Name: production of monoclonal antibodies targeting aminopeptidase n in the porcine intestinal mucosal epithelium
Uploaded: 2021-05-18T13:00:00
Description: Watch this Scientific Journal Video about Production of Monoclonal Antibodies Targeting Aminopeptidase N in the Porcine Intestinal Mucosal Epithelium at JoVE.com

This study was supported by the Chinese National Science Foundation Grant (No. 32072820, 31702242), grants from Jiangsu Government Scholarship for Overseas Studies (JS20190246) and High-level Talents of Yangzhou University Scientific Research Foundation, a project founded by the Priority Academic Program of Development Jiangsu High Education Institution.

All animal experiments in this study were approved by the Yangzhou University Institutional Animal Care and Use Committee (SYXK20200041).
1. Preparation of porcine APN protein antigen
NOTE: The pET28a (+)-APN-BL21 (DE3) strain and the APN stably expressed cells pEGFP-C1-APN-IPEC-J2 were constructed in a previous study11.
<ol>
	<li>Recover bacteria from a frozen glycerol stock and streak onto Luria-Bertani (LB) plates containing 50 &#181;g/m...

<ol>
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Induction of mucosal immunity is one of the most effective approaches in counteracting pathogens and in prevention and treatment of various diseases. APN, a highly expressed membrane-bound protein in the intestinal mucosa, is involved in the induction of adaptive immune response and in receptor-mediated viral and bacterial endocytosis1,5,8. APN is used as antigen particulate in many formats of antigen loading and vaccine deliver...

Aminopeptidase N (APN), a moonlighting enzyme that belongs to the metalloproteinase M1 family, acts as a tumor marker, receptor, and signaling molecule via enzyme-dependent and enzyme-independent pathways1,2. In addition to cleaving the N-terminal amino-acid residues of various bioactive peptides for the regulation of their biological activity, APN plays an important role in the pathogenesis of various inflammatory diseases. APN participates in antigen processing and presentation by trimmed peptides that bind tightly to major histocompatibility complex class II molecules2,3. APN also exerts anti-inflammatory effects by binding with G protein-coupled receptors participating in multiple signal transduction, modulating cytokine secretion, and contributing to Fc gamma receptor-mediated phagocytosis in the immune response4,5,6,7.
As a widely distributed membrane-bound exopeptidase, APN is abundant in the porcine small intestinal mucosa and is closely associated with receptor-mediated endocytosis1,5,8. APN recognizes and binds the spike protein of the transmissible gastroenteritis virus for cell entry, and directly interacts with the FaeG subunit of enterotoxigenic Escherichia coli F4 fimbriae to affect bacterial adherence with host cells9,10,11. Thus, APN is a potential therapeutic target in the treatment of viral and bacterial infectious diseases.
Since the development of hybridoma technology and other strategies for monoclonal antibodies (mAbs) production in 1975, mAbs have been widely used in immunotherapy, drug delivery, and diagnosis12,13,14. Currently, mAbs are successfully used to treat diseases, such as cancer, inflammatory bowel disease, and multiple sclerosis12,15. Because of their strong affinity and specificity, mAbs can be ideal targets in the development of antibody-drug conjugates (ADC) or new vaccines16,17. The APN protein is critical for selectively delivering antigens to specific cells, and can elicit a specific and strong mucosal immune response against pathogens without any interference including low protein expression, enzyme inactivity, or structural changes5,8,18. Therefore, therapeutic products based on APN-specific mAbs show promise against bacterial and viral infections. In this study, we describe the production of APN-specific mAbs using hybridoma technology, and expression of anti-APN recombinant antibodies (rAbs) using prokaryotic and eukaryotic vectors. The result indicates that the APN protein was recognized by both rAbs expressed in pIRES2-ZSGreen1-rAbs-APN-CHO cells and hybridoma-derived mAbs.

