Puértolas-Balint Fabiola, Rossen John W A, Oliveira Dos Santos Claudy, Chlebowicz Monika M A, Raangs Erwin C, van Putten Maarten L, Sola-Campoy Pedro J, Han Li, Schmidt Martina, García-Cobos Silvia
University of Groningen, University Medical Center Groningen, Department of Medical Microbiology and Infection Prevention, Groningen, Netherlands.
University of Groningen, Department of Molecular Pharmacology, Groningen, Netherlands.
Front Microbiol. 2019 Sep 4;10:1970. doi: 10.3389/fmicb.2019.01970. eCollection 2019.
is considered a common causative agent of human fungal infections. A restricted number of virulence factors have been described, and none of them lead to a differentiation in the virulence level among different strains. Variations in the virulence phenotype depending on the isolate origin, measured as survival percentage in animal infection models, have been previously reported. In this study, we analyzed the whole-genome sequence of isolates from clinical and environmental origins to determine their virulence genetic content. The sample included four isolates sequenced at the University Medical Center Groningen (UMCG), three clinical (two of them isolated from the same patient) and the experimental strain B5233, and the draft genomes of one reference strain, two environmental and two clinical isolates obtained from a public database. The fungal genomes were screened for the presence of virulence-related genes (VRGs) using an in-house database of 244 genes related to thermotolerance, resistance to immune responses, cell wall formation, nutrient uptake, signaling and regulation, and production of toxins and secondary metabolites and allergens. In addition, we performed a variant calling analysis to compare the isolates sequenced at the UMCG and investigated their genetic relatedness using the TRESP (Tandem Repeats located within Exons of Surface Protein coding genes) genotyping method. We neither observed a difference in the virulence genetic content between the clinical isolates causing an invasive infection and a colonizing clinical isolate nor between isolates from the clinical and environmental origin. The four novel sequences had a different TRESP genotype and a total number of genetic variants ranging from 48,590 to 68,352. In addition, a comparative genomics analysis showed the presence of single nucleotide polymorphisms in VRGs and repetitive genetic elements located next to VRG groups, which could influence the regulation of these genes. In conclusion, our genomic analysis revealed a high genetic diversity between environmental and clinical isolates, as well as between clinical isolates from the same patient, indicating an infection with a mixed-population in the latter case. However, all isolates had a similar virulence genetic content, demonstrating their pathogenic potential at least at the genomic level.
被认为是人类真菌感染的常见病原体。已描述的毒力因子数量有限，且它们均未导致不同菌株间毒力水平的差异。先前已有报道称，根据分离株来源不同，毒力表型存在差异，可通过动物感染模型中的存活率来衡量。在本研究中，我们分析了来自临床和环境来源的分离株的全基因组序列，以确定其毒力基因内容。样本包括在格罗宁根大学医学中心（UMCG）测序的4株分离株，3株临床分离株（其中2株来自同一患者）和实验菌株B5233，以及从公共数据库获得的1株参考菌株、2株环境分离株和2株临床分离株的基因组草图。使用一个包含244个与耐热性、免疫反应抗性、细胞壁形成、营养摄取、信号传导和调控以及毒素、次生代谢产物和过敏原产生相关基因的内部数据库，对真菌基因组进行毒力相关基因（VRGs）筛查。此外，我们进行了变异检测分析，以比较在UMCG测序的分离株，并使用TRESP（位于表面蛋白编码基因外显子内的串联重复序列）基因分型方法研究它们的遗传相关性。我们既未观察到引起侵袭性感染的临床分离株与定殖临床分离株之间在毒力基因内容上的差异，也未观察到临床和环境来源分离株之间的差异。这4个新序列具有不同的TRESP基因型，遗传变异总数在48,590至68,352之间。此外，比较基因组学分析表明，VRGs中存在单核苷酸多态性以及位于VRG组旁边的重复遗传元件，这可能会影响这些基因的调控。总之，我们的基因组分析揭示了环境和临床分离株之间以及同一患者的临床分离株之间存在高度的遗传多样性，表明在后一种情况下存在混合群体感染。然而，所有分离株都具有相似的毒力基因内容，表明它们至少在基因组水平上具有致病潜力。
