Targeted gene disruption in Candida parapsilosis demonstrates a role for CPAR2_404800 in adhesion to a biotic surface and in a murine model of ascending urinary tract infection

Abstract

Candida parapsilosis is an emerging opportunistic pathogen, second in frequency only to C. albicans and commonly associated with both mucosal and systemic infections. Adhesion to biotic surfaces is a key step for the development of mycoses. The C. parapsilosis genome encodes 5 predicted agglutinin-like sequence proteins and their precise role in the adhesion process still remains to be elucidated. In this study, we focused on the putative adhesin Cpar2_404800, in view of its high homology to the most important adhesion molecule in C. albicans. Two independent lineages of C. parapsilosis CPAR2_404800 heterozygous and null mutants were obtained by site-specific deletion. CPAR2_404800 mutants did not differ from wild-type strain in terms of in vitro growth or in their ability to undergo morphogenesis. However, when compared for adhesion to a biotic surface, CPAR2_404800 null mutants exhibited a marked reduction in their adhesion to buccal epithelial cells (>60% reduction of adhesion index). Reintroduction of one copy of CPAR2_404800 gene in the null background restored wild type phenotype. A murine model of urinary tract infection was used to elucidate the in vivo contribution of CPAR2_404800. A 0.5 and 1 log10 reduction in colony forming unit numbers (per gram) was observed respectively in bladder and kidneys obtained from mice infected with null mutant compared to wild-type infected ones. Taken together, these findings provide the first evidence for a direct role of CPAR2_404800 in C. parapsilosis adhesion to host surfaces and demonstrate its contribution to the pathogenesis of murine urinary candidiasis.

Role of the Inducible Adhesin CpAls7 in Binding of Candida parapsilosis to the Extracellular Matrix under Fluid Shear

“…A role for CpAls7 in adhesion was first suggested by a study showing that the protein was isolated from a fibronectin affinity column (17). Another study showed that a strain deficient in CpALS7 had reduced adhesion to buccal epithelial cells in vitro and a reduction in the fungal burden in a mouse model of urinary tract infection (19). Our study provides additional evidence to support a role for CpAls7 in adhesion.…”

“…Yeast cells that contained the vector without CpALS7 showed minimal adhesion regardless of the carbon source. To further investigate the effect of CpALS7 on adhesion, a CpALS7 deletion strain (KO) (19) and its wild-type parent (ATCC 22019) were tested in the adhesion assay ( Fig. 7B).…”

“…These same 2 gene products were purified from extracts of C. parapsilosis surface proteins based on their binding affinity for human plasminogen and high-molecular-mass kininogen (18). Furthermore, the site-specific deletion of CPAR2_404800 reduced the adhesion of C. parapsilosis to buccal epithelial cells and significantly attenuated virulence in a murine model of urinary tract infection (19). This gene was selected for targeting in this study because its product bears the highest sequence identity to C. albicans Als3.…”

Adhesins inCandida parapsilosis: Understudied players in virulence

“…The work by Bertini et al 13 highlights the need for more detailed investigations of one of the most important features of the pathogenesis program by fungi-the adhesion to host tissues and cells-not only in C. albicans but in other emerging Candida pathogens. There are several reports about the different adhesion capacities for individual Candida species, including C. parapsilosis.…”

“…13 The authors identified and disrupted a hypothetical, adhesion effecting gene "CPAR2_404800," (ortholog of C. albicans ALS genes), using a previously described gene deletion method.…”