Do immune system changes at metamorphosis predict vulnerability to chytridiomycosis? An update

Humphries, Josephine E.; Lanctôt, Chantal M.; Robert, Jacques; McCallum, Hamish; Newell, David; Grogan, Laura F.

doi:10.1016/j.dci.2022.104510

Cited by 13 publications

(15 citation statements)

References 146 publications

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“…We are hesitant to suggest that juvenile frogs were less affected by Bd than adult frogs; however, our data suggest that juvenile M. fleayi are not experiencing greater disease impact in the field, contrary to the results of many previous studies (Sauer et al 2020;Humphries et al 2022) but somewhat in line with some recent results (Bradley, Snyder, and Blaustein 2019). One study found Bd-related mortality in Rana aurora and Pseudacris regilla increased with age, but this study did not incorporate recently metamorphosed (< 4 weeks post-metamorphosis) (Bradley, Snyder, and Blaustein 2019).…”

Section: Discussioncontrasting

confidence: 99%

“…True infection prevalence (0.35 [0.14, 0.52]) was much higher, however, after correcting for imperfect pathogen detection in the multievent model fitted to the mark-recapture data. It has been widely assumed that juvenile frogs are more susceptible to Bd infection than adults frogs (Humphries et al 2022); our study suggests that this is not the caes for M. fleayi.…”

Section: Discussionmentioning

confidence: 52%

“…Disease susceptibility is influenced by a number of factors, including host species (Scheele et al 2019), Bd lineage (O'Hanlon et al 2018), history of Bd exposure (Knapp et al 2016;Waddle et al 2019;, environmental conditions (Kriger and Hero 2007), and host life stage (Sauer et al 2020). Recently metamorphosed (juvenile) frogs are often reported to be more susceptible to chytridiomycosis than older life stages, potentially caused by restructuring of the immune system that occurs during metamorphosis (Rollins-Smith et al 2011;Waddle et al 2019;Sauer et al 2020;Humphries et al 2022).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Limited impact of chytridiomycosis on juvenile frogs in a recovered species

Hollanders

Grogan

McCallum

et al. 2022

Preprint

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The amphibian chytrid fungus *Batrachochytrium dendrobatidis* (*Bd*) has caused catastrophic frog declines on several continents, but disease outcome is mediated by a number of factors. Host life stage is an important consideration, and many studies have highlighted the vulnerability of recently metamorphosed or juvenile frogs compared to adults. The majority of these studies have taken place in a laboratory setting, and there is a general paucity of longitudinal field studies investigating the influence of life stage on disease outcome. In this study, we assessed the effect of endemic *Bd* on juvenile *Mixophyes fleayi* (Fleay’s barred frog) in subtropical eastern Australian rainforest. Using photographic mark-recapture, we made 386 captures of 116 individuals and investigated the effect of *Bd* infection intensity on the apparent mortality rates of frogs using a multievent model correcting for infection state misclassification. We found that *Bd* infection status nor infection intensity were not correlated with mortality in juvenile frogs, counter to the expectation that early life stages are more vulnerable to disease, despite high infection prevalence (0.35, 95% HDPI [0.14, 0.52]). Additionally, we found that observed infection prevalence and intensity were somewhat lower for juveniles than adults. Our results indicate that in this *Bd*-recovered species, the realised impacts of chytridiomycosis on juveniles were apparently low, likely resulting in high recruitment contributing to population stability. We highlight the importance of investigating factors relating to disease outcome in a field setting and make recommendations for future studies.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

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Limited impact of chytridiomycosis on juvenile frogs in a recovered species

Hollanders

Grogan

McCallum

et al. 2022

Preprint

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“…Immune defenses may vary greatly by life stage in amphibians because of reorganization of the immune system during metamorphosis (Gantress et al 2003; Humphries et al 2022). Although Bd metabolites have been effective at inducing resistance when applied pre-Bd exposure in both tadpoles (Nordheim et al 2022) and adults (Barnett et al 2021), it is possible that adult frogs or frogs undergoing metamorphosis may respond differently than tadpoles to postexposure Bd metabolite treatment.…”

