Production of rabbit polyclonal antibody against apobec-1 by genetic immunization

Production of monoclonal antibody by DNA immunization with electroporation

DNA immunization with in vivo electroporation is an efficient alternative protocol for the production of monoclonal antibodies (mAb). Generation of mAb by DNA immunization is a novel approach to circumvent the following technical hurdles associated with problematic antigens: low abundance and protein instability and use of recombinant proteins that lack posttranslational modifications. This chapter describes the use of a DNA-based immunization protocol for the production of mAb against a house dust mite allergen, designated as Blo t 11, which is a paramyosin homologue found in Blomia tropicalis mites. The Blo t 11 cDNA fused at the N terminus to the sequence of a signal peptide was cloned into the pCI mammalian expression vector. The DNA construct was injected intramuscularly with in vivo electroporation into mice, and the specific antibody production in mice was analyzed by enzyme-linked immunosorbent assay (ELISA). Hybridomas were generated by fusing mouse splenocytes with myeloma cells using the ClonaCell-HY Hybridoma Cloning Kit. Six hybridoma clones secreting Blo t 11 mAb were successfully generated, and these mAb are useful reagents for immunoaffinity purification and immunoassays.

DNA immunization for the production of monoclonal antibodies to Blo t 11, a paramyosin homolog from Blomia tropicalis

BACKGROUND

Blo t 11 is a high molecular weight allergen from Blomia tropicalis with significant immunoglobulin (Ig)E binding frequency. Native and recombinant Blo t 11 are susceptible to degradation and the isolation and expression of the allergen is problematic thus obtaining sufficient amounts of purified Blo t 11 for antibody production is limiting. DNA-based immunization is an attractive alternative strategy that bypasses antigen purification for antibody production.

OBJECTIVES

To use a DNA-based immunization protocol for the production and characterization of Blo t 11 monoclonal antibodies (mAbs).

METHODS

The 2625 bp cDNA coding for Blo t 11 was cloned into a mammalian expression vector and immunized intramuscularly with electroporation into mice. Monoclonal antibodies to Blo t 11 were generated using a methylcellulose-based hybridoma cloning kit. These mAbs were utilized for native Blo t 11 isolation and the development of sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Six mAbs recognizing the native and recombinant Blo t 11 were generated and characterized. Native Blo t 11 was affinity purified from Bt extract and its identity was confirmed by matrix assisted laser desorption/ionization - time of flight mass spectrometry. The native Blo t 11 showed IgE reactivity with 67% of mite allergic sera. A two-site ELISA developed showed a detection limit of 100 pg/ml of Blo t 11.

CONCLUSION

A DNA-based immunization protocol was successfully used to generate Blo t 11 mAbs with a spectrum of distinct epitopes located throughout the whole molecule, and they are useful for immunoaffinity purification and immunoassays.

Production of monoclonal antibodies for immunoaffinity purification and quantitation of Blo t 1 allergen in mite and dust extracts

BACKGROUND

Blo t 1 is a cysteine protease-like allergen from Blomia tropicalis. Recombinant Blo t 1 binds up to 90% of IgE from allergic patients and shows limited cross-reactivity to Der p 1. The generation of monoclonal antibodies (mAbs) against Blo t 1 is important for the detection, isolation and characterization of the native form of the allergen.

METHODS

Mice were immunized intramuscularly with naked plasmid DNA encoding Blo t 1 gene with in vivo electroporation and boosted intraperitoneally with recombinant Blo t 1. mAbs against Blo t 1 were generated using a methylcellulose-based hybridoma cloning kit. The native Blo t 1 was isolated by mAb affinity purification and its allergenicity was determined by ELISA. A two-site ELISA for Blo t 1 was developed using the mAbs generated.

RESULTS

A DNA-based immunization protocol induced high titre Blo t 1-specific antibodies in mice. Six stable hybridoma clones secreting mAbs recognizing the native and recombinant Blo t 1 were generated. The native Blo t 1 was affinity-purified from a B. tropicalis extract and its allergenicity was determined at 63% using a panel of Singaporean and Malaysian mite allergic patients' sera. A two-site ELISA was developed, which showed a detection limit of 10 ng/mL of Blot t 1.

