Effect of gga-miR-155 on cell proliferation, apoptosis and invasion of Marek's disease virus (MDV) transformed cell line MSB1 by targeting RORA.

BACKGROUND: Marek's disease (MD) is caused by the oncogenic Marek's disease virus (MDV), and is a highly contagious avian infection with a complex underlying pathology that involves lymphoproliferative neoplasm formation. MicroRNAs (miRNAs) act as oncogenes or tumor suppressors in most cancers. The gga-miR-155 is downregulated in the MDV-infected chicken tissues or lymphocyte lines, although its exact role in tumorigenesis remains unclear. The aim of this study was to analyze the effects of gga-miR-155 on the proliferation, apoptosis and invasiveness of an MDV-transformed lymphocyte line MSB1 and elucidate the underlying mechanisms. RESULTS: The expression level of gga-miR-155 was manipulated in MSB1 cells using specific mimics and inhibitors. While overexpression of gga-miR-155 increased proliferation, decreased the proportion of G1 phase cells relative to that in S and G2 phases, reduced apoptosis rates and increased invasiveness. However, its downregulation had the opposite effects. Furthermore, gga-miR-155 directly targeted the RORA gene and downregulated its expression in the MSB1 cells. CONCLUSION: The gga-miR-155 promotes the proliferation and invasiveness of the MDV-transformed lymphocyte line MSB1 and inhibits apoptosis by targeting the RORA gene.

Identification and characterization of a Streptococcus suis immunogenic ornithine carbamoytransferase involved in bacterial adherence.

BACKGROUND: Streptococcus suis (SS) is a major swine pathogen and a serious zoonotic pathogen causing septicemia and meningitis in piglets and humans. Using an immunoproteomic approach, we previously brought evidence that ornithine carbamoytransferase (OCT) may represent a vaccine candidate to protect against S. suis biofilm-related and acute infections. METHOD: In this study, the gene encoding OCT was cloned into the expression vector pET-28a and the recombinant protein was expressed in Escherichia coli BL21. The immunogenicity and protective efficacy of the SS OCT was further investigated in a mouse model. RESULTS: The protein was found to be expressed in vivo and elicited high antibody titers following SS infections in mice. An animal challenge experiment with SS showed that 62.5% of mice immunized with the OCT protein were protected. Using an in vitro competitive adherence inhibition assay of adherence, evidence was obtained that OCT could significantly reduce the number of SS cells adhered to porcine kidney PK-15 cells. The bacterial levels recovered in mice of the OCT immunized group were significantly decreased in some organs, compared with the control group. CONCLUSION: In summary, our results suggest that the recombinant SS OCT protein, which is involved in bacterial adherence, may efficiently stimulate an immune response conferring protection against SS infections. It may therefore be considered as a potential vaccine candidate, although further studies are necessary to evaluate their use in swine.

Recombinant-attenuated Salmonella Pullorum strain expressing the hemagglutinin-neuraminidase protein of Newcastle disease virus (NDV) protects chickens against NDV and Salmonella Pullorum challenge.

Newcastle disease virus (NDV) and Salmonella Pullorum have significant damaging effects on the poultry industry, but no previous vaccine can protect poultry effectively. In this study, a recombinant-attenuated S. Pullorum strain secreting the NDV hemagglutinin-neuraminidase (HN) protein, C79-13ΔcrpΔasd (pYA-HN), was constructed by using the suicide plasmid pREasd-mediated bacteria homologous recombination method to form a new bivalent vaccine candidate against Newcastle disease (ND) and S. Pullorum disease (PD). The effect of this vaccine candidate was compared with those of the NDV LaSota and C79-13ΔcrpΔasd (pYA) strains. The serum hemagglutination inhibition antibody titers, serum immunoglobulin G (IgG) antibodies, secretory IgA, and stimulation index in lymphocyte proliferation were increased significantly more (p < 0.01) in chickens inoculated with C79-13ΔcrpΔasd (pYA-HN) than with C79-13ΔcrpΔasd (pYA) but were not significantly increased compared with the chickens immunized with the LaSota live vaccine (p > 0.05). Moreover, the novel strain provides 60% and 80% protective efficacy against the NDV virulent strain F48E9 and the S. Pullorum virulent strain C79-13. In summary, in this study, a recombinant-attenuated S. Pullorum strain secreting NDV HN protein was constructed. The generation of the S. Pullorum C79-13ΔcrpΔasd (pYA-HN) strain provides a foundation for the development of an effective living-vector double vaccine against ND and PD.

[Expression and analysis of recombinant chicken IL-18 in Pichia pastoris.].

AIM: Expression and analysis of recombinant chicken IL-18 in Pichia pastoris. METHODS: Chicken IL-18 mature peptide gene was amplified from the recombinant plasmid pMD18-T-ChIL-18 by PCR, and was subcloned into Pichia pastoris expression vector pPICZalphaA to construct the recombinant plasmid pPICZalphaA-ChIL-18. After identified by restriction enzymes digestion analysis, PCR and DNA sequencing, the recombinant plasmid was transformed into Pichia pastoris X-33.Then choosing the multi-copy recombinant strains to be induced for expression.Then the bioactivity of rchIL-18 was analysed by Western blot, ELISA and MTT after purified by Sephadex G-100 column. RESULTS: The chicken IL-18 with the immunogenicity was secreted by Pichia pastoris. It could induce T lymphocytes proliferation and secreting IFN-gamma in vitro. CONCLUSION: The chicken IL-18 with obvious biological activity is secreted by Pichia pastoris X-33.