Role of CpALS4790 and CpALS0660 in Candida parapsilosis Virulence: Evidence from a Murine Model of Vaginal Candidiasis.

Marina Zoppo,Marisa Colone,Fabrizio Fiorentini,Arianna Tavanti,Flavia De Bernardis,Mariagrazia Di Luca,Daria Bottai,Antonella Lupetti,Cosmeri Rizzato,Annarita Stringaro

doi:10.3390/jof6020086

Abstract

The Candida parapsilosis genome encodes for five agglutinin-like sequence (Als) cell-wall glycoproteins involved in adhesion to biotic and abiotic surfaces. The work presented here is aimed at analyzing the role of the two still uncharacterized ALS genes in C. parapsilosis, CpALS4790 and CpALS0660, by the generation and characterization of CpALS4790 and CpALS066 single mutant strains. Phenotypic characterization showed that both mutant strains behaved as the parental wild type strain regarding growth rate in liquid/solid media supplemented with cell-wall perturbing agents, and in the ability to produce pseudohyphae. Interestingly, the ability of the CpALS0660 null mutant to adhere to human buccal epithelial cells (HBECs) was not altered when compared with the wild-type strain, whereas deletion of CpALS4790 led to a significant loss of the adhesion capability. RT-qPCR analysis performed on the mutant strains in co-incubation with HBECs did not highlight significant changes in the expression levels of others ALS genes. In vivo experiments in a murine model of vaginal candidiasis indicated a significant reduction in CFUs recovered from BALB/C mice infected with each mutant strain in comparison to those infected with the wild type strain, confirming the involvement of CpAls4790 and CpAls5600 proteins in C. parapsilosis vaginal candidiasis in mice.

Highlights

The agglutinin-like sequence (Als) family encodes for cell-wall glycoproteins involved in fungal adhesion to both biotic and abiotic surfaces [1]
To evaluate the role of CpALS4790 and CpALS0660 in C. parapsilosis virulence and pathogenicity, both alleles were deleted in C. parapsilosis ATCC 22019 reference strain, using the SAT1-flipper cassette strategy (Figure 1a)
C. parapsilosis mutant strains containing the SAT1-flipper cassette integrated in the genome (CpALS4790HC, CpALS4790KOC, CpALS0660HC and CpALS0660KOC) were Nourseothricin resistant and were maintained on YPD-NTC

Summary

Introduction

The agglutinin-like sequence (Als) family encodes for cell-wall glycoproteins involved in fungal adhesion to both biotic and abiotic surfaces [1]. Since the description of the first ALS gene more than two decades ago [2], the ALS gene family has been extensively studied in Candida albicans, where eight Als members have been identified and characterized [1]. The Candida parapsilosis species complex encompasses three closely related species named Candida parapsilosis, Candida orthopsilosis and Candida metapsilosis [3]. C. parapsilosis has recently gained importance as one of the leading causes of invasive candidiasis among non-albicans species [4,5]. J. Fungi 2020, 6, 86; doi:10.3390/jof6020086 www.mdpi.com/journal/jof

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