remains to be identified. So far, the knowledge about the HEV life cycle and pathogenesis has been severely hampered because of the lack of an efficient HEV cell culture system. A robust cell culture system is essential for the study of the viral life cycle which also includes the viral pathogenesis. With the method described here one can produce viral titers of up to 3 x 106 focus forming unit/mL (FFU/mL) of non-enveloped HEV and up to 5 x 104 FFU/mL of enveloped HEV. Using these particles, it is possible to infect a variety of cells of diverse origins including primary cells and human, as well as animal cell lines. The production of infectious HEV particles from plasmids poses an infinite source, which makes this protocol exceedingly efficient.

In this protocol, we describe the production of high titer infectious HEVcc. The first step is to isolate plasmid DNA (pBluescript_SK_HEVp654 and pBluescript_SK_HEVp6-G1634R37, Figure 8a), which then is linearized by restriction digestion and purified for in vitro transcription (Figure 1). A successful linearization can be verified by comparing the non-digested plasmid-DNA to the digested plasmid-DNA using gel elec...

Watch this Scientific Journal Video about A Cell Culture Model for Producing High Titer Hepatitis E Virus Stocks at JoVE.com

A Cell Culture Model for Producing High Titer Hepatitis E Virus Stocks

Described here is an effective method on how to produce high viral titer stocks of hepatitis E virus (HEV) to efficiently infect hepatoma cells. With the presented method, both non-enveloped, as well as enveloped viral particles can be harvested and used for inoculating various cell lines.

Hepatitis E virus is the leading cause of liver cirrhosis and liver failure with increasing prevalence worldwide. The single-stranded RNA virus is ...

a-cell-culture-model-for-producing-high-titer-hepatitis-e-virus-stocks

Research

JoVE Journal

Immunology and Infection

9.6K Views.  Ruhr University Bochum. Described here is an effective method on how to produce high viral titer stocks of hepatitis E virus (HEV) to efficiently infect hepatoma cells. With the presented method, both non-enveloped, as well as enveloped viral particles can be harvested and used for inoculating various cell lines.

Video: A Cell Culture Model for Producing High Titer Hepatitis E Virus Stocks

Detection of Infectious Virus from Field-collected Mosquitoes by Vero Cell Culture Assay

Mosquitoes transmit a number of distinct viruses including important human pathogens such as West Nile virus, dengue virus, and chickungunya virus. Many of these viruses have intensified in their endemic ranges and expanded to new territories, necessitating effective surveillance and control programs to respond to these threats. One strategy to monitor virus activity involves collecting large numbers of mosquitoes from endemic sites and testing them for viral infection. In this article, we describe how to handle, process, and screen field-collected mosquitoes for infectious virus by Vero cell culture assay. Mosquitoes are sorted by trap location and species, and grouped into pools containing &le;50 individuals. Pooled specimens are homogenized in buffered saline using a mixer-mill and the aqueous phase is inoculated onto confluent Vero cell cultures (Clone E6). Cell cultures are monitored for cytopathic effect from days 3-7 post-inoculation and any viruses grown in cell culture are identified by the appropriate diagnostic assays. By utilizing this approach, we have isolated 9 different viruses from mosquitoes collected in Connecticut, USA, and among these, 5 are known to cause human disease. Three of these viruses (West Nile virus, Potosi virus, and La Crosse virus) represent new records for North America or the New England region since 1999. The ability to detect a wide diversity of viruses is critical to monitoring both established and newly emerging viruses in the mosquito population.

We describe a method to process and screen field-collected mosquitoes for a diversity of viruses by Vero cell culture assay. By employing this technique, we have detected 9 different viruses from 4 taxonomic families in mosquitoes collected in Connecticut.

Mosquitoes transmit a number of distinct viruses including important human pathogens such as West Nile virus, dengue virus, and chickungunya virus. Many ...

