Search Results (82)

Oocysts of Toxoplasma gondii exhibit remarkable resistance to environmental stressors and most conventional disinfectants. Despite its ability to infect a wide variety of host species, sexual reproduction and oocyst formation occur exclusively within felid definitive hosts. Despite the epidemiological significance of oocyst-mediated transmission, the molecular mechanisms governing oocyst production and sporulation remain incompletely understood. Glutaredoxin, serving as a central regulator of cellular redox homeostasis and multiple vital cellular processes in cells, is a potential regulator for oocyst sporulation. Here, we investigated the role of TGME49_227100 (glutaredoxin 5, Grx5) in the T. gondii Pru strain-a type II strain capable of oocyst formation, with a particular focus on its functions during oocyst formation and sporulation. We found that Grx5-knockout tachyzoites exhibited no defects in growth or virulence. Neither in vitro nor in vivo tachyzoite-to-bradyzoite differentiation was affected compared to wild-type parasites. Notably, Grx5 deletion significantly reduced oocyst production in cats by approximately 70%. Additionally, the collected oocysts showed a 50% decrease in sporulation rate. These results indicate that Grx5 plays a predominant role within feline host and the external environmental stage of sporulation, which of these is likely to provide a crucial molecular target for developing a transmission-blocking vaccine. Full article

Understanding antimicrobial resistance (AMR) within a One Health framework requires examining how human–animal–environment interactions shape bacterial populations, and captive wildlife offers a unique context to explore these dynamics. This study aimed to characterise the phenotypic resistance and virulence profiles of Escherichia coli isolated from faecal samples of captive non-domestic felids housed in a wildlife sanctuary in the United Kingdom and evaluate the influence of captive conditions in E. coli traits. A total of 41 faecal samples were collected from 36 animals representing 11 non-domestic felid species, from which it was possible to obtain 108 E. coli isolates identified using IMViC testing. The isolates were characterised regarding their susceptibility to 12 antibiotics by disc diffusion and screened for the phenotypic expression of six virulence factors, including protease, DNase, gelatinase, lecithinase, haemolysins, and biofilm formation. The highest resistance rates were observed for tetracycline (19.4%) and ampicillin (10.2%), while isolates presented complete susceptibility regarding half of the tested antibiotics. Also, 9.3% of the isolates presented a multidrug-resistant profile. Biofilm formation was the only virulence factor expressed by the isolates under study (8.3%). Significant associations were detected between resistance outcomes and levels of human proximity and enclosure type. These findings suggest that captivity-related factors may influence AMR profiles in wild felids and highlight the importance of continued AMR surveillance and appropriate management practices to reduce selective pressures in captive wildlife. Full article

Highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b viruses spread efficiently via migratory wild birds and increasingly infect mammals. The leopard cat (Prionailurus bengalensis) is an endangered mesopredator in South Korea that frequents wetland–forest ecotones and overlaps with wild waterbirds, placing it at risk of exposure. We describe a fatal HPAI H5N1 infection in a free-ranging leopard cat detected through national wildlife surveillance during a period of widespread H5N1 activity in wild birds along the East Asian–Australasian Flyway. The animal showed acute neurological and respiratory signs and died shortly after rescue. H5 viral RNA was detected by RT-qPCR in all examined tissues, with the highest load in the brain, and infectious virus was isolated from the brain, bronchoalveolar lavage fluid, and nasal swab. Pathology revealed acute serofibrinous pneumonia, severe nonsuppurative meningoencephalitis, necrotizing vasculitis with thrombosis, and necrotizing enteritis with secondary mesenteritis. Immunohistochemistry demonstrated abundant viral antigen in nasal and olfactory epithelium, olfactory bulb, neurons, endothelial cells, and bronchial and bronchiolar epithelium, supporting combined olfactory and hematogenous dissemination. This clinicopathological description expands the spectrum of HPAI-associated lesions in felids and underscores the value of wild carnivores as bioindicators of avian influenza spillover in a One Health context. Full article

