Construction of human adenovirus type 4 vector expressing enhanced green fluorescence protein / 中华微生物学和免疫学杂志

Objective To prepare human adenovirus type 4 (Ad4) vector expressing enhanced green fluorescence protein (EGFP). Methods This study used a previously prepared plasmid pBRAd4 containing the whole genome DNA of Ad4-GZ01 strain. The Ad4 genome E3 region of pBRAd4 was deleted and replaced with the EGFP expression frame by conventional molecular cloning method. Then the recombi-nant plasmid was transfected into AD293 cells to rescue recombinant virus which was identified by sequen-cing,SDS-PAGE and ELISA. The purified virions were injected to mice and the induced immune responses were detected by ELISA and microneutralization test. Results The recombinant Ad4 vector rAd4EGFP ex-pressing EGFP was obtained and could be recognized and neutralized by monoclonal antibody MN4b and an-tisera against Ad4. The Ad4-specific and EGFP-specific antibodies with high titers could be detected in mice immunized with rAd4EGFP. Conclusion Human Ad4 vector expressing EGFP was successfully obtained and could be used in research on vaccine development,drug evaluation and transgene vector.

Engineering of Thiamin Pyrophosphate Fluorescent Biosensors Based on Ribozyme Switches in Mammalian Cells / 分析化学

Thiamin pyrophosphate (TPP) is a thiamine (vitamin B1) derivative and an essential cofactor in oxidative metabolism of the sugars,fatty acids and amino acids in living cells.By now,numerous TPP-dependent artificial riboswitch systems have been developed to regulate target gene expression but limited in bacteria,fungi or plant cells.Herein,the activating (switch-on) and inhibiting (switch-off) TPP-depended hammerhead ribozyme switches,which are from previous reported structures of prokaryotes screening,were investigated in mammalian cells.These ribozyme switches were inserted into the 3'UTR of the enhanced green fluorescence protein (EGFP) gene to construct the efficient ribozyme-based artificial switches through overlap extension PCR cloning.The HEK293 cells were transfected with the engineered ribozyme switches at increasing concentration of TPP.The EGFP gene-regulatory ability was analyzed with fluorescent microscope and flow cytometry.These TPP-inducible gene regulation devices showed the obvious ligand dose-dependency and excellent specificity.Two switch-on and one switch-off constructs demonstrated 3.1-fold or 1.9-fold increment and 2.3-fold reduction of EGFP level respectively with 150 μ mol/L TPP.The ligand-responsive ribozyme switches,by tuning the change of TPP concentration into the visual reporter genetic expression in cells,enable an efficient development of label-free,noninvasive and high-specific biosensors in living mammalian cells.

Construction and Co-expression of Grass Carp Reovirus VP6 Protein and Enhanced Green Fluorescence Protein in the Insect Cells / 中国病毒学

Grass carp reovirus (GCRV), a disaster agent to aquatic animals, belongs to Genus Aquareovirus of family Reoviridea. Sequence analysis revealed GCRV genome segment 8 (s8) was 1296 bp nucleotides in length encoding an inner capsid protein VP6 of about 43kDa. To obtain in vitro non-fusion expression of a GCRV VP6 protein containing a molecular of fluorescence reporter, the recombinant baculovirus, which contained the GCRVs8 and eGFP (enhanced green fluorescence protein)genes, was constructed by using the Bac-to-Bac insect expression system. In this study, the whole GCRVs8 and eGFP genes, amplified by PCR, were constructed into a pFastBacDual vector under polyhedron (PH) and p10 promoters, respectively. The constructed dual recombinant plasmid (pFbDGCRVs8/eGFP) was transformed into DH10Bac cells to obtain recombinant Bacmid (AcGCRVs8/eGFP) by transposition. Finally, the recombinant bacluovirus (vAcGCRVs8/eGFP) was obtained from transfected Sf9 insect cells. The green fluorescence that was expressed by transfected Sf9 cells was initially observed 3 days post transfection, and gradually enhanced and extended around 5days culture in P1(Passage1) stock. The stable high level expression of recombinant protein was observed in P2 and subsequent passage budding virus (BV) stock. Additionally, PCR amplification from P1 and amplified P2 BV stock further confirmed the validity of the dual-recombinant baculovirus. Our results provide a foundation for expression and assembly of the GCRV structural protein in vitro.