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KMID : 0620919990310020101
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Experimental & Molecular Medicine
1999 Volume.31 No. 2 p.101 ~ p.107
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Development of two novel nontoxic mutants of Escherichia coli heat-labile enterotoxin
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Jung Sun Yum/Eun Jeong Park
Ji Hoon Chang/Jang Seong Kim/Soo Il Chung/Jung Sun Yum
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Abstract
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Escherichia coli heat-labile enterotoxin (LT) is composed of catalytic A and non-catalytic homo-pentameric B subunits and causes diarrheal disease in human and animals. In order to produce a nontoxic LT for vaccine and adjuvant development, two novel derivatives of LT were constructed by a site-directed mutagenesis of A subunit; Ser63 to Tyr63 in LTS63Y and Glu110, Glu112 were deleted in LT delta 110/112. The purified mutant LTs (mLTs) showed a similar molecular structural complex as AB5 to that of wild LT. In contrast to wild-type LT, mLTs failed to induce either elongation activity, ADP-ribosyltransferase activity, cAMP synthesis in CHO cells or fluid accumulation in mouse small intestine in vivo. Mice immunized with mLTs either intragastrically or intranasally elicited high titers of LT-specific serum and mucosal antibodies comparable to those induced by wild-type LT. These results indicate that substitution of Ser63 to Tyr63 or deletion of Glu110 and Glu112 eliminate the toxicity of LT without a change of AB5 conformation, and both mutants are immunogenic to LT itself. Therefore, both mLTs may be used to develop novel anti-diarrheal vaccines against enterotoxigenic E. coli.
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KEYWORD
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mutant LT (mLT), ADP-ribosyltransferase activity, cAMP, immunogenicity, secretory IgA (sIgA),
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