Postnatal testicular maturation in domestic cats remains poorly quantified despite its relevance for reproductive biology, veterinary practice, and the management of threatened felid species. This study aimed to characterize age-related changes in testicular structure from six to thirty-six months of age. Testes were collected from clinically healthy cats undergoing routine orchiectomy, and design-based stereology was used to estimate the volumes and densities of the main testicular components, including the seminiferous epithelium, interstitial tissue, Sertoli cells, and Leydig cells. Immunohistochemical detection of Desert Hedgehog, a developmental signaling molecule, was performed to assess interstitial maturation. Testicular volume and the absolute volumes of the seminiferous epithelium, Sertoli cells, and Leydig cells increased significantly with age, while the numerical density of Leydig cells remained stable, indicating hypertrophy rather than proliferation. Desert Hedgehog immunoreactivity declined progressively across age groups, consistent with the transition from immature to mature interstitial cells. Principal component analysis revealed a clear separation between immature and mature testes based on volumetric and density variables. These results demonstrate that feline testicular maturation follows a coordinated pattern of tubular and interstitial growth and provide quantitative reference values useful for reproductive assessment, comparative studies, and conservation programs in domestic and wild felids. Full article

Feline herpesvirus-1 (FHV-1) is taxonomically classified within the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus, and species Felid alphaherpesvirus 1. The genome of FHV-1 is 135,797 bp in length and encodes 74 proteins. Among these proteins, serine/threonine protein kinase (pK) and thymidine kinase (TK) have been identified as potential virulence factors in alphaherpesviruses, although these kinases are dispensable for viral replication. As kinases, regulating phosphorylation modification is one of their functions, while the mechanism by which phosphorylation modification affects cell physiological functions and thereby influences viral replication remains unclear. In this study, we generated pK- and TK-deficient FHV-1 mutants by CRISPR/Cas9-mediated homologous recombination. The pK-deficient virus produced significantly smaller plaques than the TK-deficient virus. The replication kinetics of the pK-deficient virus were attenuated in multistep growth compared to the TK-deficient virus. These results indicate that deletion of the pK gene markedly reduces the replicative capacity of FHV-1. We applied data-independent acquisition (DIA) quantitative proteomics to profile changes in global protein expression and phosphorylation in F81 cells upon infection with TK⁻, pK^−, and wild-type FHV-1 strain. The pK-deficient virus exhibited 3632 differentially phosphorylated proteins containing 11,936 modification sites; the TK-deficient virus showed 4529 differentially phosphorylated proteins with 19,225 phosphorylation sites. Functional characterization through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses identified significant involvement of phosphoproteins in spliceosome pathways in pK-deficient virus and ATP-dependent chromatin remodeling pathway in TK-deficient virus. Notably, several splicing regulators—including Ess-2 and CDK13, which modulate host spliceosomal function—displayed significantly reduced phosphorylation levels in pK-deficient viruses. A significant enrichment of ATP-dependent factors, such as SMARCA5 and RSF1, was observed in the TK-deficient virus. To our knowledge, this is the first investigation into the effects of FHV-1 infection on the host cell phosphoproteome. These data offer new insights into the phosphoregulatory circuits and signaling networks triggered by FHV-1 and may enhance our understanding of the FHV-1 replication mechanism. Full article

Toxoplasma gondii is a protozoan parasite with a complex life cycle that involves warm-blooded animals as intermediate hosts and felids as definitive hosts. Its epidemiology in alpine ecosystems remains poorly understood. This study presents the first long-term investigation of T. gondii exposure in wild ruminants in the Pyrenees (NE Spain), where definitive hosts are scarce. Pyrenean chamois (Rupicapra pyrenaica; n = 1045) and mouflon (Ovis aries musimon; n = 115) sera collected between 2001 and 2024 were tested (Modified Agglutination Test, ELISA-IDvet, ELISA-IDEXX) for the presence of T. gondii antibodies. Sera from 53 chamois and 27 mouflon foetuses and hearts and brains from 38 chamois and 35 mouflon foetuses were analysed for the presence of antibodies and parasite’s DNA, respectively. Moreover, heart and brain (n = 3) and faeces (n = 91) from Pyrenean wildcats (Felis silvestris) were analysed for parasite’s DNA. Seroprevalence was overall low (chamois: 5.24%; mouflon: 1.74%). In multivariate analyses performed in chamois, seroprevalence variation was mainly associated with geographic origin and the diagnostic method used, with little influence of the individual traits of sex or age. No antibodies or T. gondii DNA were detected in chamois or mouflon foetuses. However, chamois did not show a clear age-related increase in exposure to T. gondii, as would be expected if indirect horizontal transmission were the predominant route. In contrast, T. gondii DNA was detected in brain and faecal samples from wildcats, confirming their role as definitive hosts in this ecosystem. Overall, our results reinforce the hypothesis that alpine ecosystems are environments with low T. gondii oocyst contamination and that the parasite most probably relies on sylvatic cycles. These results suggest that wild ruminants, such as chamois and mouflon, could serve as effective sentinels of changes in the extent of this parasite under ongoing environmental and ecological changes. Full article