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			<td>Complete Freund&#8217;s adjuvant</td>
			<td>Sigma-Aldrich</td>
			<td>F5881</td>
			<td>Animal immunization</td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Beyotime&#160; Biotechnology</td>
			<td>C1002</td>
			<td>Nuclear counterstain</td>
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		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>11965092</td>
			<td>Cell culture</td>
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			<td>DMEM-F12</td>
			<td>Gibco</td>
			<td>12634010</td>
			<td>Cell culture</td>
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		<tr>
			<td>Dylight 549-conjugated goat anti-mouse IgG secondary antibody</td>
			<td>Abbkine</td>
			<td>A23310</td>
			<td>Indirect immunofluorescence analysis</td>
		</tr>
		<tr>
			<td>Enhanced Cell Counting Kit-8</td>
			<td>Beyotime&#160; Biotechnology</td>
			<td>C0042</td>
			<td>Measurement&#160;of&#160;cell&#160;viability and vitality</td>
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		<tr>
			<td>Fetal bovine serum</td>
			<td>Gibco</td>
			<td>10091</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Geneticin&#8482; Selective Antibiotic</td>
			<td>Gibco</td>
			<td>11811098</td>
			<td>Selective antibiotic</td>
		</tr>
		<tr>
			<td>HAT Supplement (50X)</td>
			<td>Gibco</td>
			<td>21060017</td>
			<td>Cell selection</td>
		</tr>
		<tr>
			<td>HT Supplement (100X)</td>
			<td>Gibco</td>
			<td>11067030</td>
			<td>Cell selection</td>
		</tr>
		<tr>
			<td>Incomplete Freund&#8217;s adjuvant</td>
			<td>Sigma-Aldrich</td>
			<td>F5506</td>
			<td>Animal immunization</td>
		</tr>
		<tr>
			<td>isopropyl &#946;-d-1-thiogalactopyranoside</td>
			<td>Sigma-Aldrich</td>
			<td>I5502</td>
			<td>Protein expression</td>
		</tr>
		<tr>
			<td>kanamycin</td>
			<td>Beyotime&#160; Biotechnology</td>
			<td>ST102</td>
			<td>Bactericidal antibiotic</td>
		</tr>
		<tr>
			<td>Leica TCS SP8 STED confocal microscope</td>
			<td>Leica Microsystems</td>
			<td>&#160;SP8 STED</td>
			<td>Fluorescence imaging</td>
		</tr>
		<tr>
			<td>Lipofectamine&#174; 2000 Reagent</td>
			<td>Thermofisher</td>
			<td>11668019</td>
			<td>Transfection</td>
		</tr>
		<tr>
			<td>LSRFortessa&#8482; fluorescence-activated cell sorting</td>
			<td>BD</td>
			<td>FACS LSRFortessa</td>
			<td>Flow cytometry</td>
		</tr>
		<tr>
			<td>Microplate reader</td>
			<td>BioTek</td>
			<td>BOX 998</td>
			<td>ELISA analysis</td>
		</tr>
		<tr>
			<td>Micro spectrophotometer</td>
			<td>Thermo Fisher</td>
			<td>Nano Drop one</td>
			<td>Nucleic acid concentration detection</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10019308</td>
			<td>Culture broth</td>
		</tr>
		<tr>
			<td>(NH4)2SO4</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10002917</td>
			<td>Culture broth</td>
		</tr>
		<tr>
			<td>Opti-MEM</td>
			<td>Gibco</td>
			<td>31985088</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Polyethylene glycol 1500</td>
			<td>Roche Diagnostics</td>
			<td>10783641001</td>
			<td>Cell fusion</td>
		</tr>
		<tr>
			<td>PrimeScript&#8482; 1st strand cDNA Synthesis Kit</td>
			<td>Takara Bio</td>
			<td>RR047</td>
			<td>qPCR</td>
		</tr>
		<tr>
			<td>protein A agarose</td>
			<td>Beyotime&#160; Biotechnology</td>
			<td>P2006</td>
			<td>Antibody protein purification</td>
		</tr>
		<tr>
			<td>Protino&#174; Ni+-TED 2000 Packed Columns</td>
			<td>MACHEREY-NAGEL</td>
			<td>745120.5</td>
			<td>Protein purification</td>
		</tr>
		<tr>
			<td>SBA Clonotyping System-HRP</td>
			<td>Southern Biotech</td>
			<td>May-00</td>
			<td>Isotyping of mouse monoclonal antibodies</td>
		</tr>
		<tr>
			<td>Seamless Cloning Kit</td>
			<td>Beyotime&#160; Biotechnology</td>
			<td>D7010S</td>
			<td>Construction of plasmids</td>
		</tr>
		<tr>
			<td>Shake flasks</td>
			<td>Beyotime&#160; Biotechnology</td>
			<td>E3285</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Sodium carbonate-sodium bicarbonate buffer</td>
			<td>Beyotime&#160; Biotechnology</td>
			<td>C0221A</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Trans-Blot SD Semi-Dry Transfer Cell</td>
			<td>Bio-rad</td>
			<td>&#160;170-3940</td>
			<td>Western blot</td>
		</tr>
		<tr>
			<td>Tryptone</td>
			<td>Oxoid</td>
			<td>LP0042</td>
			<td>Culture broth</td>
		</tr>
		<tr>
			<td>Ultrasonic Homogenizer</td>
			<td>Ningbo Xinzhi Biotechnology</td>
			<td>JY92-IIN</td>
			<td>Sample homogenization</td>
		</tr>
		<tr>
			<td>Yeast extract</td>
			<td>Oxoid</td>
			<td>LP0021</td>
			<td>Culture broth</td>
		</tr>
		<tr>
			<td>96-well microplate</td>
			<td>Corning</td>
			<td>3599</td>
			<td>Cell culture</td>
		</tr>
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production of monoclonal antibodies targeting aminopeptidase n in the porcine intestinal mucosal epithelium

