Name: quantification of antibody-dependent enhancement of the zika virus in primary human cells
Uploaded: 2019-01-18T13:30:00
Description: Watch this Scientific Journal Video about Quantification of Antibody-dependent Enhancement of the Zika Virus in Primary Human Cells at JoVE.com

This work was generously supported by 1R21AI129881-01 (to T.M.C.), start-up funds from the National Emerging Infectious Diseases Laboratories, and the Boston University School of Medicine.

Serum samples used in this study were obtained from human participants of a cohort from Columbia. Sample collection was approved by the internal review board (IRB) at Universidad de Pamplona (Columbia, South America) and Los Potios Hospital8. The samples were anonymously provided and investigators had no access to patient information. The serum samples were checked for the DENV serotype. The samples were further confirmed to neutralize DENV infection in vitro. For control, serum samples f...

<ol>
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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=Zika+Virus.">Zika Virus.</a> Clinical Microbiology Reviews. 29 (3), 487-524 (2016).</li><li>Vaughn, D. W., 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=Dengue+viremia+titer,+antibody+response+pattern,+and+virus+serotype+correlate+with+disease+severity.">Dengue viremia titer, antibody response pattern, and virus serotype correlate with disease severity.</a> The Journal of Infectious Diseases. 181 (1), 2-9 (2000).</li><li>Khandia, 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=Modulation+of+Dengue/Zika+Virus+Pathogenicity+by+Antibody-Dependent+Enhancement+and+Strategies+to+Protect+Against+Enhancement+in+Zika+Virus+Infection.">Modulation of Dengue/Zika Virus Pathogenicity by Antibody-Dependent Enhancement and Strategies to Protect Against Enhancement in Zika Virus Infection.</a> Frontiers of Immunology. 9, 597 (2018).</li><li>Londono-Renteria, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+relevant+in+vitro+human+model+for+the+study+of+Zika+virus+antibody-dependent+enhancement.">A relevant in vitro human model for the study of Zika virus antibody-dependent enhancement.</a> Journal of General Virology. 98 (7), 1702-1712 (2017).</li><li>Ganger, M. T., Dietz, G. D., Ewing, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+common+base+method+for+analysis+of+qPCR+data+and+the+application+of+simple+blocking+in+qPCR+experiments.">A common base method for analysis of qPCR data and the application of simple blocking in qPCR experiments.</a> BMC Bioinformatics. 18 (1), 534 (2017).</li><li>Renn, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+quantitative+real-time+RT-PCR+assay+for+determining+expression+profiles+of+types+I+and+III+interferon+subtypes.">High-throughput quantitative real-time RT-PCR assay for determining expression profiles of types I and III interferon subtypes.</a> Journal of Visualized Experiments. (97), e52650 (2015).</li><li>McArthur, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dengue+vaccines:+recent+developments,+ongoing+challenges+and+current+candidates.">Dengue vaccines: recent developments, ongoing challenges and current candidates.</a> Expert Review of Vaccines. 12 (8), 933-953 (2013).</li><li>Priyamvada, L., 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=Humoral+cross-reactivity+between+Zika+and+dengue+viruses:+implications+for+protection+and+pathology.">Humoral cross-reactivity between Zika and dengue viruses: implications for protection and pathology.</a> Emerging Microbes and Infections. 6 (5), 33 (2017).</li><li>Dai, L., 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=Molecular+basis+of+antibody-mediated+neutralization+and+protection+against+flavivirus.">Molecular basis of antibody-mediated neutralization and protection against flavivirus.</a> IUBMB Life. 68 (10), 783-791 (2016).</li><li>Dai, L., 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=Structures+of+the+Zika+Virus+Envelope+Protein+and+Its+Complex+with+a+Flavivirus+Broadly+Protective+Antibody.">Structures of the Zika Virus Envelope Protein and Its Complex with a Flavivirus Broadly Protective Antibody.</a> Cell Host &amp; Microbe. 19 (5), 696-704 (2016).</li><li>Sirohi, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+3.8+A+resolution+cryo-EM+structure+of+Zika+virus.">The 3.8 A resolution cryo-EM structure of Zika virus.</a> Science. 352 (6284), 467-470 (2016).</li><li>George, J., 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=Prior+Exposure+to+Zika+Virus+Significantly+Enhances+Peak+Dengue-2+Viremia+in+Rhesus+Macaques.">Prior Exposure to Zika Virus Significantly Enhances Peak Dengue-2 Viremia in Rhesus Macaques.</a> Scientific Reports. 7 (1), 10498 (2017).</li><li>Morens, D. M., Halstead, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+antibody-dependent+infection+enhancement+of+four+dengue+virus+serotypes+by+monoclonal+and+polyclonal+antibodies.">Measurement of antibody-dependent infection enhancement of four dengue virus serotypes by monoclonal and polyclonal antibodies.</a> Journal of General Virology. 71, 2909-2914 (1990).</li><li>Dejnirattisai, W., 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=Cross-reacting+antibodies+enhance+dengue+virus+infection+in+humans.">Cross-reacting antibodies enhance dengue virus infection in humans.</a> Science. 328 (5979), 745-748 (2010).</li><li>Priyamvada, L., 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=Human+antibody+responses+after+dengue+virus+infection+are+highly+cross-reactive+to+Zika+virus.">Human antibody responses after dengue virus infection are highly cross-reactive to Zika virus.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (28), 7852-7857 (2016).</li><li>Charles, A. S., Christofferson, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Utility+of+a+Dengue-Derived+Monoclonal+Antibody+to+Enhance+Zika+Infection+In+Vitro.">Utility of a Dengue-Derived Monoclonal Antibody to Enhance Zika Infection In Vitro.</a> PLoS Currents. 8, (2016).</li><li>Swanstrom, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dengue+Virus+Envelope+Dimer+Epitope+Monoclonal+Antibodies+Isolated+from+Dengue+Patients+Are+Protective+against+Zika+Virus.">Dengue Virus Envelope Dimer Epitope Monoclonal Antibodies Isolated from Dengue Patients Are Protective against Zika Virus.</a> MBio. 7 (4), (2016).</li></ol>

