We thank Britta Weseloh and Bettina Abel for technical assistance. We also thank Arne D&#252;sedau and Jana Hennesen (flow cytometry technology platform, Heinrich Pette Institut) for technical support.

<ol>
	<li>Hughes, S. H., Coffin, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+Integration+Sites+Tell+Us+about+HIV+Persistence.">What Integration Sites Tell Us about HIV Persistence.</a> Cell Host and Microbe. 19 (5), 588-598 (2016).</li><li>Marini, B., Kertesz-Farkas, 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=Nuclear+architecture+dictates+HIV-1+integration+site+selection.">Nuclear architecture dictates HIV-1 integration site selection.</a> Nature. 521 (7551), 227-231 (2015).</li><li>Cesana, D., Santoni de Sio, F. 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=HIV-1-mediated+insertional+activation+of+STAT5B+and+BACH2+trigger+viral+reservoir+in+T+regulatory+cells.">HIV-1-mediated insertional activation of STAT5B and BACH2 trigger viral reservoir in T regulatory cells.</a> Nature Communications. 8 (1), 498 (2017).</li><li>Cohn, L. B., Silva, I. T., 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=HIV-1+Integration+Landscape+during+Latent+and+Active+Infection.">HIV-1 Integration Landscape during Latent and Active Infection.</a> Cell. 160 (3), 420-432 (2015).</li><li>Han, Y., Lassen, 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=Resting+CD4++T+cells+from+human+immunodeficiency+virus+type+1+(HIV-1)-infected+individuals+carry+integrated+HIV-1+genomes+within+actively+transcribed+host+genes.">Resting CD4+ T cells from human immunodeficiency virus type 1 (HIV-1)-infected individuals carry integrated HIV-1 genomes within actively transcribed host genes.</a> Journal of Virology. 78 (12), 6122-6133 (2004).</li><li>Ikeda, T., Shibata, J., Yoshimura, K., Koito, A., Matsushita, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recurrent+HIV-1+integration+at+the+BACH2+locus+in+resting+CD4++T+cell+populations+during+effective+highly+active+antiretroviral+therapy.">Recurrent HIV-1 integration at the BACH2 locus in resting CD4+ T cell populations during effective highly active antiretroviral therapy.</a> The Journal of Infectious Diseases. 195 (5), 716-725 (2007).</li><li>Wagner, T. A., Mclaughlin, S., 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=Proliferation+of+cells+with+HIV+integrated+into+cancer+genes+contributes+to+persistent+infection.">Proliferation of cells with HIV integrated into cancer genes contributes to persistent infection.</a> Science. 345 (6196), 570-573 (2014).</li><li>Maldarelli, F., Wu, X., 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=Specific+HIV+integration+sites+are+linked+to+clonal+expansion+and+persistence+of+infected+cells.">Specific HIV integration sites are linked to clonal expansion and persistence of infected cells.</a> Science. 345 (6193), 179-183 (2014).</li><li>Jordan, A., Bisgrove, D., Verdin, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HIV+reproducibly+establishes+a+latent+infection+after+acute+infection+of+T+cells+in+vitro.">HIV reproducibly establishes a latent infection after acute infection of T cells in vitro.</a> The EMBO Journal. 22 (8), 1868-1877 (2003).</li><li>Mack, K. D., Jin, X., 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=HIV+insertions+within+and+proximal+to+host+cell+genes+are+a+common+finding+in+tissues+containing+high+levels+of+HIV+DNA+and+macrophage-associated+p24+antigen+expression.">HIV insertions within and proximal to host cell genes are a common finding in tissues containing high levels of HIV DNA and macrophage-associated p24 antigen expression.</a> Journal of Acquired Immune Deficiency Syndromes. 33 (3), 308-320 (2003).</li><li>Byrne, S. M., Ortiz, L., Mali, P., Aach, J., Church, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-kilobase+homozygous+targeted+gene+replacement+in+human+induced+pluripotent+stem+cells.">Multi-kilobase homozygous targeted gene replacement in human induced pluripotent stem cells.</a> Nucleic Acids Research. 43 (3), 1-12 (2014).</li><li>CRISPR Genome Engineering Toolbox: Target Sequence Cloning Protocol. Addgene website Available from: <a target="_blank" href="https://www.addgene.org/static/cms/filer_public/e6/5a/e65a9ef8-c8ac-4f88-98da-3b7d7960394c/zhang-lab-general-cloning-protocol.pdf">https://www.addgene.org/static/cms/filer_public/e6/5a/e65a9ef8-c8ac-4f88-98da-3b7d7960394c/zhang-lab-general-cloning-protocol.pdf</a> (2013)</li><li>Gibson Assembly Protocol. Addgene website Available from: <a target="_blank" href="https://www.addgene.org/protocols/gibson-assembly/">https://www.addgene.org/protocols/gibson-assembly/</a> (2009)</li><li>Addgene Plasmid Cloning by PCR. Addgene website Available from: <a target="_blank" href="https://www.addgene.org/protocols/pcr-cloning/">https://www.addgene.org/protocols/pcr-cloning/</a> (2014)</li><li>Addgene Plasmid Cloning by Restriction Enzyme Digest (aka Subcloning). Addgene website Available from: <a target="_blank" href="https://www.addgene.org/protocols/subcloning/">https://www.addgene.org/protocols/subcloning/</a> (2013)</li><li>Stemmer, M., Thumberger, T., Del Sol Keyer, M., Wittbrodt, J., Mateo, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CCTop:+An+intuitive,+flexible+and+reliable+CRISPR-Cas9+target+prediction+tool.">CCTop: An intuitive, flexible and reliable CRISPR-Cas9 target prediction tool.</a> Public Library of Science (PLoS) ONE. 10 (4), (2015).</li><li>Lange, U. C., Bialek, J. K., Walther, T., Hauber, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pinpointing+recurrent+proviral+integration+sites+in+new+models+for+latent+HIV-1+infection.">Pinpointing recurrent proviral integration sites in new models for latent HIV-1 infection.</a> Virus Research. 249, (2018).</li><li>Bialek, J. K., Dunay, G. 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=Targeted+HIV-1+Latency+Reversal+Using+CRISPR-Cas9-Derived+Transcriptional+Activator+Systems.">Targeted HIV-1 Latency Reversal Using CRISPR-Cas9-Derived Transcriptional Activator Systems.</a> PloS ONE. 11 (6), e0158294 (2016).</li><li>Lee, C. M., Davis, T. H., Bao, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Examination+of+CRISPR-Cas9+design+tools+and+the+effect+of+target+site+accessibility+on+Cas9+activity.">Examination of CRISPR-Cas9 design tools and the effect of target site accessibility on Cas9 activity.</a> Experimental Physiology. 103 (4), 456-460 (2018).</li><li>Jensen, K. T., Fl&#248;e, 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=Chromatin+accessibility+and+guide+sequence+secondary+structure+affect+CRISPR-Cas9+gene+editing+efficiency.">Chromatin accessibility and guide sequence secondary structure affect CRISPR-Cas9 gene editing efficiency.</a> FEBS Letters. 591 (13), 1892-1901 (2017).</li><li>Simonetti, F. R., Sobolewski, M. 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=Clonally+expanded+CD4+++T+cells+can+produce+infectious+HIV-1+in+vivo.">Clonally expanded CD4 + T cells can produce infectious HIV-1 in vivo.</a> Proceedings of the National Academy of Sciences. 113 (7), 1883-1888 (2016).</li><li>Chen, H. C., Martinez, J. P., Zorita, E., Meyerhans, A., Filion, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Position+effects+influence+HIV+latency+reversal.">Position effects influence HIV latency reversal.</a> Nature Structural and Molecular Biology. 24 (1), 47-54 (2017).</li></ol>