Porcine aminopeptidase N (APN), a membrane-bound metallopeptidase abundantly present in small intestinal mucosa, can initiate a mucosal immune response without any interference such as low protein expression, enzyme inactivity, or structural changes. This makes APN an attractive candidate in the development of vaccines that selectively target the mucosal epithelium. Previous studies have shown that APN is a receptor protein for both enterotoxigenic Escherichia coli (E. coli) F4 and transmissible gastroenteritis virus. Thus, APN shows promise in the development of antibody-drug conjugates or novel vaccines based on APN-specific antibodies. In this study, we compared production of APN-specific monoclonal antibodies (mAbs) using traditional hybridoma technology and recombinant antibody expression method. We also established a stably transfected Chinese hamster ovary (CHO) cell line using pIRES2-ZSGreen1-rAbs-APN and an E. coli expression BL21(DE3) strain harboring the pET28a (+)-rAbs-APN vector. The results show that antibodies expressed in pIRES2-ZSGreen1-rAbs-APN-CHO cells and mAbs produced using hybridomas could recognize and bind to the APN protein. This provides the basis for further elucidation of the APN receptor function for the development of therapeutics targeting different APN-specific epitopes.

In this study, the purified soluble APN protein (2.12 mg/mL) was used for mouse immunization. Mice immunized with the APN protein four times at 14-day intervals exhibited a higher antibody titer against APN in their sera. Although 14 hybridomas were obtained using the fusion experiments, only 9 hybridomas survived the three continuous freeze-thaw cycles, resulting in 9 stable clones that secreted antibodies against APN. All these cells are round, bright, and clear (Figure 1). The purified mA...

Watch this Scientific Journal Video about Production of Monoclonal Antibodies Targeting Aminopeptidase N in the Porcine Intestinal Mucosal Epithelium at JoVE.com

Production of Monoclonal Antibodies Targeting Aminopeptidase N in the Porcine Intestinal Mucosal Epithelium

The recombinant antibody protein expressed in pIRES2-ZSGreen1-rAbs-APN-CHO cells and monoclonal antibodies produced using traditional hybridoma technology can recognize and bind to the porcine aminopeptidase N (APN) protein.

Porcine aminopeptidase N (APN), a membrane-bound metallopeptidase abundantly present in small intestinal mucosa, can initiate a mucosal immune response ...

