Whole-Genome Sequencing of the Opportunistic Yeast Pathogen Candida inconspicua Uncovers Its Hybrid Origin.

Verónica Mixão,Antonio Perez Hansen,Teun Boekhout,Cornelia Lass-Florl,Toni Gabaldón,Ester Saus

doi:10.3389/fgene.2019.00383

Abstract

Fungal infections such as those caused by Candida species are increasingly common complications in immunocompromised patients. The list of causative agents of candidiasis is growing and comprises a set of emerging species whose relative global incidence is rare but recurrent. This is the case of Candida inconspicua, which prevalence has increased 10-fold over the last years. To gain novel insights into the emergence of this opportunistic pathogen and its genetic diversity, we performed whole genome sequencing of the type strain (CBS180), and of 10 other clinical isolates. Our results revealed high levels of genetic heterozygosity structured in non-homogeneous patterns, which are indicative of a hybrid genome shaped by events of loss of heterozygosity (LOH). All analyzed strains were hybrids and could be clustered into two distinct clades. We found large variability across strains in terms of ploidy, patterns of LOH, and mitochondrial genome heterogeneity that suggest potential admixture between hybrids. Altogether, our results identify a new hybrid species with virulence potential toward humans and underscore the potential role of hybridization in the emergence of novel pathogenic lineages.

Highlights

IntroductionFungal infections are an increasingly common problem in hospital environments, very often leading to patient’s death (Pfaller and Diekema, 2007; Lass-Flörl, 2009; Brown et al, 2012; Gabaldón and Carreté, 2016)
The number of tested strains is low, the absence of homozygous parentals among clinical isolates suggests that the parental lineages are/might be less able to cause infections when compared to hybrid strains
This adds to a growing list of hybrid yeast opportunist lineages and underscores the relevance of hybridization in the origin of new virulent lineages (Mixão and Gabaldón, 2018)

Summary

Introduction

Fungal infections are an increasingly common problem in hospital environments, very often leading to patient’s death (Pfaller and Diekema, 2007; Lass-Flörl, 2009; Brown et al, 2012; Gabaldón and Carreté, 2016). Candida species have been the most common causative agents of hospital-acquired fungal infections (Pfaller and Diekema, 2007; Lass-Flörl, 2009; Brown et al, 2012; Gabaldón and Carreté, 2016). Candida auris is an emerging multi-drug resistant pathogen responsible for many outbreaks all over the world in the last few years (Forsberg et al, 2019)

Methods

Results

Discussion

Conclusion