Coqui frogs persist with the deadly chytrid fungus despite a lack of defensive antimicrobial peptides

Rollins‐Smith, Louise A.; Reinert, Laura K.; Burrowes, Patricia A.

doi:10.3354/dao02823

Cited by 13 publications

(9 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On one hand, natural variation in temperature impacts the expression of amphibian immunity and influences susceptibility to disease (Maniero and Carey, 1997;Raffel et al, 2006). On the other hand, warmer temperatures decrease the activity period and lifespan of Bd zoospores (Woodhams et al, 2008; Rollins-Smith et al, 2015), but they may rely on adaptive immunity, as has been shown for other frogs (Savage and Zamudio, 2011;Ellison et al, 2014;McMahon et al, 2014;Savage et al, 2016). The fact that we found a positive relationship between previous exposure and Bd infection intensity during the experiment indicates that acquired immunity may not confer full resistance to coqui frogs (Figure 4), because individuals still get infected when challenged with the pathogen at high doses.…”

Section: Discussionmentioning

confidence: 99%

Environmental fluctuations and host skin bacteria shift survival advantage between frogs and their fungal pathogen

2016

View full text Add to dashboard Cite

Fluctuating environments can modulate host-pathogen interactions by providing a temporary advantage to one of the interacting organisms. However, we know very little about how environmental conditions facilitate beneficial interactions between hosts and their microbial communities, resulting in individual persistence with a particular pathogen. Here, we experimentally infected Eleutherodactylus coqui frogs with the fungal pathogen Batrachochytrium dendrobatidis (Bd) under environmental conditions known to confer the survival advantage to the host during the warm-wet season, or alternatively to the pathogen during the cool-dry season. We used 16S rRNA amplicon sequencing to quantify changes in bacterial richness and phylogenetic diversity, and identified operational taxonomic units (OTUs) that became overrepresented or suppressed as a consequence of Bd infection. During the warm-wet season, frogs limited Bd infections, recruited putatively beneficial bacteria and returned to pre-infection levels of richness and phylogenetic diversity. In contrast, during the cool-dry season, Bd infections kept increasing through time, and bacterial diversity remained constant. Our findings confirm that infection outcome not only depends on abiotic factors, but also on biotic interactions between hosts and their associated bacterial communities.

show abstract

Section: Discussionmentioning

confidence: 99%

Environmental fluctuations and host skin bacteria shift survival advantage between frogs and their fungal pathogen

2016

View full text Add to dashboard Cite

show abstract

“…The ability to synthesize AMPs has been suggested to confer an evolutionary advantage to frogs but is not required for the survival of a species (118). For example, Coqui frogs ( Eleutherodactylus coqui ) have been shown to survive with a lack of AMPs, even when the deadly chytrid fungus, Bd , is detected on their skin (119). However, discovery of AMPs has traditionally relied on the isolation of active fractions from amphibian skin or amphibian skin secretions and in vitro testing on microbes of human importance (120, 121).…”

Section: Chemical Barriersmentioning

confidence: 99%

Frog Skin Innate Immune Defences: Sensing and Surviving Pathogens

2019

View full text Add to dashboard Cite

Amphibian skin is a mucosal surface in direct and continuous contact with a microbially diverse and laden aquatic and/or terrestrial environment. As such, frog skin is an important innate immune organ and first line of defence against pathogens in the environment. Critical to the innate immune functions of frog skin are the maintenance of physical, chemical, cellular, and microbiological barriers and the complex network of interactions that occur across all the barriers. Despite the global decline in amphibian populations, largely as a result of emerging infectious diseases, we understand little regarding the cellular and molecular mechanisms that underlie the innate immune function of amphibian skin and defence against pathogens. In this review, we discuss the structure, cell composition and cellular junctions that contribute to the skin physical barrier, the antimicrobial peptide arsenal that, in part, comprises the chemical barrier, the pattern recognition receptors involved in recognizing pathogens and initiating innate immune responses in the skin, and the contribution of commensal microbes on the skin to pathogen defence. We briefly discuss the influence of environmental abiotic factors (natural and anthropogenic) and pathogens on the immunocompetency of frog skin defences. Although some aspects of frog innate immunity, such as antimicrobial peptides are well-studied; other components and how they contribute to the skin innate immune barrier, are lacking. Elucidating the complex network of interactions occurring at the interface of the frog's external and internal environments will yield insight into the crucial role amphibian skin plays in host defence and the environmental factors leading to compromised barrier integrity, disease, and host mortality.

show abstract

“…Bd has been associated with many amphibian population declines in recent decades since it was first observed in dead and dying frogs from both Central America and Australia (Berger et al, 1998 ). The adaptive and innate immune systems, and in particular the production of antimicrobial peptides in amphibian skin, has an important role in preventing Bd infection in some host species (McMahon et al, 2014 ; Rollins-Smith et al, 2015 ). However, the skin of healthy amphibians is also host to a diverse resident bacterial community (McKenzie et al, 2012 ; Walke et al, 2014 ), and a number of these bacteria can inhibit Bd growth (Harris et al, 2006 ; Flechas et al, 2012 ; Bell et al, 2013 ; Becker et al, 2015b ; Woodhams et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Panamanian frog species host unique skin bacterial communities

et al. 2015

View full text Add to dashboard Cite

Vertebrates, including amphibians, host diverse symbiotic microbes that contribute to host disease resistance. Globally, and especially in montane tropical systems, many amphibian species are threatened by a chytrid fungus, Batrachochytrium dendrobatidis (Bd), that causes a lethal skin disease. Bd therefore may be a strong selective agent on the diversity and function of the microbial communities inhabiting amphibian skin. In Panamá, amphibian population declines and the spread of Bd have been tracked. In 2012, we completed a field survey in Panamá to examine frog skin microbiota in the context of Bd infection. We focused on three frog species and collected two skin swabs per frog from a total of 136 frogs across four sites that varied from west to east in the time since Bd arrival. One swab was used to assess bacterial community structure using 16S rRNA amplicon sequencing and to determine Bd infection status, and one was used to assess metabolite diversity, as the bacterial production of anti-fungal metabolites is an important disease resistance function. The skin microbiota of the three Panamanian frog species differed in OTU (operational taxonomic unit, ~bacterial species) community composition and metabolite profiles, although the pattern was less strong for the metabolites. Comparisons between frog skin bacterial communities from Panamá and the US suggest broad similarities at the phylum level, but key differences at lower taxonomic levels. In our field survey in Panamá, across all four sites, only 35 individuals (~26%) were Bd infected. There was no clustering of OTUs or metabolite profiles based on Bd infection status and no clear pattern of west-east changes in OTUs or metabolite profiles across the four sites. Overall, our field survey data suggest that different bacterial communities might be producing broadly similar sets of metabolites across frog hosts and sites. Community structure and function may not be as tightly coupled in these skin symbiont microbial systems as it is in many macro-systems.

show abstract

Coqui frogs persist with the deadly chytrid fungus despite a lack of defensive antimicrobial peptides

Cited by 13 publications

References 10 publications

Environmental fluctuations and host skin bacteria shift survival advantage between frogs and their fungal pathogen

Environmental fluctuations and host skin bacteria shift survival advantage between frogs and their fungal pathogen

Frog Skin Innate Immune Defences: Sensing and Surviving Pathogens

Panamanian frog species host unique skin bacterial communities

Contact Info

Product

Resources

About