derived monoclonal antibodies are primarily used in diagnostic therapeutic immune reagents highlighting the need to produce stable and reliable antibodies in limited production prepared. The methods described here proved that recombinant antibody production could increase monoclonal antibody production efficiency and minimize labor and time associated costs. The methods are used to develop aminopeptidase and antibody-based antibody drug conjugates and other therapeutic products, which aids in clarifying the role of APN in the prevention and treatment of bacterial and viral infections.Demonstrating the procedure will be Yan Li, a postgrad student from my laboratory. To begin, intraperitoneally inject 100 micrograms of APN protein into the selected adult female mice for a final antigen boost. After three days of injection, collect the spleens from mice and wash with DMEM twice to remove blood and fat cells.Filter the spleen cell suspension using a 200 mesh copper grid to remove tissue debris and harvest spleen cells using centrifugation to remove the spleen membrane. Seed the mouse SP20 myeloma cells in a 25 square centimeter flask containing five milliliters of DMEM supplemented with 6%fetal bovine serum and culture the cells at 37 degrees Celsius and 6%carbon dioxide atmosphere to maintain cell viability. After five to six days of culture, the cells should reach 80 to 90%confluence post resuscitation and appear round, bright, and clear under the microscope.One day before hybridization, collect macrophages from the peritoneal cavities of the mice. Seed peritoneal macrophages at a density of 0.1 to 0.2 times 10 to the fifth per milliliter in 96-well plates, each containing 100 microliters of HAT medium and incubate them overnight. For hybridization, gently aspirate SP20 cells with a pipette from 8 to 10 bottles and suspend them in 10 milliliters of serum-free DMEM medium.Wash the cells with fresh DMEM and centrifuge them twice, then resuspend them in 10 milliliters of DMEM. Mix the quantified spleen cells with SB20 cells at a ratio of 10:1 and transfer them into 50 milliliter tubes. After centrifugation, discard the supernatant and collect the pellets at the bottom of the tubes.Tap the tube to loosen the pellets before hybridization. Using a dropper, add one milliliter of polyethylene glycol 1500 pre-warmed to 37 degrees Celsius dropwise to the loosened cell pellet over 45 seconds while gently rotating the bottom of the tube. Then slowly add one milliliter of DMEM pre-warmed to 37 degrees Celsius to the mixture for 90 seconds, followed by another 30 milliliters of fresh DMEM and place the fusion tube into a 37 degree Celsius water bath for 30 minutes.After incubation, harvest the cells. Resuspend the HAT medium and culture in a 96-well plate inoculated with peritoneal macrophages. After five days, add 100 microliters of fresh HAT medium to each well.And again after five days of incubation, replace the medium with HAT medium. Use a microtiter plate coated with five micrograms per milliliter APN protein diluted in 0.05 molar PBS to analyze monoclonal antibodies in the hybridomas supernatant using ELISA assay. Grow the pET28a plus recombinant antibodies aminopeptidase NBL21 transformed bacteria in the presence of 0.4 millimolar beta-d-1-thiogalactopyranoside in an orbital shaker at 37 degrees Celsius for 10 hours.Seed 100 microliters 0.5 times 10 to the fifth Chinese hamster ovary cells per well into a 96-well plate for incubation at 37 degrees Celsius and a 6%carbon dioxide atmosphere for 18 to 24 hours. When the cells reach 80 to 90%confluence, dilute the pIRES2-zs Green one recombinant antibodies aminopeptidase and plasmid with Opti-MEM to a final concentration of 0.1 micrograms per microliter. After five minutes, mix the 50 microliters of diluted pIRES2-zs Green one recombinant antibodies aminopeptidases and plasmid with one microliter of Lipofectamine 2000 and 49 microliters of Opti-MEM.After 20 minutes of incubation, add 100 microliters of the mixture to each well of a 96-well plate containing CHO cells. At four to six hours post transfection, replace the medium with DMEM F12 supplemented with 10%FBS. After 48 hours of incubation, add 400 micrograms per microliter G418 to each well to select the stably transfected cells.After 10 days of selection using DMEM F12 medium supplemented with 10%FBS and 400 micrograms per microliter G418, sort the cells with fluorescence-activated cell sorting. Serially dilute the harvested positive cells. Seed them at an average of 0.5 to 2 cells per well in a 96-well plate and culture in 37 degrees Celsius, 6%carbon dioxide incubator.In representative microscopic analysis, all hybridomas cells appeared round, bright, and clear. The purified monoclonal antibodies possessing heavy 50 kilodalton and light 25 kilodalton chains were confirmed by SDS-PAGE and were found in the purified ascites. The titers of these anti-APN monoclonal antibodies in culture supernatants and ascites are shown here.Mouse monoclonal antibody isotyping revealed that antibodies derived from clones 5B31, 5B36, 3C48, 5C51, and 6C56 possessed immunoglobulin G2B subclasses while APN 2A20 was an immunoglobulin G2A kappa type antibody and monoclonal antibody APN 3FD9, 3F10, and 10F3 belonged to immunoglobulin M type and processed kappa light chains. Most of these monoclonal antibodies showed AV values of over 50%indicating that they targeted different epitopes in the APN while the APN 5C51 antibody recognized antigenic epitopes like those recognized by APN 3C48, 5B31, and 6C56 monoclonal antibodies. The amplified APN 5B36 VHVL gene was ligated into a pET28a positive or pIRES2-zs Green one vector to construct the recombinant expression plasmids pET28a positive RABS APN and pIRES2-zs Green one RABS APN respectively.The antibodies expressed by both pET28a plus recombinant antibodies aminopeptidase NBL21 and pIRES2-zs Green one recombinant antibodies aminopeptidase NCHO cells were purified and analyzed using ELISA and IFA assays. However, only the antibody expressed in the supernatant of pIRES2-zs Green one recombinant antibodies aminopeptidase NCHO cells recognize the APN protein. Binding of APN 5B36 monoclonal antibodies to APN proteins reached an equilibrium earlier than recombinant antibodies.Purification of the monoclonal antibodies in the supernatant using protein A agarose is better than using saturated ammonia sulfate precipitation.