The authors have nothing to disclose.

Here, we describe a protocol to generate HIV-1-derived Jurkat reporter models with chosen proviral integration sites applying CRISPR-Cas9-based genome engineering.
Several points of the protocol require careful attention during the planning stage. First, the locus to be targeted should be chosen carefully, as some loci might be easier to target than others (e.g., depending on the chromatin status of the region and the target sequence itself). Repetitive sequences are hard to clone int...

Integration of proviral DNA into the host genome upon infection is a critical step in the life cycle of human immunodeficiency virus (HIV). Following integration, HIV persists by establishing latency in long-lived CD4+ T cell subsets such as memory CD4+ T cells. HIV integration appears to be non-random1,2. A number of genomic hotspots with recurrently integrated proviral DNA has been detected in several studies through the sequencing of integration sites in acutely and chronically infected individuals2,3,4,5,6,7,8. Interestingly, at some of these integration sites, the same locus was detected in a large fraction of infected cells, leading to the idea that integration at recurrent sites might positively affect clonal expansion1.
To advance our understanding of the significance of recurrent integration sites, proviral integration site choice must be explored. However, several technical aspects hamper studying HIV integration site choice and the consequences. Broadly used cell culture models for HIV latency like JLat cell lines do not reflect clinically relevant recurrent integration sites9. Studies on primary patient-derived cells, on the one hand, enable description of integration site landscape by sequencing but do not allow for functional analyses. To our knowledge, no adequate experimental model is available to functionally analyze selected clinically relevant integration sites.
Here we present a detailed workflow to generate novel models for HIV infection using CRISPR-Cas9-based genome engineering technology. The workflow described herein can be used to generate T cell-derived reporter cell lines that model HIV infection, carrying a genomically integrated proviral reporter at a chosen integration site. They are thus serving as new tools to explore how the proviral integration site can impact HIV biology and how the provirus responds to different treatment strategies (e.g., inducibility by latency reversing agents). Our method uses the advantages of CRISPR-Cas9-based genome engineering, in which integration of the reporter sequence by homologous recombination is facilitated by a Cas9 nuclease-induced double-strand break at the target site. Target sites for integration are chosen according to proximity to the described recurrent integration sites from studies on HIV-infected individuals and the presence of suitable PAM motifs for Cas9-mediated genome engineering.
In our exemplary results, we have focused on the BACH2 gene locus, which codes for the BTB And CNC Homology transcriptional regulator 2. In chronically HIV-infected individuals on antiretroviral therapy, BACH2 is one of the loci showing enrichment of integrated HIV-1 sequences3,6,7,8,10. We have chosen a minimal HIV-derived reporter consisting of HIV-1-derived long terminal repeat (LTR), tdTomato coding sequence, and bovine growth hormone (BGH) polyadenylation signal (PA), which we have targeted to two specific sites in BACH2 intron 5. The presented protocol is optimized for Jurkat cells, a human CD4+ T cell-derived suspension cell line, but other cell lines may be used and the protocol adapted accordingly. We present a detailed workflow for selection of target site, construction of target vector with homology arms, CRISPR-Cas9-mediated targeting of the reporter into the chosen genomic site, generation and selection of clonal lines, and comprehensive verification of newly generated, targeted reporter cell lines.

