C.K. is supported by Columbia University Graduate program. U.B. is Fellow of the Leukemia and Lymphoma Society of America, the recipient of New Investigator Award from the Leukemia Research Foundation and is supported by Columbia University New Faculty start-up funds.

1. Splenic B-Lymphocyte Isolation and Stimulation 
<ol>
	<li>Harvest the spleens from AID-deficient mice 12 between 2-3 months of age. The isolation of spleen is performed in sterile conditions and the organs are temporarily kept in cold phosphate buffer saline (PBS) containing 15% fetal bovine serum (FBS).</li>
	<li>The spleen is then transferred to a sterile tissue culture hood and homogenized in 5 mL of PBS supplemented with 2.5% FBS. Transfer the homogenate to a 15 mL falcon tube.</li>
	<li>Centrifuge the homogenized splenic tissue sample at 1000rpm for 10 minutes at 4&deg;C to pellet the cells. </li>
	<li>Decant the supernatant after centrifugation. Resuspend the cell pellet in 10 mL red blood cell (RBC) lysis buffer at room temperature for 7 minutes to avoid contamination by red blood cells.</li>
	<li>Centrifuge sample at 1000 rpm for 10 minutes and decant the supernatant and resuspend the cells in 10 mL PBS containing 2.5% FBS.</li>
	<li>Remove 100 &mu;L aliquot and count the cells at a 1:1000 dilution using a standard hemacytometer using trypan blue to exclude any dead cells. Approximately 20-30 million cells can be obtained per spleen.</li>
	<li>Centrifuge sample at 1000rpm for 10 minutes and decant the supernatant.</li>
	<li>Resuspend the pellet in 0.5%BSA/PBS containing 2mM EDTA at a concentration of 107cells per 90 &mu;L.</li>
	<li>Add anti-CD43 antibody coated magnetic beads to the cells to specifically bind non-B cells. Use 10 &mu;L beads per 90 &mu;L (107cells). Mix well and incubate at 4&deg;C for 20 minutes.</li>
	<li>Once the cells have been labeled, wash them by adding 2.5% FBS/PBS to top of the tube. Centrifuge sample at 1000 rpm for 10 minutes.</li>
	<li>Decant the supernatant. Resuspend the cells in 0.1% BSA/PBS at a concentration of 10x107cells per ml.</li>
	<li>Mount a magnetic sorting column on a magnetic separator. Position a conical tube directly underneath the column to collect the flow-through and load the column with 3mL 0.5% BSA/PBS to prime and wash.</li>
	<li>Once the wash fluid has flowed through, replace with a new collection tube. If the sample is less than 1 mL, adjust sample volume to 1 mL with 0.5 %BSA/PBS/EDTA and load the sample in the column. Load only 1 mL maximum of cells per column and use multiple columns if necessary. </li>
	<li>Allow the cells to passively flow through the column and collect the unbound cells in the conical tube under the column. Wash the column 4 times with 3 mL 0.5% BSA/PBS while continuing to collect the flow-through.</li>
	<li>Collect all flow-through in which CD43 negative resting B cells will be enriched. Discard the column. Centrifuge flow-through at 1000 rpm for 10 minutes. </li>
	<li>Drain the supernatant and add 10 mL medium (15% FCS/ +glutamine, Pen/Strep, Non-Essential amino acids, 50 &mu;M &#914;-ME)</li>
	<li>Count the cells and culture at 106 cells per ml.</li>
	<li>In order to stimulate B cell growth and proliferation, supplement the medium with recombinant IL-4 and anti-CD40 antibody such that the final concentrations are 20 &mu;g/mL and 1 &mu;g/mL, respectively, and transfer the cells to a culture flask. </li>
	<li>Culture the cells overnight. Count cells and dilute to 106 cells per ml, adding IL-4 and CD40 as appropriate.</li>
	<li>Culture cells for 72 hours before viral infection.</li>
</ol>
2. Transfection of Producer Cells
Use established protocols for transfection using either cationic lipids or calcium phosphate. Transfect 10cm3 plate per DNA construct, using 100 &mu;g plasmid DNA per plate. We routinely use calcium phosphate transfection method 13, 14 and note high viral titer when supplemented with chloroquine.
<ol>
	<li>Use 60%-70% confluent Phoenix cells as producer cells to be transfected. At this confluence cell count should be 5 million cells per 10 cm plate. </li>
	<li>One hour prior to transfection, replace the media with fresh complete media for Phoenix cell growth. </li>
	<li>In a sterile eppendorpf tube, combine 100 &mu;g of packaging construct DNA, 250 &mu;L of 0.5M CaCl2, and adjust the final volume to 500 &mu;L with sterile water </li>
	<li>Using a 1 mL pipette, vigorously mix this solution with 500 &mu;L 2X HNP in a 15mL polypropylene tube </li>
	<li>Allow this mixture to rest at room temperature for 8-10 minutes. During this time a precipitate will form. </li>
	<li>Add the transfection mixture drop-wise to the cells while swirling the medium to evenly distribute the mixture throughout. </li>
	<li>Incubate the cells at 37&deg;C for 12 hours. </li>
	<li>12 hours post-transfection, replace the medium with 8ml complete B cell growth medium and return the cells to the 37&deg;C incubator.</li>
</ol>
3. Infection of Stimulated Splenic B Cells
<ol>
	<li>Remove supernatant from Phoenix cells 48hr post-transfection and pass the supernatant through a 0.2 micron filter to remove any cell debris. </li>
	<li>Mix 3 mL of virus-containing supernatant with 3 mL of pre-activated B cells (as in step 1). In order to enhance viral adsorption to the cells, add polybrene at a final concentration of 16 &mu;g per mL.</li>
	<li>Infect the cells by centrifugation at 2500 rpm for 90 minutes at 30&deg;C.</li>
	<li>Immediately after the spin, incubate for a further 48-72 hrs at 37&deg;C to allow for cell growth and proliferation. </li>
</ol>
4. Flow Cytometry Analysis
<ol>
	<li>Using a flow cytometer, analyze the cells for surface expression of B220 and surface IgG1. The presence of IgG1 at the surface of the cells indicates that class switch recombination has occurred as a result of successful rescue via the retroviral complementation of the AID gene.</li>
</ol>
5. Representative Results
We have successfully rescued the deficiency of the protein factor Activation Induced Cytidine Deaminase (AID) from AID-deficient (AID-/-) B-lymphocytes using retroviral transduction. Briefly, we generated recombinant retroviruses expressing mouse AID (mAID) protein by transfecting Phoenix cells with pMX-mAID-GFP 15-18. The harvested viruses were infected into AID-deficient B cells obtained from AID-deficient mice in ex vivo class switch recombination (CSR) stimulation conditions 19. The infected B cells were then analyzed for CSR to IgG1 after 72hrs in culture using flow cytometry analysis. Figure 2 shows the detection of IgG1 at the surface of B cells with AID but not the empty construct, indicating that CSR has occurred as a result of AID expression rescue. 
<img src="/files/ftp_upload/2371/2371fig1.jpg" alt="Figure 1" /> Figure 1: Scheme of retroviral packaging within producer cells: Gene of interest, represented by &Psi;, was subcloned into pMX-IRES-GFP, as previously described 15. The plasmid was transfected into an ecotropic viral packaging cell line capable of producing gag-pol and envelope protein (Phoenix, Orbigen), using calcium phosphate method 13, 14. Forty-eight hours after transfection, supernatant containing viral particles was harvested for infection into target primary B cells obtained from mice. 
<img src="/files/ftp_upload/2371/2371fig2.jpg" alt="Figure 2" /> Figure 2: AID deficient B cells, stimulated with anti-CD40 and IL-4 were infected with a retrovirus containing pMX-mAID-GFP or a retrovirus expressing GFP alone. The level of CSR to IgG1 was evaluated by FACS analysis.

