Through the process of selective breeding, amphibians are developed with improved tolerance to Batrachochytrium spp. A method for reducing the consequences of chytridiomycosis, a fungal ailment, has been proposed as a strategy. Defining infection tolerance and resistance within the context of chytridiomycosis, we present evidence for differing degrees of tolerance and explore associated epidemiological, ecological, and evolutionary implications. Risk exposure and environmental moderation of infection burdens are major confounders of resistance and tolerance; chytridiomycosis's core characteristic is variability in constitutive, not adaptive, resistance. The epidemiological significance of tolerance is substantial in influencing pathogen spread and sustenance. Heterogeneity in tolerance leads to ecological compromises. Selection pressures for resistance and tolerance are likely to be diluted. Understanding infection tolerance more fully allows for stronger methods to lessen the ongoing effects of emerging infectious diseases, including chytridiomycosis. This article is included in a themed issue exploring 'Amphibian immunity stress, disease and ecoimmunology'.

Exposure to microbes in early life, as indicated by the immune equilibrium model, preconditions the immune system for efficient pathogen responses later in life. Recent studies utilizing gnotobiotic (germ-free) model organisms lend credence to this theory, yet a manageable model for investigating the microbiome's influence on immune system development is currently unavailable. Using the amphibian Xenopus laevis, this study investigated the microbiome's contribution to larval development and its subsequent impact on susceptibility to infectious diseases. Our experiments on tadpoles revealed that reduced microbiomes during embryonic and larval periods directly impacted microbial richness, diversity, and altered community structure prior to metamorphosis. biocontrol agent Concurrently, our antimicrobial treatments showed little to no detrimental impact on larval development, physical state, and survival during the process of metamorphosis. In contrast to our forecasts, our antimicrobial treatments did not impact the vulnerability of adult amphibians to the lethal fungal pathogen Batrachochytrium dendrobatidis (Bd). Even though our treatments to diminish the microbiome during early development in X. laevis did not have a decisive role in shaping susceptibility to Bd-caused disease, they nonetheless demonstrate the considerable benefit of a gnotobiotic amphibian model for future immunology research. The theme issue 'Amphibian immunity stress, disease and ecoimmunology' includes this article.

In all vertebrates, including amphibians, macrophage (M)-lineage cells are critical to their immune protection. The activation of the colony-stimulating factor-1 (CSF1) receptor by CSF1 and interleukin-34 (IL34) cytokines is crucial for the differentiation and function of M cells across vertebrate organisms. Filgotinib price The amphibian (Xenopus laevis) Ms cells, differentiated by CSF1 and IL34, exhibit a unique and distinctive set of morphological, transcriptional, and functional characteristics. It's noteworthy that mammalian macrophages (Ms) stem from the same ancestral population as dendritic cells (DCs), which differentiate through the action of FMS-like tyrosine kinase 3 ligand (FLT3L), whereas X. laevis IL34-Ms display a significant resemblance to mammalian DCs, exhibiting many characteristic traits. A comparative study of X. laevis CSF1- and IL34-Ms was undertaken in parallel with FLT3L-derived X. laevis DCs in the present investigation. 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. In contrast to X. laevis CSF1-Ms, IL34-Ms and FLT3L-DCs display elevated surface levels of major histocompatibility complex (MHC) class I molecules, but not MHC class II, leading to enhanced in vitro mixed leucocyte responses and improved in vivo immune responses against re-exposure to Mycobacterium marinum. Investigating non-mammalian myelopoiesis, employing methods analogous to those described here, will provide novel perspectives on the evolutionary conservation and diversification of M and DC functional specializations. Part of the special publication, 'Amphibian immunity stress, disease and ecoimmunology', is this article.

