Construction of a novel Shigella live-vector strain co-expressing CS3 and LTB/STm of enterotoxigenic E.coli.
OBJECTIVE
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.


CONCLUSIONS
This novel candidate diarrheal vaccine can effectively induce serum and mucosal antibody responses against ETEC and Shigella.
Zheng
Ji-Ping
JP
Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
Zhang
Zhao-Shan
ZS
Li
Shu-Qin
SQ
Liu
Xiang-Xin
XX
Yuan
Sheng-Ling
SL
Wang
Peng
P
Zhan
De-Wen
DW
Wang
Ling-Chun
LC
Huang
Cui-Fen
CF
D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics*; D004405:Dysentery, Bacillary / Q000517:prevention & control*; D004768:Enterotoxins / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005260:Female; D036781:Fimbriae Proteins / Q000235:genetics*; D005822:Genetic Vectors / Q000235:genetics*; D006168:Guinea Pigs; D051379:Mice; D008807:Mice, Inbred BALB C; D011817:Rabbits; D022281:Shigella Vaccines / Q000235:genetics*; D012763:Shigella flexneri / Q000235:genetics*
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022281:Shigella Vaccines; C081391:nfaE protein, E coli; D036781:Fimbriae Proteins; C027538:heat-labile enterotoxin, E coli