production-monoclonal-antibodies-targeting-aminopeptidase-n-porcine

Research

JoVE Journal

Immunology and Infection

Passive Administration of Monoclonal Antibodies Against H. capsulatum and Others Fungal Pathogens

The purpose of the use of this methodology is 1) to advance our capacity to protect individuals with antibody or vaccine for preventing or treating histoplasmosis caused by the fungus Histoplasma capsulatum and 2) to examine the role of virulence factors as target for therapy. To generate mAbs, mice are immunized, the immune responses are assessed using a solid phase ELISA system developed in our laboratory, and the best responder mice are selected for isolation of splenocytes for fusion with hybridoma cells. C57BL/6 mice have been extensively used to study H. capsulatum pathogenesis and provide the best model for obtaining the data required. In order to assess the role of the mAbs in infection, mice are intraperitoneally administered with either mAb to H. capsulatum or isotype matched control mAb and then infected by either intravenous (i.v.), intraperitoneal (i.p.), or intranasal (i.n.) routes. In the scientific literature, efficacy of mAbs for fungal infections in mice relies on mortality as an end point, in conjunction with colony formin units (CFU) assessments at earlier time points. Survival (time to death) studies are necessary as they best represent human disease. Thus, efficacy of our intervention would not adequately be established without survival curves. This is also true for establishing efficacy of vaccine or testing of mutants for virulence. With histoplasmosis, the mice often go from being energetic to dead over several hours. The capacity of an intervention such as the administration of a mAb may initially protect an animal from disease, but the disease can relapse which would not be realized in short CFU experiments. In addition to survival and fungal burden assays, we examine the inflammatory responses to infection (histology, cellular recruitment, cytokine responses). For survival/time to death experiments, the mice are infected and monitored at least twice daily for signs of morbidity. To assess fungal burden, histopathology, and cytokine responses, the mice are euthanized at various times after infection. Animal experiments are performed according to the guidelines of the Institute for Animal Studies of the Albert Einstein College of Medicine.

Passive Administration of Monoclonal Antibodies Against H. capsulatum and Others Fungal Pathogens

C57BL/6 mice have been used to study Hc pathogenesis and provide the best model. We are exploring the potential benefits of humoral immunity against this fungus and generated several mAbs [to histone H2B and a heat shock protein 60kDa] that we tested for their protective efficacy after intraperitoneal administration.

The purpose of the use of this methodology is 1) to advance our capacity to protect individuals with antibody or vaccine for preventing or treating ...