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	<li>Bartholdy, B., Matthias, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+control+of+B+cell+development+and+function.">Transcriptional control of B cell development and function.</a> Gene. 327, 1-23 (2004).</li><li>Henderson, A., Calame, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+regulation+during+B+cell+development.">Transcriptional regulation during B cell development.</a> Annu Rev Immunol. 16, 163-200 (1998).</li><li>Graf, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+plasticity+of+hematopoietic+cells.">Differentiation plasticity of hematopoietic cells.</a> Blood. 99, 3089-30101 (2002).</li><li>Xiao, C., Rajewsky, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA+control+in+the+immune+system:+basic+principles.">MicroRNA control in the immune system: basic principles.</a> Cell. 136, 26-36 (2009).</li><li>Waterston, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Initial+sequencing+and+comparative+analysis+of+the+mouse+genome.">Initial sequencing and comparative analysis of the mouse genome.</a> Nature. 420, 520-562 (2002).</li><li>Griffiths, A. J. F., Miller, J. H., Suzuki, D. T., Lewontin, R. C., Gelbart, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Introduction to Genetic Analysis. , (2000).</li><li>Gondo, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Next-generation+gene+targeting+in+the+mouse+for+functional+genomics.">Next-generation gene targeting in the mouse for functional genomics.</a> BMB Rep. 42, 315-3123 (2009).</li><li>Plachy, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proviruses+selected+for+high+and+stable+expression+of+transduced+genes+accumulate+in+broadly+transcribed+genome+areas.">Proviruses selected for high and stable expression of transduced genes accumulate in broadly transcribed genome areas.</a> J Virol. 84, 4204-4211 (2010).</li><li>Felice, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcription+factor+binding+sites+are+genetic+determinants+of+retroviral+integration+in+the+human+genome.">Transcription factor binding sites are genetic determinants of retroviral integration in the human genome.</a> PLoS One. 4, e4571-e4571 (2009).</li><li>Karavanas, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+targeting+by+murine+retroviral+vectors.">Cell targeting by murine retroviral vectors.</a> Crit Rev Oncol Hematol. 28, 7-30 (1998).</li><li>Noelle, R. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AID+from+bony+fish+catalyzes+class+switch+recombination.">AID from bony fish catalyzes class switch recombination.</a> J Exp Med. 202, 733-738 (2005).</li><li>Delphin, S., Stavnezer, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+antibody+class+switching+to+IgE:+characterization+of+an+IL-4-responsive+region+in+the+immunoglobulin+heavy-chain+germline+epsilon+promoter.">Regulation of antibody class switching to IgE: characterization of an IL-4-responsive region in the immunoglobulin heavy-chain germline epsilon promoter.</a> Ann N Y Acad Sci. 764, 123-135 (1995).</li><li>Castigli, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD40+expression+and+function+in+murine+B+cell+ontogeny.">CD40 expression and function in murine B cell ontogeny.</a> Int Immunol. 8, 405-411 (1996).</li><li>Ballantyne, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+recombination+of+a+switch+substrate+retrovector+in+CD40-+activated+B+lymphocytes:+implications+for+the+control+of+CH+gene+switch+recombination.">Efficient recombination of a switch substrate retrovector in CD40- activated B lymphocytes: implications for the control of CH gene switch recombination.</a> J Immunol. 161, 1336-1347 (1998).</li></ol>