<table><tbody><tr><td>pX330-U6-Chimeric_BB-cBh-hSpCas9</td><td>Addgene</td><td>42230</td><td>vector for expression of SpCas9 and gRNA</td></tr><tr><td>pMK</td><td>GeneArt</td><td></td><td>mammalian expression vector for cloning</td></tr><tr><td>cDNA3.1</td><td>Invitrogen</td><td>V79020</td><td>mammalian expression vector for cloning</td></tr><tr><td>BbsI</td><td>New England Biolabs</td><td>R0539S</td><td>restriction enzyme</td></tr><tr><td>NEBuilder Hifi DNA Assembly Cloning Kit</td><td>New England Biolabs</td><td>E5520S</td><td>Assembly cloning kit used for target vector generation</td></tr><tr><td>TaqPlus Precision PCR System</td><td>Agilent Technologies</td><td>600210</td><td>DNA polymerase with proofreading activity used for amplification of homology arms (step 1.2.2.2), verification of integration site and reporter sequence (step 3.3.3 and 3.3.5), generation of genomic probe for Southern blot (step 3.4.1.5) and analysis of off-target events (step 3.5.4)</td></tr><tr><td>96-well tissue culture plate (round-bottom)</td><td>TPP</td><td>92097</td><td>tissue culture plates for dilution plating</td></tr><tr><td>Phusion High-Fidelity DNA polymerase</td><td>New England Biolabs</td><td>M0530 L</td><td>DNA polymerase used for detection of targeting events (step 2.4.2) and generation ofreporter-specific probe for Southern blot (step 3.4.1.4)</td></tr><tr><td>Dimethyl sulfoxide (DMSO)</td><td>Sigma-Aldrich</td><td>D9170</td><td>dimethyl sulfoxide as PCR additive</td></tr><tr><td>Magnesium Chloride (MgCl&lt;sub&gt;2&lt;/sub&gt;) Solution</td><td>New England Biolabs</td><td>B9021S</td><td>MgCl&lt;sub&gt;2&lt;/sub&gt; solution as PCR additive</td></tr><tr><td>Deoxynucleotide (dNTP) Solution Mix</td><td>New England Biolabs</td><td>N0447S</td><td>dNTP mixture with 10 mM of each nt for PCR reactions</td></tr><tr><td>5PRIME HotMasterMix</td><td>5PRIME</td><td>2200400</td><td>ready-to-use PCR mix used for screening PCR (step 3.2.11)</td></tr><tr><td>QIAamp DNA blood mini kit</td><td>Qiagen</td><td>51106</td><td>DNA isolation and purification kit</td></tr><tr><td>QIAquick PCR Purification Kit</td><td>Qiagen</td><td>28106</td><td>PCR Purification Kit</td></tr><tr><td>RPMI 1640 without glutamine</td><td>Lonza</td><td>BE12-167F</td><td>cell culture medium</td></tr><tr><td>Fetal Bovine Serum South Africa Charge</td><td>PAN Biotech</td><td>P123002</td><td>cell culture medium supplement</td></tr><tr><td>L-glutamine</td><td>Biochrom</td><td>K 0282</td><td>cell culture medium supplement</td></tr><tr><td>Penicillin/Streptomycin 10.000 U/mL/ 10.000 &amp;micro;g/mL</td><td>Biochrom</td><td>A 2212</td><td>cell culture medium supplement</td></tr><tr><td>Gibco Opti-MEM Reduced Serum Media</td><td>Thermo Fisher Scientific</td><td>31985062</td><td>cell culture medium with reduced serum concentration optimized for transfection</td></tr><tr><td>TransIT-Jurkat</td><td>Mirus Bio</td><td>MIR2125</td><td>transfection reagent</td></tr><tr><td>phorbol 12-myristate 13-acetate</td><td>Sigma-Aldrich</td><td>P8139-1MG</td><td>cell culture reagent</td></tr><tr><td>Ionomycin</td><td>Sigma-Aldrich</td><td>I0634-1MG</td><td>cell culture reagent</td></tr><tr><td>Syringe-driven filter unit, PES membrane, 0,22 &amp;micro;m</td><td>Millex</td><td>SLGP033RB</td><td>filter unit for sterile filtration</td></tr><tr><td>Heracell 150i incubator</td><td>Thermo Fisher Scientific</td><td>51026280</td><td>tissue culture incubator</td></tr><tr><td>Amershan Hybond-N+</td><td>GE Healthcare</td><td>RPN1520B</td><td>positively charged nylon membrane for DNA and RNA blotting</td></tr><tr><td>Stratalinker 1800</td><td>Stratagene</td><td>400072</td><td>UV crosslinker</td></tr><tr><td>High Prime</td><td>Roche</td><td>11585592001</td><td>kit for labeling of DNA with radioactive dCTP using random oligonucleotides as primers</td></tr><tr><td>illustra ProbeQuant G-50 Micro Columns</td><td>GE Healthcare</td><td>28-9034-08</td><td>chromatography spin-columns for purification of labeled DNA</td></tr></tbody></table>