High-throughput Detection Method for Influenza Virus

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, precise diagnosis of the infecting strain and rapid high-throughput screening of vast numbers of clinical samples is paramount to control the spread of pandemic infections. Current clinical diagnoses of influenza infections are based on serologic testing, polymerase chain reaction, direct specimen immunofluorescence and cell culture 1,2.
Here, we report the development of a novel diagnostic technique used to detect live influenza viruses. We used the mouse-adapted human A/PR/8/34 (PR8, H1N1) virus 3 to test the efficacy of this technique using MDCK cells 4. MDCK cells (104 or 5 x 103 per well) were cultured in 96- or 384-well plates, infected with PR8 and viral proteins were detected using anti-M2 followed by an IR dye-conjugated secondary antibody. M2 5 and hemagglutinin 1 are two major marker proteins used in many different diagnostic assays. Employing IR-dye-conjugated secondary antibodies minimized the autofluorescence associated with other fluorescent dyes. The use of anti-M2 antibody allowed us to use the antigen-specific fluorescence intensity as a direct metric of viral quantity. To enumerate the fluorescence intensity, we used the LI-COR Odyssey-based IR scanner. This system uses two channel laser-based IR detections to identify fluorophores and differentiate them from background noise. The first channel excites at 680 nm and emits at 700 nm to help quantify the background. The second channel detects fluorophores that excite at 780 nm and emit at 800 nm. Scanning of PR8-infected MDCK cells in the IR scanner indicated a viral titer-dependent bright fluorescence. A positive correlation of fluorescence intensity to virus titer starting from 102-105 PFU could be consistently observed. Minimal but detectable positivity consistently seen with 102-103 PFU PR8 viral titers demonstrated the high sensitivity of the near-IR dyes. The signal-to-noise ratio was determined by comparing the mock-infected or isotype antibody-treated MDCK cells.
Using the fluorescence intensities from 96- or 384-well plate formats, we constructed standard titration curves. In these calculations, the first variable is the viral titer while the second variable is the fluorescence intensity. Therefore, we used the exponential distribution to generate a curve-fit to determine the polynomial relationship between the viral titers and fluorescence intensities. Collectively, we conclude that IR dye-based protein detection system can help diagnose infecting viral strains and precisely enumerate the titer of the infecting pathogens.

This method describes the use of Infrared dye based imaging system for detection of H1N1 in bronchioalveolar lavage (BAL) fluid of infected mice at a high sensitivity. This methodology can be performed in a 96- or 384-well plate, requires &lt;10 &mu;l volume of test material and has the potential for concurrent screening of multiple pathogens.

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, ...

A Primary Neuron Culture System for the Study of Herpes Simplex Virus Latency and Reactivation

Herpes simplex virus type-1 (HSV-1) establishes a life-long latent infection in peripheral neurons. This latent reservoir is the source of recurrent reactivation events that ensure transmission and contribute to clinical disease. Current antivirals do not impact the latent reservoir and there are no vaccines. While the molecular details of lytic replication are well-characterized, mechanisms controlling latency in neurons remain elusive. Our present understanding of latency is derived from in vivo studies using small animal models, which have been indispensable for defining viral gene requirements and the role of immune responses. However, it is impossible to distinguish specific effects on the virus-neuron relationship from more general consequences of infection mediated by immune or non-neuronal support cells in live animals. In addition, animal experimentation is costly, time-consuming, and limited in terms of available options for manipulating host processes. To overcome these limitations, a neuron-only system is desperately needed that reproduces the in vivo characteristics of latency and reactivation but offers the benefits of tissue culture in terms of homogeneity and accessibility.
Here we present an in vitro model utilizing cultured primary sympathetic neurons from rat superior cervical ganglia (SCG) (Figure 1) to study HSV-1 latency and reactivation that fits most if not all of the desired criteria. After eliminating non-neuronal cells, near-homogeneous TrkA+ neuron cultures are infected with HSV-1 in the presence of acyclovir (ACV) to suppress lytic replication. Following ACV removal, non-productive HSV-1 infections that faithfully exhibit accepted hallmarks of latency are efficiently established. Notably, lytic mRNAs, proteins, and infectious virus become undetectable, even in the absence of selection, but latency-associated transcript (LAT) expression persists in neuronal nuclei. Viral genomes are maintained at an average copy number of 25 per neuron and can be induced to productively replicate by interfering with PI3-Kinase / Akt signaling or the simple withdrawal of nerve growth factor1. A recombinant HSV-1 encoding EGFP fused to the viral lytic protein Us11 provides a functional, real-time marker for replication resulting from reactivation that is readily quantified. In addition to chemical treatments, genetic methodologies such as RNA-interference or gene delivery via lentiviral vectors can be successfully applied to the system permitting mechanistic studies that are very difficult, if not impossible, in animals. In summary, the SCG-based HSV-1 latency / reactivation system provides a powerful, necessary tool to unravel the molecular mechanisms controlling HSV1 latency and reactivation in neurons, a long standing puzzle in virology whose solution may offer fresh insights into developing new therapies that target the latent herpesvirus reservoir.

