Douce G, Turcotte C, Cropley I, Roberts M, Pizza M, Domenghini M, Rappuoli R, Dougan G
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, United Kingdom.
Proc Natl Acad Sci U S A. 1995 Feb 28;92(5):1644-8. doi: 10.1073/pnas.92.5.1644.
A nontoxic mutant (LTK7) of the Escherichia coli heat-labile enterotoxin (LT) lacking ADP-ribosylating activity but retaining holotoxin formation was constructed. By using site-directed mutagenesis, the arginine at position 7 of the A subunit was replaced with lysine. This molecule, which was nontoxic in several assays, was able to bind to eukaryotic cells and acted as a mucosal adjuvant for co-administered proteins; BALB/c mice immunized intranasally with LTK7 and ovalbumin developed high levels of serum and local antibodies to ovalbumin and toxin. In addition, mice immunized intranasally with fragment C of tetanus toxin and LTK7 were protected against lethal challenge with tetanus toxin. Thus nontoxic mutants of heat-labile toxin can act as effective intranasal mucosal adjuvants.
构建了一种大肠杆菌不耐热肠毒素（LT）的无毒突变体（LTK7），其缺乏ADP核糖基化活性，但保留全毒素形成能力。通过定点诱变，将A亚基第7位的精氨酸替换为赖氨酸。该分子在多种检测中均无毒，能够结合真核细胞，并作为共同给药蛋白质的黏膜佐剂；用LTK7和卵清蛋白经鼻免疫的BALB/c小鼠产生了高水平的针对卵清蛋白和毒素的血清及局部抗体。此外，用破伤风毒素C片段和LTK7经鼻免疫的小鼠对破伤风毒素的致死性攻击具有抵抗力。因此，不耐热毒素的无毒突变体可作为有效的经鼻黏膜佐剂。
