Exploring FeLV-Gag-Based VLPs as a New Vaccine Platform-Analysis of Production and Immunogenicity.

Feline leukemia virus (FeLV) is one of the most prevalent infectious diseases in domestic cats. Although different commercial vaccines are available, none of them provides full protection. Thus, efforts to design a more efficient vaccine are needed. Our group has successfully engineered HIV-1 Gag-based VLPs that induce a potent and functional immune response against the HIV-1 transmembrane protein gp41. Here, we propose to use this concept to generate FeLV-Gag-based VLPs as a novel vaccine strategy against this retrovirus. By analogy to our HIV-1 platform, a fragment of the FeLV transmembrane p15E protein was exposed on FeLV-Gag-based VLPs. After optimization of Gag sequences, the immunogenicity of the selected candidates was evaluated in C57BL/6 and BALB/c mice, showing strong cellular and humoral responses to Gag but failing to generate anti-p15E antibodies. Altogether, this study not only tests the versatility of the enveloped VLP-based vaccine platform but also sheds light on FeLV vaccine research.

Canine metabolomics advances.

INTRODUCTION: Canis lupus familiaris is a domestic dog and many owners consider their pets as a family member. Medical bills with dogs are overcame only by the health care received by humans. Medical care is constantly progressing, and so is veterinary care. Metabolomics is the ''omic" technique aimed to the study of metabolome, low-molecular weight molecules, through biofluids or tissue samples. And it also allows to evaluate disease diagnosis and prognosis, therapeutic evaluation and toxicological studies. OBJECTIVES: The goal of this paper is to review the current and potential applications of metabolomics in domestic dogs. METHOD: ScienceDirect, Scopus, Reaxys and PubMed were searched for papers that performed canine metabolomics in any research area. RESULTS: We analysed 38 papers, published until April 2019 in canine metabolomics approach. Metabolomic research in dogs so far can be divided into three areas: (a) Metabolomics studies in veterinary science, such as improving pet dogs health and welfare. (b) Diet, breeds and species discrimination. (c) Use of dogs as animal model in different diseases and drug development (evaluation toxicity and effect). CONCLUSIONS: The results of this review showed that interest in metabolomics is growing in veterinary research. Several canine diseases have been evaluated with some promise for potential biomarker and/or disease mechanism discovery. Because canine metabolomics is a relatively new area, the researches spread across different research areas and with few studies in each area.

Anatomical templates for tissue (re)generation and beyond.

Induced pluripotent stem cells (iPSCs) represent a valuable alternative to stem cells in regenerative medicine overcoming their ethical limitations, like embryo disruption. Takahashi and Yamanaka in 2006 reprogrammed, for the first time, mouse fibroblasts into iPSCs through the retroviral delivery of four reprogramming factors: Oct3/4, Sox2, c-Myc, and Klf4. Since then, several studies started reporting the derivation of iPSC lines from animals other than rodents for translational and veterinary medicine. Here, we review the potential of using these cells for further intriguing applications, such as "cellular agriculture." iPSCs, indeed, can be a source of in vitro, skeletal muscle tissue, namely "cultured meat," a product that improves animal welfare and encourages the consumption of healthier meat along with environmental preservation. Also, we report the potential of using iPSCs, obtained from endangered species, for therapeutic treatments for captive animals and for assisted reproductive technologies as well. This review offers a unique opportunity to explore the whole spectrum of iPSC applications from regenerative translational and veterinary medicine to the production of artificial meat and the preservation of currently endangered species.

The road less travelled: The efficacy of canine pluripotent stem cells.

The path-breaking discovery of induced pluripotent stem cells has fuelled the scientific advancements of stem cells. Nevertheless, the need to ensure the safety of stem cell therapy at translational level is still at large, prompting scientists to use animal models which are genetically and anatomically homologous to that of humans. Dogs, being genomically and physiologically more similar to humans serve as better models in mimicking human diseases as compared to rodents. The heterogeneity in canine breeds offers an excellent opportunity to comprehend the complexities of many genetic diseases, making them exceptional tools for stem cell therapies. Various canine gene therapy models have paved the foundation for strategizing therapies for humans. But a similar progress is lacking in utilizing canine stem cells for stem cell-based therapies in both dogs and humans. This review attempts to bridge the gap, by articulating the key differences in canine pluripotency pathways, based on the recent derivation of canine embryonic stem cells (cESCs) and canine induced pluripotent stem cells (ciPSCs), thereby attempting to position dog in the reprogramming landscape. The potential clinical application of canine iPSCs also offers great hope to canine patients and might lead to significant contributions in veterinary medicine.