Section: Discussionmentioning

confidence: 99%

“…Although metamorphs are more likely to succumb to Bd-induced mortality than tadpoles (Rachowicz al. 2006), metamorphs' immune systems are more mature than that of tadpoles, exemplified by their increased expression of major histocompatibility complex classes I and II and presence of antimicrobial peptides (Humphries et al 2022). Given the maturity of their immune system, metamorphs and adult frogs may be able to acquire resistance by postexposure treatment with Bd metabolites even though this study found postexposure prophylaxis was ineffective in tadpoles.…”

Section: Discussionmentioning

confidence: 99%

Fungal Metabolites Provide Pre-Exposure Protection but No Postexposure Benefit or Harm Against Batrachochytrium Dendrobatidis

Barnett

Hilgendorff

Civitello

et al. 2023

Journal of Wildlife Diseases

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Disease control tools are needed to mitigate the effect of the fungal pathogen Batrachochytrium dendrobatidis (Bd) on amphibian biodiversity loss. In previous experiments, Bd metabolites (i.e., noninfectious chemicals released by Bd) have been shown to induce partial resistance to Bd when administered before live pathogen exposure and therefore have potential as an intervention strategy to curb Bd outbreaks. In the wild, however, amphibians inhabiting Bd-endemic ecosystems may have already been exposed to or infected with Bd before metabolite administration. It is therefore critical to evaluate the efficacy and safety of Bd metabolites applied postexposure to live Bd. We tested whether Bd metabolites administered postexposure would induce resistance, exacerbate infections, or have no effect. The results confirmed that Bd metabolites applied before pathogen exposure significantly reduced infection intensity, but Bd metabolites applied after pathogen exposure neither protected against nor exacerbated infections. These results reveal the importance of timing the application of Bd metabolites early in the transmission season for Bd-endemic ecosystems and emphasize that Bd metabolites prophylaxis may be a useful tool in captive reintroduction campaigns where Bd threatens the success of re-establishing endangered amphibian populations.

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Limited impact of chytridiomycosis on juvenile frogs in a recovered species

et al. 2023

Self Cite

View full text Add to dashboard Cite

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused catastrophic frog declines on several continents, but disease outcome is mediated by a number of factors. Host life stage is an important consideration and many studies have highlighted the vulnerability of recently metamorphosed or juvenile frogs compared to adults. The majority of these studies have taken place in a laboratory setting, and there is a general paucity of longitudinal field studies investigating the influence of life stage on disease outcome. In this study, we assessed the effect of endemic Bd on juvenile Mixophyes fleayi (Fleay’s barred frog) in subtropical eastern Australian rainforest. Using photographic mark-recapture, we made 386 captures of 116 individuals and investigated the effect of Bd infection intensity on the apparent mortality rates of frogs using a multievent model correcting for infection state misclassification. We found that neither Bd infection status nor infection intensity predicted mortality in juvenile frogs, counter to the expectation that early life stages are more vulnerable to disease, despite average high infection prevalence (0.35, 95% HDPI [0.14, 0.52]). Additionally, we found that observed infection prevalence and intensity were somewhat lower for juveniles than adults. Our results indicate that in this Bd-recovered species, the realized impacts of chytridiomycosis on juveniles were apparently low, likely resulting in high recruitment contributing to population stability. We highlight the importance of investigating factors relating to disease outcome in a field setting and make recommendations for future studies.

show abstract

Do immune system changes at metamorphosis predict vulnerability to chytridiomycosis? An update

Cited by 13 publications

References 146 publications

Limited impact of chytridiomycosis on juvenile frogs in a recovered species

Limited impact of chytridiomycosis on juvenile frogs in a recovered species

Fungal Metabolites Provide Pre-Exposure Protection but No Postexposure Benefit or Harm Against Batrachochytrium Dendrobatidis

Limited impact of chytridiomycosis on juvenile frogs in a recovered species

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