Open AccessNovel inactivation of the causative fungal pathogen of white-nose syndrome with methoxsalen plus ultraviolet A or B radiation
Author(s) -
Colin J. Hartman,
Joseph C. Mester,
Patrick M. Hare,
Alan I. Cohen
Publication year - 2020
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0239001
Subject(s) - methoxsalen , fungal pathogen , ultraviolet radiation , pathogen , ultraviolet b , nose , ultraviolet , dermatology , microbiology and biotechnology , biology , medicine , chemistry , psoriasis , optics , physics , anatomy , radiochemistry
White-nose syndrome is a fungal disease responsible for the rapid decline of North American bat populations. This study addressed a novel method for inactivating Pseudogymnoascus destructans , the causative agent of WNS, using ultraviolet A (UVA) or B (UVB) radiation in combination with methoxsalen, a photosensitizer from the furanocoumarin family of compounds. Fungal spore suspensions were diluted in micromolar concentrations of methoxsalen (50–500 μM), then exposed to fixed doses of UVA radiation (500–5000 mJ/cm 2 ), followed by plating on germination media. These plates were examined for two to four weeks for evidence of spore germination or inactivation, along with resultant growth or inhibition of P . destructans colonies. Pretreatment of fungal spores with low doses of methoxsalen resulted in a UVA dose-dependent inactivation of the P . destructans spores. All doses of methoxsalen paired with 500 mJ/cm 2 of UVA led to an approximate two-log 10 (~99%) reduction in spore viability, and when paired with 1000 mJ/cm 2 , a four-log 10 or greater (>99.99%) reduction in spore viability was observed. Additionally, actively growing P . destructans colonies treated directly with methoxsalen and either UVA or UVB radiation demonstrated UV dose-dependent inhibition and termination of colony growth. This novel approach of using a photosensitizer in combination with UV radiation to control fungal growth may have broad, practical application in the future.