Disciplining cattle reproduction: Veterinary reproductive science, bull infertility, and the mid-twentieth century transformation of Swedish dairy cattle breeding.

From the 1940s, reproductive physiology and livestock genetics transformed dairy cattle breeding and became, in conjunction with the new reproductive technology of artificial insemination, important drivers of agricultural modernization in most countries with significant dairying. While this is well known, we know less about the longer-term interplay between specifically veterinary interests in reproduction and the institutional development of cattle breeding. In the present paper, I therefore examine the veterinary disciplining of cattle reproduction-its constitution as a veterinary scientific discipline and the extension of veterinary control over it-in mid-twentieth century Sweden. I show how veterinary scientists derived legitimacy for their fledgling discipline by engaging with the problems of practical breeding, and that in doing so they also exercised influence over breeding's development. By making bulls' reproductive disturbances visible and framing them as hereditary, they undermined the conservative interests of commercial breeders. The development of veterinary reproductive science thereby played an important role in reshaping the culture, economy, and regulations of cattle breeding in Sweden as it shifted from a prewar regime dominated by elite breeders to a postwar regime that, ostensibly, served all dairy farmers in the country.

Metabolomic studies as a tool for determining the post-mortem interval (PMI) in stillborn calves.

BACKGROUND: Perinatal mortality may vary between herds, but the cost of deaths are always higher than value of the calf. When diagnosing the cause of a calf's death it is important to determine when it occurred, before or after calving. Metabolomics is widely used to identify many human diseases, but quite rarely applied in veterinary science. The aim of this study was to compare the metabolic profiles of calves with different times of death and those of calves born alive. Into the study, twenty one healthy controls (singleton, normal assisted calving, born alive) and 75 stillborn (SB) calves (with a gestation length of ≥260 days, SB, or dead within 6 h of birth) were enrolled. Plasma and urine from SB and control calves were investigated by proton nuclear magnetic resonance based metabolomic methods. SB calves were divided into four PMI groups. One PMI group included calves that died after calving and the other groups - three comprised in utero deaths, based on pathophysiological changes (lung inflation, autolysis in internal organs, hemoglobin imbibition in the pleura and aortic arch). Partial Least Squares - Discriminant Analysis models based on plasma metabolites were calculated, reflecting assumed data clustering. RESULTS: Twenty six metabolites in plasma and 29 in urine changed significantly with PMI according to one way analysis of variance. Half the metabolites in plasma and the majority in urine increased with PMI. Six metabolites increased simultaneously in plasma and urine: acetate, sn-glycero-3-phosphocholine (GPC), leucine, valine, creatine, and alanine. CONCLUSIONS: Post-mortem changes in calves were associated with molecular variations in blood plasma and urine, showing the greatest differences for the group in which the post-mortem pathological changes were the most advanced. The results of the study show that evaluation of calf plasma or urine may be used as a diagnostic method for the determination of the PMI. Moreover, the metabolites, which unambiguously increased or decreased, can be used as potential biomarkers of PMI.

Physiologically based modelling of the pharmacokinetics of three beta-lactam antibiotics after intra-mammary administration in dairy cows.

Understanding the pharmacokinetics of intra-mammary antibiotics is important for the prediction of drug residues in milk and for the design of optimal dosage regimens. Unfortunately, compartmental pharmacokinetic models are not valid for this unique system. A minimal physiologically based pharmacokinetic model is presented incorporating the physiology of milk secretion, drug administration at the quarter level, drug absorption and dispersion, drug retention during the inter-milking interval and episodic drug elimination at milking. The primary objective of the study was the development and exploration of a model for major factors controlling drug concentration in milk, rather than generation of rigorously predictive pharmaco-statistical models for any particular drug. This model was implemented in a two-stage approach, using published concentration data for penicillin, cefuroxime, cephapirin and desacetyl-cephapirin in milk of healthy cows. Model simulations evaluated sensitivity and developed predictions of drug residues. The model successfully predicted both drug concentrations and drug residues in milk. The postmilking residual milk volume did not adequately explain antibiotic pharmacokinetics, requiring additional considerations for drug retention. Local sensitivity analysis indicated that increasing the number of quarters treated, the dosage, or the duration of the inter-milking interval prolonged both the persistence of drug residues and the duration that antibiotic concentration exceeded typical minimum inhibitory concentrations. The model was flexible across different beta-lactam drugs as a general description of intra-mammary pharmacokinetics. This model is suitable for the design and analysis of dosage regimens, and could be applied for the prediction of withholding periods when these antibiotic preparations are used off-label. The final model indicates that explicit consideration of the milking regimen is fundamental to the design and interpretation of pharmacokinetic studies of antibiotics in bovine milk.

