Nahimana Aimable, Blanc Dominique S, Francioli Patrick, Bille Jacques, Hauser Philippe M
Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
J Med Microbiol. 2000 Aug;49(8):753-758. doi: 10.1099/0022-1317-49-8-753.
Broncho-alveolar lavage specimens from patients with Pneumocystis carinii pneumonia were investigated by PCR-single strand conformation polymorphism (SSCP) analysis of four genomic regions for P. carinii f. sp. hominis. In all, 32% of specimens produced two bands (one allele) for each of the four genomic regions, suggesting an infection with a single P.c. hominis type. The other specimens displayed more than two bands for at least one of the four genomic regions, suggesting several theoretical possibilities: co-infections, heterozygosity of diploid or polyploid organisms, or multicopy genes. Quantification of the different alleles and analysis of mixtures of specimens showed that different alleles of a genomic region were most often present in different proportions in a given specimen. In contrast, experiments with plasmid insertion of two alleles resulted in the detection of identical proportions of the two alleles. This suggests that neither heterozygosity of diploid organisms nor multicopy genes are responsible for the presence of two alleles. Unequal proportions are most likely explained by the occurrence of co-infections. The putative co-infecting types could be identified in the majority of specimens.
通过对卡氏肺孢子虫人型变种四个基因组区域进行聚合酶链反应-单链构象多态性（PCR-SSCP）分析，对卡氏肺孢子虫肺炎患者的支气管肺泡灌洗标本进行了研究。总共32%的标本在四个基因组区域中的每个区域都产生了两条带（一个等位基因），表明感染了单一类型的卡氏肺孢子虫人型变种。其他标本在四个基因组区域中的至少一个区域显示出两条以上的带，这表明存在几种理论上的可能性：混合感染、二倍体或多倍体生物的杂合性或多拷贝基因。对不同等位基因的定量分析和标本混合物分析表明，基因组区域的不同等位基因在给定标本中最常以不同比例存在。相比之下，对两个等位基因进行质粒插入的实验结果显示，两个等位基因的比例相同。这表明二倍体生物的杂合性和多拷贝基因都不是两个等位基因存在的原因。比例不均最有可能是由混合感染的发生所解释的。在大多数标本中都可以鉴定出假定的混合感染类型。
