Selection and evaluation of the immunogenicity of protective antigen mutants as anthrax vaccine candidates.
Selection and evaluation of the immunogenicity of protective antigen mutants as anthrax vaccine candidates.
复制标题
作为炭疽疫苗候选物的保护性抗原突变体的免疫原性的选择和评估。
DOI：
10.1016/j.vaccine.2007.11.087
复制
发表时间：
2008
期刊：
影响因子：
5.5
通讯作者：
Wang,JuliaY
中科院分区：
文献类型：
--
作者：
Yan,Ming;Roehrl,MichaelH;Basar,Emre;Wang,JuliaY
保护性抗原（PA）是炭疽毒素的核心成分，也是炭疽疫苗的主要抗原。然而，使用天然PA作为疫苗不是最佳的。如果给刚接触过炭疽的人使用PA，PA实际上可能有助于炭疽毒素的形成，因此可能对接种后的疫苗应用造成严重的安全问题。无功能的PA突变体可能是更安全的替代方案。为了确定一种改进的炭疽疫苗抗原，我们研究了PA的四个非功能性突变体，每个突变体在PA的细胞中毒途径的关键步骤中受损。这些突变体是Rec−（不能结合PA受体）、SSSR（对弗林蛋白酶激活有抗性）、Oligo−（不能形成寡聚体）和显性负抑制（DNI）（不能形成内体跨膜孔）。当在小鼠中进行测试时，在三次免疫后，所有四种突变体都能高度有效地引发PA特异性毒素中和抗体，免疫原性以PA<Rec−<SSSR<Oligo−<DNI的顺序增加。虽然Rec−或SSSR与PA之间的差异很小，且无统计学显著性，但DNI和Oligo−的免疫原性显著高于野生型PA。免疫后1年，与PA免疫小鼠相比，DNI免疫小鼠的抗PA IgG水平显著升高，毒素中和活性滴度相应升高。相比之下，Oligo−免疫的小鼠具有高水平的抗PA IgG，但毒素中和活性的滴度较低，这表明Oligo−突变位点可能与PA的关键保护性表位重叠。我们的研究表明，基于PA的疫苗可以通过策略性突变来改善安全性和有效性，这些突变不仅使PA无功能，而且同时增强其免疫原性效力。重组PA突变体，特别是DNI，作为比野生型PA更好和更安全的抗原用于疫苗接种后具有很大的前景。
Protective antigen (PA) is a central component of anthrax toxin and a major antigen in anthrax vaccines. However, the use of native PA as a vaccine is not optimal. If administered to people who have been freshly exposed to anthrax, PA may actually aid in anthrax toxin formation and thus may pose a serious safety concern for postexposure vaccination applications. A non-functional PA mutant may be a much safer alternative. To identify an improved anthrax vaccine antigen, we examined four non-functional mutants of PA, each being impaired in a critical step of the cellular intoxication pathway of PA. These mutants were Rec−(unable to bind PA-receptors), SSSR (resistant to activation by furin), Oligo−(unable to form oligomers), and dominant negative inhibitory (DNI) (unable to form endosomal transmembrane pores). When tested in mice and after three doses of immunization, all four mutants were highly potent in eliciting PA-specific, toxin-neutralizing antibodies, with immunogenicity increasing in the order of PA<Rec−<SSSR<Oligo−<DNI. While the differences between Rec−or SSSR and PA were small and not statistically significant, DNI and Oligo−were significantly more immunogenic than wild-type PA. One year after immunization and compared with PA-immunized mice, DNI-immunized mice maintained significantly higher levels of anti-PA IgG with correspondingly higher titers of toxin-neutralizing activity. In contrast, Oligo−-immunized mice had high levels of anti-PA IgG but lower titers of toxin-neutralizing activity, suggesting that Oligo−mutation sites may overlap with critical protective epitopes of PA. Our study demonstrates that PA-based vaccines could be improved both in terms of safety and efficacy by strategic mutations that not only render PA non-functional but also simultaneously enhance its immunogenic potency. Recombinant PA mutants, particularly DNI, hold great promise as better and safer antigens than wild-type PA for use in postexposure vaccination.