The protocol describes an efficient and reproducible model system to study herpes simplex virus type 1 (HSV-1) latency and reactivation. The assay employs homogenous sympathetic neuron cultures and allows for the molecular dissection of virus-neuron interactions using a variety of tools including RNA interference and expression of recombinant proteins.

Herpes simplex virus type-1 (HSV-1) establishes a life-long latent infection in peripheral neurons. This latent reservoir is the source of recurrent ...

A Tetracycline-regulated Cell Line Produces High-titer Lentiviral Vectors that Specifically Target Dendritic Cells

Lentiviral vectors (LVs) are a powerful means of delivering genetic material to many types of cells. Because of safety concerns associated with these HIV-1 derived vectors, producing large quantities of LVs is challenging. In this paper, we report a method for producing high titers of self-inactivating LVs. We retrovirally transduce the tet-off stable producer cell line GPR to generate a cell line, GPRS, which can express all the viral components, including a dendritic cell-specific glycoprotein, SVGmu. Then, we use concatemeric DNA transfection to transfect the LV transfer plasmid encoding a reporter gene GFP in combination with a selectable marker. Several of the resulting clones can produce LV at a titer 10-fold greater than what we achieve with transient transfection. Plus, these viruses efficiently transduce dendritic cells in vitro and generate a strong T cell immune response to our reporter antigen. This method may be a good option for producing strong LV-based vaccines for clinical studies of cancer or infectious diseases.

Here, we use retroviral transduction and concatemeric transfection to create a cell line that can express the components of a lentiviral vector (LV) in the absence of tetracycline. This LV encodes GFP and is pseudotyped with a glycoprotein, SVGmu, which is specific for a receptor on dendritic cells.

Lentiviral  vectors (LVs) are a powerful means of delivering genetic material to many types  of cells. Because of safety concerns associated with these ...

A Protocol for Analyzing Hepatitis C Virus Replication

Hepatitis C Virus (HCV) affects 3% of the world&#8217;s population and causes serious liver ailments including&#160;chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HCV is an enveloped RNA virus belonging to the family Flaviviridae. Current treatment is not fully effective and causes adverse side effects. There is no HCV vaccine available. Thus, continued effort is required for developing a vaccine and better therapy. An HCV cell culture system is critical for studying various stages of HCV growth including viral entry, genome replication, packaging, and egress. In the current procedure presented, we used a wild-type intragenotype 2a chimeric virus, FNX-HCV, and a recombinant FNX-Rluc virus carrying a Renilla luciferase reporter gene to study the virus replication. A human hepatoma cell line (Huh-7 based) was used for transfection of in vitro transcribed HCV genomic RNAs. Cell-free culture supernatants, protein lysates and total RNA were harvested at various time points post-transfection to assess HCV growth. HCV genome replication status was evaluated by quantitative RT-PCR and visualizing the presence of HCV double-stranded RNA. The HCV protein expression was verified by Western blot and immunofluorescence assays using antibodies specific for HCV NS3 and NS5A proteins. HCV RNA transfected cells released infectious particles into culture supernatant and the viral titer was measured. Luciferase assays were utilized to assess the replication level and infectivity of reporter HCV. In conclusion, we present various virological assays for characterizing different stages of the HCV replication cycle.

Hepatitis C Virus (HCV) is a major human pathogen that causes liver disorders, including cirrhosis and cancer. An HCV infectious cell culture system is essential for understanding the molecular mechanism of HCV replication and developing new therapeutic approaches. Here we describe a protocol to investigate various stages of the HCV replication cycle.

Hepatitis C Virus (HCV) affects 3% of the world&#8217;s population and causes serious liver ailments including&#160;chronic hepatitis, cirrhosis, and ...

