Host-Fungal Interactions: Pathogenicity versus Immunity

Fungal pathogens represent a leading cause of life-threatening infections in debilitated patients and exert a substantial toll on health care resources. A major development in the past few years, resulting from extremely rapid technological advances, has been the elucidation of the genome sequences of all of the major human fungal pathogens. Together with the development of transcriptomics and proteomics, fungal pathogen research has entered the so-called " omics " era. However, despite the remarkable acceleration in the understanding of many molecular mechanisms underlying phenomena such as drug resistance, fungal virulence, and patho-genesis, many key aspects of the host-fungal interactions are still not fully understood. This current issue provides in-depth review articles drafted by international experts tackling different perspectives of the host-pathogen interplay. Their contributions offer insights into aspects related to fungal virulence and drug resistance of both established and emerging fungal pathogens, as well as models to study their pathogenicity. The paper by G. P. Moran and colleagues explains why Candida albicans has evolved to become such a successful op-portunistic pathogen, by comparative global gene expression analysis performed on C. albicans and its most closely related species C. dubliniensis. The epidemiology of invasive fungal infections has evolved over the past twenty years. Yeasts other than C. albicans and moulds other than Aspergillus fumigatus have emerged as significant causes of invasive mycoses in severely immunocompromised patients. Tools allowing a prompt diagnosis for these emerging pathogenic fungi are lacking, often leading to a delay in effective treatment and high mortality rates. This is the case for invasive mucormycosis, a rapidly progressing infection often refractory to antifungal therapy, with a negative prognosis in individuals with impaired immune defence. The key role of iron uptake, angioin-vasion, and neurotropism in the virulence repertoire of this fascinating group of fungi is reviewed by G. Morace and E. Borghi. Chitin is one of the most abundant biopolymers in nature and comprises part of the fungal cell wall structure. Although humans do not biosynthesize chitin, they do express chitin degrading enzymes. The targeted recognition of fungal chitin by the host may have implications for diagnostic assays, as well as for potential new therapeutic approaches. This emerging topic is reviewed by K. Vega and M. Kalkum. Another major process that influences fungal cell wall structure is protein glycosylation, which is essential for eukaryotic cells. However, the mechanisms by which carbohydrates play a role in the development of fungal diseases …