Chytrid fungus infection in zebrafish demonstrates that the pathogen can parasitize non-amphibian vertebrate hosts

Abstract

Aquatic chytrid fungi threaten amphibian biodiversity worldwide owing to their ability to rapidly expand their geographical distributions and to infect a wide range of hosts. Combating this risk requires an understanding of chytrid host range to identify potential reservoirs of infection and to safeguard uninfected regions through enhanced biosecurity. Here we extend our knowledge on the host range of the chytrid Batrachochytrium dendrobatidis by demonstrating infection of a non-amphibian vertebrate host, the zebrafish. We observe dose-dependent mortality and show that chytrid can infect and proliferate on zebrafish tissue. We also show that infection phenotypes (fin erosion, cell apoptosis and muscle degeneration) are direct symptoms of infection. Successful infection is dependent on disrupting the zebrafish microbiome, highlighting that, as is widely found in amphibians, commensal bacteria confer protection against this pathogen. Collectively, our findings greatly expand the limited tool kit available to study pathogenesis and host response to chytrid infection.

Genomic epidemiology of the emerging pathogen Batrachochytrium dendrobatidis from native and invasive amphibian species in Chile

“…The exact time of introduction of X. laevis into Chile is unknown, but it is thought to have occurred sometime in the 1970s (Jaksic, ). Additional means of Bd GPL introduction, possibly assisted via tourism, research or salmon farming (Liew et al., ), should also be considered.…”

“…We obtained three isolates across central and southern Chile is unknown, but it is thought to have occurred sometime in the 1970s (Jaksic, 1998). Additional means of BdGPL introduction, possibly assisted via tourism, research or salmon farming (Liew et al, 2017), should also be considered. (Farrer et al, 2011;Rosenblum et al, 2013;Vredenburg, Knapp, Tunstall, & Briggs, 2010 (Woodhams et al, 2011).…”

Relationships between community composition, productivity and invasion resistance in semi-natural bacterial microcosms

“…A high value of %IncM SE indicates predictor makes a large contribution to the overall predictive power of the model. As noted above, error estimates are incorporated into these statistics given that they are calculated from average predictive error, as described by [33].…”

Chytrid fungi and global amphibian declines

“…The development of new models of infection is needed to increase understanding of batrachochytrids biology. Recent advances, such as amphibian cell culture and skin-explant models 69 , and in vivo zebrafish Bd infection models 70 , are exciting developments. The observation that different genotypes and lineages show some variation in plastic morphological traits such as the number and size of infectious zoospores suggests that virulence traits may be to some extent governed by simple parameters such as growth rate and fecundity 71,72 .…”