crispr-cas9-based genome engineering to generate jurkat reporter models for hiv-1 infection with selected proviral integration sites

Human immunodeficiency virus (HIV) integrates its proviral DNA non-randomly into the host cell genome at recurrent sites and genomic hotspots. Here we present a detailed protocol for the generation of novel in vitro models for HIV infection with chosen genomic integration sites using CRISPR-Cas9-based genome engineering technology. With this method, a reporter sequence of choice can be integrated into a targeted, chosen genomic locus, reflecting clinically relevant integration sites.
In the protocol, the design of an HIV-derived reporter and choosing of a target site and gRNA sequence are described. A targeting vector with homology arms is constructed and transfected into Jurkat T cells. The reporter sequence is targeted to the selected genomic site by homologous recombination facilitated by a Cas9-mediated double-strand break at the target site. Single-cell clones are generated and screened for targeting events by flow cytometry and PCR. Selected clones are then expanded, and correct targeting is verified by PCR, sequencing, and Southern blotting. Potential off-target events of CRISPR-Cas9-mediated genome engineering are analyzed.
By using this protocol, novel cell culture systems that model HIV infection at clinically relevant integration sites can be generated. Although the generation of single-cell clones and verification of correct reporter sequence integration is time-consuming, the resulting clonal lines are powerful tools to functionally analyze proviral integration site choice.

In this representative experiment we have chosen to target a minimal HIV-1-derived reporter consisting of a LTR, tdTomato-coding sequence, and polyA-signal sequence to two loci in intron 5 of the BACH2 gene17. The loci for targeting were chosen according to proximity to published recurrent integration sites found in different studies on primary T cells from HIV-infected patients2,4,<sup class="xr...

Watch this Scientific Journal Video about CRISPR-Cas9-based Genome Engineering to Generate Jurkat Reporter Models for HIV-1 Infection with Selected Proviral Integration Sites at JoVE.com

CRISPR-Cas9-based Genome Engineering to Generate Jurkat Reporter Models for HIV-1 Infection with Selected Proviral Integration Sites

We present a genome engineering workflow for the generation of new in vitro models for HIV-1 infection that recapitulate proviral integration at selected genomic sites. Targeting of HIV-derived reporters is facilitated by CRISPR-Cas9-mediated, site-specific genome manipulation. Detailed protocols for single-cell clone generation, screening, and correct targeting verification are provided.

