Laboratorio de Parasitología, Facultad de Farmacia, Universidad San Pablo CEU, Urbanización Montepríncipe, CP 28668, Boadilla del Monte, Madrid, Spain; Escuela de Microbiología, Grupo de Parasitología, Universidad de Antioquia, Calle 67 No. 53-108, Medellín, Colombia.
Infect Genet Evol. 2013 Dec;20:26-33. doi: 10.1016/j.meegid.2013.07.024. Epub 2013 Aug 2.
Microsporidia are ubiquitous fungi with genomes that have undergone a strong reduction to the extreme cases of Encephalitozoon cuniculi and Encephalitozoon intestinalis. Genetic variability within species of the Encephalitozoon genus has been reported, with most of the studies based on the internal transcribed spacer (ITS) of the rDNA. However, in contrast to the picture of E. cuniculi and Encephalitozoon hellem, where different strains have been identified, no genetic variability has yet been observed in E. intestinalis. We have analysed tandem repeats included in putative coding sequences which could be used as polymorphic markers in E. intestinalis. Eight candidate loci (M2, M2A, M3, M5, M7, M7A, M8 and PTP1) were established and 9 E. intestinalis cultured strains from North America, South America and Europe were analysed. M2, M7 and PTP1 nucleotide sequences were identical among the different strains and the GenBank sequence. In contrast, we observed variants in 4 markers (M2A, M3, M7A and M8) which did not correspond to their respective reference sequences. The most noticeable finding was that with the M5 marker two genotypes were defined among the different strains studied, demonstrating genotypic variability of E. intestinalis. Although the diversity described is certainly not high, which can be explained by a lower chance of genetic variability in its minimal genome, we have demonstrated that polymorphisms actually exist in E. intestinalis. Epidemiological studies using this genetic marker should now be conducted to elucidate the genetic variability in E. intestinalis and improve our knowledge of the epidemiology of this microsporidia.
微孢子虫是具有基因组的普遍真菌，其基因组已经经历了强烈的减少，达到了极端的脑炎原虫和脑炎原虫肠的情况。脑炎原虫属种内的遗传变异已经有报道，大多数研究都是基于 rDNA 的内部转录间隔区（ITS）。然而，与脑炎原虫和脑炎原虫 hellem 的情况不同，在那里已经确定了不同的菌株，在脑炎原虫肠中尚未观察到遗传变异。我们已经分析了包含在假定编码序列中的串联重复，这些重复可以作为脑炎原虫肠中的多态性标记。建立了 8 个候选基因座（M2、M2A、M3、M5、M7、M7A、M8 和 PTP1），并分析了来自北美、南美和欧洲的 9 株脑炎原虫肠培养菌株。不同菌株和 GenBank 序列中的 M2、M7 和 PTP1 核苷酸序列是相同的。相比之下，我们观察到 4 个标记（M2A、M3、M7A 和 M8）发生了变异，与各自的参考序列不对应。最引人注目的发现是，M5 标记在不同研究菌株中定义了两种基因型，证明了脑炎原虫肠的基因型变异。尽管描述的多样性肯定不高，这可以用其最小基因组遗传变异的机会较低来解释，但我们已经证明了脑炎原虫肠中确实存在多态性。现在应该进行使用这种遗传标记的流行病学研究，以阐明脑炎原虫肠的遗传变异，并提高我们对这种微孢子虫流行病学的认识。
