Preparation of human parvovirus B19 virus-like particles / 生物工程学报

The baculovirus expression system was employed to prepare the virus-like particles (VLPs) of human parvovirus B19. The synthesized VP2 gene of B19 was inserted into the multi-cloning site (MCS) of pFastBac1 vector; the resulting plasmid was transferred to the Escherichia coli DH10Bac competent cells, which contain a baculovirus shuttle vector (Bacmid), to generate Bacmid-VP2 by site-specific transposition. Recombinant baculovirus carrying VP2 gene (rBac-VP2) was then rescued from Bacmid-VP2-transfected Sf9 cells. Indirect immunofluorescence and Western blotting were used to identify the VP2 protein in rBac-VP2-infected Sf9 cells, and the VLPs were observed under transmission electron microscope after being enriched by ultracentrifugation. The B19 VLPs were successfully produced in insect cells with baculovirus expression system, which will facilitate the development of diagnostic reagents to detect the antibody against B19 virus in human serum.

Epididymis-specific lipocalin promoters / 亚洲男科学杂志(英文版)

Our goal is to decipher which DNA sequences are required for tissue-specific expression of epididymal genes. At least 6 epididymis-specific lipocalin genes are known. These are differently regulated and regionalized in the epididymis. Lipocalin 5 (Lcn5 or mE-RABP) and Lipocalin 8 (Lcn8 or mEP17) are homologous genes belonging to the epididymis-specific lipocalin gene cluster. Both the 5 kb promoter fragment of the Lcn5 gene and the 5.3 kb promoter fragment of the Lcn8 gene can direct transgene expression in the epididymis (Lcn5 to the distal caput and Lcn8 to the initial segment), indicating that these promoter fragments contain important cis-regulatory element(s) for epididymis-specific gene expression. To define further the fragments regulating gene expression, the Lcn5 promoter was examined in transgenic mice and immortalized epididymal cell lines. After serial deletion, the 1.8 kb promoter fragment of the Lcn5 gene was sufficient for tissue-specific and region-specific gene expression in transgenic mice. Transient transfection analysis revealed that a transcription factor forkhead box A2 (Foxa2) interacts with androgen receptor and binds to the 100 bp fragment of the Lcn5 promoter between 1.2 kb and 1.3 kb and that Foxa2 expression inhibits androgen-dependent induction of the Lcn5 promoter activity. Immunohistochemistry indicated a restricted expression of Foxa2 in the epididymis where endogenous Lcn5 gene expression is suppressed and that the Foxa2 inhibition of the Lcn5 promoter is consistent with the lack of expression of Lcn5 in the corpus and cauda. Our approach provides a basic strategy for further analysis of the epididymal lipocalin gene regulation and flexible control of epididymal function.

Optimized codon usage enhances the expression and immunogenicity of DNA vaccine encoding the HPV 6b E7 gene / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To analyze the influence of optimal codon usage on the expression levels and immunogenicity of DNA vaccines, encoding the human papillomavirus type 6b (HPV 6b) E7 gene.</p><p><b>METHODS</b>The full length E7 gene of HPV 6b was modified to substitute human preferred codon for rarely used codon, and three mutations were introduced into the pRB binding site of HPV 6b E7 to eliminate its transformation potential. The codon optimized and mutated E7 gene (hu-mE7) were cloned into the Kpn I and EcoR I site of the pcDNA3 mammalian expression vector, the in vitro expression of the hu-mE7 gene and the immunogenicity of hu-mE7 DNA vaccine were compared with the wt-E7gene.</p><p><b>RESULTS</b>The in vitro expression of pcDNA3-hu-mE7 was much higher than the classical wt-E7 plasmid in monkey COS-1 cell line. Mice immunized intramuscularly with the pcDNA3-hu-mE7 showed that the codon modified E7 gene induced a stronger IFN-gamma ratios than the wt-E7 gene.</p><p><b>CONCLUSIONS</b>These results suggest that the optimized codon usage contributes to the enhancement of gene expression and immunogenicity of HPV 6b E7 gene.</p>

The construction of eukaryotic expressive vector of RI gene and the effects of the transfected pLNCX-ri on the growth of C6 glioma cells / 中国癌症杂志

Purpose:To clone and construct an eukaryotic expressive vector of ribonuclease inhibitor (RI) gene ,as well as to observe the effects of the transfected pLNCX-ri on the growth of C6 glioma cells.Methods:A segment of RI gene of 1.4 kb was obtained by Nde I/Xho digestion and cloned into pLNCX. Transfective agent and selective antibiotic were lipofect AMINE and G418 respectively. The expression of pLNCX-ri in C6 glioma cells was detected by Western blotting. And SD rats were inoculated by the transfected C6 glioma cells.Results:An eukaryotic expressive vector of RI gene was constructed successfully. RI content was remarkably higher in the transfected cells than that of in the untransfected cells. After SD rats were inoculated by the transfected C6 glioma cells,the tumorigenic time was prolonged, the tumor weight was reduced and the density of tumor vessels was notably decreased. Conclusions:These results indicated that RI gene powerfully inhibited the growth of C6 glioma cells via decreasing tumor vessels formation.