Chytridiomycosis in amphibians: Designing a efficient treatment protocol and defining the mechanisms of host-specificity

One of the key factors contributing to the current extinction crisis in amphibians is the fungus Batrachochytrium dendrobatidis (Bd) which causes chytridiomycosis, a lethal skin infection in amphibians. The establishment of Bd free amphibian breeding colonies has become one of the emergency measures to save threatened amphibian species from extinction. The aims of this PhD project are to improve current diagnostic techniques, design an efficient treatment protocol based on antimicrobial agents and study the mechanisms of host-specificity for chytridiomycosis in amphibians. The first part of this project is the development of a technique that allows selective quantification of viable Bd cells. Until recently the most reliable techniques for detecting Bd cells was based on detecting and quantifying the amount of Bd DNA present in a sample, but these methods make no distinction between viable and dead Bd cells can be made. In 2012 we developed a technique based on real-time PCR ( EMA PCR) which allows to distinguish between living and dead Bd cells (Blooi et al 2013a ). In 2013, EMA PCR was successfully used to demonstrate biocidal capacity of skin secretions of salamanders of the genus Speleomantes (Pasmans et al , 2013). Using the same EMA PFR we were able to show a significant correlation between the abundance of microorganisms in water samples and the likelihood of amphibians becoming infected with Bd. Rotifers and protozoa in water samples were demonstrated to filter the infectious stages of Bd from the water by predation, and thus exert a great effect on the infection dynamics of Bd in nature (Schmeller et al 2013). These findings open up new possibilities for combating Bd in the natural environment. A previously undescribed chytrid fungus (B. salamandrivorans) was isolated in 2013 from a Dutch population of fire salamanders (Salamandra salamandra) (Martel et al, 2013) . This new fungus is responsible for the near extirpation of the entire population in the Netherlands. A rapid diagnostic test was developed which allows to test for the occurrence of both B. salamandrivorans and B. dendrobatidis (Blooi et al 2013b ). We are currently developing a treatment protocol using various antimicrobial agents and increased ambient temperatures. Supervision: Francis Vercammen | Frank Pasmans (Ghent University) | An Martel (Ghent University) Time line: PhD 2011-2014 Funding: CRC (KMDA Dehousse)

Project type:PhD project