Neutrophil Isolation and Analysis to Determine their Role in Lymphoma Cell Sensitivity to Therapeutic Agents

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of inflammation. They are key players in the innate immune system and play major roles in cancer biology. Neutrophils have been proposed as key mediators of malignant transformation, tumor progression, angiogenesis and in the modulation of the antitumor immunity; through their release of soluble factors or their interaction with tumor cells. To characterize the specific functions of neutrophils, a fast and reliable method is coveted for in vitro isolation of neutrophils from human blood. Here, a density gradient separation method is demonstrated to isolate neutrophils as well as mononuclear cells from the blood. The procedure consists of layering the density gradient solution such as Ficoll carefully above the diluted blood obtained from patients diagnosed with chronic lymphocytic leukemia (CLL), followed by centrifugation, isolation of mononuclear layer, separation of neutrophils from RBCsby dextran then lysis of residual erythrocytes. This method has been shown to isolate neutrophils &#8805; 90 % pure. To mimic the tumor microenvironment, 3-dimensional (3D) experiments were performed using basement membrane matrix such as Matrigel. Given the short half-life of neutrophils in vitro, 3D experiments with fresh human neutrophils cannot be performed. For this reason promyelocytic HL60 cells are differentiated along the granulocytic pathway using the differentiation inducers dimethyl sulfoxide (DMSO) and retinoic acid (RA). The aim of our experiments is to study the role of neutrophils on the sensitivity of lymphoma cells to anti-lymphoma agents. However these methods can be generalized to study the interactions of neutrophils or neutrophil-like cells with a large range of cell types in different situations.

Neutrophils are the most abundant type of white blood cells. The isolation of neutrophils from human blood by density gradient separation method and the differentiation of human promyelocytic (HL60) cells along the granulocytic pathway are described here; to test their role on sensitivity of lymphoma cells to anti-lymphoma agents.

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of ...

Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), that carry foreign genes such as a reporter or marker protein in their genomes. These recombinant viruses usually faithfully mimic the life cycle of the original virus in infected cells and exhibit the same host range dependence. The development of a recombinant virus enables the efficient screening of inhibitors and the identification of specific host factors. However, to date the construction of recombinant hepatitis B virus (HBV) has been difficult because of various experimental limitations. The main limitation is the compact genome size of HBV, and a fairly strict genome size that does not exceed 1.3 genome sizes, that must be packaged into virions. Thus, the size of a foreign gene to be inserted should be smaller than 0.4 kb if no deletion of the genome DNA is to be performed. Therefore, to overcome this size limitation, the deletion of some HBV DNA is required. Here, we report the construction of recombinant HBV encoding a reporter gene to monitor the early stage of the HBV replication cycle by replacing part of the HBV core-coding region with the reporter gene by deleting part of the HBV pol coding region. Detection of recombinant HBV infection, monitored by the reporter activity, was highly sensitive and less expensive than detection using the currently available conventional methods to evaluate HBV infection. This system will be useful for a number of applications including high-throughput screening for the identification of anti-HBV inhibitors, host factors and virus-susceptible cells.

Here we describe a newly developed hepatitis B virus (HBV) reporter system to monitor the early stages of the HBV life cycle. This simplified in vitro system will aid in the screening of anti-HBV agents using a high-throughput strategy.

Currently, it is possible to construct recombinant forms of various viruses, such as human immunodeficiency virus 1 (HIV-1) and hepatitis C virus (HCV), ...

Rapid, Safe, and Simple Manual Bedside Nucleic Acid Extraction for the Detection of Virus in Whole Blood Samples

