Staphylococcus aureus cause serious infections in human and animal bodies. Development of a combination vaccine, containing several bacterial virulence factors, is a promising strategy against S. aureus infections. Cl...
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Staphylococcus aureus cause serious infections in human and animal bodies. Development of a combination vaccine, containing several bacterial virulence factors, is a promising strategy against S. aureus infections. Clumping factor A (ClfA), clumping factor B (ClfB) and fibronectin-binding protein (FnBPA) are three important adhesins of S. aureus and potential antigens for a multi-component vaccine. To evaluate the protective immunity of ClfA, ClfB, FnBPA and their combination of two against S. aureus infections in a murine lethal challenge model, mice were immunized with the antigens alone or combinations of two antigens by intramuscular injection. Antigen-specific antibody responses, opsonic activity of serum antibody and cytokines induced by the antigens in mice were assessed. Furthermore, the mice were challenged with three S. aureus strains-Newman, Wood46 and HLJ23/1. The results of high levels of IgG, number of specific IL-4 and IFN-γ secreting cells and amount of interleukin-17A (IL-17A) produced by the splenic lymphocytes showed all antigens could elicit strong humoral and cellular responses in mice, but combined-antigens could not elicit stronger humoral and cellular responses than individual antigens. The mice immunized with FnBPA showed a higher survival rate than others after challenged with a lethal dose of S. aureus Newman, Wood 46 and HLJ 23/1 strain. Consistently, the survival rates of mice immunized with combined antigens were not increased. In summary, these data suggested that ClfA, ClfB and FnBPA could induce a mixed Th1-Th2 immune response in mice and IL-17-mediated immune response. The FnBPA antigen could provide a better immune protection in the murine lethal challenge model.
Porcine circovirus type 2 (PCV2) is an important pathogen in swine and it is assumed that PCV2 replication is cell cycle-dependent (especially during S phase). However, the cellular molecules that regulate PCV2 replic...
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Porcine circovirus type 2 (PCV2) is an important pathogen in swine and it is assumed that PCV2 replication is cell cycle-dependent (especially during S phase). However, the cellular molecules that regulate PCV2 replication have not been fully identified. Here, we cloned the porcine cyclin A (CycA) and CDK2 genes, the major regulators of the S-phase, and established CycAor CDK2 overexpression or lower-expression cell lines. The propagation efficiency of strains PCV2a/CL or PCV2b/YJ in these cell lines were investigated using a capture enzyme-linked immunosorbent assay (ELISA) or an immunoperoxidase monolayer assay (IPMA), and the cell cycle was analyzed by flow cytometry. The results showed that CycA overexpression suppressed PCV2 replication. In contrast, CycA down-regulation by shRNA induced increases during the S and G2/M phases and resulted in increased PCV2 propagation. In contrast, overexpression or lower expression of CDK2 exhibited no significant influence on PCV2 replication. Furthermore, the subcellular localization of the PCV2 replicase protein (Rep) and capsid protein (Cap), CycA, and CDK2 in PK-15 cells was analyzed by confocal microscopy. Results showed that CycA, rather than CDK2, overexpression altered normal nuclear localization of PCV2-Rep, which was transferred to the cytoplasm. In conclusion, PCV2 replication is both S and G2/M phase-dependent and CycAis an important regulator of the PCV2 life cycle.
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