Amphibian immune memory, for the most part, does not persist beyond metamorphosis, which leads to diverse immune response complexities at various life stages. To determine whether host immune system development impacts the interplay of co-infecting parasites, we simultaneously exposed Cuban treefrogs (Osteopilus septentrionalis) to a fungus (Batrachochytrium dendrobatidis, Bd) and a nematode (Aplectana hamatospicula) during the tadpole, metamorphic, and post-metamorphic stages of their life cycle. The metrics of host immunity, host health, and parasite abundance were determined by our team. We hypothesized that co-infecting parasites would interact favorably, given the significant energetic demands of the diverse immune responses mobilized by the host to combat these infectious agents, which would limit simultaneous activation. Our investigation revealed ontogenetic distinctions in IgY levels and cellular immunity, but did not uncover any evidence supporting the idea that metamorphic frogs are more immunosuppressed than their tadpole counterparts. Likewise, there was minimal evidence that these parasites supported one another, and no evidence that an infection of A. hamatospicula affected the immune system or health of the host. Despite its immunosuppressive nature, Bd notably reduced the immune capabilities of metamorphic frogs. Bd infection proved less manageable in metamorphic frogs compared to other life stages, resulting in both diminished resistance and tolerance. Immune system fluctuations, as indicated by these findings, led to changes in how the host reacted to parasite exposures throughout development. This theme issue, 'Amphibian immunity stress, disease and ecoimmunology,' features this article.
The escalating threat of emerging diseases highlights the urgent requirement to identify and unravel novel prophylactic mechanisms within vertebrate hosts. Through prophylaxis, inducing resistance to emerging pathogens is an ideal management strategy, which may significantly impact both the pathogen and its associated host microbiome. Despite the host microbiome's crucial contribution to immunity, the impact of prophylactic inoculation on this complex system is yet to be fully elucidated. This research investigates the effects of prophylactic interventions on the microbial community composition of the host, particularly highlighting the selection of anti-pathogenic organisms that augment the host's acquired immunity. We focus on a model host-fungal disease system, exemplified by amphibian chytridiomycosis. Against the fungal pathogen Batrachochytrium dendrobatidis (Bd), a Bd metabolite-based prophylactic was administered to larval Pseudacris regilla. Significant increases in prophylactic concentration and duration of exposure were associated with a substantial rise in the proportion of putatively Bd-inhibiting host-associated bacterial taxa, indicating a protective prophylactic-induced shift towards antagonistic microbiome members. Consistent with the adaptive microbiome hypothesis, our results demonstrate that exposure to a pathogen leads to microbiome modifications that enhance the microbiome's capacity to handle future pathogen exposures. Our investigation explores the temporal intricacies of microbiome memory and how prophylactic interventions shape microbiomes, ultimately influencing the efficacy of prophylaxis. The theme issue 'Amphibian immunity stress, disease and ecoimmunology' encompasses this article.
Vertebrate immune responses are subject to modulation by testosterone (T), affecting immune function with both immunostimulatory and immunosuppressive properties. We studied the correlation between plasma testosterone (T) and corticosterone (CORT) levels and immune responses (bacterial killing ability and neutrophil-to-lymphocyte ratio) in male Rhinella icterica toads, within and outside their reproductive season. Steroids displayed a positive association with immune traits, particularly in toads undergoing reproduction, where elevated levels of T, CORT, and BKA were evident. Transdermal T exposure in captive toads was correlated with changes in T, CORT, blood phagocytosis, BKA, and NLR levels, which were also investigated. Toads were treated with T (1, 10, or 100 grams) or sesame oil (vehicle) for a duration of eight days. Animals underwent blood draws on days one and eight of the treatment protocol. The administration of T-treatment resulted in increased plasma T levels on both the first and last days, and each dose of T on the final day was accompanied by an increase in BKA, with a positive correlation between T and BKA levels being apparent. On the final day, all T-treated and vehicle groups exhibited elevated plasma CORT, NLR, and phagocytosis levels. A positive correlation was found between T and immune characteristics in both field and captive R. icterica males, coupled with T-induced improvements in BKA, indicating an immunoenhancing function of T. Part of a themed collection on 'Amphibian immunity stress, disease, and ecoimmunology', this article appears.