The rapid diagnosis of an infection is essential for the outbreak management, risk containment, and patient care. We have previously shown a method for the rapid bedside inactivation of the Ebola virus during blood sampling for safe nucleic acid (NA) tests by adding a commercial lysis/binding buffer directly into the vacuum blood collection tubes. Using this bedside inactivation approach, we have developed a safe, rapid, and simplified bedside NA extraction method for the subsequent detection of a virus in lysis/binding buffer-inactivated whole blood. The NA extraction is directly performed in the blood collection tubes and requires no equipment or electricity. 
After the blood is collected into the lysis/binding buffer, the contents are mixed by flipping the tube by hand, and the mixture is incubated for 20 min at room temperature. Magnetic glass particles (MGPs) are added to the tube, and the contents are mixed by flipping the collection tube by hand. The MGPs are then collected on the side of the blood collection tube using a magnetic holder or a magnet and a rubber band. The MGPs are washed three times, and after the addition of elution buffer directly into the collection tube, the NAs are ready for NA tests, such as qPCR or isothermal loop amplification (LAMP), without the removal of the MGPs from the reaction. The NA extraction method is not dependent on any laboratory facilities and can easily be used anywhere (e.g., in field hospitals and hospital isolation wards). When this NA extraction method is combined with LAMP and a portable instrument, a diagnosis can be obtained within 40 min of the blood collection.

Here, we present a protocol for the rapid virus nucleic acid extraction from the virus-inactivated whole blood. The extraction is performed directly in the blood collection tubes and requires no equipment or electricity. The method is not dependent on laboratory facilities and can be used anywhere (e.g., in field hospitals).

The rapid diagnosis of an infection is essential for the outbreak management, risk containment, and patient care. We have previously shown a method for ...

"Liver-on-a-Chip" Cultures of Primary Hepatocytes and Kupffer Cells for Hepatitis B Virus Infection

Despite the exceptional infectivity of the hepatitis B virus (HBV) in vivo, where only three viral genomes can result in a chronicity of experimentally infected chimpanzees, most in vitro models require several hundreds to thousands of viral genomes per cell in order to initiate a transient infection. Additionally, static 2D cultures of primary human hepatocytes (PHH) allow only short-term studies due to their rapid dedifferentiation. Here, we describe 3D liver-on-a-chip cultures of PHH, either in monocultures or in cocultures with other nonparenchymal liver-resident cells. These offer a significant improvement to studying long-term HBV infections with physiological host cell responses. In addition to facilitating drug efficacy studies, toxicological analysis, and investigations into pathogenesis, these microfluidic culture systems enable the evaluation of curative therapies for HBV infection aimed at eliminating covalently closed, circular (ccc)DNA. This presented method describes the set-up of PHH monocultures and PHH/Kupffer cell co-cultures, their infection with purified HBV, and the analysis of host responses. This method is particularly applicable to the evaluation of long-term effects of HBV infection, treatment combinations, and pathogenesis.

&quot;Liver-on-a-Chip&quot; Cultures of Primary Hepatocytes and Kupffer Cells for Hepatitis B Virus Infection

The goal of this protocol is to provide a step-by-step guide to perform 3-D &#34;liver-on-a-chip&#34; infection experiments with the hepatitis B virus.

Despite the exceptional infectivity of the hepatitis B virus (HBV) in vivo, where only three viral genomes can result in a chronicity of experimentally ...

An Ex Vivo Chicken Primary Bursal-cell Culture Model to Study Infectious Bursal Disease Virus Pathogenesis

Infectious bursal disease virus (IBDV) is a birnavirus of economic importance to the poultry industry. The virus infects B cells, causing morbidity, mortality, and immunosuppression in infected birds. In this study, we describe the isolation of chicken primary bursal cells from the bursa of Fabricius, the culture and infection of the cells with IBDV, and the quantification of viral replication. The addition of chicken CD40 ligand significantly increased cell proliferation fourfold over six days of culture and significantly enhanced cell viability. Two strains of IBDV, a cell-culture adapted strain, D78, and a very virulent strain, UK661, replicated well in the ex vivo cell cultures. This model will be of use in determining how cells respond to IBDV infection and will permit a reduction in the number of infected birds used in IBDV pathogenesis studies. The model can also be expanded to include other viruses and could be applied to different species of birds.

An Ex Vivo Chicken Primary Bursal-cell Culture Model to Study Infectious Bursal Disease Virus Pathogenesis

Here we describe the isolation of chicken primary bursal cells from the bursa of Fabricius, the culture and infection of the cells with infectious bursal disease virus, and the quantification of viral replication.

Infectious bursal disease virus (IBDV) is a birnavirus of economic importance to the poultry industry. The virus infects B cells, causing morbidity, ...