Australian and New Zealand Veterinary Students' Opinions on Animal Welfare and Ethical Issues Concerning Animal Use within Sport, Recreation, and Display.

Animals used for sport, recreation and display are highly visible and can divide community attitudes. The study of animal welfare and ethics (AWE) as part of veterinary education is important because it is the responsibility of veterinarians to use their scientific knowledge and skills to promote animal welfare in the context of community expectations. To explore the attitudes of veterinary students in Australia and New Zealand to AWE, a survey of the current cohort was undertaken. The survey aimed to reveal how veterinary students in Australia and New Zealand rate the importance of five selected AWE topics for Day One Competences in animals used in sport, recreation and display and to establish how veterinary students' priorities were associated with gender and stage of study. The response rate (n = 851) across the seven schools was just over 25%. Results indicated little variation on ratings for topics. The topics were ranked in the following order (most to least important): Pushing of animals to their physiologic/behavioral limits; ownership/responsibility; euthanasia; educating the public; and behavior, selection, and training for sport and recreation displays. In contrast to related studies, ratings were not associated with stage of study and there were few differences associated with gender. More females rated the pushing of animals to physiologic/behavioral limits as extremely important than did males ( p < .001). The role of veterinarians in advocating for and educating the public about the welfare of animals used in sport, recreation and display merits further discussion.

Assessing Veterinary Students' Ethical Sensitivity to Farm Animal Welfare Issues.

Ethical sensitivity has been identified as one of the four necessary components of moral action, yet little has been done to assess ethical sensitivity to animal issues in animal-related professions. The aim of this study was to develop assessment tools to measure and enhance ethical sensitivity to animal issues, and determine relationships between ethical sensitivity and moral reasoning. Of a cohort of 115 third-year veterinary students from the University of Queensland, Australia, 104 students gave permission to use their responses to written ethical sensitivity and moral judgment tests, and 51 to use their video role-plays to demonstrate ethical sensitivity to current animal farming issues. Inter-rater reliability of scoring by an expert panel was moderate to substantial for the written assessment, but only slight to moderate for the video response. In the written test, students' mean scores for recognition of animals' emotions, expression of empathy and recognition of alternative actions and their impacts improved after teaching. Scores did not increase for identification of their own emotions, moral conflicts between stakeholders, and conflicts between legal, organizational and ethical responsibilities as a professional. There was no overall relationship between ethical sensitivity and moral reasoning scores. However, high scores for reasoning using universal principles were correlated with high scores for recognition of moral conflicts between stakeholders and between legal, organizational, and ethical responsibilities as a professional. Further development of these ethical sensitivity assessment tools is encouraged to enable veterinary and animal science students to raise and address animal ethics issues and alleviate moral distress.

Mixed-method tutoring support improves learning outcomes of veterinary students in basic subjects.

BACKGROUND: Tutoring is a useful tool in the university teaching-learning binomial, although its development is impaired in large classes. Recent improvements in information and communication technologies have made tutoring possible via the Internet. The aim of this study was to evaluate the efficacy of mixed-method academic tutoring in two basic subjects in Veterinary Science studies at the University of León (Spain) to optimize the usefulness of tutoring support in the college environment. This quasi-experimental study was firstly carried out as a pilot study in a small group of tutored students of "Cytology and Histology" (CH) (47/186; 25.3%) and "Veterinary Pharmacology" (VP) (33/141; 23.4%) subjects, and was implemented in a large class of CH the next academic year (150 students) while comparing the results with those obtained in a previous tutorless course (162 students). Tutored students were given access to online questionnaires with electronic feedback on each subject. In addition to traditional tutoring carried out in both tutored and tutorless students, the pilot study included three sessions of face-to-face tutoring in order to monitor the progress of students. Its efficacy was assessed by monitoring students' examination scores and attendance as well as a satisfaction survey. RESULTS: Although the examination attendance rate in the pilot study was not significantly different between tutored and tutorless groups in both subjects, an increase for numerical scores in tutored groups was observed, with a significant higher final score in VP (p = 0.001) and in the CH practice exams (first term, p = 0.009; final, p = 0.023). Good and merit scores were also better in tutored students with significant differences in VP (p = 0.005). Students felt comfortable with the tutoring service (100% in CH; 91.7% in VP). Implementation of this additional support in CH also resulted in a significant increase of attendance at the final exam in tutored courses (87.3% versus 77.2%; p = 0.026), scaled (p = 0.001) and numerical scores (final score, p = 0.001). CONCLUSIONS: Online tutoring support, together with conventional teaching methods, may be a useful method to incorporate student-centered learning in basic subjects in Veterinary Science.

