[Expression of VP0 protein of enterovirus 71 in Escherichia coli and generation of the corresponding polyclonal antibodies in guinea pigs].

AIM: To obtain recombinant VP0 protein of enterovirus 71, and generate the corresponding VP0-specific polyclonal antibodies, for molecular detection and characterization of EV71. METHODS: The VP0 gene was amplified by PCR and cloned into vector pET26b to make pET-VP0 for the prokaryotic expression of VP0. The recombinant VP0 protein was expressed in E.coli BL21 harboring pET-VP0, purified from inclusion bodies, renatured, and subsequently used to immunize guinea pigs. The resultant antisera were evaluated for anti-VP0 titer, binding capacity and specificity by ELISA, immunofluorescence staining and Western blot assays. RESULTS: Recombinant protein VP0 was efficiently produced in E.coli. Immunization of guinea pigs with recombinant VP0 elicited high-titer (1:10(6)) VP0-specific antibodies. Western blot analysis showed the resultant anti-VP0 sera reacted with E.coli-expressed VP0 as well as EV71 propagated in Vero cells. Moreover, the antisera positively recognized EV71 infected cells by immunofluorescence staining. CONCLUSION: The recombinant VP0 and the corresponding polyclonal antibodies can be used to identify and characterize EV71, and therefore represent useful agents and tools for the development of new diagnostic methods and vaccines for EV71.

[Cloning and expression of the extracellular region of human LIGHT gene in E.coli.].

AIM: To construct a recombinant prokaryotic expression vector containing the extracellular region of human LIGHT gene and perform the express in E.coli. METHODS: Total RNA was extracted from human immature bone marrow-derived dendritic cells. The extracellular region of human LIGHT gene was amplified by RT-PCR and cloned into pET32a(+) vector, the recombinant plasmid was identified by restriction endonuclease digestion analysis and DNA sequencing. After the recombinant plasmid was transformed into E.coli BL21 and induced with IPTG, the expressed protein was analyzed by SDS-PAGE and Western blot. RESULTS: A 543 bp of the extracellular region of human LIGHT gene was obtained and the sequence was confirmed correct by DNA sequencing. SDS-PAGE and Western blot analysis showed that a protein with molecular weight of 41 000 was expressed in E.coli BL21. CONCLUSION: The extracellular region of LIGHT gene is cloned successfully and expressed in E.coli BL21 and the elementary expression conditions were obtained, which lays a basis on the further functional research of LIGHT.

B7-DC-silenced dendritic cells induce stronger anti-HBV immunity in transgenic mice.

Hepatitis B virus (HBV) is a noncytopathic DNA virus and is the pathogen of acute and chronic hepatitis. Interferon and nucleotide analogues such as lamivudine and adefovir are the current treatment strategies of HBV infection; however, it is still a serious disease. Therefore, the development of new therapeutic options against HBV is needed. In the present study, we have investigated whether the vectors carrying short hairpin RNA (shRNA) targeting the murine B7-DC gene could silence the expression of B7-DC and analyzed the function of gene-modified dendritic cells (DCs) by mixed lymphocyte reaction. The results demonstrated that two shRNA vectors efficiently suppressed the expression of B7-DC. The MLR assay showed that shRNA-B7-DC-transfected DCs induced markedly higher allogeneic lymphocyte proliferation than transfected DCs with the vector plasmid pAS and untreated DCs at all dilutions. The most efficient shRNA plasmid vector against B7-DC was then used to silence the expression of B7-DC on DCs, the gene-modified DCs were pulsed with HBV-specific peptides, and HBV transgenic mice were immunized. After three rounds of immunization, the splenocytes were stimulated in vitro and tested for cytotoxicitic T lymphocyte activity, while the sera were used to detect the level of HBsAg and HBV DNA. The data demonstrated that blockade of B7-DC on DCs augmented the cytolytic activity induced by immunization with peptide-pulsed DCs and significantly reduced the concentration of serum HBsAg and HBV DNA, suggesting that silencing of B7-DC is of potential value in DC-based therapy of HBV infection.

[Construction and expression of prokaryotic vector encoding extracellular region of murine B7-DC].

AIM: To construct a prokaryotic expression vector for the extracellular domain of murine B7-DC(B7-DC(ECD)) gene, and to express the gene in E.coli BL21. METHODS: The total RNA was extracted from murine immature bone marrow-derived dendritic cells and the extracellular fragment of B7-DC cDNA was amplified by RT-PCR. The recombinant plasmid pET32a(+)-B7-DC(ECD) was constructed by cloning the extracellular fragment of B7-DC cDNA into the prokaryotic expression vector pET32a(+). After the recombinant plasmid was identified by restriction endonuclease digestion analysis and DNA sequencing, pET32a(+)-B7-DC(ECD) was transformed into E.coli BL21 through IPTG induction to express the target protein, and the protein was analyzed by SDS-PAGE and Western blot. RESULTS: A 582 bp of extracellular fragment B7-DC cDNA was obtained and the sequence was confirmed right by DNA sequencing. SDS-PAGE and Western blot analysis showed that a protein with molecular weight of 41 000 was expressed in E.coli BL21. CONCLUSION: The extracellular fragment of B7-DC is successfully cloned into pET32a (+) and expressed in E.coli BL21, which lays a foundation for the further functional research of B7-DC.

Therapeutic potential of dendritic cell-based immunization against HBV in transgenic mice.

Hepatitis B virus (HBV) transgenic mice that express HBV envelope proteins represent a model of chronic HBV infection suitable for the development of therapeutic immunization strategies. To address immunologically therapeutic effects induced by peptide-pulsed DCs, HBV transgenic mice were immunized with peptide-pulsed DCs, and the mice were killed after three times of immunization and the splenocytes were stimulated in vitro and detected by IFN-gamma ELISPOT and cytotoxic T lymphocyte (CTL) activity. The data demonstrated that HBV-specific CD8+ T cell response could be induced and CD8+ T cells had specific CTL activity. Furthermore, ELISA and fluorescent quantitative PCR were performed to detect the level of serum HBsAg and HBV DNA and the results demonstrated that HBV-specific peptide-pulsed DCs could significantly reduce the concentration of serum HBsAg and HBV DNA. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were measured and no significant differences were observed between the different groups, which indicated that no hepatocellular injury occurred. Taken together, the data strongly demonstrated that CD8+ T cell responses and antiviral immunity were elicited in HBV transgenic mice, suggesting that peptide-pulsed DCs could elicit an effective antiviral immunity.