Human immunodeficiency virus (HIV) integrates its proviral DNA non-randomly into the host cell genome at recurrent sites and genomic hotspots. Here we ...

crispr-cas9-based-genome-engineering-to-generate-jurkat-reporter

Research

JoVE Journal

Immunology and Infection

9.7K Views.  Leibniz Institute for Experimental Virology. Deze methode kan helpen bij het beantwoorden van de vraag hoe HIV provirus integratie beïnvloedt androgyne genexpressie, en waarom bepaalde genomische integratie sites worden geselecteerd in de laatste tijd HIV-geïnfecteerde cellen. Het belangrijkste voordeel van deze techniek is dat in-vitro modellen voor HIV-infectie kunnen worden geproduceerd, die pro-virale verslaggevers gericht op gekozen integratie sites met behulp van CRISPR / Cas9-gebaseerde genoom engineering. Het aantonen van de p...

Video: CRISPR-Cas9-based Genome Engineering to Generate Jurkat Reporter Models for HIV-1 Infection with Selected Proviral Integration Sites

Efficient Generation of hiPSC Neural Lineage Specific Knockin Reporters Using the CRISPR/Cas9 and Cas9 Double Nickase System

Gene targeting is a critical approach for characterizing gene functions in modern biomedical research. However, the efficiency of gene targeting in human cells has been low, which prevents the generation of human cell lines at a desired rate. The past two years have witnessed a rapid progression on improving efficiency of genetic manipulation by genome editing tools such as the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas (CRISPR-associated) system. This manuscript describes a protocol for generating lineage specific human induced pluripotent stem cell (hiPSC) reporters using CRISPR/Cas system assisted homologous recombination. Procedures for obtaining necessary components for making neural lineage reporter lines using the CRISPR/Cas system, focusing on construction of targeting vectors and single guide RNAs, are described. This protocol can be extended to platform establishment and mutation correction in hiPSCs.

Genome editing tools such as the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas (CRISPR-associated) system have greatly improved gene targeting efficiency in human induced pluripotent stem cells (hiPSCs). This manuscript describes a protocol for generating lineage specific hiPSC reporter using CRISPR/Cas system assisted homologous recombination.

Gene targeting is a critical approach for characterizing gene functions in modern biomedical research. However, the efficiency of gene targeting in human ...

Developmental Biology

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration of transgenes. However, due to the low efficiency of homologous recombination (HR) and various indel mutations of non-homologous end joining (NHEJ)-based strategies in non-dividing cells, in vivo genome editing remains a great challenge. Here, we describe a homology-mediated end joining (HMEJ)-based CRISPR/Cas9 system for efficient in vivo precise targeted integration. In this system, the targeted genome and the donor vector containing homology arms (~800 bp) flanked by single guide RNA (sgRNA) target sequences are cleaved by CRISPR/Cas9. This HMEJ-based strategy achieves efficient transgene integration in mouse zygotes, as well as in hepatocytes in vivo. Moreover, a HMEJ-based strategy offers an efficient approach for correction of fumarylacetoacetate hydrolase (Fah) mutation in the hepatocytes and rescues Fah-deficiency induced liver failure mice. Taken together, focusing on targeted integration, this HMEJ-based strategy provides a promising tool for a variety of applications, including generation of genetically modified animal models and targeted gene therapies.

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

The clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system provides a promising tool for genetic engineering, and opens up the possibility of targeted integration of transgenes. We describe a homology-mediated end joining (HMEJ)-based strategy for efficient DNA targeted integration in vivo and targeted gene therapies using CRISPR/Cas9.

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration ...