Global climate changes and the spread of infectious diseases are causing a precipitous drop in amphibian populations across the globe. Among the primary causes of amphibian population decline are infectious diseases such as ranavirosis and chytridiomycosis, ailments that have recently received heightened attention. Although some amphibian populations are dwindling toward extinction, others exhibit disease resistance. Although the host's immune system is crucial in defending against illnesses, the immune responses specific to amphibians and their interactions with pathogens remain enigmatic. Temperature and rainfall variations directly affect amphibians, which are ectothermic, altering their stress-related physiological processes, including the functioning of their immune systems and the physiology of pathogens associated with diseases. Understanding amphibian immunity necessitates consideration of the interconnectedness of stress, disease, and ecoimmunology. The ontogeny of the amphibian immune system, encompassing crucial innate and adaptive immune functions, and the resultant impact on resistance to diseases, are the focus of this issue. Concurrently, the papers in this publication offer a comprehensive insight into the workings of the amphibian immune system, focusing on the impact of stress on immune-endocrine system interactions. The body of research presented within reveals valuable insights into the mechanisms governing disease outcomes in natural populations, especially within the context of fluctuating environmental conditions. Forecasting effective conservation strategies for amphibian populations could ultimately be aided by these findings. This piece contributes to the larger theme of 'Amphibian immunity stress, disease and ecoimmunology'.
Amphibians represent a crucial link in the evolutionary chain, connecting mammals to more ancient, jawed vertebrates. Currently, various ailments affect amphibian species, and understanding their immune systems holds importance exceeding their value as research models. The immune system found in the African clawed frog, Xenopus laevis, maintains a high degree of conservation relative to those of mammals. The adaptive and innate immune systems, despite their distinct roles, share structural similarities, evident in the existence of B cells, T cells, and specialized innate-like T cells. The utilization of *Xenopus laevis* tadpoles in research is beneficial to the study of the immune system during its early developmental stages. Tadpoles' innate immune responses, involving pre-configured or innate-like T cells, are their primary defense mechanisms until the point of metamorphosis. This review details the current understanding of the innate and adaptive immune systems in X. laevis, encompassing lymphoid organs, and comparing/contrasting these systems with other amphibian immune responses. biliary biomarkers Furthermore, an account of how the amphibian immune system handles viral, bacterial, and fungal invasions will be provided. The 'Amphibian immunity stress, disease and ecoimmunology' theme issue features this article.
Resource variability in food sources frequently leads to considerable and often dramatic shifts in the condition of dependent animals. Tunicamycin ic50 Lowering body weight can disturb the established patterns of energy distribution, causing stress and thereby affecting the proper functioning of the immune system. This study explored correlations between alterations in the body mass of captive cane toads (Rhinella marina), their circulating white blood cell counts, and their performance in immune function assessments. Within the three-month period of weight loss, captive toads experienced increased levels of monocytes and heterophils, with a corresponding reduction in eosinophils. There was no discernible link between alterations in mass and basophil and lymphocyte levels. The observed higher heterophil levels, coupled with stable lymphocyte counts in individuals who lost mass, resulted in a proportionally elevated heterophil-to-lymphocyte ratio, somewhat mirroring a stress response. The enhanced phagocytic capacity within the whole blood of toads exhibiting weight loss was attributed to a rise in circulating phagocytic cells. Kampo medicine Mass change exhibited no correlation with other immune performance metrics. Invasive species encountering novel environments face substantial seasonal food scarcity, a stark contrast to the consistent resources available in their native ranges, as these results demonstrate. For individuals subjected to energy restrictions, a shift in immune function might occur, leaning towards more economical and generalized methods of pathogen neutralization. This theme issue, 'Amphibian immunity stress, disease and ecoimmunology,' includes this article.
Animal defenses against infection are facilitated by two independent, yet complementary, strategies, tolerance and resistance. Whereas resistance describes the ability to lessen the intensity of an infection, tolerance indicates the capacity of an animal to curtail the detrimental consequences stemming from that infection. Where tolerance is a crucial defensive mechanism, especially in the context of highly prevalent, persistent, or endemic infections where traditional resistance mechanisms are less effective or have evolved stable resistance, mitigation strategies are limited.