Virulence phenotypes result from an interaction between pathogen ploidy and genetic background

Abstract

Studying fungal virulence is often challenging and frequently depends on many contexts, including host immune status and pathogen genetic background. However, ploidy has often been overlooked when studying virulence in eukaryotic pathogens. Since fungal pathogens, including the human opportunistic pathogen Candida albicans, can display extensive ploidy variation, assessing how ploidy impacts virulence has important clinical relevance. Here, we assessed how C. albicans ploidy and genetic background impact virulence phenotypes in both healthy and immunocompromised nematode hosts. In addition to reducing overall host survival, Candida negatively impacted host reproduction, which allowed us to survey lethal and non-lethal virulence phenotypes. While we did not detect any global differences in virulence between diploid and tetraploid pathogens, there were significant interactions between ploidy and C. albicans genetic background, regardless of host immune function.