No conflicts of interest declared.

Retroviral transduction of splenic B cells as described here and as depicted in Figure 1 is a genetic approach that is useful in the study of B-lymphocytes because many of the developmental events in lymphopoesis are controlled by transcriptional regulation 1, 2. In the later stages of B cell maturation, triggering via CD40L is essential for the induction of B cell growth, entry into the cell cycle, and proliferation 11, 20. As shown in Figure 2, B cells can be stim...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>FCS</td>
<td>&nbsp;</td>
<td>Atlanta Biologicals</td>
<td>S11550</td>
<td>&nbsp;</td>
<tr>
<td>RPMI</td>
<td>&nbsp;</td>
<td>Invitrogen/Gibco</td>
<td>22400</td>
<td>&nbsp;</td>
<tr>
<td>PBS</td>
<td>&nbsp;</td>
<td>Invitrogen/Gibco</td>
<td>20012</td>
<td>&nbsp;</td>
<tr>
<td>Red Blood Cell (RBC) lysis buffer</td>
<td>&nbsp;</td>
<td>Sigma Aldrich</td>
<td>R7757</td>
<td>&nbsp;</td>
<tr>
<td>CD43 beads</td>
<td>&nbsp;</td>
<td>Miltenyi</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>B Cell Complete Media</td>
<td>&nbsp;</td>
<td>Various components</td>
<td>Various Components</td>
<td>RPMI, 15% FCS, 1% Non-Essential Amino Acids, 1% Sodium Pyruvate, 1% HEPES, 1% Pen-Strep, 50&mu;M &beta;-Mercaptoethanol</td>
</tr>
<tr>
<td>IL-4</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Anti-CD40</td>
<td>&nbsp;</td>
<td>BD Pharmigen</td>
<td>553787</td>
<td>&nbsp;</td>
<tr>
<td>polybrene</td>
<td>&nbsp;</td>
<td>Sigma Aldrich</td>
<td>107689 &#x2028;</td>
<td>&nbsp;</td>
<tr>
<td>Chloroquine diphosphate salt</td>
<td>&nbsp;</td>
<td>Sigma Aldrich</td>
<td>C6628</td>
<td>Used at 100mM</td>
</tr>
<tr>
<td>Phoenix Eco cells (Murine)</td>
<td>&nbsp;</td>
<td>Orbigen</td>
<td>RVC-10002</td>
<td>&nbsp;</td>
<tr>
<td>PE-Cy5-&alpha;-mouse-CD45R (B220)</td>
<td>&nbsp;</td>
<td>eBioscience</td>
<td>15-0452-81</td>
<td>&nbsp;</td>
<tr>
<td>PE-&alpha;-mouse-IgG1</td>
<td>&nbsp;</td>
<td>BD Pharmigen</td>
<td>A85-1</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

