The detection of protective antigen (PA) associated with spores of Bacillus anthracis and the effects of anti-PA antibodies on spore germination and macrophage interactions
The detection of protective antigen (PA) associated with spores of Bacillus anthracis and the effects of anti-PA antibodies on spore germination and macrophage interactions
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DOI：
10.1016/j.micpath.2005.02.001
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发表时间：
2005-05-01
影响因子：
3.8
通讯作者：
Welkos, SL
中科院分区：
文献类型：
--
作者：
Cote, CK;Rossi, CA;Welkos, SL
炭疽毒素的保护性抗原（PA）成分是炭疽芽孢杆菌必不可少的毒力因子，是主要的保护性免疫原。炭疽芽胞杆菌在生长过程中产生PA的动力学以及抗PA抗体在宿主免疫中的作用尚不清楚。营养生物的PA产量在生长从指数阶段向平稳阶段转变时达到峰值。最近，PA也被发现与孢子有关。在我们的研究中，通过RT-PCR在孢子暴露于萌发物15分钟内检测到pa特异性mRNA。用免疫电磁电化学发光法（ECL）在孢子暴露于萌发培养基1 h内检测PA蛋白，并迅速释放到上清液中。通过RNA分析、ECL或基于孢子的抗PA酶联免疫吸附试验（ELISA），未发芽孢子上未发现PA，但通过免疫电镜（immunoem）检测到PA。在家兔中，PA诱导多克隆抗体（Abs），除了具有抗毒素中和活性外，还具有抗孢子活性。在这项研究中，研究了人源性PA特异性单克隆抗体（AVP-hPA mAb, Avanir Pharmaceuticals）的抗孢子作用。AVP-hPA单抗在体外抑制巨噬细胞萌发，增强巨噬细胞的吞噬和杀孢活性。其活性与兔抗rpa抗体相当。对接种小鼠和豚鼠血清中萌发抑制活性（GIA）的检测表明，抗pa抗体可能具有保护作用。因此，抗pa - ab介导的抗孢子活性可能在炭疽感染的早期阶段发挥保护作用。(c) 2005 Elsevier Ltd版权所有。
The protective antigen (PA) component of the anthrax toxins is an essential virulence factor of Bacillus anthracis and is the major protective immunogen. The kinetics of PA production during growth of B. anthracis, and the roles of anti-PA antibody in host immunity are not clearly defined. Production of PA by the vegetative organisms peaks during the shift from exponential to stationary phase of growth. Recently, PA was also found to be associated with spores. In our study, PA-specific mRNA was detected in spores by RT-PCR within 15-min of exposure to germinant. PA protein was detected by immunomagnetic electrochemiluminescence (ECL) on spores within I h of exposure to a germination medium and was rapidly released into the supernatant. PA was not demonstrated on ungerminated spores by RNA analysis, ECL, or spore-based anti-PA ELISA: however, it was detected on ungerminated spores by immunoelectron microscopy (immunoem). In rabbits, PA induces polyclonal antibodies (Abs) that, in addition to their anti-toxin neutralizing activities, exhibit anti-spore activities. In this study, the anti-spore effects of a human monoclonal Ab specific for PA (AVP-hPA mAb, Avanir Pharmaceuticals) were characterized. AVP-hPA mAb retarded germination in vitro, and enhanced the phagocytic and sporicidal activities of macrophages. The activities were comparable to those of the polyclonal rabbit anti-rPA Ab. Assays to detect germination inhibitory activity (GIA) in serum from vaccinated mice and guinea pigs suggested a possible role for anti-PA Abs in protection. Thus, anti-PA Ab-mediated, anti-spore activities may play a role in protection during the early stages of an anthrax infection. (c) 2005 Elsevier Ltd. All rights reserved.