Modeling Mucosal Candidiasis in Larval Zebrafish by Swimbladder Injection

Early defense against mucosal pathogens consists of both an epithelial barrier and innate immune cells. The immunocompetency of both, and their intercommunication, are paramount for the protection against infections. The interactions of epithelial and innate immune cells with a pathogen are best investigated in vivo, where complex behavior unfolds over time and space. However, existing models do not allow for easy spatio-temporal imaging of the battle with pathogens at the mucosal level.
The model developed here creates a mucosal infection by direct injection of the fungal pathogen, Candida albicans, into the swimbladder of juvenile zebrafish. The resulting infection enables high-resolution imaging of epithelial and innate immune cell behavior throughout the development of mucosal disease. The versatility of this method allows for interrogation of the host to probe the detailed sequence of immune events leading to phagocyte recruitment and to examine the roles of particular cell types and molecular pathways in protection. In addition, the behavior of the pathogen as a function of immune attack can be imaged simultaneously by using fluorescent protein-expressing C. albicans. Increased spatial resolution of the host-pathogen interaction is also possible using the described rapid swimbladder dissection technique.
The mucosal infection model described here is straightforward and highly reproducible, making it a valuable tool for the study of mucosal candidiasis. This system may also be broadly translatable to other mucosal pathogens such as mycobacterial, bacterial or viral microbes that normally infect through epithelial surfaces.

In vivo spatio-temporal interactions of pathogen and immune defenses at the mucosal level are not easily imaged in existing vertebrate hosts. The method presented here describes a versatile platform to study mucosal candidiasis in live vertebrates using the swimbladder of the juvenile zebrafish as an infection site.

Early defense against mucosal pathogens consists of both an epithelial barrier and innate immune cells. The immunocompetency of both, and their ...

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, ...

Evaluation of the Efficacy And Toxicity of RNAs Targeting HIV-1 Production for Use in Gene or Drug Therapy

Small RNA therapies targeting post-integration steps in the HIV-1 replication cycle are among the top candidates for gene therapy and have the potential to be used as drug therapies for HIV-1 infection. Post-integration inhibitors include ribozymes, short hairpin (sh) RNAs, small interfering (si) RNAs, U1 interference (U1i) RNAs and RNA aptamers. Many of these have been identified using transient co-transfection assays with an HIV-1 expression plasmid and some have advanced to clinical trials. In addition to measures of efficacy, small RNAs have been evaluated for their potential to affect the expression of human RNAs, alter cell growth and/or differentiation, and elicit innate immune responses. In the protocols described here, a set of transient transfection assays designed to evaluate the efficacy and toxicity of RNA molecules targeting post-integration steps in the HIV-1 replication cycle are described. We have used these assays to identify new ribozymes and optimize the format of shRNAs and siRNAs targeting HIV-1 RNA. The methods provide a quick set of assays that are useful for screening new anti-HIV-1 RNAs and could be adapted to screen other post-integration inhibitors of HIV-1 replication.

Methods to evaluate the efficacy and toxicity of RNA molecules targeting post-integration steps of the HIV-1 replication cycle are described. These methods are useful for screening new molecules and optimizing the format of existing ones.

Small RNA therapies targeting post-integration steps in the HIV-1 replication cycle are among the top candidates for gene therapy and have the potential ...

Generation of Murine Monoclonal Antibodies by Hybridoma Technology

Monoclonal antibodies are universal binding molecules and are widely used in biomedicine and research. Nevertheless, the generation of these binding molecules is time-consuming and laborious due to the complicated handling and lack of alternatives. The aim of this protocol is to provide one standard method for the generation of monoclonal antibodies using hybridoma technology. This technology combines two steps. Step 1 is an appropriate immunization of the animal and step 2 is the fusion of B lymphocytes with immortal myeloma cells in order to generate hybrids possessing both parental functions, such as the production of antibody molecules and immortality. The generated hybridoma cells were then recloned and diluted to obtain stable monoclonal cell cultures secreting the desired monoclonal antibody in the culture supernatant. The supernatants were tested in enzyme-linked immunosorbent assays (ELISA) for antigen specificity. After the selection of appropriate cell clones, the cells were transferred to mass cultivation in order to produce the desired antibody molecule in large amounts. The purification of the antibodies is routinely performed by affinity chromatography. After purification, the antibody molecule can be characterized and validated for the final test application. The whole process takes 8 to 12 months of development, and there is a high risk that the antibody will not work in the desired test system.

An optimized protocol is presented for the generation of monoclonal antibodies based on the hybridoma technology. Mice were immunized with an immunoconjugate. Spleen cells were fused by PEG and an electric impulse with immortal myeloma cells. Antibody-producing hybridoma cells were selected by HAT and antigen-specific ELISA screening.