Cross-reactivity of DENV antibodies leading to the ADE of other DENV serotypes has hindered the development of an effective vaccine11. ZIKV belongs to the same family, Flaviviridae, and has a considerable homology with other flaviviruses, especially DENV12. The main target of neutralizing antibodies for both ZIKV and DENV is the envelope protein, which shares a very high structural and quaternary sequence homology between the two viruses13,</sup...

Among the mosquitoes-borne viral diseases, Zika infection is one of the most clinically important1. The infection is caused by the flavivirus ZIKV which, in most cases, uses Aedes aegypti as its primary vector1,2. However, there are studies that have reported Aedes albopictus as a primary vector in some ZIKV outbreaks3. Although the infection is asymptomatic in many cases, the most common symptoms are fever, headache, and muscle pain2. There is no cure or vaccine available for ZIKV infection and the treatment available is mostly supportive. Recent outbreaks of ZIKV in South America led to severe cases of the disease and an approximately 20-fold increase in the neurodevelopmental disorder in fetuses named microcephaly2. As South America is an area endemic to several arboviruses such as DENV and West Nile virus, it is crucial to investigate whether prior immunity to other flavivirus(es) plays a role in the severity of ZIKV infections and disease.
Throughout the ages, viruses have evolved different strategies to increase their chance of infectivity in order to take over the host cell machinery and suppress the antiviral response. One of the most fascinating of all is the use of host pre-immune antibodies by viruses to enhance their replication with the phenomenon ADE4. ADE across all four serotypes of DENV has been well studied and demonstrated to increase viral titers and disease outcome5,6,7. In a previous in vitro study, we have shown significant enhancement of ZIKV replication due to pre-existing DENV immunity in primary human immune cells8. We also demonstrated a relevant in vitro method to quantify the capability of DENV pre-existing antibodies to enhance ZIKV replication in primary cells.
The protocol that we have developed uses human serum samples that are tested for DENV neutralization in TCID-50 or plaque reduction neutralization test (PRNT) assays, along with ZIKV in biologically relevant cells or cells derived from tissues that ZIKV can infect.