recombinant retroviral production and infection of b cells

The transgenic expression of genes in eukaryotic cells is a powerful reverse genetic approach in which a gene of interest is expressed under the control of a heterologous expression system to facilitate the analysis of the resulting phenotype. This approach can be used to express a gene that is not normally found in the organism, to express a mutant form of a gene product, or to over-express a dominant-negative form of the gene product. It is particularly useful in the study of the hematopoetic system, where transcriptional regulation is a major control mechanism in the development and differentiation of B cells 1, reviewed in 2-4.
Mouse genetics is a powerful tool for the study of human genes and diseases. A comparative analysis of the mouse and human genome reveals conservation of synteny in over 90% of the genome 5. Also, much of the technology used in mouse models is applicable to the study of human genes, for example, gene disruptions and allelic replacement 6. However, the creation of a transgenic mouse requires a great deal of resources of both a financial and technical nature. Several projects have begun to compile libraries of knock out mouse strains (KOMP, EUCOMM, NorCOMM) or mutagenesis induced strains (RIKEN), which require large-scale efforts and collaboration 7. Therefore, it is desirable to first study the phenotype of a desired gene in a cell culture model of primary cells before progressing to a mouse model. 
Retroviral DNA integrates into the host DNA, preferably within or near transcription units or CpG islands, resulting in stable and heritable expression of the packaged gene of interest while avoiding transcriptional silencing 8 9. The genes are then transcribed under the control of a high efficiency retroviral promoter, resulting in a high efficiency of transcription and protein production. Therefore, retroviral expression can be used with cells that are difficult to transfect, provided the cells are in an active state during mitosis. Because the structural genes of the virus are contained within the packaging cell line, the expression vectors used to clone the gene of interest contain no structural genes of the virus, which both eliminates the possibility of viral revertants and increases the safety of working with viral supernatants as no infectious virions are produced 10. 
Here we present a protocol for recombinant retroviral production and subsequent infection of splenic B cells. After isolation, the cultured splenic cells are stimulated with Th derived lymphokines and anti-CD40, which induces a burst of B cell proliferation and differentiation 11. This protocol is ideal for the study of events occurring late in B cell development and differentiation, as B cells are isolated from the spleen following initial hematopoetic events but prior to antigenic stimulation to induce plasmacytic differentiation.

Watch this Scientific Journal Video about Recombinant Retroviral Production and Infection of B Cells at JoVE.com

Recombinant Retroviral Production and Infection of B Cells

An efficient system of structure and function analysis of a gene in an ex vivo culture of splenic B-lymphocytes is described. This method takes advantage of recombinant retroviral production in a helper free, ecotrophic packaging cell line. Stable, heritable expression of a gene of interest within primary lymphocytes is achieved leading to generation of surface antibodies on B cells undergoing class switch recombination.

The transgenic expression of genes in eukaryotic cells is a powerful reverse genetic approach in which a gene of interest is expressed under the control ...

recombinant-retroviral-production-and-infection-of-b-cells

Research

JoVE Journal

Immunology and Infection

14.0K Views.  Columbia University College of Physicians and Surgeons. An efficient system of structure and function analysis of a gene in an ex vivo culture of splenic B-lymphocytes is described. This method takes advantage of recombinant retroviral production in a helper free, ecotrophic packaging cell line. Stable, heritable expression of a gene of interest within primary lymphocytes is achieved leading to generation of surface antibodies on B cells undergoing class switch recombination.