Virtual Microscopy in Histopathology Training: Changing Student Attitudes in 3 Successive Academic Years.

Several veterinary faculties have integrated virtual microscopy into their curricula in recent years to improve and refine their teaching techniques. The many advantages of this recent technology are described in the literature, including remote access and an equal and constant slide quality for all students. However, no study has analyzed the change of perception toward virtual microscopy at different time points of students' academic educations. In the present study, veterinary students in 3 academic years were asked for their perspectives and attitudes toward virtual microscopy and conventional light microscopy. Third-, fourth-, and fifth-year veterinary students filled out a questionnaire with 12 questions. The answers revealed that virtual microscopy was overall well accepted by students of all academic years. Most students even suggested that virtual microscopy be implemented more extensively as the modality for final histopathology examinations. Nevertheless, training in the use of light microscopy and associated skills was surprisingly well appreciated. Regardless of their academic year, most students considered these skills important and necessary, and they felt that light microscopy should not be completely replaced. The reasons for this view differed depending on academic year, as the perceived main disadvantage of virtual microscopy varied. Third-year students feared that they would not acquire sufficient light microscopy skills. Fifth-year students considered technical difficulties (i.e., insufficient transmission speed) to be the main disadvantage of this newer teaching modality.

Implementing the Flipped Classroom in a Veterinary Pre-clinical Science Course: Student Engagement, Performance, and Satisfaction.

There has been a recent move toward active learning pedagogies in veterinary education, with increasing use of a blended approach that incorporates both online resources and live classroom sessions. In this study, an established veterinary pre-clinical course in introductory animal health was transitioned from a traditional didactic lecture delivery mode to a flipped classroom approach with core content delivered online. This study compared the experiences of two cohorts of students who studied the same course in the different formats in consecutive years. Online learning resources included short video segments and a variety of short problems and activities. Online materials were complemented with weekly small-group case-based learning classes facilitated by academic staff. A mixed methods evaluation strategy was applied using student grades, surveys, and focus groups to compare student academic performance, satisfaction, and engagement between the two cohorts. The flipped classroom cohort achieved significantly higher grades in the written answer section of the final examination. Student satisfaction with learning resources was also higher in this cohort. However, satisfaction with other aspects of the course was largely the same for both cohorts. This study revealed some of the challenges associated with achieving adequate student preparation for class using online resources. The outcomes of this study have implications for veterinary educators considering the design and development of new online learning resources.

Career Preferences and Opinions on Animal Welfare and Ethics: A Survey of Veterinary Students in Australia and New Zealand.

Historically, the veterinary profession has understood animal welfare primarily in terms of animal health and productivity, with less recognition of animals' feelings and mental state. Veterinary students' career preferences and attitudes to animal welfare have been the focus of several international studies. As part of a survey in Australia and New Zealand, this study reports on whether veterinary students prioritize animal welfare topics or professional conduct on the first day of practice and examines links between students' career preferences and their institution, gender, and year of study. The questionnaire was designed to explore the importance that students assign to topics in animal welfare and ethics. Of the 3,320 students invited to participate in the online survey, a total of 851 students participated, representing a response rate of 25.5%. Students' preferences increased for companion-animal practice and decreased for production-animal practice as they progressed through their studies. Females ranked the importance of animal welfare topics higher than males, but the perceived importance declined for both genders in their senior years. In line with previous studies, this report highlighted two concerns: (1) the importance assigned to animal welfare declined as students progressed through their studies, and (2) males placed less importance overall on animal welfare than females. Given that veterinarians have a strong social influence on animal issues, there is an opportunity, through enhanced education in animal welfare, to improve student concern for animal welfare and in turn improve animal care and policy making by future veterinarians.

Antiviral therapy in cats progressively infected with feline leukaemia virus: lessons from a series of 18 consecutive cases from Australia.