The kodkod (Leopardus guigna) is a vulnerable wild felid native to South America whose population is steadily declining. ARTs offer valuable tools for the preservation of its genetic diversity. Our study provides the first evaluation of the morphological and functional acquisition of competence in kodkod oocytes using protocols previously established for domestic cat oocytes. In total, 29 iCOCs were obtained from the ovaries of a single juvenile female kodkod that deceased in a wildlife rehabilitation center. Based on morphological criteria, 13 oocytes were selected for IVM and subsequently evaluated for developmental competence following parthenogenetic activation (PA) and in vitro culture (IVC). Kodkod oocytes appear to be smaller and have a thinner zona pellucida compared to those of domestic cat oocytes. These kodkod oocytes demonstrated the ability to mature in vitro, underwent cleavage, and developed in vitro to the blastocyst stage by day 9. Here, we show that protocols to manage domestic cat oocytes and embryos can support kodkod in vitro oocyte maturation, activation, and in vitro embryo development. However, given that the results were obtained from a single individual and the protocols were tested in a limited number of oocytes, further studies involving additional specimens are essential to validate these observations and refine ART applications for kodkod conservation. Full article

Background/Objectives: Toxoplasma gondii is a major cause of zoonotic infections in both humans and animals, resulting in significant mortality in susceptible species, such as New World primates and marsupials. Toxoplasmosis is particularly concerning in zoos and wildlife reserves, where outbreaks threaten conservation efforts for endangered species. In the absence of a commercially available vaccine against toxoplasmosis for humans and captive wild animals, current prevention strategies are limited to restricting the access of cats to enclosures, controlling rodent populations, and maintaining strict food hygiene. Recent research has shown promising results with an intranasal vaccine (VXN-Toxo) composed of maltodextrin nanoparticles conjugated with a purified, inactivated T. gondii parasite. This experimental vaccine does not pose a risk of causing disease and offers advantages such as better stability compared with live pathogen-based vaccines. Methods: This study presents a large-scale evaluation of the effect of VXN-Toxo administered to captive wildlife across 20 zoos in Europe and the Americas between 2017 and 2025. Seven hundred and eighty-four animals, representing over 58 species (including primates, marsupials, rodents, and felids), were vaccinated without any adverse events reported. Results: Retrospective mortality data from 20 participating zoological institutions revealed an overall 96.7% reduction—and, in many cases, a complete elimination—of toxoplasmosis-associated deaths post vaccination. Conclusions: These results demonstrate, for the first time, consistent and broad-spectrum protection against T. gondii of different strains in a wide array of captive wildlife species. This universal vaccine represents a promising tool for toxoplasmosis prevention in zoological collections, with significant implications for animal health and conservation strategies. Full article

Although trap-neuter-return (TNR) is a popular method for managing free-roaming domestic cat populations, a common criticism is that sterilization fails to mitigate the public health risks posed by free-roaming cats. One of these risks is the environmental contamination of Toxoplasma gondii, a parasite that can be spread in the feces of actively infected felids (both domestic and wild). In healthy humans, toxoplasmosis tends to be mild or asymptomatic; however, the disease can have severe consequences (e.g., for pregnant women) and even be fatal in immunocompromised individuals. Previous research has examined the extent to which free-roaming domestic cats might contaminate sites frequented by young children (e.g., schools and parks). However, the model used included several assumptions that are not reflective of sterilized cats in an urban setting (e.g., smaller home range). By properly accounting for several key factors (e.g., reproductive status, home range), our modeling revealed considerably lower rates of potential incursions by sterilized free-roaming cats than those reported previously. More importantly, our results show that sterilization contributes to a considerable reduction in the risk of environmental contamination; TNR therefore appears to be a valuable harm reduction strategy in mitigating the risks of T. gondii infection. Full article

