Selective breeding programs aim to increase amphibian resilience to Batrachochytrium spp. infections. The strategy of combating chytridiomycosis, a fungal illness, has been recommended. Chytridiomycosis tolerance and resistance are defined, along with presented evidence of tolerance variation, and explored are the resulting epidemiological, ecological, and evolutionary implications of this tolerance. Exposure risks and environmental mitigation of infection burdens heavily confound resistance and tolerance mechanisms; chytridiomycosis's defining feature is variability in constitutive, not adaptive, resistance. Tolerance's epidemiological impact is significant in propelling and maintaining pathogen spread. Tolerance's heterogeneity forces ecological trade-offs, and natural selection favoring resistance and tolerance is possibly reduced. Expanding our knowledge of infection tolerance enhances our ability to lessen the ongoing consequences of emerging infectious diseases, such as chytridiomycosis. Within the thematic focus of 'Amphibian immunity stress, disease and ecoimmunology', this piece is situated.

The immune equilibrium model suggests that initial microbial exposures in early life help the immune system anticipate and react effectively to pathogen threats in subsequent phases. Though recent studies using gnotobiotic (germ-free) model organisms support this proposition, a readily adaptable model system for studying the microbiome's effect on immune system development has yet to be established. This investigation into the importance of the microbiome for larval development and later life susceptibility to infectious disease employed Xenopus laevis, an amphibian species. Microbial richness, diversity, and community composition were significantly altered in tadpoles before metamorphosis due to experimental microbiome reduction during embryonic and larval stages. learn more Beyond this, our antimicrobial treatments yielded limited negative consequences in larval development, physical condition, or survival to the metamorphic stage. Our anticipated effects of antimicrobial treatments on susceptibility to the deadly fungal pathogen, Batrachochytrium dendrobatidis (Bd), were not observed in the adult stage. Our microbiome reduction treatments applied during early development in X. laevis, while not impacting susceptibility to Bd-related diseases, nevertheless suggest a highly promising future for immunological investigations using a gnotobiotic amphibian model system. This article is featured in the thematic issue dedicated to amphibian immunity stress, disease, and ecoimmunology.

Macrophage (M)-lineage cells are indispensable for the immune systems of every vertebrate, amphibians included. The activation of the colony-stimulating factor-1 (CSF1) receptor by the cytokines CSF1 and interleukin-34 (IL34) is essential for the maintenance of M cell differentiation and functionality in vertebrate organisms. fluoride-containing bioactive glass Following differentiation with CSF1 and IL34, the amphibian (Xenopus laevis) Ms cells display unique and separate morphologies, gene expression patterns, and functionalities. It is noteworthy that mammalian macrophages (Ms) and dendritic cells (DCs) possess a common lineage, the differentiation of DCs being contingent upon FMS-like tyrosine kinase 3 ligand (FLT3L), while X. laevis IL34-Ms share a striking similarity with the characteristics of mammalian dendritic cells. Presently, a comparative analysis was carried out on X. laevis CSF1- and IL34-Ms, and FLT3L-derived X. laevis DCs. Our analysis of transcription and function revealed that frog IL34-Ms and FLT3L-DCs shared numerous similarities with CSF1-Ms, encompassing comparable transcriptional profiles and functional capabilities. X. laevis CSF1-Ms displayed reduced levels of surface major histocompatibility complex (MHC) class I molecules compared to IL34-Ms and FLT3L-DCs, which showed heightened MHC class I expression, but not MHC class II. This higher MHC class I expression contributed to their superior capability in eliciting mixed leucocyte responses in vitro and generating enhanced immune responses in vivo to Mycobacterium marinum re-exposure. Subsequent studies of non-mammalian myelopoiesis, utilizing the methodologies described here, will reveal distinct insights into the evolutionarily conserved and diverged mechanisms of macrophage and dendritic cell functional differentiation. This article is included in the 'Amphibian immunity stress, disease and ecoimmunology' special issue.