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			<td height="21" style="height:21px;width:259px;">Fetal Bovine Serum&#160;</td>
			<td style="width:119px;">GEMINI</td>
			<td style="width:119px;">100-106</td>
			<td style="width:277px;"></td>
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			<td height="21" style="height:21px;width:259px;">iCycler&#160;</td>
			<td style="width:119px;">BioRad</td>
			<td style="width:119px;">785BR02188</td>
			<td>Model No. CFX96 Optics Module</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:259px;">Microfuge 18 Centrifuge</td>
			<td style="width:119px;">Beckman Coulter&#160;</td>
			<td style="width:119px;">367160</td>
			<td></td>
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			<td height="21" style="height:21px;width:259px;">Nanodrop-1000</td>
			<td style="width:119px;">Thermoscientific&#160;</td>
			<td style="width:119px;">1072</td>
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			<td height="21" style="height:21px;width:259px;">Quantifast SYBR-One step RT-PCR kit&#160;</td>
			<td style="width:119px;">Qiagen&#160;</td>
			<td style="width:119px;">204154</td>
			<td>Used for 1 step RT-qPCR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:259px;">RNeasy RNA Isolation Kit&#160;</td>
			<td style="width:119px;">Qiagen&#160;</td>
			<td style="width:119px;">74106</td>
			<td>Used for RNA extraction</td>
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			<td height="21" style="height:21px;width:259px;">RPMI-medium&#160;</td>
			<td style="width:119px;">Gibco</td>
			<td style="width:119px;">11875093</td>
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quantification of antibody-dependent enhancement of the zika virus in primary human cells

The recent emergence of the flavivirus Zika and neurological complications, such as Guillain-Barr&#233; syndrome and microcephaly in infants, has brought serious public safety concerns. Among the risk factors, antibody-dependent enhancement (ADE) poses the most significant threat, as the recent re-emergence of the Zika virus (ZIKV) is primarily in areas where the population has been exposed and is in a state of pre-immunity to other closely related flaviviruses, especially dengue virus (DENV). Here, we describe a protocol for quantifying the effect of human serum antibodies against DENV on ZIKV infection in primary human cells or cell lines.

In Figure 1, there is a step-by-step diagrammatic illustration of all the steps involved to carry out the ADE protocol. It is a schematic diagram showing the whole procedure of ADE of ZIKV due to pre-existing immunity to DENV. Figure 2 shows how human serum samples were categorized into three different groups: DENV infection-confirmed samples are referred to as the DENV-infected group, DENV antibody-confirmed samples are referred...

Watch this Scientific Journal Video about Quantification of Antibody-dependent Enhancement of the Zika Virus in Primary Human Cells at JoVE.com

Quantification of Antibody-dependent Enhancement of the Zika Virus in Primary Human Cells

We describe a method to evaluate the effect of pre-existing immunity against dengue virus on the Zika virus infection by using human serum, primary human cells, and infection quantification by quantitative real-time polymerase chain reaction.

The recent emergence of the flavivirus Zika and neurological complications, such as Guillain-Barr&#233; syndrome and microcephaly in infants, has brought ...

