Basic Research
Copyright ©2005 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 14, 2005; 11(22): 3411-3418
Published online Jun 14, 2005. doi: 10.3748/wjg.v11.i22.3411
Construction of a novel Shigella live-vector strain co-expressing CS3 and LTB/STm of enterotoxigenic E.coli
Ji-Ping Zheng, Zhao-Shan Zhang, Shu-Qin Li, Xiang-Xin Liu, Sheng-Ling Yuan, Peng Wang, De-Wen Zhan, Ling-Chun Wang, Cui-Fen Huang
Ji-Ping Zheng, Zhao-Shan Zhang, Shu-Qin Li, Xiang-Xin Liu, Sheng-Ling Yuan, Peng Wang, De-Wen Zhan, Ling-Chun Wang, Cui-Fen Huang, Beijing Institute of Biotechnology, Beijing 100071, China
Author contributions: All authors contributed equally to the work.
Correspondence to: Zhao-Shan Zhang, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China. zhangzs@nic.bmi.ac.cn
Telephone: +86-10-63834140 Fax: +86-10-63833521
Received: September 13, 2004
Revised: September 14, 2004
Accepted: December 9, 2004
Published online: June 14, 2005
Abstract

AIM: To construct and evaluate a polyvalent recombinant vaccine strain Shigella flexneri 2a T32 against enterotoxigenic E.coli (ETEC).

METHODS: By using a host-plasmid balanced lethal system based on asd gene, a polyvalent recombinant strain was constructed to highly express CS3 and regularly express fusion enterotoxin of LTB subunit and mutant ST (LTB/STm) in a vaccine strain Shigella flexneri 2a T32 with specific deletion of asd gene. Fimbria CS3 was observed by immunofluorescence and electron microscopy assay. The security of LTB/STm was examined by ileal loop assay and suckling mouse assay. To evaluate this new candidate vaccine, it was compared with a previous vaccine strain in plasmid and protein level, growth assay and immunogenicity in Balb/c mice.

RESULTS: The newly constructed vaccine expressed CS3 and grew better than the previously constructed vaccine except for the lower expression of LTB/STm. Serum IgG and mucosal IgA against CS3, LTB, ST, and host lipopolysaccharide (LPS) were produced after immunization of Balb/c mice by oral route with the new strain. The titers were not significantly different from the Balb/c mice with the previous strain.

CONCLUSION: This novel candidate diarrheal vaccine can effectively induce serum and mucosal antibody responses against ETEC and Shigella.

Keywords: ETEC; Shigella flexneri; CS3; LTB; ST; Vector vaccine; Immunogenicity