Robbins J D, Robbins J B
J Infect Dis. 1984 Sep;150(3):436-49. doi: 10.1093/infdis/150.3.436.
The role of the Vi antigen, the capsular polysaccharide of Salmonella typhi, in the pathogenesis of and immunity to typhoid fever remains the subject of controversy. Vi-positive S. typhi resist phagocytosis and the action of serum complement, both of which actions are initiated by antibodies to Vi antigen. Both the laboratory potency in mice and the clinical effectiveness of whole-cell vaccines were related to their content of immunogenic Vi antigen. A Vi polysaccharide used for immunizing humans against experimental challenge with S. typhi failed to prevent typhoid fever; experimental conditions used to prepare this ineffective Vi antigen were shown to denature it and to reduce its immunogenicity. Assay of serum antibodies to Vi antigen with purified Vi antigen is a reliable method for diagnosis of typhoid fever and asymptomatic carriage of S. typhi. Vi polysaccharides prepared by modern techniques passed the requirements for meningococcal polysaccharide vaccines and had approximately 13 times the protective activity in the mouse potency assay as did the US Standard 6A whole-cell typhoid vaccine.
伤寒杆菌的荚膜多糖Vi抗原在伤寒热发病机制和免疫中的作用仍是一个有争议的话题。Vi阳性伤寒杆菌能抵抗吞噬作用和血清补体的作用，而这两种作用均由针对Vi抗原的抗体引发。全细胞疫苗在小鼠体内的效力和临床疗效均与其免疫原性Vi抗原的含量有关。一种用于免疫人类以抵抗伤寒杆菌实验性攻击的Vi多糖未能预防伤寒热；制备这种无效Vi抗原所采用的实验条件被证明会使其变性并降低其免疫原性。用纯化的Vi抗原检测血清中针对Vi抗原的抗体是诊断伤寒热和无症状携带伤寒杆菌的可靠方法。采用现代技术制备的Vi多糖符合脑膜炎球菌多糖疫苗的要求，在小鼠效力试验中的保护活性约为美国标准6A全细胞伤寒疫苗的13倍。