This method can be used to evaluate the effects of pre-existing immunity against dengue virus on Zika virus infection, using actual human patient serum and primary human immune cells. The use of actual human patient serum samples and human primary cells provide deeper insight into the antibody dependent enhancement of Zika virus by pre-immune sera and antibodies. This method provides insight into the ability of antibodies within a patient's blood to enhance a virus infection in other human cells.It is important to ensure that the viral infection levels are high enough for detection but low enough not to overwhelm the cells or to interfere with the data interpretation. Begin by seeding three times ten to the fourth cells in 100 microliters of cell culture medium per well in a sterile, flat bottom 96-well plate. When all the cells have been plated, place the plate in a 37 degree Celsius and 5%carbon dioxide incubator and make 10 fold serial dilutions of thawed human serum samples in serum free medium.Be sure to keep the serum dilutions and dilution factor constant for all the pre-immune serums before adding the dilutions to the virus solutions and the cells. Next, thaw Zika virus strains stock solution in a 37 degree Celsius water bath for one to two minutes before quickly transferring the stock to ice. Add a 0.1 multiplicity of infection equivalent volume of Zika virus to the serum aliquots and place the plate in the cell culture incubator for one hour to allow the dengue virus antibodies to form complexes with the Zika virions.At the end of the incubation, wash the cells with 100 microliters of PBS per well and add 50 microliters of immune complex to each well. After the two hour incubation, remove the medium and wash the wells twice with 100 microliters of PBS per well to completely remove the immune complexes and any unattached virions. Then feed the cells with 100 microliters per well of cell culture medium supplemented with 10%fetal bovine serum.Then return the cells to the cell culture incubator for 48 hours. Two days after the infection, wash the cells two times with 100 microliters of sterile PBS per well before adding 250 microliters of cell lysis buffer with 10%beta mercaptoethanol to each well. Pipette up and down at least five times with scratching to speed up the lysis process and transfer the cell lysates to sterile labeled 1.5 milliliter tubes.Add an equal volume of 70%ethanol to each tube and pipette the lysate solution up and down four to five times. When the lysate suspensions are clear, transfer each solution into labeled silica-based columns in two milliliter collection tubes for centrifugation. Discard the flow-through keeping the columns in the same collection tubes and add 700 microliters of Wash Buffer 1 to each column for a second centrifugation.After discarding the flow-through, rinse the columns two more times with 500 microliters of Wash Buffer two per wash. After the second wash, transfer the columns to new two milliliter collection tubes for another centrifugation. Add 30 microliters of 42 degree Celsius RNase-Free water to the center of each column for centrifugation and recover the eluted RNA.For quantitative real-time polymerase chain reaction or QRTPCR analysis add one microliter of gene specific forward and reverse primers from 10 micromolar stocks along with 0.25 microliters of reverse transcriptase mix per reaction. Note that primers which recognize Zika virus genetic material will detect viral genes and allow for infection quantification. Next, add 12.5 microliters of SYBR Green Mix followed by 25 microliters of water to each reaction adding 15 microliters of Master Mix in each well of 96-well QPCR plate.When using a Master Mix, add 100 nanograms of the RNA sample to the mix and pipette the Master Mix into individual wells of the QRTPCR plate. Note that samples should be run in triplicate on the same QRTPCR plate. Then run the samples on a quantitative PCR machine according to the parameters outlined in the table.Clicking the melt curve tab in the system software to monitor the melt curve. The melt curve will show single peak in all of the samples for a particular gene to confirm the presence of only one amplicon. For optimum results, use 0.5 degree Celsius temperature increments between steps and a minimum holding time of 10 seconds in the melt curve protocol.Then click the quantification data tab to obtain a quantitative cycle for each sample and export the data to a spreadsheet for further quantification analysis. The human serum samples can be categorized into three different groups:dengue virus infection confirmed samples, dengue virus antibody confirmed samples, and healthy sera with no dengue virus neutralizing antibodies or RNA. After 48 hours of infection, QRTPCR analysis demonstrates that most sera containing dengue virus serotype one to four antibodies are able to enhance Zika virus replication at different levels.The highest increase in Zika virus titres is found in macrophages treated with sera-containing dengue virus serotype two and four antibodies compared to serotype one and three which show a relatively lower induction of Zika virus. It is important to maintain a sterile environment, to wear the proper personal protection equipment, and to always keep the thawed virus serum samples and QPCR reagents on ice. This protocol can easily be modified to study antibody-dependent enhancement of other flavivirus such as yellow fever virus, dengue virus, or West Nile virus using a panel of patient serum.This technique will be highly useful for carrying out future antibody-dependent enhancement studies in the arbovirus or virology fields. Proper biosafety level two personal protection equipment should be used at all times and all viral waste should be decontaminated in 10%bleach for 30 minutes before disposal.

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Immunology and Infection

piggyBac Transposon System Modification of Primary Human T Cells

The piggyBac transposon system is naturally active, originally derived from the cabbage looper moth1,2. This non-viral system is plasmid based, most commonly utilizing two plasmids with one expressing the piggyBac transposase enzyme and a transposon plasmid harboring the gene(s) of interest between inverted repeat elements which are required for gene transfer activity. PiggyBac mediates gene transfer through a "cut and paste" mechanism whereby the transposase integrates the transposon segment into the genome of the target cell(s) of interest. PiggyBac has demonstrated efficient gene delivery activity in a wide variety of insect1,2, mammalian3-5, and human cells6 including primary human T cells7,8. Recently, a hyperactive piggyBac transposase was generated improving gene transfer efficiency9,10.
Human T lymphocytes are of clinical interest for adoptive immunotherapy of cancer11. Of note, the first clinical trial involving transposon modification of human T cells using the Sleeping beauty transposon system has been approved12. We have previously evaluated the utility of piggyBac as a non-viral methodology for genetic modification of human T cells. We found piggyBac to be efficient in genetic modification of human T cells with a reporter gene and a non-immunogenic inducible suicide gene7. Analysis of genomic integration sites revealed a lack of preference for integration into or near known proto-oncogenes13. We used piggyBac to gene-modify cytotoxic T lymphocytes to carry a chimeric antigen receptor directed against the tumor antigen HER2, and found that gene-modified T cells mediated targeted killing of HER2-positive tumor cells in vitro and in vivo in an orthotopic mouse model14. We have also used piggyBac to generate human T cells resistant to rapamycin, which should be useful in cancer therapies where rapamycin is utilized15.
Herein, we describe a method for using piggyBac to genetically modify primary human T cells. This includes isolation of peripheral blood mononuclear cells (PBMCs) from human blood followed by culture, gene modification, and activation of T cells. For the purpose of this report, T cells were modified with a reporter gene (eGFP) for analysis and quantification of gene expression by flow cytometry.
PiggyBac can be used to modify human T cells with a variety of genes of interest. Although we have used piggyBac to direct T cells to tumor antigens14, we have also used piggyBac to add an inducible safety switch in order to eliminate gene modified cells if needed7. The large cargo capacity of piggyBac has also enabled gene transfer of a large rapamycin resistant mTOR molecule (15 kb)15. Therefore, we present a non-viral methodology for stable gene-modification of primary human T cells for a wide variety of purposes.