The metastrongyloid nematodes Angiostrongylus vasorum, Aelurostrongylus abstrusus, and Crenosoma vulpis can cause severe cardiopulmonary and respiratory symptoms in domestic dogs and cats and free-ranging canids and felids (e.g., foxes, wolves, wild cats, lynxes). Recent data on the prevalence of A. vasorum infections in dogs and foxes and on the prevalence of Ae. abstrusus and Troglostrongylus brevior infections in free-ranging lynxes and wild cats revealed several endemic and hyperendemic foci in Germany. Nonetheless, long-term investigations on the prevalence of metastrongyloid larvae infecting gastropod intermediate hosts are still scarce for Germany. To fill this gap, we conducted an epidemiological survey on native slugs and snails in a selected meadow close to Obrigheim, previously identified as a hyperendemic focus for canine angiostrongylosis. To re-evaluate this location as a ‘hotspot’ of canine angiostrongylosis, terrestrial slugs and snails (n = 533) were collected in all seasons, artificially digested, and microscopically and molecularly analyzed for the presence of metastrongyloid lungworm larvae. Here, the prevalence ranged greatly between seasons. In summer, 27.46% (59/215) of gastropods were infected with metastrongyloid larvae. In fall, the prevalence dropped to 10.00% (16/160) and lowest infection rates were observed in both winter (5.65%) and spring (1.47%). In total, A. vasorum was detected in 12.01% (64/533), Crenosoma sp. in 0.94% (5/533), and Ae. abstrusus in 0.38% (2/533) of gastropod samples. Even though total A. vasorum infection levels were revealed to be considerably lower than in the prior study, this epidemiological survey in principle reconfirms Obrigheim as a stable hyperendemic focus and thereby as a location with high metastrongyloid infection risk for domestic dogs, cats, and wildlife throughout the year. These results call for continuous epidemiological studies on gastropod populations to better understand metastrongyloid lungworm spread and infection dynamics over the years. Full article

Rodents are among the most abundant and ecologically diverse mammals, playing key roles in terrestrial ecosystems and often serving as reservoirs for various zoonotic and wildlife pathogens. Among these are protozoan parasites of the genera Hepatozoon and Theileria, which are known to infect a wide range of domestic and wild animals worldwide. However, little is known about the diversity and phylogenetic relationships of these hemoprotozoans in rodent hosts, particularly in the Arabian Peninsula. The aim of this study was to investigate the presence and genetic diversity of Hepatozoon sp. and Theileria sp. in rodents from different regions of Saudi Arabia and to determine potential reservoir species. A total of 111 rodents were captured and identified by molecular analysis of the mitochondrial 16S rRNA gene. Screening for parasites was performed using PCR amplification of the 18S rRNA gene, followed by sequencing, haplotype analysis, and phylogenetic reconstruction using both maximum likelihood and Bayesian inference methods. Our results represent the first molecular detection of Hepatozoon sp. in Arvicanthis niloticus (31.3%), Gerbillus cheesmani (26.5%), G. nanus (28.5%), and Rattus rattus (32.0%) and of Theileria sp. in G. nanus (21.5%) and R. rattus (24.0%) in Saudi Arabia. Haplotype network analysis revealed seven distinct Hepatozoon haplotypes forming a star-like cluster, suggesting host specificity. One divergent haplotype (Hap_2), 19 mutation steps apart, may represent a novel lineage. Phylogenetic analyses grouped Saudi Hepatozoon sequences with those from reptiles and rodents, forming a clade distinct from sequences isolated from felids and canids. In contrast, Theileria sequences showed low diversity, clustering with a single widespread haplotype found in rodents and ruminants in several regions. These findings significantly expand the current knowledge on rodent-associated apicomplexan parasites in Saudi Arabia, revealing novel Hepatozoon haplotypes and highlighting the role of rodents in the transmission of reptile-associated Hepatozoon spp. This study provides basic molecular data crucial to understanding host–parasite relationships and the potential public and veterinary health implications of these parasites in arid ecosystems. Full article

The gut microbiome plays a crucial role in the health and physiology of tigers (Panthera tigris), influencing digestion, immune function, and overall well-being. While numerous studies have characterized the gut microbiota of domestic carnivores and some wild felids, comparative analyses across different tiger subspecies under varying environmental contexts remain limited. In this exploratory study, we investigated the gut microbiome diversity and composition of 15 captive tigers, including both Siberian (P. tigris altaica) and Bengal (P. tigris tigris) subspecies, housed in two different regions in Korea. Using 16S rRNA gene sequencing of fecal samples, we analyzed microbial diversity across multiple taxonomic levels. Preliminary analyses revealed significant differences in microbial composition between geographic locations, whereas sex-based differences appeared minimal. Alpha and beta diversity metrics demonstrated substantial inter-individual variability, likely influenced by regional and environmental factors. Given the small sample size and the confounding between subspecies and housing location, the findings should be regarded as preliminary and not generalized beyond this specific cohort. Nevertheless, these insights highlight the potential utility of gut microbiome profiling for health monitoring and management in captive-tiger populations. Future research incorporating larger, more diverse cohorts will be essential to validate these trends and clarify the roles of diet, health status, and enrichment in shaping the gut microbiota. Full article

