腸道沙門氏菌「傷寒沙門菌」(S. Typhi) 致病性的生物基礎基本上是不清楚的。「傷寒沙門菌」引起致命性的系統感染，即傷寒，而其他腸道沙門氏菌血清型則要麼是無害的，要麼只會造成不太嚴重的胃部感染或食物中毒。這項研究表明，傷寒毒素（一種新型AB毒素，由「傷寒沙門菌」獨有的兩個A亞單元組成）的施用，會重現傷寒的很多急性症狀。作者進而發現細胞表面糖蛋白上的碳水化合物是傷寒毒素的受體，並且確定了該毒素的晶體結構，從而為了解這些相互作用提供了信息。這些發現表明，基於抗毒素的治療方法對治療傷寒可能會有效。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature doi: 10.1038/nature12377
Structure and function of the Salmonella Typhi chimaeric A2B5 typhoid toxin
Jeongmin Song,Xiang Gao & Jorge E. Galán
Salmonella enterica serovar Typhi (S. Typhi) differs from most other salmonellae in that it causes a life-threatening systemic infection known as typhoid fever1. The molecular bases for its unique clinical presentation are unknown2. Here we find that the systemic administration of typhoid toxin, a unique virulence factor of S. Typhi, reproduces many of the acute symptoms of typhoid fever in an animal model. We identify specific carbohydrate moieties on specific surface glycoproteins that serve as receptors for typhoid toxin, which explains its broad cell target specificity. We present the atomic structure of typhoid toxin, which shows an unprecedented A2B5 organization with two covalently linked A subunits non-covalently associated to a pentameric B subunit. The structure provides insight into the toxin’s receptor-binding specificity and delivery mechanisms and reveals how the activities of two powerful toxins have been co-opted into a single, unique toxin that can induce many of the symptoms characteristic of typhoid fever. These findings may lead to the development of potentially life-saving therapeutics against typhoid fever.