van der Giessen J W B, Fonville M, Briels I, Pozio E
Microbiological Laboratory for Health Protection, National Institute of Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
Vet Parasitol. 2005 Sep 5;132(1-2):51-5. doi: 10.1016/j.vetpar.2005.05.065.
The identification of sequence regions in the genomes of pathogens which can be useful to distinguish among species and genotypes, is of great importance for epidemiological, molecular, and phylogenetic studies. The 5S ribosomal DNA intergenic spacer region has been identified as a good target to distinguish among eight Trichinella species and genotypes. The recent discovery of two non-encapsulated species in this genus, Trichinella papuae and Trichinella zimbabwensis, which can infect both mammals and reptiles, has suggested analyzing their 5S rDNA. Amplification of the tandem repeats of the 5S rDNA intergenic region of encapsulated species of Trichinella shows a 751bp fragment, whereas the three non-encapsulated species show a fragment of 800bp with T. pseudospiralis showing an additional fragment of 522bp. Although the size of the 800bp PCR fragments of T. papuae and T. zimbabwensis are similar to that of T. pseudospiralis, there are differences in the 5S rDNA intergenic regions among the three non-encapsulated species. Phylogenetic analysis of the 5S rDNA intergenic regions shows a clustering together of the three non-encapsulated Trichinella species that is well separated from the encapsulated ones. In addition, a single PCR-based method allows distinguishing non-encapsulated and encapsulated species.
识别病原体基因组中有助于区分物种和基因型的序列区域，对于流行病学、分子和系统发育研究非常重要。5S核糖体DNA基因间隔区已被确定为区分八种旋毛虫物种和基因型的良好靶点。该属最近发现的两种非包囊型物种，巴布亚旋毛虫和津巴布韦旋毛虫，既能感染哺乳动物也能感染爬行动物，这表明需要分析它们的5S rDNA。旋毛虫包囊型物种5S rDNA基因间隔区串联重复序列的扩增显示出一个751bp的片段，而三种非包囊型物种显示出一个800bp的片段，伪旋毛虫还显示出一个522bp的额外片段。虽然巴布亚旋毛虫和津巴布韦旋毛虫800bp PCR片段的大小与伪旋毛虫相似，但这三种非包囊型物种的5S rDNA基因间隔区存在差异。对5S rDNA基因间隔区的系统发育分析表明，三种非包囊型旋毛虫物种聚在一起，与包囊型物种明显分开。此外，一种基于PCR的单一方法可以区分非包囊型和包囊型物种。
