Cushion M T, Zhang J, Kaselis M, Giuntoli D, Stringer S L, Stringer J R
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Ohio 45267-0524.
J Clin Microbiol. 1993 May;31(5):1217-23. doi: 10.1128/jcm.31.5.1217-1223.1993.
Pneumocystis carinii pneumonia is an oftentimes fatal infection for hosts in an immunocompromised state. The disease occurs in a wide variety of mammals, but the etiologic agent of this disease has been referred to as P. carinii regardless of the host species. However, even within a single host species, such as laboratory rats, distinct varieties of P. carinii have been identified from differences in the electrophoretic migration of chromosomes in agarose gels. Here we present evidence indicating that some laboratory rats can contain two different genetic variants of P. carinii that differ not only in electrophoretic karyotype but also in the presence of a particular repeated DNA sequence, in the presence of an intron in the 18S ribosomal RNA gene, and in the sequence of part of the 18S rRNA gene. Most of the rat colonies studied were infected with P. carinii that contained the repeated DNA and the 18S rRNA gene intron. The other type of rat-derived P. carinii, which lacked the repeated DNA and the intron in the 18S rRNA gene, was found as a coinfection with the first. Parasite populations from different coinfected rats contained the two variants in different proportions.
卡氏肺孢子虫肺炎对于免疫功能低下的宿主而言往往是一种致命性感染。该疾病在多种哺乳动物中均有发生，但无论宿主物种如何，这种疾病的病原体一直被称为卡氏肺孢子虫。然而，即使在单一宿主物种（如实验大鼠）中，通过琼脂糖凝胶中染色体电泳迁移的差异，也已鉴定出卡氏肺孢子虫的不同变种。在此，我们提供的证据表明，一些实验大鼠可能携带两种不同的卡氏肺孢子虫基因变体，它们不仅在电泳核型上存在差异，而且在特定重复DNA序列的存在情况、18S核糖体RNA基因中内含子的存在情况以及18S rRNA基因部分序列方面也有所不同。大多数所研究的大鼠群体感染的卡氏肺孢子虫含有重复DNA和18S rRNA基因内含子。另一种源自大鼠的卡氏肺孢子虫类型，其缺乏重复DNA和18S rRNA基因内含子，被发现与第一种类型共同感染。来自不同共同感染大鼠的寄生虫群体中，这两种变体的比例各不相同。