Monoclonal antibodies are universal binding molecules and are widely used in biomedicine and research. Nevertheless, the generation of these binding ...

Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels

This protocol describes noninvasive sampling of undisturbed upper airway mucosal lining fluid. It also details the extraction procedure used prior to the analysis of immune mediators in fluid eluates for the study of the airway topical immune signature, without the need for stimulation procedures (often used by other techniques). The mucosal lining fluid is sampled on a strip of filter paper placed at the anterior part of the inferior turbinate and left for 2 min of absorption. Analytes are eluted from the filter papers, and the extracted protein-based eluates are analyzed by an electrochemiluminescence-based immunoassay, allowing for the high-sensitivity quantification of low- and high-level analytes in the same sample. We measured the in vivo levels of 20 preselected immune mediators related to specific immune signaling pathways in the upper airway mucosa, but the technique is not limited to that specific panel or sampling site. The technique was first implemented in 7-year-old children from the Copenhagen Prospective Studies on Asthma in Childhood2000 (COPSAC2000) cohort with allergic rhinitis. It was thereafter used in the longitudinal COPSAC2010 birth cohort, sampled at 1 month, 2 years, and 6 years of age and at instances of acute respiratory symptoms. We successfully obtained and analyzed samples from 620 (89%) of 700 1-month-old children; a few samples were below the assay detection limit (reported as the median (Inter-Quartile Range (IQR)). The number of samples below the detection limit (i.e.&#160;from 0 to the set point for the lower limit of detection) for each mediator was 29 (7.25 - 119.5). This technique enables the quantification of the in vivo airway mucosal immune profile from birth, can be applied longitudinally, and can be applied to studies on the effect of genetics and early-life environmental exposures, pathophysiology, endotyping, and monitoring of respiratory diseases, and development and evaluation of novel therapeutics.

Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels

This protocol describes a noninvasive technique for the sampling of undisturbed mucosal lining fluid from the upper airways. It can be used to perform the quantification of in vivo levels of protein mediators, such as cytokines and chemokines, in subjects of all ages.

This protocol describes noninvasive sampling of undisturbed upper airway mucosal lining fluid. It also details the extraction procedure used prior to the ...

Generation of Escape Variants of Neutralizing Influenza Virus Monoclonal Antibodies

Influenza viruses exhibit a remarkable ability to adapt and evade the host immune response. One way is through antigenic changes that occur on the surface glycoproteins of the virus. The generation of escape variants is a powerful method in elucidating how viruses escape immune detection and in identifying critical residues required for antibody binding. Here, we describe a protocol on how to generate influenza A virus escape variants by utilizing human or murine monoclonal antibodies (mAbs) directed against the viral hemagglutinin (HA). With the use of our technique, we previously characterized critical residues required for the binding of antibodies targeting either the head or stalk of the novel avian H7N9 HA. The protocol can be easily adapted for other virus systems. Analyses of escape variants are important for modeling antigenic drift, determining single nucleotide polymorphisms (SNPs) conferring resistance and virus fitness, and in the designing of vaccines and/or therapeutics.

We describe a method by which we identify critical residues required for the binding of human or murine monoclonal antibodies that target the viral hemagglutinin of influenza A viruses. The protocol can be adapted to other virus surface glycoproteins and their corresponding neutralizing antibodies.

Influenza viruses exhibit a remarkable ability to adapt and evade the host immune response. One way is through antigenic changes that occur on the surface ...

Generation of Discriminative Human Monoclonal Antibodies from Rare Antigen-specific B Cells Circulating in Blood

Monoclonal antibodies (mAbs) are powerful tools useful for both fundamental research and in biomedicine. Their high specificity is indispensable when the antibody needs to distinguish between highly related structures (e.g., a normal protein and a mutated version thereof). The current way of generating such discriminative mAbs involves extensive screening of multiple Ab-producing B cells, which is both costly and time consuming. We propose here a rapid and cost-effective method for the generation of discriminative, fully human mAbs starting from human blood circulating B lymphocytes. The originality of this strategy is due to the selection of specific antigen binding B cells combined with the counter-selection of all other cells, using readily available Peripheral Blood Mononuclear Cells (PBMC). Once specific B cells are isolated, cDNA (complementary deoxyribonucleic acid) sequences coding for the corresponding mAb are obtained using single cell Reverse Transcription-Polymerase Chain Reaction (RT-PCR) technology and subsequently expressed in human cells. Within as little as 1 month, it is possible to produce milligrams of highly discriminative human mAbs directed against virtually any desired antigen naturally detected by the B cell repertoire.