Video: Recombinant Retroviral Production and Infection of B Cells

Murine Model of CD40-activation of B cells

Research on B cells has shown that CD40 activation improves their antigen presentation capacity. When stimulated with interleukin-4 and CD40 ligand (CD40L), human B cells can be expanded without difficulties from small amounts of peripheral blood within 14 days to very large amounts of highly-pure CD40-B cells (&gt;109 cells per patient) from healthy donors as well as cancer patients1-4. CD40-B cells express important lymph node homing molecules and can attract T cells in vitro5. Furthermore they efficiently take up, process and present antigens to T cells6,7. CD40-B cells were shown to not only prime na&iacute;ve, but also expand memory T cells8,9. Therefore CD40-activated B cells (CD40-B cells) have been studied as an alternative source of immuno-stimulatory antigen-presenting cells (APC) for cell-based immunotherapy1,5,10. In order to further study whether CD40-B cells induce effective T cell responses in vivo and to study the underlying mechanism we established a cell culture system for the generation of murine CD40-activated B cells. Using splenocytes or purified B cells from C57BL/6 mice for CD40-activation, optimal conditions were identified as follows: Starting from splenocytes of C57BL/6 mice (haplotype H-2b) lymphocytes are purified by density gradient centrifugation and co-cultured with HeLa cells expressing recombinant murine CD40 ligand (tmuCD40L HeLa)11. Cells are recultured every 3-4 days and key components such as CD40L, interleukin-4, -Mercaptoethanol and cyclosporin A are replenished. In this protocol we demonstrate how to obtain fully activated murine CD40-B cells (mCD40B) with similar APC-phenotype to human CD40-B cells (Fig 1a,b). CD40-stimulation leads to a rapid outgrowth and expansion of highly pure (&gt;90%) CD19+ B cells within 14 days of cell culture (Fig 1c,d). To avoid contamination with non-transfected cells, expression of the murine CD40 ligand on the transfectants has to be controlled regularly (Fig 2). Murine CD40-activated B cells can be used to study B-cell activation and differentiation as well as to investigate their potential to function as APC in vitro and in vivo. Moreover, they represent a promising tool for establishing therapeutic or preventive vaccination against tumors and will help to answer questions regarding safety and immunogenicity of this approach12.

In this video, we demonstrate the procedure of CD40-activation and expansion of murine B cells from splenocytes of C57BL/6 mice, which can be used as a model antigen-presenting cell (APC) to study induction of immunity.

Research on B cells has shown that CD40 activation improves their antigen presentation capacity. When stimulated with interleukin-4 and CD40 ligand ...

Retroviral Transduction of T-cell Receptors in Mouse T-cells

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen presenting cells (APCs)1. This recognition leads to the activation of T-cells and a series of functional outcomes (e.g. cytokine production, killing of the target cells). Understanding the functional role of TCRs is critical to harness the power of the immune system to treat a variety of immunology related diseases (e.g. cancer or autoimmunity).
It is convenient to study TCRs in mouse models, which can be accomplished in several ways. Making TCR transgenic mouse models is costly and time-consuming and currently there are only a limited number of them available2-4. Alternatively, mice with antigen-specific T-cells can be generated by bone marrow chimera. This method also takes several weeks and requires expertise5. Retroviral transduction of TCRs into in vitro activated mouse T-cells is a quick and relatively easy method to obtain T-cells of desired peptide-MHC specificity. Antigen-specific T-cells can be generated in one week and used in any downstream applications. Studying transduced T-cells also has direct application to human immunotherapy, as adoptive transfer of human T-cells transduced with antigen-specific TCRs is an emerging strategy for cancer treatment6.
Here we present a protocol to retrovirally transduce TCRs into in vitro activated mouse T-cells. Both human and mouse TCR genes can be used. Retroviruses carrying specific TCR genes are generated and used to infect mouse T-cells activated with anti-CD3 and anti-CD28 antibodies. After in vitro expansion, transduced T-cells are analyzed by flow cytometry.

We present a protocol to produce antigen-specific mouse T-cells using retroviral transduction

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen ...

