Wang J Y, Pasetti M F, Noriega F R, Anderson R J, Wasserman S S, Galen J E, Sztein M B, Levine M M
Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Infect Immun. 2001 Aug;69(8):4734-41. doi: 10.1128/IAI.69.8.4734-4741.2001.
A promising live attenuated typhoid vaccine candidate strain for mucosal immunization was developed by introducing a deletion in the guaBA locus of pathogenic Salmonella enterica serovar Typhi strain Ty2. The resultant DeltaguaBA mutant, serovar Typhi CVD 915, has a gene encoding resistance to arsenite replacing the deleted sequence within guaBA, thereby providing a marker to readily identify the vaccine strain. CVD 915 was compared in in vitro and in vivo assays with wild-type strain Ty2, licensed live oral typhoid vaccine strain Ty21a, or attenuated serovar Typhi vaccine strain CVD 908-htrA (harboring mutations in aroC, aroD, and htrA). CVD 915 was less invasive than CVD 908-htrA in tissue culture and was more crippled in its ability to proliferate after invasion. In mice inoculated intraperitoneally with serovar Typhi and hog gastric mucin (to estimate the relative degree of attenuation), the 50% lethal dose of CVD 915 (7.7 x 10(7) CFU) was significantly higher than that of wild-type Ty2 (1.4 x 10(2) CFU) and was only slightly lower than that of Ty21a (1.9 x 10(8) CFU). Strong serum O and H antibody responses were recorded in mice inoculated intranasally with CVD 915, which were higher than those elicited by Ty21a and similar to those stimulated by CVD 908-htrA. CVD 915 also elicited potent proliferative responses in splenocytes from immunized mice stimulated with serovar Typhi antigens. Used as a live vector, CVD 915(pTETlpp) elicited high titers of serum immunoglobulin G anti-fragment C. These encouraging preclinical data pave the way for phase 1 clinical trials with CVD 915.
通过在致病性肠炎沙门氏菌伤寒杆菌Ty2菌株的guaBA位点引入缺失，开发出了一种有前景的用于黏膜免疫的减毒活伤寒疫苗候选菌株。所得的DeltaguaBA突变体，即伤寒杆菌CVD 915，有一个编码对亚砷酸盐抗性的基因取代了guaBA内缺失的序列，从而提供了一个易于识别疫苗菌株的标记。在体外和体内试验中，将CVD 915与野生型菌株Ty2、已获许可的口服减毒活伤寒疫苗菌株Ty21a或减毒伤寒杆菌疫苗菌株CVD 908-htrA（在aroC、aroD和htrA中存在突变）进行了比较。在组织培养中，CVD 915的侵袭性低于CVD 908-htrA，并且在侵袭后增殖能力更弱。在用伤寒杆菌和猪胃粘蛋白腹腔接种的小鼠中（以评估相对减毒程度），CVD 915的50%致死剂量（7.7×10⁷CFU）显著高于野生型Ty2（1.4×10²CFU），仅略低于Ty21a（1.9×10⁸CFU）。在用CVD 915鼻内接种的小鼠中记录到了强烈的血清O和H抗体反应，高于Ty21a引发的反应，与CVD 908-htrA刺激产生的反应相似。CVD 915在用伤寒杆菌抗原刺激的免疫小鼠脾细胞中也引发了强烈的增殖反应。用作活载体时，CVD 915(pTETlpp)引发了高滴度的血清免疫球蛋白G抗片段C。这些令人鼓舞的临床前数据为CVD 915的1期临床试验铺平了道路。
