Pertussis toxin plays an early role in respiratory tract colonization by Bordetella pertussis
Pertussis toxin plays an early role in respiratory tract colonization by Bordetella pertussis
复制标题
DOI：
10.1128/iai.71.11.6358-6366.2003
复制
发表时间：
2003-11-01
影响因子：
3.1
通讯作者：
Worthington, ZEV
中科院分区：
文献类型：
--
作者：
Carbonetti, NH;Artamonova, GV;Worthington, ZEV
在这项研究中，我们试图通过小鼠鼻内感染模型来确定百日咳毒素(PT)，一种由百日咳杆菌独有产生的外毒素毒力因子，是否对该病原体在呼吸道的定植起重要作用。通过比较野生型Tohama I株和编码PT(DeltaPT)的PTX基因框内缺失的突变株，我们发现在一定的细菌接种量范围内，PT的缺乏会导致显著的(第7天)定植缺陷(1-2log(10)单位)，并且这种缺陷在接种后1-2天内明显。在混合菌株感染实验中，DeltaPT菌株与野生型菌株相比没有显示出竞争劣势，并且定殖率高于单一菌株感染实验。为了验证野生型菌株在混合感染中产生的可溶性PT增强DeltaPT对呼吸道定植的假设，我们将纯化的PT与DeltaPT接种剂共同接种，发现定殖率增加到野生型水平。当PT通过全身途径联合给药时，没有观察到这种影响。在接种DeltaPT前14天滴鼻给予纯化PT可显著增加细菌定植，但与磷酸盐缓冲盐水对照相比，在细菌接种后1天给予PT并不能增强定植。对感染野生型和DeltaPT菌株的小鼠的早期支气管肺泡灌洗液样本的分析表明，感染后48h中性粒细胞流入肺部的数量明显多于DeltaPT感染，提示中性粒细胞的趋化可能是PT活性促进百日咳杆菌在呼吸道定植的一个靶标。
In this study, we sought to determine whether pertussis toxin (PT), an exotoxin virulence factor produced exclusively by Bordetella pertussis, is important for colonization of the respiratory tract by this pathogen by using a mouse intranasal infection model. By comparing a wild-type Tohama I strain to a mutant strain with an in-frame deletion of the ptx genes encoding PT (DeltaPT), we found that the lack of PT confers a significant peak (day 7) colonization defect (1 to 2 log(10) units) over a range of bacterial inoculum doses and that this defect was apparent within 1 to 2 days postinoculation. In mixed-strain infection experiments, the DeltaPT strain showed no competitive disadvantage versus the wild-type strain and colonized at higher levels than in the single-strain infection experiments. To test the hypothesis that soluble PT produced by the wild-type strain in mixed infections enhanced respiratory tract colonization by DeltaPT, we coadministered purified PT with the DeltaPT inoculum and found that colonization was increased to wild-type levels. This effect was not observed when PT was coadministered via a systemic route. Intranasal administration of purified PT up to 14 days prior to inoculation with DeltaPT significantly increased bacterial colonization, but PT administration 1 day after bacterial inoculation did not enhance colonization versus a phosphate-buffered saline control. Analysis of bronchoalveolar lavage fluid samples from mice infected with either wild-type or DeltaPT strains at early times after infection revealed that neutrophil influx to the lungs 48 h postinfection was significantly greater in response to DeltaPT infection, implicating neutrophil chemotaxis as a possible target of PT activity promoting B. pertussis colonization of the respiratory tract.