Production and Titering of Recombinant Adeno-associated Viral Vectors

In recent years recombinant adeno-associated viral vectors (AAV) have become increasingly valuable for in vivo studies in animals, and are also currently being tested in human clinical trials. Wild-type AAV is a non-pathogenic member of the parvoviridae family and inherently replication-deficient. The broad transduction profile, low immune response as well as the strong and persistent transgene expression achieved with these vectors has made them a popular and versatile tool for in vitro and in vivo gene delivery. rAAVs can be easily and cheaply produced in the laboratory and, based on their favourable safety profile, are generally given a low safety classification. Here, we describe a method for the production and titering of chimeric rAAVs containing the capsid proteins of both AAV1 and AAV2. The use of these so-called chimeric vectors combines the benefits of both parental serotypes such as high titres stocks (AAV1) and purification by affinity chromatography (AAV2). These AAV serotypes are the best studied of all AAV serotypes, and individually have a broad infectivity pattern. The chimeric vectors described here should have the infectious properties of AAV1 and AAV2 and can thus be expected to infect a large range of tissues, including neurons, skeletal muscle, pancreas, kidney among others. The method described here uses heparin column purification, a method believed to give a higher viral titer and cleaner viral preparation than other purification methods, such as centrifugation through a caesium chloride gradient. Additionally, we describe how these vectors can be quickly and easily titered to give accurate reading of the number of infectious particles produced.

Recombinant adeno-associated virus (rAAVs) vectors are becoming increasingly valuable for in vivo studies in animals. We describe how rAAVs can be produced in the laboratory and how these vectors can be titered to give an accurate reading of the number of infectious particles produced.

In recent years recombinant adeno-associated viral vectors (AAV) have become increasingly valuable for in vivo studies in animals, and are also currently ...

Efficient Recombinant Parvovirus Production with the Help of Adenovirus-derived Systems

Rodent parvoviruses (PV) such as rat H-1PV and MVM, are small icosahedral, single stranded, DNA viruses. Their genome includes two promoters P4 and P38 which regulate the expression of non-structural (NS1 and NS2) and capsid proteins (VP1 and VP2) respectively1. They attract high interest as anticancer agents for their oncolytic and oncosuppressive abilities while being non-pathogenic for humans2. NS1 is the major effector of viral cytotoxicity3. In order to further enhance their natural antineoplastic activities, derivatives from these vectors have been generated by replacing the gene encoding for the capsid proteins with a therapeutic transgene (e.g. a cytotoxic polypeptide, cytokine, chemokine, tumour suppressor gene etc.)4. The recombinant parvoviruses (recPVs) vector retains the NS1/2 coding sequences and the PV genome telomeres which are necessary for viral DNA amplification and packaging. Production of recPVs occurs only in the producer cells (generally HEK293T), by co-transfecting the cells with a second vector (pCMV-VP) expressing the gene encoding for the VP proteins (Fig. 1)4. The recPV vectors generated in this way are replication defective. Although recPVs proved to possess enhanced oncotoxic activities with respect to the parental viruses from which they have been generated, their production remains a major challenge and strongly hampers the use of these agents in anti-cancer clinical applications.
We found that introduction of an Ad-5 derived vector containing the E2a, E4(orf6) and the VA RNA genes (e.g. pXX6 plasmid) into HEK293T improved the production of recPVs by more than 10 fold in comparison to other protocols in use. Based on this finding, we have constructed a novel Ad-VP-helper that contains the genomic adenoviral elements necessary to enhance recPVs production as well as the parvovirus VP gene unit5. The use of Ad-VP-helper, allows production of rec-PVs using a protocol that relies entirely on viral infection steps (as opposed to plasmid transfection), making possible the use of cell lines that are difficult to transfect (e.g. NB324K) (Fig. 2). We present a method that greatly improves the amount of recombinant virus produced, reducing both the production time and costs, without affecting the quality of the final product5. In addition, large scale production of recPV (in suspension cells and bioreactors) is now conceivable.

Here we describe a protocol based only on cell infection, which improves the efficiency of recombinant parvovirus production by more than 100 fold in comparison to other protocols in use. This protocol relies on the use of a novel adenovirus 5-based helper containing the parvovirus VP transcription unit (Ad-VP).

Rodent parvoviruses (PV) such as rat H-1PV and MVM, are small icosahedral, single stranded, DNA viruses. Their genome includes two promoters P4 and P38 ...

