Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Spain.
Genome Biol Evol. 2013;5(12):2382-92. doi: 10.1093/gbe/evt185.
Invasive candidiasis is the most commonly reported invasive fungal infection worldwide. Although Candida albicans remains the main cause, the incidence of emerging Candida species, such as C. parapsilosis is increasing. It has been postulated that C. parapsilosis clinical isolates result from a recent global expansion of a virulent clone. However, the availability of a single genome for this species has so far prevented testing this hypothesis at genomic scales. We present here the sequence of three additional strains from clinical and environmental samples. Our analyses reveal unexpected patterns of genomic variation, shared among distant strains, that argue against the clonal expansion hypothesis. All strains carry independent expansions involving an arsenite transporter homolog, pointing to the existence of directional selection in the environment, and independent origins of the two clinical isolates. Furthermore, we report the first evidence for the existence of recombination in this species. Altogether, our results shed new light onto the dynamics of genome evolution in C. parapsilosis.
侵袭性念珠菌病是全球最常见的侵袭性真菌感染。虽然白念珠菌仍然是主要原因，但新兴念珠菌物种的发病率（如近平滑念珠菌）正在增加。有人假设近平滑念珠菌临床分离株是由最近全球范围内一个毒力克隆的扩张引起的。然而，到目前为止，由于该物种只有一个基因组可用，因此无法在基因组范围内检验这一假设。我们在这里介绍了来自临床和环境样本的另外三个菌株的序列。我们的分析揭示了在不同菌株之间存在意想不到的基因组变异模式，这与克隆扩张假说相矛盾。所有菌株都携带独立的扩张，涉及亚砷酸盐转运体同源物，这表明在环境中存在定向选择，并且两个临床分离株具有独立的起源。此外，我们报告了该物种中存在重组的第一个证据。总之，我们的结果为近平滑念珠菌的基因组进化动态提供了新的认识。
