Name: development of a hepatitis b virus reporter system to monitor the early stages of the replication cycle
Uploaded: 2017-02-01T13:00:00
Description: Watch this Scientific Journal Video about Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle at JoVE.com

This work was supported in part by the Research Program on Hepatitis from Japan Agency for Medical Research and Development (AMED) and by Grants-in-Aids for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.

1. Production of Recombinant HBV Encoding the Reporter Protein
<ol>
	<li>Preparation of HepG2 cells
	<ol>
		<li>Prepare cell culture medium (Dulbecco&#39;s modified Eagle&#39;s medium (DMEM) supplemented with 10% fetal bovine serum (FBS), 100 U/ml penicillin, 100 &#181;g/ml streptomycin, and 100 U/ml nonessential amino acids).</li>
		<li>Plate 4 x 106 HepG2 cells in a 10-cm collagen-coated dish in 10 ml of culture medium the day before transfection. Incubate HepG2 cells at 37 &#176;C in a hu...

<ol>
	<li>Fattovich, G., Stroffolini, T., Zagni, I., Donato, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hepatocellular+carcinoma+in+cirrhosis:+incidence+and+risk+factors.">Hepatocellular carcinoma in cirrhosis: incidence and risk factors.</a> Gastroenterology. 127 (5), 35-50 (2004).</li><li>Revill, P., Testoni, B., Locarnini, S., Zoulim, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+strategies+are+required+to+cure+and+eliminate+HBV+infection.">Global strategies are required to cure and eliminate HBV infection.</a> Nat. Rev. Gastroenterol. Hepatol. 13 (4), 239-248 (2016).</li><li>Wursthorn, 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=Peginterferon+alpha-2b+plus+adefovir+induce+strong+cccDNA+decline+and+HBsAg+reduction+in+patients+with+chronic+hepatitis+B.">Peginterferon alpha-2b plus adefovir induce strong cccDNA decline and HBsAg reduction in patients with chronic hepatitis B.</a> Hepatology. 44 (3), 675-684 (2006).</li><li>Stuyver, L. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+replicative+and+nonreplicative+hepatitis+B+virus+vectors.">Development of replicative and nonreplicative hepatitis B virus vectors.</a> Gene. Ther. 4 (12), 1330-1340 (1997).</li><li>Hong, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+recombinant+hepatitis+B+virus+vectors+efficiently+deliver+protein+and+RNA+encoding+genes+into+primary+hepatocytes.">Novel recombinant hepatitis B virus vectors efficiently deliver protein and RNA encoding genes into primary hepatocytes.</a> J. Virol. 87 (12), 6615-6624 (2013).</li><li>Hall, M. 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=Engineered+luciferase+reporter+from+a+deep+sea+shrimp+utilizing+a+novel+imidazopyrazinone+substrate.">Engineered luciferase reporter from a deep sea shrimp utilizing a novel imidazopyrazinone substrate.</a> ACS. Chem. Biol. 7 (11), 1848-1857 (2012).</li><li>Nishitsuji, 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=Novel+reporter+system+to+monitor+early+stages+of+the+hepatitis+B+virus+life+cycle.">Novel reporter system to monitor early stages of the hepatitis B virus life cycle.</a> Cancer. 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H., Ganem, D., Varmus, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+the+major+transcripts+of+ground+squirrel+hepatitis+virus:+the+presumptive+template+for+reverse+transcriptase+is+terminally+redundant.">Mapping the major transcripts of ground squirrel hepatitis virus: the presumptive template for reverse transcriptase is terminally redundant.</a> Cell. 42 (1), 297-308 (1985).</li><li>Haines, K. M., Loeb, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+sequence+of+the+RNA+primer+and+the+DNA+template+influence+the+initiation+of+plus-strand+DNA+synthesis+in+hepatitis+B+virus.">The sequence of the RNA primer and the DNA template influence the initiation of plus-strand DNA synthesis in hepatitis B virus.</a> J. Mol. Biol. 370 (3), 471-480 (2007).</li><li>Hirsch, R. C., Lavine, J. 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The HBV genome has four primary open reading frames (ORFs) including the core, polymerase, surface and X ORFs (Figure 1). Transcription of these four HBV ORFs is tightly regulated by four promoters: the precore/core promoter containing enhancer II, S1 promoter, S2 promoter and X promoter containing enhancer I18. The 3.5 kb and 3.4 kb mRNAs are translated into PreCore and Core proteins, respectively. The large envelop protein (L) is produced from the largest subgenomic mRNA (2.5 kb...

