Search Results (184)

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

Understanding how carnivores coexist is central to ecological theory and conservation. Coexistence among sympatric species arises through niche partitioning across spatial, temporal, and trophic dimensions, yet these mechanisms remain poorly explored in Central African forests where leopards (Panthera pardus) and African golden cats (Caracal aurata) act as dominant and subordinate carnivores. Using camera trap data and molecular scat analyses from two sites in northern Congo, we provided the first robust leopard density estimates for the region (i.e., semideciduous forests in Central Africa) and assessed coexistence mechanisms between the two felids across spatial, temporal, and trophic axes. Spatially explicit capture–recapture models revealed comparable leopard densities across sites (5–6 individuals/100 km²), exceeding the regional average for Central and East Africa. Spatiotemporal occupancy models indicated spatial and temporal overlap, with no evidence of predictive or reactive temporal avoidance, though fine-scale co-occurrence declined near linear forest features (i.e., main rivers and roads) where both species’ marginal occupancy was highest. Conversely, dietary analyses showed trophic segregation: leopards consumed medium- to large-sized ungulates (>20 kg), whereas golden cats relied on smaller prey (≤5 kg), identifying trophic partitioning as the main axis facilitating coexistence in this prey-rich system. Maintaining prey diversity and minimizing disturbance are key to sustaining both species and their coexistence mechanisms. Such multidimensional approaches are essential to understand intraguild interactions and anticipate community shifts under increasing pressure. 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

Feline herpesvirus type-1 (FHV-1), a double-stranded DNA virus, which is a highly infectious upper respiratory tract infection of felids, particularly in kittens. Droplet digital PCR (ddPCR) provides an absolute quantification method with high sensitivity and accuracy. This study aimed to develop a highly sensitive and accurate ddPCR assay for the detection of FHV-1. We designed primers and a probe targeting the FHV-1 glycoprotein D (gD) gene and evaluated the assay’s limit of detection (LOD), sensitivity, repeatability, and specificity in comparison to quantitative real-time PCR (qPCR). The developed ddPCR assay demonstrated a strong linear dynamic range (R² ≥ 0.99) and an exceptionally low LOD of 0.18 copies/μL, which was significantly more sensitive than the method qPCR (LOD ~10 copies/μL). Additionally, the assay exhibited high specificity with no cross-reactivity against other common feline pathogens (feline calicivirus, FCV; feline panleukopenia virus, FPV; feline infectious peritonitis virus, FIPV; Bordetella bronchiseptica and Chlamydia felis) and displayed outstanding repeatability (inter-run CV < 1.35). When applied to 118 clinical samples, the ddPCR assay achieved a significantly higher positive detection rate (27.4%) compared to qPCR (14.8%). In conclusion, we have successfully established a reliable ddPCR assay for the absolute quantification of FHV-1, providing a superior tool for laboratory diagnosis and research. 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

New postcranial material of Panthera gombaszoegensis, a large pantherine felid, is analyzed from the English site of Corton (early Middle Pleistocene, possibly 0.7–0.6 mya) and the Polish site of Rogóżka Cave (0.45–0.35 mya). Both records are attributable to Panthera gombaszoegensis gombaszoegensis. This robust chronosubspecies is characteristic of the late Early and Middle Pleistocene, ca. last 1.5 mya. Both findings contribute valuable data on the knowledge of the species. The most likely factors that contributed to the extinction of P. gombaszoegensis were intraspecific competition with African newcomers, such as P. s. fossilis and C. crocuta, combined with climatic fluctuations and shifts in prey availability. 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

The filarioid nematode Dirofilaria immitis is the causative agent of heartworm disease, a major parasitic infection of canids, felids and occasionally humans. Current prevention relies on macrocyclic lactone-based chemoprophylaxis, but the emergence of drug resistance highlights the need for new intervention strategies. Here, we applied a machine learning (ML)-based framework to predict and prioritise essential genes in D. immitis in silico, using genomic, transcriptomic and functional datasets from the model organisms Caenorhabditis elegans and Drosophila melanogaster. With a curated set of 26 predictive features, we trained and evaluated multiple ML models and, using a defined threshold, we predicted 406 ‘high-priority’ essential genes. These genes showed strong transcriptional activity across developmental stages and were inferred to be enriched in pathways related to ribosome biogenesis, translation, RNA processing and signalling, underscoring their potential as anthelmintic targets. Transcriptomic analyses suggested that these genes are associated with key reproductive and neural tissues, while chromosomal mapping revealed a relatively even genomic distribution, in contrast to patterns observed in C. elegans and Dr. melanogaster. In addition, initial evidence suggested structural variation in the X chromosome compared with a recently published D. immitis assembly, indicating the importance of integrating long-read sequencing with high-throughput chromosome conformation capture (Hi-C) mapping. Overall, this study reinforces the potential of ML-guided approaches for essential gene discovery in parasitic nematodes and provides a foundation for downstream validation and therapeutic target development. Full article

Background: Due to the wide host range of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), vaccination has been recommended for susceptible species in zoological collections, particularly to protect endangered species. The Zoetis^® Experimental Mink Coronavirus Vaccine (Subunit) was temporarily authorized in 2021–2024 for emergency use in North America for this purpose. However, there are limited data regarding its safety or efficacy in non-domestic mammals. The present study was conducted to assess the ability of this vaccine to elicit serum neutralizing titers against SARS-CoV-2 in selected animals from the Toronto Zoo (TZ) vaccinated during 2022. Methods: Serum samples were collected from 24 individuals across four families (Cervidae, Felidae, Ursidae, and Hyaenidae) and tested using a surrogate virus neutralization test (sVNT) and a plaque-reduction neutralization test (PRNT). Results: The results showed that all species developed some neutralizing titers after at least one vaccine dose, except for polar bears, which showed no seroconversion. Felids and hyenas had the highest neutralizing titers, which peaked at 3 and declined between 4 and 6 months after boost. These differences may stem from species-specific immune responses or lack of vaccination protocols tailored to individual species. Conclusions: While natural infection with SARS-CoV-2 could not be ruled out in the cohort of this study, insights from our results have the potential to inform future vaccine recommendations for non-domestic species. Furthermore, our study highlighted the value of competitive assays in assessing serological responses across a broad range of exotic species, for which reagents, such as anti-isotype antibodies, are often unavailable. Full article