Genetics

Interview: HIV-1 Proviral DNA Excision Using an Evolved Recombinase

HIV-1 integrates into the host chromosome of infected cells and persists as a provirus flanked by long terminal repeats. Current treatment strategies primarily target virus enzymes or virus-cell fusion, suppressing the viral life cycle without eradicating the infection. Since the integrated provirus is not targeted by these approaches, new resistant strains of HIV-1 may emerge. Here, we report that the engineered recombinase Tre (see Molecular evolution of the Tre recombinase , Buchholz, F., Max Planck Institute for Cell Biology and Genetics, Dresden) efficiently excises integrated HIV-1 proviral DNA from the genome of infected cells. We produced loxLTR containing viral pseudotypes and infected HeLa cells to examine whether Tre recombinase can excise the provirus from the genome of HIV-1 infected human cells. A virus particle-releasing cell line was cloned and transfected with a plasmid expressing Tre or with a parental control vector. Recombinase activity and virus production were monitored. All assays demonstrated the efficient deletion of the provirus from infected cells without visible cytotoxic effects. These results serve as proof of principle that it is possible to evolve a recombinase to specifically target an HIV-1 LTR and that this recombinase is capable of excising the HIV-1 provirus from the genome of HIV-1-infected human cells.
Before an engineered recombinase could enter the therapeutic arena, however, significant obstacles need to be overcome. Among the most critical issues, that we face, are an efficient and safe delivery to targeted cells and the absence of side effects.

Current HIV-1 strategies act to suppress the viral life cycle but do not effectively eradicate infection. Here, we demonstrate that an engineered recombinase can efficiently excise integrated HIV-1 proviral DNA from the genome of infected cells.

HIV-1 integrates into the host chromosome of infected cells and persists as a provirus flanked by long terminal repeats. Current treatment strategies ...

Biology

Lentiviral Vector Platform for the Efficient Delivery of Epigenome-editing Tools into Human Induced Pluripotent Stem Cell-derived Disease Models

The use of hiPSC-derived cells represents a valuable approach to study human neurodegenerative diseases. Here, we describe an optimized protocol for the differentiation of hiPSCs derived from a patient with the triplication of the alpha-synuclein gene (SNCA) locus into Parkinson&#8217;s disease (PD)-relevant dopaminergic neuronal populations. Accumulating evidence has shown that high levels of SNCA are causative for the development of PD. Recognizing the unmet need to establish novel therapeutic approaches for PD, especially those targeting the regulation of SNCA expression, we recently developed a CRISPR/dCas9-DNA-methylation-based system to epigenetically modulate SNCA transcription by enriching methylation levels at the SNCA intron 1 regulatory region. To deliver the system, consisting of a dead (deactivated) version of Cas9 (dCas9) fused with the catalytic domain of the DNA methyltransferase enzyme 3A (DNMT3A), a lentiviral vector is used. This system is applied to cells with the triplication of the SNCA locus and reduces the SNCA-mRNA and protein levels by about 30% through the targeted DNA methylation of SNCA intron 1. The fine-tuned downregulation of the SNCA levels rescues disease-related cellular phenotypes. In the current protocol, we aim to describe a step-by-step procedure for differentiating hiPSCs into neural progenitor cells (NPCs) and the establishment and validation of pyrosequencing assays for the evaluation of the methylation profile in the SNCA intron 1. To outline in more detail the lentivirus-CRISPR/dCas9 system used in these experiments, this protocol describes how to produce, purify, and concentrate lentiviral vectors and to highlight their suitability for epigenome- and genome-editing applications using hiPSCs and NPCs. The protocol is easily adaptable and can be used to produce high titer lentiviruses for in vitro and in vivo applications.

Targeted DNA epigenome editing represents a powerful therapeutic approach. This protocol describes the production, purification, and concentration of all-in-one lentiviral vectors harboring the CRISPR-dCas9-DNMT3A transgene for epigenome-editing applications in human induced pluripotent stem cell (hiPSC)-derived neurons.

The use of hiPSC-derived cells represents a valuable approach to study human neurodegenerative diseases. Here, we describe an optimized protocol for the ...

Engineering Oncogenic Heterozygous Gain-of-Function Mutations in Human Hematopoietic Stem and Progenitor Cells

Throughout their lifetime, hematopoietic stem and progenitor cells (HSPCs) acquire somatic mutations. Some of these mutations alter HSPC functional properties such as proliferation and differentiation, thereby promoting the development of hematologic malignancies. Efficient and precise genetic manipulation of HSPCs is required to model, characterize, and better understand the functional consequences of recurrent somatic mutations. Mutations can have a deleterious effect on a gene and result in loss-of-function (LOF) or, in stark contrast, may enhance function or even lead to novel characteristics of a particular gene, termed gain-of-function (GOF). In contrast to LOF mutations, GOF mutations almost exclusively occur in a heterozygous fashion. Current genome-editing protocols do not allow for the selective targeting of individual alleles, hampering the ability to model heterozygous GOF mutations. Here, we provide a detailed protocol on how to engineer heterozygous GOF hotspot mutations in human HSPCs by combining CRISPR/Cas9-mediated homology-directed repair and recombinant AAV6 technology for efficient DNA donor template transfer. Importantly, this strategy makes use of a dual fluorescent reporter system to allow for the tracking and purification of successfully heterozygously edited HSPCs. This strategy can be employed to precisely investigate how GOF mutations affect HSPC function and their progression toward hematological malignancies.

