Amphibian immunity often fails to carry over most immune memory after the metamorphosis process, causing variable immune response complexities across life stages. Simultaneously introducing a fungus (Batrachochytrium dendrobatidis, Bd) and a nematode (Aplectana hamatospicula) into Cuban treefrogs (Osteopilus septentrionalis) during their tadpole, metamorphic, and post-metamorphic life stages allowed us to investigate whether the ontogeny of host immunity drives interactions between co-infecting parasites. Metrics of host immunity, health status, and parasite density were measured by us. We projected that co-infecting parasites would exhibit facilitative interactions, due to the considerable energetic burden imposed on the host's immune system when mounting simultaneous responses to multiple infections. We observed differences in IgY levels and cellular immunity linked to ontogenetic development, but no evidence of a greater immunosuppressive state in metamorphic frogs than in tadpoles. Moreover, scant evidence suggested these parasites collaborated with one another, and no evidence confirmed that A. hamatospicula infection altered the host's immunity or health. In contrast, Bd, being immunosuppressive, negatively affected the immune response of metamorphic frogs. Bd infection proved less manageable in metamorphic frogs compared to other life stages, resulting in both diminished resistance and tolerance. The study's findings demonstrate that modifications to the immune system resulted in varied responses of the host to parasite exposures during ontogeny. The current article contributes to the larger theme of amphibian immunity, stress, disease, and ecoimmunology.

The ascent of emerging diseases necessitates the urgent identification and study of novel strategies for protective measures against vertebrate organisms. An ideal management approach to induce resistance against emerging pathogens, using prophylaxis, may have effects on both the pathogen and its host microbiome. The host's microbiome, a crucial element in immunity, remains a subject of inquiry regarding the effects of preventative inoculation. This study examines the impact of prophylactic measures on the host microbiome's composition, concentrating on the selection of antimicrobial agents that enhance host immunity within a model host-fungal disease system, namely, amphibian chytridiomycosis. Against the fungal pathogen Batrachochytrium dendrobatidis (Bd), a Bd metabolite-based prophylactic was administered to larval Pseudacris regilla. Prophylactic concentrations and exposure durations showed a strong association with significant increases in putatively Bd-inhibitory host-associated bacterial taxa, indicating a prophylactic-induced shift towards antagonistic microbiome members. Our findings are in agreement with the adaptive microbiome hypothesis, which suggests that exposure to a pathogen leads to microbiome changes, optimizing the microbiome's response to future pathogen exposures. Our research advances knowledge of the temporal evolution of microbiome memory, focusing on the contribution of prophylaxis-driven alterations in microbial composition to overall prophylaxis success. The theme issue 'Amphibian immunity stress, disease and ecoimmunology' encompasses this article.

In several vertebrates, testosterone (T) plays a role in immune function, manifesting both immunostimulatory and immunosuppressive impacts. Plasma levels of testosterone (T) and corticosterone (CORT) were correlated with immune parameters (bacterial killing ability and neutrophil-to-lymphocyte ratio), and these relationships were assessed in free-ranging male Rhinella icterica toads, across reproductive and non-reproductive phases. Steroids displayed a positive association with immune traits, particularly in toads undergoing reproduction, where elevated levels of T, CORT, and BKA were evident. Our investigation included the transdermal administration of T to captive toads, analyzing the resulting changes in T, CORT, blood phagocytosis, BKA, and NLR in the toads. For eight successive days, toads were given T (1, 10, or 100 grams) or sesame oil (the vehicle). Treatment subjects were bled on the initial and eighth day of the treatment regimen. On the first and last days of T-treatment, an increase in plasma T was noted, while following all T dosages on the final day, BKA levels also rose, exhibiting a positive correlation between T and BKA. All T-treated and vehicle-administered groups displayed a rise in plasma CORT, NLR, and phagocytosis on the last day of the study. Across both field and captive studies of R. icterica males, a positive link was evident between T and immune traits. T's augmentation of BKA underscores the immunoenhancing effect of T. The theme issue 'Amphibian immunity stress, disease and ecoimmunology' features this specific article.

Amphibian populations around the world are in a state of decline, with the primary contributors being global climate change and infectious disease outbreaks. Infectious ailments, including ranavirosis and chytridiomycosis, are key contributors to amphibian population declines, a phenomenon that has recently garnered significant concern. Some amphibian populations are tragically driven to extinction, while others prove resistant to illness. 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. The ectothermic nature of amphibians makes them highly sensitive to changes in temperature and rainfall, factors that significantly influence their stress responses, affecting physiological processes like immunity and the pathogens associated with diseases. The interplay of stress, disease, and ecoimmunology contexts is indispensable for a more thorough comprehension of amphibian immunity. 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. The papers of this issue, in addition, offer a comprehensive view of the amphibian immune system, indicating how stress factors influence the intricate immune-endocrine mechanisms. Insights into the disease mechanisms influencing natural populations, as detailed in this research, can be valuable, particularly with evolving environmental contexts. The ability to forecast effective conservation strategies for amphibian populations may ultimately be enhanced by these discoveries. Within the thematic focus of 'Amphibian immunity stress, disease and ecoimmunology', this article is presented.

Amphibians occupy a key evolutionary position bridging the gap between the mammalian line and older, jawed vertebrates. Amphibians are currently facing numerous diseases, and understanding their immune systems has importance that transcends their role as models for scientific research. The African clawed frog, Xenopus laevis, possesses an immune system that is remarkably similar to that found in mammals, demonstrating high conservation. Both the adaptive and innate immune responses exhibit overlapping features, a prominent example being the presence of B cells, T cells, and 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. Predominantly, tadpoles utilize innate immune mechanisms, including predetermined or innate-like T cells, for immunity until after their metamorphosis. Within this review, we delineate the current knowledge on the innate and adaptive immune responses of X. laevis, including its lymphoid organs, and highlight similarities and divergences compared to other amphibian immune systems. personalised mediations Moreover, we will give a detailed description of how the amphibian immune system manages its defense against assaults by viruses, bacteria, and fungi. The 'Amphibian immunity, stress, disease, and ecoimmunology' themed issue contains this article as a constituent part.

Animals whose food sources are inconsistent may experience substantial variations in their body condition. intravaginal microbiota Decreased body mass can lead to disruptions in the way energy is distributed, resulting in stress and ultimately impacting the effectiveness of the immune system. This study examined the link between modifications in the body weight of captive cane toads (Rhinella marina), the levels of their circulating white blood cells, and their performance in immune assays. Captive toads which shed weight over three months displayed a rise in monocytes and heterophils, concomitant with a fall in eosinophils. Basophil and lymphocyte concentrations held no bearing on the observed shifts in mass. 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. Owing to increased circulating phagocytic cell levels, the phagocytic performance of whole blood was stronger in toads that had lost weight. LYN-1604 price Mass modification had no bearing on other indicators of immune system performance. These findings reveal the difficulties invasive species encounter when their range extends to new environments, where seasonal variations in food resources drastically differ from those in their native habitat. Individuals who are experiencing energy limitations may alter their immune functions to utilize more economical and generalized strategies for battling pathogens. Encompassed within the broader thematic issue of 'Amphibian immunity stress, disease and ecoimmunology,' this article is included.

Two interwoven safeguards, tolerance and resistance, are intrinsic to animal defense mechanisms against infection. Resistance is the capacity to lessen the severity of an infection, whereas tolerance represents the ability of an animal to curtail the harmful 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.