We describe a method for the production of human antibodies specific for an antigen of interest, starting from rare B cells circulating in human blood. Generation of these natural antibodies is efficient and rapid, and the antibodies obtained can discriminate between highly related antigens.

Monoclonal antibodies (mAbs) are powerful tools useful for both fundamental research and in biomedicine. Their high specificity is indispensable when the ...

Generation of Monoclonal Antibodies Against Natural Products

The analysis of the bioactive components present in foods and natural products has become a popular area of study in many fields, including traditional Chinese medicine and food safety/toxicology. Many of the classical analysis techniques require expensive equipment and/or expertise. Notably, enzyme-linked immunosorbent assays (ELISAs) have become an emerging method for the analysis of foods and natural products. This method is based on antibody-mediated detection of the target components. However, as many of the bioactive components in natural products are small (&lt;1,000 Da) and do not induce an immune response, creating monoclonal antibodies (mAbs) against them is often difficult. In this protocol, we provide a detailed explanation of the steps required to generate mAbs against target molecules as well as those needed to create the associated indirect competitive (ic)ELISA for the rapid analysis of the compound in multiple samples. The procedure describes the synthesis of the artificial antigen (i.e., the hapten-carrier conjugate), immunization, cell fusion, monoclonal hybridoma preparation, characterization of the mAb, and the ELISA-based application of the mAb. The hapten-carrier conjugate was synthesized by the sodium periodate method and evaluated by MALDI-TOF-MS. After immunization, splenocytes were isolated from the immunized mouse with the highest antibody titer and fused with the hypoxanthine-aminopterin-thymidine (HAT)-sensitive mouse myeloma cell line Sp2/0 -Ag14 using a polyethylene glycol (PEG)-based method. The hybridomas secreting mAbs reactive to the target antigen were screened by icELISA for specificity and cross-reactivity. Furthermore, the limiting dilution method was applied to prepare monoclonal hybridomas. The final mAbs were further characterized by icELISA and then utilized in an ELISA-based application for the rapid and convenient detection of the example hapten (naringin (NAR)) in natural products.

This article provides a detailed protocol for the preparation and evaluation of monoclonal antibodies against natural products for use in various immunoassays. This procedure includes immunization, cell fusion, indirect competitive ELISA for positive clone screening, and monoclonal hybridoma preparation. The specifications for antibody characterization using MALDI-TOF-MS and ELISA analyses are also provided.

The analysis of the bioactive components present in foods and natural products has become a popular area of study in many fields, including traditional ...

Human Colonoid Monolayers to Study Interactions Between Pathogens, Commensals, and Host Intestinal Epithelium

Human 3-dimensional (3D) enteroid or colonoid cultures derived from crypt base stem cells are currently the most advanced ex vivo model of the intestinal epithelium. Due to their closed structures and significant supporting extracellular matrix, 3D cultures are not ideal for host-pathogen studies. Enteroids or colonoids can be grown as epithelial monolayers on permeable tissue culture membranes to allow manipulation of both luminal and basolateral cell surfaces and accompanying fluids. This enhanced luminal surface accessibility facilitates modeling bacterial-host epithelial interactions such as the mucus-degrading ability of enterohemorrhagic E. coli (EHEC) on colonic epithelium. A method for 3D culture fragmentation, monolayer seeding, and transepithelial electrical resistance (TER) measurements to monitor the progress towards confluency and differentiation are described. Colonoid monolayer differentiation yields secreted mucus that can be studied by the immunofluorescence or immunoblotting techniques. More generally, enteroid or colonoid monolayers enable a physiologically-relevant platform to evaluate specific cell populations that may be targeted by pathogenic or commensal microbiota.

Here, we present a protocol to culture human enteroid or colonoid monolayers that have intact barrier function to study host epithelial-microbiota interactions at the cellular and biochemical level.

Human 3-dimensional (3D) enteroid or colonoid cultures derived from crypt base stem cells are currently the most advanced ex vivo model of the intestinal ...