Chronic infection with hepatitis B virus (HBV) is a major risk factor for chronic liver diseases1. Although current therapeutic strategies are based on nucleotide analogs that inhibit HBV pol function and/or the administration of type I interferon that activates immune responses in infected individuals as well as indirectly suppressing HBV proliferation through interferon-stimulated gene functions2, these treatments cannot eliminate HBV DNA completely3. Moreover, the emergence of HBVs that are resistant to anti-pol agents is of concern4. The administration of combined anti-viral agents directly targeting the different steps of human immunodeficiency virus (HIV) or hepatitis C virus (HCV) life cycle was shown to successfully suppress or eradicate the virus(es). Similar to this idea, the development of anti-HBV agent(s) that act directly on the different stages of the HBV life cycle is important for establishing future HBV therapies.
In general, the establishment of a simple in vitro culture system of the target virus facilitates the development of anti-virus agents. However, there are at least two barriers to the development of in vitro culture systems to screen anti-HBV agents. The first is the lack of a convenient in vitro cell culture system for HBV infection/proliferation. Unlike other viruses, such as HIV and HCV, which are propagated in established cell lines, it is difficult to cultivate HBV in vitro because of experimental limitations including a narrow host range. The use of specific cell culture systems such as the human hepatoma cell line HepaRG, which is susceptible to HBV infection,5,6,7 have been developed to overcome these problems. Moreover, PXB cells, isolated from urokinase-type plasminogen activator transgenic/SCID mice inoculated with primary human hepatocyte (PHH), were shown to be susceptible to HBV infection and replication8. However, HBV replication levels in HepaRG are dependent on the cellular differentiation state after culture, which can cause inconsistent and irreproducible results of HBV infection/replication levels. PXB is commonly used for HBV infection experiments but is limited by its availability. A tetracycline inducible HBV expression cell line, HepAD38, has also been widely used to study HBV replication, but this system only allows evaluation after transcription and not at the entry step of HBV infection9. Recently, the identification of sodium taurocholate cotransporting polypeptide (NTCP) as a functional receptor for HBV has allowed the development of a variable HBV culture system10. Indeed, NTCP expression in non-susceptible hepatocarcinoma cells such as Huh7 and HepG2 enables HBV infection10 and thus, the choice of HBV susceptible cell lines has been expanded, resolving many of the experimental limitations. The second problem is the lack of a simple assay system to evaluate HBV infection and replication. Evaluation of HBV infection is usually conducted by analyzing HBV DNA, RNA and proteins. However, quantification of these virus markers is time consuming, often costly and not always simple. Therefore, the development of a simple assay system, such as using a reporter gene, might overcome problems associated with HBV assay systems.
However, because the genome size that can be packaged into an HBV capsid is limited &#8212; less than 3.7 kb11 &#8212; the size of a reporter gene should be as short as possible. Furthermore, the presence of multiple cis elements scattered throughout the genome, which are essential for viral replication, limits the positions available for insertion of the reporter gene into the genome. Several reports have attempted to insert foreign genes, including HIV-1 Tat, green fluorescent protein, and DsRed, into the HBV genome11,12,13. However, these recombinant HBVs are not useful for screening HBV infection/replication, or for the high-throughput screening of factors affecting HBV infection/replication. This is mainly because of the low productivity of recombinant viruses and the reduced intensity of reporter gene expression caused by inefficient virus production.
To overcome these issues, we constructed a reporter HBV with a high yield of virus production. This virus is highly sensitive for monitoring the early stages of the HBV replication cycle, from entry to transcription. To achieve this, NanoLuc (NL) was chosen as a marker gene because it is a small (171 amino acids) engineered luminescent reporter14. Moreover, NL is approximately 150-fold brighter than firefly or Renilla luciferase, and the luminescent reaction is ATP-independent, suggesting that the false hit rate will be low for high-throughput screening. The production efficiency of the recombinant HBV is approximately 1/5 of the parent HBV, and similar to levels reported for previous HBV recombinant viruses; however, the brightness of NL overcomes virus productivity issues so it can be used for the mass screening of anti-HBV agents.
Screening of anti-HBV agents using primary hepatocytes, HepaRG, HepAD38 and NTCP-transduced hepatocytes might be useful for the screening of anti-HBV agents by conventional method(s). However, the system described here has various advantages such as simple handling, high sensitivity, and low cost for screening. These advantages are suitable for high throughput assays to develop and identify new HBV agents for therapeutic purposes.

