Palmer R J, Settnes O P, Lodal J, Wakefield A E
Molecular Infectious Diseases Group, Department of Paediatrics, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom.
Appl Environ Microbiol. 2000 Nov;66(11):4954-61. doi: 10.1128/AEM.66.11.4954-4961.2000.
The rat model of Pneumocystis carinii pneumonia is frequently used to study human P. carinii infection, but there are many differences between the rat and human infections. We studied naturally acquired P. carinii in wild rats to examine the relevance of the rat model for human infection. P. carinii DNA was detected in 47 of 51 wild rats and in 10 of 12 nonimmunosuppressed laboratory rats. Evidence for three novel formae speciales of rat-derived P. carinii was found, and these were provisionally named Pneumocystis carinii f. sp. rattus-secundi, Pneumocystis carinii f. sp. rattus-tertii, and Pneumocystis carinii f. sp. rattus-quarti. Our data suggest that low-level carriage of P. carinii in wild rats and nonimmunosuppressed laboratory rats is common and that wild rats are frequently coinfected with more than one forma specialis of P. carinii. We also examined the diversity in the internally transcribed spacer (ITS) regions of the nuclear rRNA operon of Pneumocystis carinii f. sp. carinii by using samples from wild rats and laboratory rats and spore trap samples. We report a lack of variation in the ITS1 and ITS2 regions that is consistent with an evolutionary bottleneck in the P. carinii f. sp. carinii population. This study shows that human- and rat-derived P. carinii organisms are very different, not only in genetic composition but also in population structure and natural history.
卡氏肺孢子虫肺炎的大鼠模型常用于研究人类卡氏肺孢子虫感染，但大鼠感染与人类感染存在许多差异。我们研究了野生大鼠自然感染的卡氏肺孢子虫，以检验大鼠模型与人类感染的相关性。在51只野生大鼠中的47只以及12只非免疫抑制的实验大鼠中的10只检测到了卡氏肺孢子虫DNA。发现了三种源自大鼠的新型卡氏肺孢子虫变种，它们被暂时命名为卡氏肺孢子虫f. sp. rattus-secundi、卡氏肺孢子虫f. sp. rattus-tertii和卡氏肺孢子虫f. sp. rattus-quarti。我们的数据表明，野生大鼠和非免疫抑制实验大鼠中卡氏肺孢子虫的低水平携带很常见，并且野生大鼠经常同时感染不止一种卡氏肺孢子虫变种。我们还通过使用来自野生大鼠、实验大鼠的样本以及孢子捕捉样本，研究了卡氏肺孢子虫f. sp. carinii核rRNA操纵子内部转录间隔区（ITS）的多样性。我们报告ITS1和ITS2区域缺乏变异，这与卡氏肺孢子虫f. sp. carinii种群中的进化瓶颈一致。这项研究表明，源自人类和大鼠的卡氏肺孢子虫生物体不仅在基因组成上，而且在种群结构和自然史方面都非常不同。