piggyBac Transposon System Modification of Primary Human T Cells

We describe a method to genetically modify primary human T cells with a transgene using the non-viral piggyBac transposon system. T cells modified to using the piggyBac transposon system exhibit stable transgene expression.

The piggyBac transposon system is naturally active, originally derived from the cabbage looper moth1,2. This non-viral system is plasmid based, most ...

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 ...

Zika Virus Infectious Cell Culture System and the In Vitro Prophylactic Effect of Interferons

Zika Virus (ZIKV) is an emerging pathogen that is linked to fetal developmental abnormalities such as microcephaly, eye defects, and impaired growth. ZIKV is an RNA virus of the Flaviviridae family. ZIKV is mainly transmitted by mosquitoes, but can also be spread by maternal to fetal vertical transmission as well as sexual contact. To date, there are no reliable treatment or vaccine options available to protect those infected by the virus. The development of a reproducible, effective Zika virus infectious cell culture system is critical for studying the molecular mechanisms of ZIKV replication as well as drug and vaccine development. In this regard, a protocol describing a mammalian cell-based in vitro Zika virus culture system for viral production and growth analysis is reported here. Details on the formation of plaques by Zika virus on a cell monolayer and plaque assay for measuring viral titer are presented. Viral genome replication kinetics and double-stranded RNA genome replicatory intermediates are determined. This culture platform was utilized to screen against a library of a small set of cytokines resulting in the identification of interferon-&#945; (IFN-&#945;), IFN-&#946; and IFN-&#947; as potent inhibitors of Zika viral growth. In summary, an in vitro infectious Zika viral culture system and various virological assays are demonstrated in this study, which has the potential to greatly benefit the research community in elucidating further the mechanisms of viral pathogenesis and the evolution of viral virulence. Antiviral IFN-alpha can further be evaluated as a prophylactic, post-exposure prophylactic, and treatment option for Zika virus infections in high-risk populations, including infected pregnant women.

Zika Virus Infectious Cell Culture System and the In Vitro Prophylactic Effect of Interferons

Zika Virus (ZIKV), an emerging pathogen, is linked to fetal developmental abnormalities and microcephaly. The establishment of an effective infectious cell culture system is crucial for studies of ZIKV replication as well as vaccine and drug development. In this study, various virological assays pertaining to ZIKV are illustrated and discussed.

Zika Virus (ZIKV) is an emerging pathogen that is linked to fetal developmental abnormalities such as microcephaly, eye defects, and impaired growth. ZIKV ...

Dextran Enhances the Lentiviral Transduction Efficiency of Murine and Human Primary NK Cells

The efficient transduction of specific genes into natural killer (NK) cells has been a major challenge. Successful transductions are critical to defining the role of the gene of interest in the development, differentiation, and function of NK cells. Recent advances related to chimeric antigen receptors (CARs) in cancer immunotherapy accentuate the need for an efficient method to deliver exogenous genes to effector lymphocytes. The efficiencies of lentiviral-mediated gene transductions into primary human or mouse NK cells remain significantly low, which is a major limiting factor. Recent advances using cationic polymers, such as polybrene, show an improved gene transduction efficiency in T cells. However, these products failed to improve the transduction efficiencies of NK cells. This work shows that dextran, a branched glucan polysaccharide, significantly improves the transduction efficiency of human and mouse primary NK cells. This highly reproducible transduction methodology provides a competent tool for transducing human primary NK cells, which can vastly improve clinical gene delivery applications and thus NK cell-based cancer immunotherapy.