CONCLUSION

Six Blo t 1 mAbs were successfully generated by DNA immunization. These mAbs are useful for nBlo t 1 immunoaffinity isolation and quantitative immunoassays for Blo t 1 in mite and environmental dust extracts.

Generation of high titer antisera in rabbits by DNA immunization

Mesothelin is a GPI-linked, membrane-associated differentiation antigen that is over-expressed in several forms of human cancers. Intradermal injection into rabbits of plasmid DNA encoding full length mesothelin resulted in antisera with titers as high as 1:100,000. Each immunization consisted of 320 microg of DNA delivered into 4 sites. After the initial three injections antisera titers were moderate (between 10 to 30,000) and fell over the course of about 7 weeks. When the titers had fallen, an injection of a booster dose of DNA resulted in very high titers of antisera. These antisera contained IgGs that could bind to both recombinant mesothelin made in Eschericha coli and to mesothelin present on human cells in Western blots and in immunofluorescence assays. These observations indicate that simple intradermal DNA immunization of rabbits can result in high titers of antibodies that can be used for a variety of purposes.

Vaxfectin enhances the humoral immune response to plasmid DNA-encoded antigens

This report characterizes Vaxfectin, a novel cationic and neutral lipid formulation which enhances antibody responses when complexed with an antigen-encoding plasmid DNA (pDNA). In mice, intramuscular injection of Vaxfectin formulated with pDNA encoding influenza nucleoprotein (NP) increased antibody titers up to 20-fold, to levels that could not be reached with pDNA alone. As little as 1 microg of pDNA formulated with Vaxfectin per muscle resulted in higher anti-NP titers than that obtained with 25 microg naked pDNA. The antibody titers in animals injected with Vaxfectin-pDNA remained higher than in the naked pDNA controls for at least 9 months. The enhancement in antibody titers was dependent on the Vaxfectin dose and was accomplished without diminishing the strong anti-NP cytolytic T cell response typical of pDNA-based vaccines. In rabbits, complexing pDNA with Vaxfectin enhanced antibody titers up to 50-fold with needle and syringe injections and also augmented humoral responses when combined with a needle-free injection device. Vaxfectin did not facilitate transfection and/or increase synthesis of beta-galactosidase reporter protein in muscle tissue. ELISPOT assays performed on bone marrow cells from vaccinated mice showed that Vaxfectin produced a three- to five-fold increase in the number of NP-specific plasma cells. Thus, Vaxfectin should be a useful adjuvant for enhancing pDNA-based vaccinations.

Generation of high-affinity rabbit polyclonal antibodies to the murine urokinase receptor using DNA immunization

The urokinase receptor (uPAR) is a glycolipid anchored cell surface glycoprotein that plays a central role in extracellular proteolysis during tissue remodeling processes and cancer invasion. By intramuscular (i.m.) injection of rabbits with plasmid DNA coding for a carboxy-terminally truncated secreted form of the murine uPAR (muPAR), specific anti-sera with a titer of 64,000, as measured by ELISA, have been obtained. Rabbits received a total of 10 monthly injections of 1 mg DNA in phosphate-buffered saline. The antibody titer peaked between the 5th and 7th injection and slowly declined after the 8th injection. After the final immunization the immune response persisted for at least 6 months without further injections. The antibodies generated by DNA immunization were useful for immunohistochemistry and immunoblotting, recognizing the antigen both in its native and in its reduced and alkylated form. Using the antibodies in immunoblotting muPAR was identified in lysates of peritoneal macrophages, spleen and lung tissue. Both the intact and cleaved form of muPAR were identified in lysates of a murine monocyte cell line P388D.1. No cross-reaction with human uPAR was observed. In immunohistochemical analysis of normal mouse lung tissue uPAR immunoreactivity was located in the alveoli and pulmonary vessels, whereas the bronchial epithelium was negative. These results demonstrate that DNA immunization of rabbits using i.m. injection is a very effective and easy method to raise polyclonal antibodies which can be used for characterization and localization of muPAR in mouse tissue.