Detection of True IgE-expressing Mouse B Lineage Cells

B lymphocyte immunoglobulin heavy chain (IgH) class switch recombination (CSR) is a process wherein initially expressed IgM switches to other IgH isotypes, such as IgA, IgE and IgG. Measurement of IgH CSR in vitro is a key method for the study of a number of biologic processes ranging from DNA recombination and repair to aspects of molecular and cellular immunology. In vitro CSR assay involves the flow cytometric measurement surface Ig expression on activated B cells. While measurement of IgA and IgG subclasses is straightforward, measurement of IgE by this method is problematic due to soluble IgE binding to Fc&#949;RII/CD23 expressed on the surface of activated B cells. Here we describe a unique procedure for accurate measurement of IgE-producing mouse B cells that have undergone CSR in culture. The method is based on trypsin-mediated cleavage of IgE-CD23 complexes on cell surfaces, allowing for detection of IgE-producing B lineage cells by cytoplasmic staining. This procedure offers a convenient solution for flow cytometric analysis of CSR to IgE.

In vitro analysis of class switch recombination in mice is challenging due to cytophilic IgE molecules bound to Fc receptors on the surface of B cells. We describe a method for IgE detection using trypsin-mediated cleavage of surface-bound IgE prior to fixation and permeabilization for cytoplasmic fluorescence staining.

B lymphocyte immunoglobulin heavy chain (IgH) class switch recombination (CSR) is a process wherein initially expressed IgM switches to other IgH ...

Generation of Recombinant Human IgG Monoclonal Antibodies from Immortalized Sorted B Cells

Finding new methods for generating human monoclonal antibodies is an active research field that is important for both basic and applied sciences, including the development of immunotherapeutics. However, the techniques to identify and produce such antibodies tend to be arduous and sometimes the heavy and light chain pair of the antibodies are dissociated. Here, we describe a relatively simple, straightforward protocol to produce human recombinant monoclonal antibodies from human peripheral blood mononuclear cells using immortalization with Epstein-Barr Virus (EBV) and Toll-like receptor 9 activation. With an adequate staining, B cells producing antibodies can be isolated for subsequent immortalization and clonal expansion. The antibody transcripts produced by the immortalized B cell clones can be amplified by PCR, sequenced as corresponding heavy and light chain pairs and cloned into immunoglobulin expression vectors. The antibodies obtained with this technique can be powerful tools to study relevant human immune responses, including autoimmunity, and create the basis for new therapeutics.

Synthesis of human monoclonal antibodies is the first step in studies aimed at unraveling the pathophysiological mechanisms of auto-antibody-mediated immune responses. We have developed a protocol to generate recombinant human immunoglobulin G (IgG) monoclonal antibodies from blood sorted B cells, including B-cell isolation, antibody cloning and in vitro synthesis.

Finding new methods for generating human monoclonal antibodies is an active research field that is important for both basic and applied sciences, ...

Retroviral Transduction of Bone Marrow Progenitor Cells to Generate T-cell Receptor Retrogenic Mice

T cell receptor (TCR) signaling is essential in the development and differentiation of T cells in the thymus and periphery, respectively. The vast array of TCRs proves studying a specific antigenic response difficult. Therefore, TCR transgenic mice were made to study positive and negative selection in the thymus as well as peripheral T cell activation, proliferation and tolerance. However, relatively few TCR transgenic mice have been generated specific to any given antigen. Thus, studies involving TCRs of varying affinities for the same antigenic peptide have been lacking. The generation of a new TCR transgenic line can take six or more months. Additionally, any specific backcrosses can take an additional six months. In order to allow faster generation and screening of multiple TCRs, a protocol for retroviral transduction of bone marrow was established with stoichiometric expression of the TCR&#945; and TCR&#946; chains and the generation of retrogenic mice. Each retrogenic mouse is essentially a founder, virtually negating a founder effect, while the length of time to generate a TCR retrogenic is cut from six months to approximately six weeks. Here we present a rapid and flexible alternative to TCR transgenic mice that can be expressed on any chosen background with any particular TCR.

We present a rapid and flexible protocol for a single T cell receptor (TCR) retroviral-based in vivo expression system. Retroviral vectors are used to transduce bone marrow progenitor cells to study T cell development and function of a single TCR in vivo as an alternative to TCR transgenic mice.

T cell receptor (TCR) signaling is essential in the development and differentiation of T cells in the thymus and periphery, respectively.  The vast array ...