The goal of this study was to formulate technologies that allow for successful gene transduction in primary natural killer (NK) cells. The dextran-mediated lentiviral transduction of human or mouse primary NK cells results in higher gene expression efficiencies. This method of gene transduction will vastly improve NK cell genetic manipulation.

The efficient transduction of specific genes into natural killer (NK) cells has been a major challenge. Successful transductions are critical to defining ...

Rescue and Characterization of Recombinant Virus from a New World Zika Virus Infectious Clone

Infectious cDNA clones allow for genetic manipulation of a virus, thus facilitating work on vaccines, pathogenesis, replication, transmission and viral evolution. Here we describe the construction of an infectious clone for Zika virus (ZIKV), which is currently causing an explosive outbreak in the Americas. To prevent toxicity to bacteria that is commonly observed with flavivirus-derived plasmids, we generated a two-plasmid system which separates the genome at the NS1 gene and is more stable than full-length constructs that could not be successfully recovered without mutations. After digestion and ligation to join the two fragments, full-length viral RNA can be generated by in vitro transcription with T7 RNA polymerase. Following electroporation of transcribed RNA into cells, virus was recovered that exhibited similar in vitro growth kinetics and in vivo virulence and infection phenotypes in mice and mosquitoes, respectively.

This protocol describes the recovery of infectious Zika virus from a two-plasmid infectious cDNA clone.

Infectious cDNA clones allow for genetic manipulation of a virus, thus facilitating work on vaccines, pathogenesis, replication, transmission and viral ...

Zika Virus Specific Diagnostic Epitope Discovery

High-density peptide microarrays allow screening of more than six thousand peptides on a single standard microscopy slide. This method can be applied for drug discovery, therapeutic target identification, and developing of diagnostics. Here, we present a protocol to discover specific Zika virus (ZIKV) diagnostic peptides using a high-density peptide microarray. A human serum sample validated for ZIKV infection was incubated with a high-density peptide microarray containing the entire ZIKV protein translated into 3,423 unique 15 linear amino acid (aa) residues with a 14-aa residue overlap printed in duplicate. Staining with different secondary antibodies within the same array, we detected peptides that bind to Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibodies present in serum. These peptides were selected for further validation experiments. In this protocol, we describe the strategy followed to design, process, and analyze a high-density peptide microarray.

In this protocol, we describe a technique to discover Zika virus specific diagnostic peptides using a high-density peptide microarray. This protocol can readly be adapted for other emerging infectious diseases.

High-density peptide microarrays allow screening of more than six thousand peptides on a single standard microscopy slide. This method can be applied for ...

A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum

Antibody dependent enhancement of infection has been shown to play a major role in Dengue viral pathogenesis. Traditional assays that measure the capacity of antibodies or serum to enhance infection in impermissible cell lines have relied on using viral output in the media followed by plaque assays to quantify infection. More recently, these assays have examined Dengue virus (DENV) infection in the cell lines using fluorescently labeled antibodies. Both these approaches have limitations that restrict the widespread use of these techniques. Here, we describe a simple in vitro assay using Dengue virus reporter viral particles (RVPs) that express green fluorescent protein and K562 cells to examine antibody dependent enhancement (ADE) of DENV infection using serum that was obtained from rhesus macaques 16 weeks after infection with Zika virus (ZIKV). This technique is reliable, involves minimal manipulation of cells, does not involve the use of live replication competent virus, and can be performed in a high throughput format to get a quantitative readout using flow cytometry. Additionally, this assay can be easily adapted to examine antibody dependent enhancement (ADE) of other flavivirus infections such as Yellow Fever virus (YFV), Japanese Equine Encephalitis virus (JEEV), West Nile virus (WNV) etc. where RVPs are available. The ease of setting up the assay, analyzing the data, and interpreting results makes it highly amenable to most laboratory settings.

A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum

We describe a simple and easy protocol for measuring antibody dependent enhancement of infection by Zika virus convalescent serum using Dengue virus Reporter Viral Particles.

Antibody dependent enhancement of infection has been shown to play a major role in Dengue viral pathogenesis. Traditional assays that measure the capacity ...

