McSorley S J, Xu D, Liew F Y
Department of Immunology, University of Glasgow, United Kingdom.
Infect Immun. 1997 Jan;65(1):171-8. doi: 10.1128/iai.65.1.171-178.1997.
The development of Salmonella vaccine vectors has been hindered by both the requirement for multiple doses to induce immune responses and a lack of plasmid stability. Direct comparisons of different promoter systems with the same antigen are necessary to address these important issues. We have previously described an AroA- AroD- deletion mutant of Salmonella typhimurium (GID101) which expresses the gene encoding the Leishmania major promastigote surface glycoprotein gp63 (GID101). While this construct provided significant protection against L. major challenge to highly susceptible BALB/c mice, this required at least two oral doses. We report here the use of two different inducible promoters, the nirB and osmC promoters, to improve vaccine efficacy. These constructs (termed GID105 and GID106, respectively) expressed gp63 in vitro under inducible conditions and colonized BALB/c mice after oral administration. GID105 demonstrated greater plasmid stability in vitro and in vivo than did either GID106 or GID101, which expresses gp63 constitutively. Spleen and lymph node cells from mice immunized with a single oral dose of GID105 proliferated in vitro in response to L. major and secreted gamma interferon, whereas cells from mice given the other constructs did not. Mice immunized with a single oral dose of GID1O5 or GID106 developed significantly smaller lesions upon challenge with L. major, whereas mice administered GID101 did not. Mice administered GID105 also showed considerable resistance to Leishmania donovani infection. These data provide a direct comparison of promoter systems and demonstrate that the use of inducible promoters such as the nirB promoter allows a considerable improvement over the previous vaccine construct in terms of protection against infection.
沙门氏菌疫苗载体的研发受到两方面阻碍，一是诱导免疫反应需要多剂接种，二是缺乏质粒稳定性。对携带相同抗原的不同启动子系统进行直接比较，对于解决这些重要问题很有必要。我们之前描述过鼠伤寒沙门氏菌的aroA - aroD缺失突变体（GID101），它表达编码利什曼原虫前鞭毛体表面糖蛋白gp63的基因（GID101）。虽然该构建体为高度易感的BALB/c小鼠提供了针对硕大利什曼原虫攻击的显著保护，但这至少需要两剂口服给药。我们在此报告使用两种不同的可诱导启动子，即nirB和osmC启动子，来提高疫苗效力。这些构建体（分别称为GID105和GID106）在可诱导条件下于体外表达gp63，并在口服给药后定殖于BALB/c小鼠体内。与组成型表达gp63的GID106或GID101相比，GID105在体外和体内均表现出更高的质粒稳定性。用单剂口服GID105免疫的小鼠的脾脏和淋巴结细胞，在体外对硕大利什曼原虫产生增殖反应并分泌γ干扰素，而给予其他构建体的小鼠的细胞则无此反应。用单剂口服GID1O5或GID106免疫的小鼠在受到硕大利什曼原虫攻击后形成的病灶明显更小，而给予GID101的小鼠则不然。给予GID105的小鼠对杜氏利什曼原虫感染也表现出相当的抵抗力。这些数据对启动子系统进行了直接比较，并表明使用nirB启动子等可诱导启动子，在预防感染方面比之前的疫苗构建体有显著改进。