Novel strategies to faithfully model somatic mutations in hematopoietic stem and progenitor cells (HSPCs) are necessary to better study hematopoietic stem cell biology and hematological malignancies. Here, a protocol to model heterozygous gain-of-function mutations in HSPCs by combining the use of CRISPR/Cas9 and dual rAAV donor transduction is described.

Throughout their lifetime, hematopoietic stem and progenitor cells (HSPCs) acquire somatic mutations. Some of these mutations alter HSPC functional ...

Cancer Research

Designing, Packaging, and Delivery of High Titer CRISPR Retro and Lentiviruses via Stereotaxic Injection

Replication defective lentiviruses or retroviruses are capable of stably integrating transgenes into the genome of an infected host cell. This technique has been widely used to encode fluorescent proteins, opto- or chemo-genetic controllers of cell activity, or heterologous expression of human genes in model organisms. These viruses have also successfully been used to deliver recombinases to relevant target sites in transgenic animals, or even deliver small hairpin or micro RNAs in order to manipulate gene expression. While these techniques have been fruitful, they rely on transgenic animals (recombinases) or frequently lack high efficacy and specificity (shRNA/miRNA). In contrast, the CRISPR/Cas system uses an exogenous Cas nuclease which targets specific sites in an organism's genome via an exogenous guide RNA in order to induce double stranded breaks in DNA. These breaks are then repaired by non-homologous end joining (NHEJ), producing insertion and deletion (indel) mutations that can result in deleterious missense or nonsense mutations. This manuscript provides detailed methods for the design, production, injection, and validation of single lenti/retro virus particles that can stably transduce neurons to express a fluorescent reporter, Cas9, and sgRNAs to knockout genes in a model organism.

The CRISPR/Cas9 system offers the potential to make targeted genome editing accessible and affordable to the scientific community. This protocol is intended to demonstrate how to create viruses that will knockout a gene of interest using the CRISPR/Cas9 system, and then inject them stereotaxically into the adult mouse brain.

Replication defective lentiviruses or retroviruses are capable of stably integrating transgenes into the genome of an infected host cell. This technique ...

Neuroscience

Generating Recombinant Avian Herpesvirus Vectors with CRISPR/Cas9 Gene Editing

Herpesvirus of turkeys (HVT) is an ideal viral vector for the generation of recombinant vaccines against a number of avian diseases, such as avian influenza (AI), Newcastle disease (ND), and infectious bursal disease (IBD), using bacterial artificial chromosome (BAC) mutagenesis or conventional recombination methods. The clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 system has been successfully used in many settings for gene editing, including the manipulation of several large DNA virus genomes. We have developed a rapid and efficient CRISPR/Cas9-mediated genome editing pipeline to generate recombinant HVT. To maximize the potential use of this method, we present here detailed information about the methodology of generating recombinant HVT expressing the VP2 protein of IBDV. The VP2 expression cassette is inserted into the HVT genome via an NHEJ (nonhomologous end-joining)-dependent repair pathway. A green fluorescence protein (GFP) expression cassette is first attached to the insert for easy visualization and then removed via the Cre-LoxP system. This approach offers an efficient way to introduce other viral antigens into the HVT genome for the rapid development of recombinant vaccines.

Herpesvirus of turkeys (HVT) is widely used as a vector platform for the generation of recombinant vaccines against a number of avian diseases. This article describes a simple and rapid approach for the generation of recombinant HVT-vectored vaccines using an integrated NHEJ-CRISPR/Cas9 and Cre-Lox system.

Herpesvirus of turkeys (HVT) is an ideal viral vector for the generation of recombinant vaccines against a number of avian diseases, such as avian ...

