Identification of protective truncated domain of Fba anchored on the surface of group A streptococcus
10.3760/cma.j.issn.1000-6680.2010.05.001
- VernacularTitle:A族链球菌表面蛋白Fba保护性区段的鉴定
- Author:
Peng WEI
;
Cuiqing MA
;
Yiyang GUO
;
Haiyan GU
;
Huidong FENG
;
Xiurong WANG
;
Lin WEI
- Publication Type:Journal Article
- Keywords:
Group A streptococcus;
Fibronectins protein;
Gene expression;
Plasmids;
Blotting,Western
- From:
Chinese Journal of Infectious Diseases
2010;28(5):257-261
- CountryChina
- Language:Chinese
-
Abstract:
Objective The truncated fibronectin-binding proteins A (Fba protein) were cloned and expressed, then animals were immunized with Fba protein and subsequently challenged with group A streptococcus (GAS) to further investigate protective antibodies induced by each domain and determine the most immunogenic domain. Methods Fba proteins, which were divided into four overlaps based on the structural domains, were truncated and expressed. The fba truncated genes were amplified by polymerase chain reaction (PCR) with SSI-9 of GAS as template, and cloned into prokaryotic expression plasmid pGEX-2T and expressed in E. coli BL-21. The products were confirmed by Western blot and purified by affinity chromatography column. Female BALB/c mice were immunized with the four truncated proteins respectively, with phosphate buffered solution (PBS) as control. The serum IgG of mice was detected by enzyme-linked immunosorbent assay (ELISA). After the third immunization, mice were challenged with fatal dose of GAS (M+ Fba+ ) to evaluate the protective rates in each group. The data were compared by analysis of variance and Fisher's exact test.Results Prokaryotic expression plasmids of pGEX-2T/FbaAl, pGEX-2T/FbaA2, pGEX-2T/FbaA3 and pGEX-2T/FbaA4 were successfully constructed and the four truncated proteins were expressed and purified successfully. Serum levels of IgG in each experimental group gradually increased with immunization with Fba protein more times. After the third immunization, the IgG titer against FbaA2 1290.2, P<0. 01). After GAS challenge, four out of eight mice were protected in FbaA2 protein group, while two out of eight mice in FbaAl protein, FbaA3 protein and FbaA4 protein groups,respectively (P<0. 05). Conclusions Four truncated Fba proteins are constructed and expressed successfully. Truncated FbaA2 protein could be able to induce strongest protective immune response.
