Rapid construction of a mammalian cell surface display library of full-length human antibodies / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a mammalian cell surface display library of full-length human antibodies.</p><p><b>METHODS</b>The total RNA was isolated from human peripheral blood mononuclear cells (PBMCs), and the genes encoding the heavy chain variable regions and kappa light chains (VH and Cκ) of the antibodies were amplified by RT-PCR. The amplified VH and Cκ gene sequences were separately inserted into the vector pDGB-HC-TM. The ligation mixtures were transformed into competent E.coli DH5α cells to construct the antibody libraries, and the library sizes and diversity were analyzed. The library DNAs were transfected into CHO cells and the expression of the full-length human antibodies on the surface of CHO cells was analyzed by flow cytometry.</p><p><b>RESULTS</b>The heavy chain gene library constructed showed a diversity of 2.6 × 10(5), and the kappa light chain gene library had a diversity of 2.0 × 10(5). Sequence analysis of 10 clones randomly selected from the constructed heavy chain gene library and 10 from the light chain gene library showed that 8 heavy chain clones and all 10 light chain clones contained correct open reading frames. Flow cytometry demonstrated that all the 18 clones expressed full-length antibodies, which could be detected on CHO cell surfaces. After co-transfection of the heavy chain and light chain gene libraries into CHO cells, the expression of full-length antibodies on CHO cell surfaces was detected with the positive cells reaching 31.5.</p><p><b>CONCLUSIONS</b>A full-length human mammalian display antibody library with a combinatory diversity of 5.2 × 10(10) can be constructed in two weeks, which allows the display of full-length antibodies on mammalian cell surface.</p>

Construction of rheumatoid arthritis-specific full-length fully human mammalian display antibody libraries / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a rheumatoid arthritis-specific full-length fully human mammalian display antibody libraries.</p><p><b>METHODS</b>Peripheral blood lymphocytes were isolated from patients with rheumatoid arthritis. The repertoires of kappa light chain (LCκ) and heavy chain variable region (VH) of the antibodies were amplified by RT-PCR. The amplified LCκ and VH genes were inserted into the vector pDGB-HC-TM separately, and the ligated libraries were transformed into competent E.coli TOPO-10 strain to construct the rheumatoid arthritis-specific antibody heavy and light chain libraries. 293T cells were co-transfected with the libraries and the full-length fully human antibody expressed on the surface of 293T cells were analyzed by flow cytometry.</p><p><b>RESULTS</b>The libraries of rheumatoid arthritis-specific antibody LCκ and heavy chain (IgG1) were constructed. The expression of full-length fully human antibody on the surface of 293T cells was confirmed by flow cytometry. With the rates of correct LCκ and heavy chain sequence insertion reaching 80% and 60%, respectively, as shown by DNA sequence analysis of the randomly selected clones, the libraries showed an expressible combinatory diversity of 6.13×10(10).</p><p><b>CONCLUSION</b>The constructed libraries provide a useful platform for screening rheumatoid arthritis-specific antibodies.</p>

Effects of UV-induced DNA damage on vector ligation and transformation into bacterial cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effects of UV irradiation on DNA ligation and transformation efficiency of the expression vector into competent bacterial cells.</p><p><b>METHODS</b>The expression vector was digested with the restriction enzyme SfiI, and the purified target DNA fragments were exposed to UV light at different wavelengths. Ligation and transformation experiments with the exposed fragments were carried out and the colony number and transformation efficiency were assessed.</p><p><b>RESULTS</b>The transformation efficiency of the DNA with a 5-min exposure to 302 nm UV was 60 colonies per nanogram of the DNA, as compared with 20400 for the DNA exposed to 365 nm UV. The time course experiment showed that prolonged DNA exposure to 365 nm UV light was associated with lowered transformation efficiency. DNA exposure for 30 min caused a reduction of the transformation efficiency to lower than 50% compared to that of DNA without UV exposure. But with a 15 min exposure, the DNA maintained a transformation efficiency more than 70%, which was sufficient for most molecular biology experiments.</p><p><b>CONCLUSION</b>In construction of the expression vector, it is advisable to prevent the target DNA from UV exposure. When UV exposure is essential, we suggest that 365 nm UV be used and the exposure time controlled within 15 min.</p>

Construction of human full-length renal cell carcinoma patient-specific antibody library by mammalian cell surface display / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct human renal cell carcinoma patient-specific full-length antibody library using mammalian cell surface display technique.</p><p><b>METHODS</b>Peripheral blood mononuclear cells (PBMC) were isolated from patients with renal cell carcinoma. The repertoires of kappa light chain (LCkappa) and heavy chain variable region (VH) of antibody were amplified by RT-PCR. The LCkappa and VH libraries were inserted into the vector pDGB-HC-TM separately, and the ligated libraries were transformed into competent E.coli TOPO10 to construct the renal cell carcinoma patient-specific antibody heavy and light chain libraries. 293T cells were co-transfected with the libraries and the full-length human antibodies expressed on the surface of 293T cells were analyzed by flow cytometry.</p><p><b>RESULTS</b>The libraries of renal cell carcinoma-specific antibody kappa light chain (LCkappa) and heavy chain (IgG1) were constructed. The expression of the full-length human antibodies on the surface of 293T cell was confirmed by flow cytometry. The libraries showed an expressible combinatory diversity of 7.5x10(10).</p><p><b>CONCLUSION</b>The expressible antibody library provides a useful platform for screening of renal cell carcinoma-specific antibodies.</p>