Targeting evolutionarily acquired insertion sequences in Candida species, for development of antifungal drugs - Abstract
Candida albicans causes half of all invasive fungal infections in humans. Its success as a pathogen is due to its
ability to adapt and thrive in various microenvironments in the host. Using a forward genetics screen, we identified
an uncharacterized gene NDU1 whose loss caused C. albicans to lose viability on alternative carbon sources
and made the organism completely avirulent in vivo. We found that Candida-Ndu1 protein possesses three
evolutionarily acquired stretches of amino acid inserts (~64 amino acids), absent from all other eukaryotes
including humans. We reported for the first time that ~17% of the Candida proteome possess “additional” sets
of evolutionarily acquired amino-acid inserts, that are absent from all non-CTG clade eukaryotes, including
humans. The role of insert regions in C. albicans proteome remains to be unraveled. We have shown that the
Ndu1 insertion sequences are vital and required for Ndu1’s activity. In aim 1, the mechanistic contribution of
Ndu1 inserts will be investigated by protein biochemistry studies. The role of insert regions in other Candida
proteins will also be evaluated , to understand if inserts are universally important for function.
Considering Ndu1 is important for growth and virulence in vivo, we targeted Ndu1 and its insert regions for
development of antifungal molecules. We identified a repurposed FDA approved drug niclosamide (NCL), and
developed Eudragit EPO nanoparticle formulations of this molecule to enhance its solubility and bioavailability.
NCL nanoparticles (NCL-EPO-NP) could prevent growth of Candida in alternative carbon sources, penetrate
and dismantle mature biofilms in vitro, and eradicate it in vivo in biofilm models of mucosal candidiasis. The
activity of NCL-NP was 6-10 fold higher than the generic drug alone. In Aim 2, we further characterize and
evaluate NCL-EPO-NP for their pharmacokinetics and oral biodistribution, toxicity profiles and in vivo efficacy in
an oral regimen for treatment of oral candidiasis, as standalone or adjunct therapy with other antifungal drugs.