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and damaging the testes. During an infection with the ZIKV, immune cells have been shown to infiltrate into the tissues. However, the cellular mechanisms that define the protection and/or immunopathogenesis of these immune cells during a ZIKV infection are still largely unknown. Herein, we describe methods to evaluate the virus-specific T-cell functionality in these immunoprivileged organs of ZIKV-infected mice. These methods include a) a ZIKV infection and vaccine inoculation in Ifnar1-/- mice; b) histopathology, immunofluorescence, and immunohistochemistry assays to detect the virus infection and inflammation in the brain, testes, and spleen; c) the preparation of a tetramer of ZIKV-derived T-cell epitopes; d) the detection of ZIKV-specific T cells in the monocytes isolated from the brain, testes, and spleen. Using these approaches, it is possible to detect the antigen-specific T cells that have infiltrated into the immunoprivileged organs and to evaluate the functions of these T cells during the infection: potential immune protection via virus clearance and/or immunopathogenesis to exacerbate the inflammation. These findings may also help to clarify the contribution of T cells induced by the immunization against ZIKV.

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

A protocol to evaluate antigen-specific T-cell responses in the immunoprivileged organs of the Ifnar1-/- murine model for the Zika virus (ZIKV) infection is described. This method is pivotal for investigating the cellular mechanisms of the protection and immunopathogenesis of ZIKV vaccines and is also valuable for their efficacy evaluation.

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and ...

Rescue of Recombinant Zika Virus from a Bacterial Artificial Chromosome cDNA Clone

The association of Zika virus (ZIKV) infection with neurological complications during the recent worldwide outbreak and the lack of approved vaccines and/or antivirals have underscored the urgent need to develop ZIKV reverse genetic systems to facilitate the study of ZIKV biology and the development of therapeutic and/or prophylactic approaches. However, like with other flaviviruses, the generation of ZIKV full-length infectious cDNA clones has been hampered due to the toxicity of viral sequences during its amplification in bacteria. To overcome this problem, we have developed a nontraditional approach based on the use of bacterial artificial chromosomes (BACs). Using this approach, the full-length cDNA copy of the ZIKV strain Rio Grande do Norte Natal (ZIKV-RGN) is generated from four synthetic DNA fragments and assembled into the single-copy pBeloBAC11 plasmid under the control of the human cytomegalovirus (CMV) immediate-early promoter. The assembled BAC cDNA clone is stable during propagation in bacteria, and infectious recombinant (r)ZIKV is recovered in Vero cells after transfection of the BAC cDNA clone. The protocol described here provides a powerful technique for the generation of infectious clones of flaviviruses, including ZIKV, and other positive-strand RNA viruses, particularly those with large genomes that have stability problems during bacterial&#160;propagation.

The recent epidemic of Zika virus highlights the importance of establishing reverse genetic approaches to develop vaccines and/or therapeutic strategies. Here, we describe the protocol to rescue an infectious recombinant Zika virus from a full-length cDNA clone assembled in a bacterial artificial chromosome under the control of the human cytomegalovirus immediate-early promoter.

The association of Zika virus (ZIKV) infection with neurological complications during the recent worldwide outbreak and the lack of approved vaccines ...

Isolation and Quantification of Zika Virus from Multiple Organs in a Mouse

The methods being presented demonstrate laboratory procedures for the isolation of organs from Zika virus infected animals and the quantification of viral load. The purpose of the procedure is to quantify viral titers in peripheral and CNS areas of the mouse at different time points post infection or under different experimental conditions to identify virologic and immunological factors that regulate Zika virus infection. The organ isolation procedures demonstrated allow for both focus forming assay quantification and quantitative PCR assessment of viral titers. The rapid organ isolation techniques are designed for the preservation of virus titer. Viral titer quantification by focus forming assay allows for the rapid throughput assessment of Zika virus. The benefit of the focus forming assay is the assessment of infectious virus, the limitation of this assay is the potential for organ toxicity reducing the limit of detection. Viral titer assessment is combined with quantitative PCR, and using a recombinant RNA copy control viral genome copy number within the organ is assessed with low limit of detection. Overall these techniques provide an accurate rapid high throughput method for the analysis of Zika viral titers in the periphery and CNS of Zika virus infected animals and can be applied to the assessment of viral titers in the organs of animals infected with most pathogens, including Dengue virus.

The goal of the protocol is to demonstrate the techniques used to investigate viral disease by isolating and quantifying Zika virus, from multiple organs in a mouse following infection.

The methods being presented demonstrate laboratory procedures for the isolation of organs from Zika virus infected animals and the quantification of viral ...