Lentiviral CRISPR/Cas9-Mediated Genome Editing for the Study of Hematopoietic Cells in Disease Models

Manipulating genes in hematopoietic stem cells using conventional transgenesis approaches can be time-consuming, expensive, and challenging. Benefiting from advances in genome editing technology and lentivirus-mediated transgene delivery systems, an efficient and economical method is described here that establishes mice in which genes are manipulated specifically in hematopoietic stem cells. Lentiviruses are used to transduce Cas9-expressing lineage-negative bone marrow cells with a guide RNA (gRNA) targeting specific genes and a red fluorescence reporter gene (RFP), then these cells are transplanted into lethally-irradiated C57BL/6 mice. Mice transplanted with lentivirus expressing non-targeting gRNA are used as controls. Engraftment of transduced hematopoietic stem cells are evaluated by flow cytometric analysis of RFP-positive leukocytes of peripheral blood. Using this method, ~90% transduction of myeloid cells and ~70% of lymphoid cells at 4 weeks after transplantation can be achieved. Genomic DNA is isolated from RFP-positive blood cells, and portions of the targeted site DNA are amplified by PCR to validate the genome editing. This protocol provides a high-throughput evaluation of hematopoiesis-regulatory genes and can be extended to a variety of mouse disease models with hematopoietic cell involvement.

Described are protocols for the highly efficient genome editing of murine hematopoietic stem and progenitor cells (HSPC) by the CRISPR/Cas9 system to rapidly develop mouse model systems with hematopoietic system-specific gene modifications.

Manipulating genes in hematopoietic stem cells using conventional transgenesis approaches can be time-consuming, expensive, and challenging. Benefiting ...

Retroviral Transduction of Guide RNA for Gene Editing in Th17 Differentiation

Retroviral CRISPR/Cas9-Mediated Gene Targeting for the Study of Th17 Differentiation in Vitro

T helper cells that produce IL-17A, known as Th17 cells, play a critical role in immune defense and are implicated in autoimmune disorders. CD4 T cells can be stimulated with antigens and well-defined cytokine cocktails in vitro to mimic Th17 cell differentiation in vivo. Research has been conducted extensively on the Th17 differentiation regulation mechanisms using the in vitro Th17 polarization assay.
Conventional Th17 polarization methods typically involve obtaining na&#239;ve CD4 T cells from genetically modified mice to study the effects of specific genes on Th17 differentiation and function. These methods can be time-consuming and costly and may be influenced by cell-extrinsic factors from the knockout animals. Thus, a protocol using retroviral transduction of guide RNA to introduce gene knockout in CRISPR/Cas9 knockin primary mouse T cells serves as a very useful alternative approach. This paper presents a protocol to differentiate na&#239;ve primary T cells into Th17 cells following retroviral-mediated gene targeting, as well as the subsequent flow cytometry analysis methods for assaying infection and differentiation efficiency.

We present a protocol for retroviral transduction of guide RNA into primary T cells from Cas9 transgenic mice, providing an efficient alternative for gene editing in studying Th17 differentiation.

T helper cells that produce IL-17A, known as Th17 cells, play a critical role in immune defense and are implicated in autoimmune disorders. CD4 T cells ...

Amplification, Next-generation Sequencing, and Genomic DNA Mapping of Retroviral Integration Sites

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of diverse libraries of retroviral integration sites using ligation-mediated PCR (LM-PCR) amplification and next-generation sequencing (NGS), (2) mapping the genomic location of each virus-host junction using BEDTools, and (3) analyzing the data for statistical relevance. Genomic DNA extracted from infected cells is fragmented by digestion with restriction enzymes or by sonication. After suitable DNA end-repair, double-stranded linkers are ligated onto the DNA ends, and semi-nested PCR is conducted using primers complementary to both the long terminal repeat (LTR) end of the virus and the ligated linker DNA. The PCR primers carry sequences required for DNA clustering during NGS, negating the requirement for separate adapter ligation. Quality control (QC) is conducted to assess DNA fragment size distribution and adapter DNA incorporation prior to NGS. Sequence output files are filtered for LTR-containing reads, and the sequences defining the LTR and the linker are cropped away. Trimmed host cell sequences are mapped to a reference genome using BLAT and are filtered for minimally 97% identity to a unique point in the reference genome. Unique integration sites are scrutinized for adjacent nucleotide (nt) sequence and distribution relative to various genomic features. Using this protocol, integration site libraries of high complexity can be constructed from genomic DNA in three days. The entire protocol that encompasses exogenous viral infection of susceptible tissue culture cells to integration site analysis can therefore be conducted in approximately one to two weeks. Recent applications of this technology pertain to longitudinal analysis of integration sites from HIV-infected patients.

We describe a protocol for amplifying retroviral integration sites from the genomic DNA of infected cells, sequencing the amplified virus-host junctions, and then mapping these sequences to a reference genome. We also describe techniques to quantify the distribution of integration sites relative to various genomic annotations using BEDTools.

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of ...

CRISPR-Cas9-based Genome Engineering to Generate Jurkat Reporter Models for HIV-1 Infection with Selected Proviral Integration Sites

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