Given the varying abilities of species in naive multi-host communities to maintain, transmit, and amplify novel pathogens, we predict that species will fulfill distinct roles during infectious disease emergence. Pinpointing these roles within wildlife populations presents a considerable hurdle, as the majority of disease outbreaks occur without warning. We employed field-collected data to analyze the impact of species-specific characteristics on exposure levels, infection probabilities, and the severity of the fungal pathogen Batrachochytrium dendrobatidis (Bd) during its emergence within a highly diverse tropical amphibian community. Our study confirmed a positive relationship between infection prevalence and intensity at the species level during the outbreak and ecological traits frequently seen as indicators of decline. We found key hosts that played a disproportionate role in community transmission dynamics, and their disease responses revealed a phylogenetic history signature, linked to increased pathogen exposure, as a result of shared life-history traits. Our research contributes a framework applicable to conservation, enabling the identification of species playing a crucial role in disease dynamics during enzootic periods, necessary before reinstating amphibians in their natural ecosystems. The limited ability of reintroduced supersensitive hosts to control infections will undermine conservation programs' success and worsen disease throughout the community. The article you are reading is part of a dedicated issue on the topic of 'Amphibian immunity stress, disease, and ecoimmunology'.

Improved comprehension of the dynamic relationship between host-microbiome interactions and anthropogenic environmental alterations, as well as their influence on pathogenic infections, is critical to advancing our understanding of stress-related disease development. We researched the consequences of growing salinity levels in freshwater areas, such as. De-icing salt runoff from roads, driving an increase in nutritional algae, influenced the assembly of gut bacteria, host physiological status, and reaction to ranavirus exposure in larval wood frogs (Rana sylvatica). The application of higher salinity and the inclusion of algae in a rudimentary larval diet promoted quicker larval growth, unfortunately, also increasing ranavirus levels. Nonetheless, larval subjects nourished by algae did not show heightened kidney corticosterone levels, accelerated developmental processes, or weight loss following infection, unlike larval subjects fed a standard diet. Subsequently, the introduction of algae mitigated a potentially disadvantageous stress response to infection, as documented in past investigations of this system. Shoulder infection The introduction of algae into the system also resulted in a reduction of gut bacterial diversity. The treatments containing algae showed a significantly higher relative abundance of Firmicutes. This outcome is comparable to increased growth and fat deposition observed in mammals. This connection might be linked to reduced stress responses to infection due to changes in host metabolism and endocrine systems. Through our study, we formulate mechanistic hypotheses about the microbiome's role in modulating host responses to infection, hypotheses that future experiments within this host-pathogen system can evaluate. Within the thematic collection on 'Amphibian immunity stress, disease and ecoimmunology', this article holds a place.

Amphibians, a class of vertebrates, face a higher risk of population decline or extinction than any other vertebrate group, including birds and mammals. A multitude of perils, including the destruction of habitats, the introduction of invasive species, overexploitation by humans, the presence of toxic chemicals, and the advent of new diseases, pose significant challenges. Climate change, manifested in unpredictable temperature fluctuations and rainfall patterns, adds another layer of danger. These multifaceted threats necessitate a robust immune response in amphibians to ensure their survival. We examine the current state of research on amphibian adaptation to natural stressors such as heat and desiccation, and the limited examination of their immune responses in these environments. Generally, current research indicates that dehydration and heat exposure can stimulate the hypothalamic-pituitary-interrenal axis, potentially dampening certain innate and cell-mediated immune reactions. The effect of elevated temperatures on amphibian skin and gut microbial communities can result in dysbiosis and a reduced resistance to invading pathogens. The theme issue 'Amphibian immunity stress, disease and ecoimmunology' encompasses this article.

Batrachochytrium salamandrivorans (Bsal), the notorious amphibian chytrid fungus, is damaging salamander biological diversity. The susceptibility to Bsal could be influenced by glucocorticoid hormones (GCs), among other factors. Detailed studies on glucocorticoids (GCs) and their role in immunity and disease resistance have been conducted in mammals, but comparable investigations into other vertebrate classes, including salamanders, are considerably less prevalent. To determine whether glucocorticoids regulate salamander immunity, we employed the eastern newt species, Notophthalmus viridescens. The first step in our procedure was to quantify the dose needed to elevate corticosterone (CORT, the primary glucocorticoid in amphibians) to levels observed in physiological conditions. Treatment with CORT or a control oil vehicle was then followed by measurement of immunity in newts, encompassing neutrophil lymphocyte ratios, plasma bacterial killing ability (BKA), skin microbiome, splenocytes, melanomacrophage centers (MMCs), and overall health.