Construction of a phage antibody library and screening of anti-epidermal growth factor receptor variant III single chain antibody / 南方医科大学学报

<p><b>OBJECTIVE</b>To obtain specific anti-epidermal growth factor receptor variant III (EGFRvIII) single chain antibody (ScFv) by phage antibody library display system.</p><p><b>METHODS</b>The total RNA was extracted from the spleen B cells of BALB/c mice immunized with pep-3-OVA protein, and the first-strand cDNA was synthesized by reverse transcription. Antibody VH and VL gene fragments were amplified and joined to a ScFv gene with the linker. The ScFv gene was ligated into the phagemid vector pCANTAB5E, which was transformed into competent E. coli TG1. The transformed cells were then infected with M13KO7 helper phage to yield the recombinant phage to construct the phage ScFv library. Pep-3-BSA protein was used to screen the phage antibody library and ELISA carried out to characterize the activity of the antibody.</p><p><b>RESULTS</b>The VH and VL gene fragments of the antibody were about 350 bp and 320 bp in length as analyzed by agarose gel electrophoresis. The ScFv gene was 780 bp, consistent with the expected length. The recombinant phagemid with ScFv gene insert was rescued, and an immune phage ScFv library with the content of 5.0x10(6) was constructed. The recombinant ScFv phage had a titer of 3.0x10(4) cfu/ml, and the fourth phage harvest yielded 56 times as much as that of the first one. SDS-PAGE demonstrated a molecular mass of the soluble ScFv of about 28 kD. ELISA results indicated good specificity of the ScFv to bind EGFRvIII.</p><p><b>CONCLUSION</b>An immune phage ScFv library is successfully constructed, and the ScFv antibody fragment is capable of specific binding to EGFRvIII.</p>

Secretory expression of PR39 following adeno-associated viral-encoding fusion gene transfer induces angiogenesis in hypoxia chick embryo / 中华心血管病杂志

<p><b>OBJECTIVES</b>To investigate the impact of AAV-encoding NT4-TAT-His-PR39 fusion gene expression on HIF-1alpha level in ECV304 cultured under hypoxic condition (1%O(2)) and on angiogenesis in hypoxic chick embryo.</p><p><b>METHODS</b>PR39 cDNA was connected with NT4, TAT, 6 x His cDNA by molecular biology methods. The recombinant AAV vector was obtained by three plasmid co-transfection in 293 cells. Then ECV304 were respectively infected with AAV-NT4-TAT-His-PR39, 6 x His expression and HIF-1alpha level in ECV304 were detected by immunocytochemistry. The chicken embryos were randomized into the AAV-PR39, EV and PBS groups (n = 10 each) subject to hypoxia (5%O(2), n = 15) or normoxia environments (n = 15), the vessel density of the chicken chorioallantoic membrane (CAM) were measured by Image Pro Plus (IPP) software.</p><p><b>RESULTS</b>The expression of 6 x His protein was detected in AAV-PR39 infected ECV304 cells. HIF-1alpha protein activity was significantly increased in AAV-PR39 infected ECV304 underwent hypoxia compared to PBS and non-infected ECV304 groups (P < 0.05). The vessel density of chicken CAM in hypoxia environment but not in normoxia environment was also significantly higher in AAV-PR39 group than in EV group and PBS group (all P < 0.05).</p><p><b>CONCLUSION</b>AAV-encoding NT4-TAT-His-PR39 fusion gene expression significantly increased HIF-1alpha level in ECV304 exposed to hypoxia and promoted angiogenesis in hypoxic chicken embryo.</p>

Construction of a prokaryotic expression vector for apoptin and preparation of polyclonal antibody of apoptin / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a prokaryotic expression vector for apoptin and prepare polyclonal antibody of apoptin.</p><p><b>METHODS</b>Apoptin gene amplified from pGEM-T/Apoptin plasmid by PCR was cloned into pET-28a (+). E.coli BL21 (DE3) was transformed by the recombinant plasmid, and apoptin protein expression induced by IPTG was analyzed by SDS-PAGE. BALB/c mice were immunized with the protein and the titer of the antibody was determined using indirect enzyme-linked immunosorbent assay (ELISA).</p><p><b>RESULTS</b>Apoptin gene was successfully cloned into pET-28a (+), and the expression of a protein with relative molecular mass of about 17 000 was identified by SDA-PAGE. After 5 immunizations of the mice with the protein, the blood antibody titer reached 1:5x10(5).</p><p><b>CONCLUSION</b>The prokaryotic expression vector for apoptin is successfully constructed and the polyclonal antibody of apoptin is obtained, which allows further functional study of apoptin.</p>