<table border="0" cellpadding="0" cellspacing="0" width="781">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:332px;">Nano-Glo Luciferase Assay Regent</td>
			<td style="width:201px;">Promega</td>
			<td style="width:160px;">N1110</td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Penicillin-Streptomycin Mixed Solution</td>
			<td>Nacalai tesque</td>
			<td>09367-34&#160;</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MEM Non-Essential Amino Acids Solution</td>
			<td>Thermo Fisher Scientific</td>
			<td>11140050</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>11995065</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Opti-MEM I Reduced Serum Medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>31985070</td>
			<td></td>
		</tr>
		<tr height="18">
			<td height="18" style="height:18px;width:332px;">100 mm/collagen-coated dish</td>
			<td>Iwaki</td>
			<td>4020-010</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Lipofectamine 3000 Transfection Reagent</td>
			<td>Thermo Fisher Scientific</td>
			<td>L3000001&#160;</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polyethylene glycol (PEG) 6000&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>81255</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polyethylene glycol (PEG) 8000&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>89510</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">NaCl</td>
			<td>Nacalai tesque</td>
			<td>31319-45&#160;</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">0.5 mol/l-EDTA Solution</td>
			<td>Nacalai tesque</td>
			<td>06894-14&#160;</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tris-HCl</td>
			<td>Nacalai tesque</td>
			<td>35434-21</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Millex-HP, 0.45 &#956;m, polyethethersulfone, filter</td>
			<td>Merck Millipore</td>
			<td>SLHP033RS</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Dimethyl sulfoxide (DMSO)</td>
			<td>Sigma-Aldrich</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Collagen coated 96-well plate</td>
			<td>Corning</td>
			<td>NO3585</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Passive Lysis 5xBuffer</td>
			<td>Promega</td>
			<td>E1941</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">GloMax 96 Microplate Luminometer</td>
			<td>Promega</td>
			<td>E6501</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Sucrose</td>
			<td>Nacalai tesque</td>
			<td>30403-55</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Luminometer plate</td>
			<td>Greiner bio-one</td>
			<td>655075</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HepG2-NTCP1-myc-clone22</td>
			<td>-</td>
			<td>-</td>
			<td>Reference 15</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">pUC1.2HBV delta epsilon</td>
			<td>-</td>
			<td>-</td>
			<td>Reference 15</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">pUC1.2HBV/NL</td>
			<td>-</td>
			<td>-</td>
			<td>Reference 15</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">50 ml tube</td>
			<td>Violamo</td>
			<td>1-3500-02</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Anti-Myc antibody</td>
			<td>Sigma-Aldrich</td>
			<td>C3956</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HBIG</td>
			<td>Japan Blood Products Organization</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">IFN-&#946;</td>
			<td>Mochida Pharmaceutical</td>
			<td>14987224005413</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Heparin</td>
			<td>Sigma-Aldrich</td>
			<td>H3393</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Figure 1 shows a schematic of the HBV genome, transcribed RNAs, virus proteins and their coding region on the genome. The reporter gene and its location in the genome are also indicated. Figure 2 shows the HBV reporter plasmid and helper plasmid containing the reporter gene. The pUC1.2HBV/NL reporter was constructed by deleting nucleotide positions 223-811 from the transcription initiation site of the preCore mRNA of pUC1.2HBV16 an...

Watch this Scientific Journal Video about Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle at JoVE.com

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

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), ...

