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Candida albicans is one of the leading pathological agents of mucosal and deep tissue infections. Considering that the variety of antifungals is restricted and that toxicity limits their use, immunotherapies against pathogenic fungi have been viewed as alternatives with reduced adverse effects. In this context, C. albicans has a protein used to capture iron from the environment and the host, known as the high-affinity iron permease Ftr1. This protein may be a new target of action for novel antifungal therapies, as it influences the virulence of this yeast. Thus, the aim of the present study was to produce and conduct the biological characterization of IgY antibodies against C. albicans Ftr1. Immunization of laying hens with an Ftr1-derived peptide resulted in IgY antibodies extracted from egg yolks capable of binding to the antigen with high affinity (avidity index = 66.6 ± 0.3%). These antibodies reduced the growth and even eliminated C. albicans under iron restriction, a favorable condition for the expression of Ftr1. This also occurred with a mutant strain that does not produce Ftr1 in the presence of iron, a circumstance in which the protein analog of iron permease, Ftr2, is expressed. Furthermore, the survival of G. mellonella larvae infected with C. albicans and treated with the antibodies was 90% higher than the control group, which did not receive treatment (p < 0.0001). Therefore, our data suggest that IgY antibodies against Ftr1 from C. albicans can inhibit yeast propagation by blocking iron uptake., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A gene encoding the entire highly expressed protein previously identified in the proteome of Paracoccidioides brasiliensis yeast cells as PbY20 has been isolated. The pby20 sequence reveals an open reading frame of 1364bp and a deduced amino acid sequence of 203 residues, which shows high identity to benzoquinone reductase from Phanerochaete chrysosporium (72.0%), Saccharomyces cerevisiae Ycp4 (65%), and Schizosaccharomyces pombe p25 (59%), and to allergens from Alternaria alternata Alt a7 (70%) and from Cladosporium herbarum, Cla h5 (68%). Low levels of the pby20 transcript in the mycelium and highly induced ones in infective yeast cells during the transition of this dimorphic fungus indicate transcriptional control of its expression. PbY20 was immunologically detected only in yeast cell extract, suggesting an important role in cell differentiation or even in the maintenance of the yeast form. Immunoelectron microscopy showed that PbY20 is found inside large granules and vacuoles, in the nucleus, and also in the cytoplasm. Through sequence comparisons analysis and fluorescence emission assay, PbY20 was recognized as a member of the flavin mononucleotide flavodoxin-like WrbA family, which are involved in heat shock and oxidative stress in biological systems. Assuming that PbY20 belongs to this family, a similar role could be attributed to this protein.