Adenovirus-mediated killing of hepatocellular carcinoma HepG2 cells by heterogeneous fusion gene NT4p53(N15)Ant / 南方医科大学学报

<p><b>UNLABELLED</b>OBJECTIVE To construct a recombinant adenovirus Ad.NT4p53(N15)Ant and explore its cytotoxic effect against hepatocellular carcinoma HepG2 cells in vitro.</p><p><b>METHODS</b>The recombinant adenovirus containing the fusion gene of neurotrophin 4 (NT4)signal peptide, N-terminal residues (12-26) of p53 and 17 amino acid Drosophila homeobox protein Antennapedia (Ant) was constructed by gene cloning protocol. The effect of this fusion gene on HepG2 cells was evaluated by MTT assay, PI staining and flow cytometry.</p><p><b>RESULTS</b>The fusion gene Ad.NT4p53(N15)Ant was successfully constructed, as verified by restriction endonuclease digestion and PCR. Ad.NT4p53(N15)Ant could strongly suppress the growth of HepG2 cells (with a growth inhibition rate of 63.3% 48 h after infection) without affecting NIH-3T3 cells. Flow cytometry showed that Ad.NT4p53(N15)Ant could induce obvious apoptosis of HepG2 cells.</p><p><b>CONCLUSION</b>The recombinant adenovirus containing NT4p53(N15)Ant fusion gene can inhibit the growth the of HepG2 cells in vitro partially by inducing cell apoptosis.</p>

Construction of a retroviral vector for RNA interference targeting human telomerase reverse transcriptase / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a recombinant retroviral vector for RNA interference targeting human telomerase reverse transcriptase (hTERT).</p><p><b>METHODS</b>The sequences coding for enhanced fluorescence protein (EGFP), U6 promoter and a small interfering RNA (siRNA) targeting hTERT were amplified by PCR, respectively, and sub-cloned sequentially into the retroviral shuttle plasmid pLXSN to construct the plasmid pLXSN-EGFP-U6-siTERT. The recombinant expression plasmid was identified by restriction enzyme digestion and sequencing. Fluorescence microscopy and flow cytometry were employed to analyze EGFP expression in NIH3T3 transfected with the recombinant plasmid, and MMT assay was performed to evaluate the growth inhibition of Hela cells resulting from RNA interference mediated by the plasmid.</p><p><b>RESULTS</b>Sequence analysis and restriction enzyme digestion showed that the recombinant expression plasmid pLXSN-EGFP-U6-siTERT was constructed successfully. Twenty-four hours after transfection of NIH3T3 cells with the recombinant plasmid, the expression rate of EGFP reached 24.1% as shown by flow cytometry. MTT assay demonstrated a cell death rate of 53.2% 72 h after transfection of Hela cells with the plasmid.</p><p><b>CONCLUSION</b>The successful construction of the recombinant retroviral plasmid mediating potent cell growth inhibition suggests the great potential of RNA interference technique in suppressing hTERT expression in mammalian tumor cells.</p>

Fusion of TGF-beta 1 antigenic determinant and HBV core antigen as an anti-TGF-beta 1 vaccine / 中华肝脏病杂志

<p><b>OBJECTIVES</b>To examine the expression and purification of the TGFbeta1 vaccine from prokaryotic expression system and to determine the antigenicity of the fusion protein of recombinant vector pET28a/ HBcAg1-71-TGFbeta132-HBcAg89-144.</p><p><b>METHODS</b>The reconstructed vector pGEMEX-1/CTC was subcloned to pET28a and transformed into E. coli BL21 (DE3). The recombinant 6xHis- HBcAg1-71- TGFbeta132- HBcAg89-144 was to be expressed after induction by IPTG and purified with Ni-NTA-His affinity chromatography. The detection of the formation of core-like particles was done under an electron microscope and of their antigenity by using ELISA and Western blot.</p><p><b>RESULTS</b>A 2.46 x 10(4) protein was obtained by optimizing the conditions for both expression and purification. The protein had the TGFbeta1 antigenicity but not a HBc antigenity and the formed core-like particles were bigger than natural core particles.</p><p><b>CONCLUSION</b>The recombinant fusion protein in the prokaryotic expressed system can be used as an anti-TGFbeta1 vaccine to inhibit hepatic fibrosis.</p>