The overall goal of this recombinant HBV reporter system is to make it easy to conduct mass screening for anti-Hepatitis B virus, or HBV agents. This method can help answer key questions in the HBV field, such as screening for anti-HBV agents and identification HBV factors. The main advantage of this technique is that the HBV reporter system can monitor the earlier stages of the HBV replication cycle.After preparing cell culture medium, the day before transvection, place four times 10 to the six HepG2 cells in medium, on a 10 cm collagen coated dish. Incubate the cells at 37 degrees C in a humidifed 5%CO2 incubator. Using a transvectionary agent according to the manufacturer's instructions, transvect the cells with 5 mcg of pUC1 2HBV delta epsilon, and 5 mcg of pUC1 2HBV/NL.The next day, remove the culture medium and add 10 mL of fresh culture medium. Then, one week after transvection, transfer the culture medium containing the recombinant HBV to a 50 mL tube. Next, add 10 mL of fresh culture medium to the plate containing transvected cells.Then collect and centrifuge the culture medium at 2, 300 x g for five minutes to remove the cell debris containing the recombinant HBV. Pass the supernatant through a 45 mcm membrane filter. Then add an equal volume of 25%PEG, 1.5 molar NaCl, to the filtrate, and gently mix.Incubate the sample overnight at four degrees C.The following day, spin the solution at 2, 300 x g and four degrees C, for 20 minutes. Discard the supernatant and dissolve the pellet in 5 mL of TNE buffer. Now centrifuge the sample again to remove cell debris, then load 5 mL of the TNE-containing recombinant HBV onto 8 mL of 20%sucrose in TNE.Centrifuge the two at 100, 000 x g and 15 degrees celsius for three hours. Discard as much of the supernatant as possible and use 1 mL of serum-free DMEM per 40 mL of starting culture to re-suspend the pellet. Incubate the suspension at four degrees celsius overnight.The following morning, filter the suspension through a 45 mcm filter. Then prepare 5 mL aliquots and store the tubes at minus 80 degrees celsius. Plate HepG2 cells, stably expressing sodium taurocholate cotransporting polypeptide, or NTCP, that are susceptible to HBV infection, and incubate at 37 degrees celsius and 5%CO2.One day before infection, plate approximately five times 10 to the fourth HepG2 NTCP cells into the wells of a 96-well collagen coated plate, in 1 mL of culture medium. Thaw recombinant HBV in a 37 degree celsius water bath, until there is a small bit of ice remaining in the vial. Prepare medium for infection by combining 78 mcL of fresh culture medium, 2 mcL of DMSO, 10 mcL of 40%PEG 8000, in 1x PBS, and 10 mcL of recombinant HPV.Add 100 mcL of recombinant HBV solution to each well of a 96-well plate. One day after infection, use 300 mcL of PBS to wash the cell three times to remove the contaminating reporter protein from the virus fraction. Add 200 mcL of culture medium, containing 2%DMSO, to the infected cells, and incubate for one week or less.To carry out analysis of the HBV infection, one week after infection, use PBS to wash the infected cells three times. Add 50 mcL of Lysis Buffer to the infected cells. Rock the culture plate for five minutes then centrifuge at 2, 000 x g for five minutes.Add 50 mcL of the reporter substrate to a Luminometer plate. Then add 20 mcL of the cell lysate to the plate and mix by briefly shaking. Finally, place the plate in the Luminometer and initiate reading.This gel shows digestion of the constructed pUC1 2HBVNL reporter plasmid, and the pUC1 2HBV delta helper plasmid with HindII and EcoRI. Both samples produce the expected band sizes. In this western blot, lysates from HepG2 cells, or HepG2 cells expressing recombinant myc-tagged NTCP and infected with recombinant HBV, were probed with an anti-myc antibody that recognizes the 34 kDa unglycosylated and the 65 kDa glycosolated recombinant proteins.The graphs shown here illustrate the kinetics of the reporter gene. RNA and DNA levels in recombinant HBV infected HepG2 NTCP myc-clone 22, or human primary hepatocyte cells. The levels of HBV RNA in the reporter activity were elevated at three days after infection, in both the infected cells and the primary hepatocytes.In contrast, there was no change in DNA levels at nine days post-infection, because recombinant HBV is deficient for functional core and pole, that play important roles in the intracellular DNA replication pathway. In this figure, inhibition of recombinant HBV by Hepatitis B Immune Globulin, or HBIG, Heparin, and IFN-beta, are illustrated. HBIG and Heparin strongly suppressed the reporter activity to less than 10%at 75 U/mL, and 150 U/mL, respectively.IFN-beta on the other hand, suppressed reporter activity to less than 50%at 1000 U/mL. Once mastered, this technique can be done in one week for preparation of recombinant HBV, in six days for infection recombinant HBV, and in summary, means for measurement of the reporter protein, if it is performed properly. While attempting this procedure, it's important to remember the washing step that removes the contaminating reporter protein from the bias fraction.Following this procedure, other results like infection with wide HBV can be performed in order to answer additional question to that the recombinant HBV did not produce first positive results. After its development, this technique paved the way for researchers in the field of HBV to explore the development of anti-HBV agent in a cell culture model. After watching this video, you should have a good understanding of how to purify and infect cells with recombinant HBV.Don't forget that working with recombinant HBV can be extremely hazardous and precautions such as wearing gloves should always be taken while performing this procedure.

Research

JoVE Journal

Immunology and Infection

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