Piroplasmids (Babesia spp., Rangelia spp., Theileria spp., Cytauxzoon spp.) are tick-borne apicomplexan protozoa that infect, depending on the species, erythrocytes and leucocytes in a wide variety of mammals and birds. The genera Bartonella and Borrelia include vector-borne bacteria that can infect and cause disease in both animals and humans. Detection of hemotropic bacteria and piroplasmids in wild animals is often challenging due to low bacteremia or parasitemia. Digital (d)PCR has proven to be an effective modality for the detection and quantification of DNA of hemotropic pathogens with low parasitemia. This study compared dPCR results from 366 biological samples from seven different Brazilian wild animal groups (5 Xenarthra species, 5 deer species, 3 felid species, 1 canid species, 3 rodent species, 1 bat species, 1 tapir species, and 12 bird species) to two other molecular diagnostic techniques: quantitative real-time (qPCR) and nested (nPCR). For this study, DNA extracted from wild animal blood and spleen samples were subjected to a multiplex dPCR assay for piroplasmids, Bartonella spp., and Borrelia spp. For comparison, the same primers and probes for each agent were used in qPCR assays. Additionally, an nPCR based on the 18S rRNA gene for piroplasmids was performed. The proportions of positive results obtained using dPCR were 85.5% for piroplasmids, 33.6% for Bartonella spp., and 16.7% for Borrelia spp. For all tested agents, dPCR proved to be the technique with the highest sensitivity, making it a useful tool for screening vector-borne agents in biological samples from wild animals with low parasitemia. Full article

Sperm cryopreservation and assisted reproduction are powerful tools for the conservation of endangered species. The domestic cat has been a useful model for studying wild felid reproductive biology due to the limited availability of endangered individuals for experimental research. Here, we investigate the effect of cryodiluents (TEST vs. Biladyl) and the timing of glycerol addition (before vs. after refrigeration, in one vs. three steps, respectively) on post-thaw sperm quality (motility, acrosome integrity) and their subsequent in vitro fertilization (IVF) ability with homologous oocytes. The results showed no statistically significant differences in sperm traits when samples were cryopreserved in TEST or Biladyl, or when glycerol was added in one or three steps. Motile sperm and intact acrosomes were significantly correlated before and after cryopreservation, indicating consistent relationships in fresh and thawed samples. The use of Biladyl significantly reduced IVF rates after cryopreservation compared to fresh sperm. Cryopreservation in TEST led to IVF rates that were not significantly different from those of fresh sperm. Using swim-up after thawing, or adding 1 mM pentoxifylline, did not enhance IVF results. Overall, a TEST cryodiluent with 4% glycerol added in one step is a reliable option for preserving epididymal cat spermatozoa. Full article

The surveillance of wildlife viromes is essential for identifying zoonotic threats within the One Health framework. This study analyzed rectal and oral swabs from 88 individuals representing 13 species as felids, wild rodents, marsupials and non-human primates in Southern Brazil using metagenomic sequencing. Akodon montensis (n = 15 individuals) and Coendou spinosus (n = 4) harbored Chikungunya virus (ChikV, Togaviridae), marking its first detection in these hosts. Molossus molossus (n = 17) presented Coronaviridae and Orthoherpesviridae, while Eptesicus furinalis (n = 1) also carried Coronaviridae. A broad virome diversity, including Togaviridae and Adenoviridae members, was identified in Didelphis albiventris (n = 43), with significant relevance to human health. Additional species, such as Callithrix jacchus (n = 1), Leopardus guttulus (n = 1), Myocastor coypus (n = 1), Monodelphis iheringi (n = 1), Thaptomys nigrita (n = 1), Sooretamys angouya (n = 1), Brucepattersonius iheringi (n = 1), and Lasiurus blossevillii (n = 1), contributed to insights into viral reservoirs. These results underscore the importance of virome studies in regions harboring high biodiversity, emphasizing genomic surveillance as a vital tool for monitoring zoonotic viruses and safeguarding global health. Full article