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins

Stromal interaction molecule-1 (STIM1) is a type-I transmembrane protein located on the endoplasmic reticulum (ER) and plasma membranes (PM). ER-resident STIM1 regulates the activity of PM Orai1 channels in a process known as store operated calcium (Ca2+) entry which is the principal Ca2+ signaling process that drives the immune response. STIM1 undergoes post-translational N-glycosylation at two luminal Asn sites within the Ca2+ sensing domain of the molecule. However, the biochemical, biophysical, and structure biological effects of N-glycosylated STIM1 were poorly understood until recently due to an inability to readily obtain high levels of homogeneous N-glycosylated protein. Here, we describe the implementation of an in vitro chemical approach which attaches glucose moieties to specific protein sites applicable to understanding the underlying effects of N-glycosylation on protein structure and mechanism. Using solution nuclear magnetic resonance spectroscopy we assess both efficiency of the modification as well as the structural consequences of the glucose attachment with a single sample. This approach can readily be adapted to study the myriad glycosylated proteins found in nature.

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins

Biochemical and structural analyses of glycosylated proteins require relatively large amounts of homogeneous samples. Here, we present an efficient chemical method for site-specific glycosylation of recombinant proteins purified from bacteria by targeting reactive Cys thiols.

Stromal interaction molecule-1 (STIM1) is a type-I transmembrane protein located on the endoplasmic reticulum (ER) and plasma membranes (PM). ER-resident ...

Retroviral Overexpression of CXCR4 on Murine B-1a Cells and Adoptive Transfer for Targeted B-1a Cell Migration to the Bone Marrow and IgM Production

As cell function is influenced by niche-specific factors in the cellular microenvironment, methods to dissect cell localization and migration can provide further insight on cell function. B-1a cells are a unique B cell subset in mice that produce protective natural IgM antibodies against oxidation-specific epitopes that arise during health and disease. B-1a cell IgM production differs depending on B-1a cell location, and therefore it becomes useful from a therapeutic standpoint to target B-1a localization to niches supportive of high antibody production. Here we describe a method to target B-1a cell migration to the bone marrow by retroviral-mediated overexpression of the C-X-C motif chemokine receptor 4 (CXCR4). Gene induction in primary murine B cells can be challenging and typically yields low transfection efficiencies of 10-20% depending on technique. Here we demonstrate that retroviral transduction of primary murine B-1a cells results in 30-40% transduction efficiency. This method utilizes adoptive cell transfer of transduced B-1a cells into B cell-deficient recipient mice so that donor B-1a cell migration and localization can be visualized. This protocol can be modified for other retroviral constructs and can be used in diverse functional assays post-adoptive transfer, including analysis of donor cell or host cell phenotype and function, or analysis of soluble factors secreted post B-1a cell transfer. The use of distinct donor and recipient mice differentiated by CD45.1 and CD45.2 allotype and the presence of a GFP reporter within the retroviral plasmid could also enable detection of donor cells in other, immune-sufficient mouse models containing endogenous B cell populations.

Here we describe a method for retroviral overexpression and adoptive transfer of murine B-1a cells to examine in vivo B-1a cell migration and localization. This protocol can be extended for diverse downstream functional assays including quantification of donor B-1a cell localization or analysis of donor cell-derived secreted factors post-adoptive transfer.

As cell function is influenced by niche-specific factors in the cellular microenvironment, methods to dissect cell localization and migration can provide ...

Modeling Hepatitis B Virus Infection in Non-Hepatic 293T-NE-3NRs Cells

HBV mainly infects human hepatocytes, but it has also been found to infect extrahepatic tissues such as kidney and testis. Nonetheless, cell-based HBV models are limited to hepatoma cell lines (such as HepG2 and Huh7) overexpressing a functional HBV receptor, sodium taurocholate co-transporting polypeptide (NTCP). Here, we used 293T-NE-3NRs (293T&#160;overexpressing human NTCP, HNF4&#945;, RXR&#945; and PPAR&#945;) and HepG2-NE (HepG2 overexpressing NTCP) as model cell lines.&#160;HBV infection in these cell lines was performed either by using concentrated HBV virus particles from HepG2.2.15 or co-culturing HepG2.2.15 with the target cell lines. HBcAg immunofluorescence for HBcAg was performed to confirm HBV infection. The two methods presented here will help us study HBV infection in non-hepatic cell lines.&#160;&#160;

This manuscript describes a detailed protocol for Hepatitis B virus (HBV) infection in novel engineered 293T cells (293T-NE-3NRs, expressing human NTCP, HNF4&#945;, RXR&#945; and PPAR&#945;) and traditional hepatic cells (HepG2-NE, expressing human NTCP).

HBV mainly infects human hepatocytes, but it has also been found to infect extrahepatic tissues such as kidney and testis. Nonetheless, cell-based HBV ...