Dataset Information

Cloning and Characterization of Surface-Localized ?-Enolase of Streptococcus iniae, an Effective Protective Antigen in Mice.

ABSTRACT: Streptococcus iniae is a major fish pathogen that can also cause human bacteremia, cellulitis and meningitis. Screening for and identification of protective antigens plays an important role in developing therapies against S. iniae infections. In this study, we indicated that the ?-enolase of S. iniae was not only distributed in the cytoplasm and associated to cell walls, but was also secreted to the bacterial cell surface. The functional identity of the purified recombinant ?-enolase protein was verified by its ability to catalyze the conversion of 2-phosphoglycerate (2-PGE) to phosphoenolpyruvate (PEP), and both the recombinant and native proteins interacted with human plasminogen. The rabbit anti-rENO serum blockade assay shows that ?-enolase participates in S. iniae adhesion to and invasion of BHK-21 cells. In addition, the recombinant ?-enolase can confer effective protection against S. iniae infection in mice, which suggests that ?-enolase has potential as a vaccine candidate in mammals. We conclude that S. iniae ?-enolase is a moonlighting protein that also associates with the bacterial outer surface and functions as a protective antigen in mice.

SUBMITTER: Wang J

PROVIDER: S-EPMC4519854 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Cloning and Characterization of Surface-Localized α-Enolase of Streptococcus iniae, an Effective Protective Antigen in Mice.

Wang Jun J Wang Kaiyu K Chen Defang D Geng Yi Y Huang Xiaoli X He Yang Y Ji Lili L Liu Tao T Wang Erlong E Yang Qian Q Lai Weimin W

International journal of molecular sciences 20150625 7

Streptococcus iniae is a major fish pathogen that can also cause human bacteremia, cellulitis and meningitis. Screening for and identification of protective antigens plays an important role in developing therapies against S. iniae infections. In this study, we indicated that the α-enolase of S. iniae was not only distributed in the cytoplasm and associated to cell walls, but was also secreted to the bacterial cell surface. The functional identity of the purified recombinant α-enolase protein was ...[more]

PMID: 26121302

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Project description:BACKGROUND: Streptococcus iniae is a Gram-positive bacterium and a severe pathogen of a wide range of farmed fish. S. iniae possesses a virulence-associated streptolysin S cluster composed of several components, one of which is SagE. SagE a transmembrane protein with one major extracellular region named ECR. This study aimed to develop a SagE-based DNA candidate vaccine against streptococcosis and examine the immunoprotective mechanism of the vaccine. RESULTS: We constructed a DNA vaccine, pSagE, based on the sagE gene and examined its immunological property in a Japanese flounder (Paralichthys olivaceus) model. The results showed that at 7 days post-vaccination, expression of SagE at transcription and translation levels was detected in the tissues of the vaccinated fish. After challenge with S. iniae at one and two months post-vaccination, pSagE-vaccinated fish exhibited relative percent survival (RPS) of 95% and 88% respectively. Immunological analysis showed that (i) pSagE significantly upregulated the expression of a wide range of immune genes, (ii) pSagE induced the production of specific serum antibodies that bound whole-cell S. iniae, and (iii) treatment of S. iniae with pSagE-induced antibodies blocked bacterial invasion of host cells. To localize the immunoprotective domain of SagE, the ECR-expressing DNA vaccine pSagEECR was constructed. Immunization analysis showed that flounder vaccinated with pSagEECR exhibited a RPS of 68%, and that pSagEECR induced serum antibody production and immune gene expression in a manner similar to, though to lower magnitudes than, those induced by pSagE. CONCLUSIONS: We in this study developed a DNA vaccine, pSagE, which induces highly protective immunity against S. iniae. The protective effect of pSagE is probably due to its ability to elicit systemic immune response, in particular that of the humoral branch, which leads to production of specific serum antibodies that impair bacterial infection. These results add insights to the immunoprotective mechanism of fish DNA vaccine.

Dataset Information

Cloning and Characterization of Surface-Localized ?-Enolase of Streptococcus iniae, an Effective Protective Antigen in Mice.

Publications

Cloning and Characterization of Surface-Localized α-Enolase of Streptococcus iniae, an Effective Protective Antigen in Mice.

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