Feline cytauxzoonosis is an emerging tick-borne disease in Europe. While infections have been reported in different European countries, the tick vector remains unknown. This study investigated 665 ticks collected in 2019 (n = 160), 2022 (n = 7), and 2024 (n = 498) in a Cytauxzoon spp. hotspot region in central Switzerland (62 ticks from cats; 603 ticks from vegetation). Ticks were morphologically characterized, pooled by origin and life-stage, and screened for Cytauxzoon spp. 18S rRNA by qPCR and conventional PCR, and positive samples confirmed by sequencing. All ticks belonged to Ixodes ricinus (50 males, 83 females, 532 nymphs). Four tick pools from 2019 tested Cytauxzoon spp. positive: one pool of 3 non-engorged male ticks from two cats and three pools of 5–6 nymphs each from vegetation. All ticks collected in 2022 and 2024 tested negative. Amplification of the almost full-length (1535 bp, one pool) or partial (140–219 bp, three pools) 18S rRNA gene revealed a sequence identity of 98.6–100% with Cytauxzoon spp. previously detected in cats from this area. The detection of Cytauxzoon spp. in questing I. ricinus nymphs suggests a potential role of this tick species in the parasites’ transmission cycle in Central Europe and raises the possibility of transstadial or potentially transovarial transmission. Mitochondrial gene sequencing was unsuccessful, but the detected Cytauxzoon spp. likely represent Cytauxzoon europaeus. Discrepancies between qPCR and conventional PCR results point to possible amplification of tick endosymbionts, highlighting the importance of confirmatory sequencing, particularly when testing tick-derived DNA. Thus, the 18S rRNA qPCR assay used appears suboptimal for screening tick samples, as its specificity in this matrix was limited. In conclusion, this is the first report of Cytauxzoon spp. in questing I. ricinus ticks in Europe. Our findings underscore the need for further research to confirm vector competence and clarify transmission dynamics. Full article

Anelloviruses have a broad mammalian host range, including Torque teno felis virus (FcTTV), a felid-associated member that remains undercharacterized. This is the first comprehensive study of FcTTV in domestic cats in Central Asia. We analyzed blood samples from 206 domestic cats from the large city of Astana, Kazakhstan, collected in 2023–2024. Using nested PCR we identified 63 FcTTV-positive samples (30.6% prevalence), and the sequences were compared to global reference strains. Potential demographic associations (sex and age) were assessed. The study revealed an overall FcTTV prevalence of 30.6%. Infection rates showed no significant sex-related differences: ages varied 4–168 months. ORF1 sequencing revealed multiple FcTTV variants in 27% of samples, with no demographic links. Phylogenetic analysis revealed distinct patterns at both nucleotide and amino acid levels: 3 groups of nucleotide sequences (max divergence 21.68%; intra-cluster 5.15–6.8%), and 3 clusters of amino acid sequences (max divergence 16.81%; intra-cluster 2.82–6.68%). Deletions were found in ORF1 in some variants. Global phylogeny aligned clusters with Asian/European strains (90–98% identity), confirming FcTTV1 affiliation and inter-regional transmission. Our study of FcTTV in Kazakhstan reveals moderate virus prevalence with considerable genetic diversity across viral strains and frequent co-infections with multiple variants. Full article

As apex predators, felids (Felidae) face unresolved phylogenetic controversies due to their recent rapid speciation and remarkable morphological conservatism. Previous studies, often relying on a limited number of genetic markers, were constrained by insufficient data and conflicting phylogenetic signals, leaving these disputes unresolved. Therefore, establishing a robust phylogenetic framework based on larger-scale genomic data is crucial. This study integrated complete mitogenomes from 37 species representing all major felid genera to characterize genomic diversity, selection pressures, and phylogenetic relationships. Results revealed conserved gene content and arrangement patterns but significant intergenic variation in nucleotide composition, with the light-strand encoded ND6 exhibiting pronounced strand-specific bias. Nucleotide diversity was highest in ND4L (Pi = 0.132) and ATP6 (Pi = 0.131), suggesting their utility as novel markers for species delimitation and population studies. Selection pressure analysis indicated strong purifying selection on cytochrome oxidase subunits (e.g., COX1 Ka/Ks = 0.00327) but relaxed constraints on ATP8 (Ka/Ks = 0.12304). Phylogenies reconstructed from the complete 13PCGs + 2rRNAs dataset (showing high congruence between maximum likelihood and Bayesian methods) clearly delineated Felidae into two primary clades (Pantherinae and Felinae), confirming monophyly of all genera and positioning Neofelis nebulosa as the basal lineage within Pantherinae. Crucially, exclusion of ND6 (12PCGs + 2rRNAs) yielded topologies congruent with the complete 13PCGs + 2rRNAs dataset, whereas single-gene or limited multi-gene datasets produced inconsistent trees (particularly at genus-level nodes). This demonstrates that near-complete mitogenomic data (≥12PCGs + 2rRNAs) are essential for reconstructing robust felid phylogenetic frameworks. Our study provides insights into carnivoran mitogenome evolution. 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