Naive multi-host communities include species that demonstrably differ in their ability to sustain, disseminate, and proliferate novel pathogens; this suggests that distinct roles are expected from each species during the emergence of infectious diseases. Characterizing the roles of these species in wildlife assemblages is difficult because the majority of disease outbreaks occur in an unpredictable manner. During the emergence of Batrachochytrium dendrobatidis (Bd) in a highly diverse tropical amphibian community, we investigated the influence of species-specific attributes on the degree of exposure, likelihood of infection, and pathogen intensity using field-collected data. During the outbreak, our findings demonstrated a positive association between infection prevalence and intensity at the species level and ecological traits usually associated with population decline. Disproportionately contributing key hosts to transmission dynamics were identified in this community, showing a disease response pattern reflecting phylogenetic history, and linked to increased pathogen exposure because of shared life-history traits. The framework we have developed, based on our findings, can be applied in conservation initiatives to detect key species influencing disease patterns during enzootic stages, prior to the reintroduction of amphibians into their original habitats. Reintroducing supersensitive hosts, ill-equipped to manage infections, will negatively impact conservation programs, leading to amplified community-level disease. The thematic issue 'Amphibian immunity stress, disease, and ecoimmunology' includes this article as a key component.

The need for greater insight into the diverse ways host-microbiome interactions change with human-caused environmental alterations and their contribution to pathogenic infections is paramount to understanding the impact of stress on disease outcomes. We examined the impact of escalating salinity levels in freshwater ecosystems, such as. Salt runoff from road de-icing, coupled with increased nutritional algae growth, altered gut bacterial communities, impacted host physiology, and modified responses to ranavirus exposure in larval wood frogs (Rana sylvatica). Elevating salinity levels in conjunction with incorporating algae into a basic larval diet spurred faster larval growth, but concomitantly increased ranavirus populations. While larvae that consumed algae failed to exhibit elevated kidney corticosterone levels, accelerated development, or weight loss post-infection, those given a fundamental diet did. Subsequently, the introduction of algae mitigated a potentially disadvantageous stress response to infection, as documented in past investigations of this system. metabolomics and bioinformatics Algae supplementation was associated with a decrease in the abundance and variety of gut bacteria. Algae-supplemented treatments exhibited a higher relative abundance of Firmicutes, correlating with increased growth and fat deposition commonly seen in mammals. This trend may potentially explain the diminished stress response to infection through adjustments in the host's metabolism and endocrine functions. Our research proposes mechanistic hypotheses concerning how the microbiome affects host responses to infection, which are amenable to experimental testing within this host-pathogen system in the future. This piece of writing forms a segment of the broader theme issue dedicated to 'Amphibian immunity stress, disease and ecoimmunology'.

Compared to all other vertebrate groups, including birds and mammals, amphibians, as a class of vertebrates, are significantly more vulnerable to extinction or population decline. Various environmental perils, including the destruction of habitats, the proliferation of invasive species, excessive human activity, the contamination with toxic materials, and the appearance of new diseases, underscore a serious threat. Climate change's effect on temperature and precipitation, marked by its unpredictability, acts as a supplementary hazard. To survive these intertwined threats, amphibian immune systems must operate with considerable efficiency and effectiveness. The current body of knowledge regarding amphibian responses to natural stressors, including heat and desiccation, and the limited research on their immune responses under these stresses, is summarized in this review. Current studies generally demonstrate that dehydration and heat stress can initiate the hypothalamic-pituitary-interrenal axis, possibly causing a suppression of specific innate and lymphocyte-mediated immune systems. Microbial communities within amphibian skin and gut are vulnerable to alteration by elevated temperatures, potentially causing dysbiosis and impairing their resistance to pathogens. This article contributes to the broader theme of 'Amphibian immunity stress, disease, and ecoimmunology'.

Salamander biodiversity faces a serious danger due to the amphibian chytrid fungus, scientifically known as Batrachochytrium salamandrivorans (Bsal). Susceptibility to Bsal potentially involves glucocorticoid hormones (GCs) as a contributing factor. Although the effects of glucocorticoids (GCs) on immunity and disease predisposition are extensively investigated in mammals, parallel studies in other animal groups, including salamanders, are still relatively limited. Our investigation into the possible role of glucocorticoids in regulating salamander immunity involved the application of the eastern newt (Notophthalmus viridescens) as the subject of our research. Our method commenced by determining the dose required to elevate corticosterone (CORT, the key glucocorticoid in amphibians) to physiologically meaningful levels. In newts subjected to treatment with CORT or an oil vehicle control, we then measured immunity (neutrophil lymphocyte ratios, plasma bacterial killing ability (BKA), skin microbiome, splenocytes, melanomacrophage centers (MMCs)), along with overall health.