BACKGROUND: It is doubtful that any of the treatments proposed for feline leukaemia virus (FeLV) infection are effective, despite the entity being described 60 years ago. METHODS: Eighteen pet cats with progressive FeLV infections were recruited in Australia. One or more antiviral drugs were trialled in 16 cats, while two FeLV-infected cats were not handleable and served as untreated controls. Six cats were administered RetroMAD1™ only (0.5 mg/kg orally twice daily), a commercially available recombinant chimeric protein with proposed antiretroviral activity. Three cats were administered the integrase inhibitor raltegravir only (10-15 mg/kg orally twice daily), a drug used as a component of highly effective antiretroviral therapy for human immunodeficiency virus (HIV-1) infection. Three cats were administered RetroMAD1™ and raltegravir concurrently, and four cats were administered raltegravir and the reverse transcriptase inhibitor zidovudine (AZT, 5 mg/kg orally twice daily) concurrently. FeLV RNA and p27 antigen loads were measured at two timepoints (T1-2 months and T3-5 months) during therapy and compared to baseline (pretreatment) levels, to assess the response to therapy using linear modelling. The median survival time (MST) of the cats from commencement of FeLV treatment to death was also determined and compared between treatments. RESULTS: The MST for the 16 FeLV-positive cats which received antiviral therapy was 634 days, while the MST from FeLV diagnosis to death for the two untreated control cats was 780 days. In cats treated with RetroMAD1™, FeLV viral load decreased from T0 to T1-2 months (median viral load reduced from 1339 × 106 to 705 × 106 copies/mL plasma; P = 0.012), but MST was reduced compared to cats not given RetroMAD1™ (426 days vs 1006 days; P = 0.049). Cats treated with raltegravir and AZT had no significant changes in FeLV viral load over time, but p27 antigen load was decreased from T0 to T3-5 months in cats treated with raltegravir (median p27 antigen level reduced from 50.2% to 42.7%; P = 0.005). All other results were not significantly affected by the treatment provided. Importantly, statistically significant and substantial associations were found between age at FeLV diagnosis and survival time (P = 0.046, R2 = 18.6) and between FeLV viral load at T0 and survival time (P = 0.004, R2 = 44.4). Younger cats, and cats with higher levels of pretreatment FeLV RNA, had reduced survival times. Cats treated with RetroMAD1™ were typically younger (median age 2.0 vs 8.0 years), likely explaining the observed reduction in MST. A significant association was found between FeLV viral load and p27 antigen load at T0 (P = 0.015, R2 = 32.9). CONCLUSIONS: Results from this small case series do not provide convincing support for the use of RetroMAD1™, raltegravir or AZT, alone or in combination, for the treatment of cats progressively infected with FeLV. The changes observed were biologically insignificant. Age and FeLV viral load at diagnosis are useful prognostic markers, and p27 antigen concentration can be used to predict viral load. Larger field trials should be performed examining antiretroviral therapy in FeLV-positive cats with progressive infections, preferably using three or more drugs from at least two classes, as is standard with human antiretroviral therapy. Future studies would be easier in countries with a higher prevalence of FeLV infections than Australia.

Temperature-bounded development of Dirofilaria immitis larvae restricts the geographical distribution and seasonality of its transmission: case study and decision support system for canine heartworm management in Australia.

Dirofilaria immitis is the causative agent of canine heartworm disease. We used the established heartworm development unit (HDU) principle to map the extrinsic incubation period (EIP) of D. immitis in Australia using historical weather data from 2013-2022. We found weather conditions suitable for EIP completion showed substantial seasonality and geographical variability. Whilst a considerable percentage of the Australian territory showed suitable weather conditions to always support EIP completion (17%), only 2.7% of the 2021 Australian human population lived in this region. Therefore, 97% of the population lived in an area that changed its EIP suitability within the study period. EIP completion is required prior to D. immitis transmission, meaning that infection risk of D. immitis is seasonal and location-dependent, being disrupted each year for most of the human population's dogs. We developed an online, open access tool allowing us to visualise EIP completion across Australia historically and in near real-time. We aim to support veterinarians to make risk-based recommendations for dirofilariosis prevention by using the tool, available at https://heartworm-mapping.adelaide.edu.au/shiny/.

Applying Iterative Student Feedback across Flipped Classroom and Flexible Teaching Approaches: Impact on Veterinary Students' Learning Experience.

No single teaching strategy supports all learning styles in veterinary science students. To facilitate more convenient and flexible teaching, learning, and revision, an innovative online digital learning platform-VetCloud-was developed to provide access to modularized programme content across courses to promote active, integrated learning. This study aimed to understand student perceptions regarding the enhancement of the student learning experience in a foundational course in gastrointestinal anatomy and physiology at The University of Queensland across two learning cycles, via applying iterative student feedback in transitioning a flipped classroom approach using VetCloud for the delivery of lecture content in 2022 to a flexible learning approach in 2023. By 2023, the use of VetCloud in the flexible learning approach improved students' work/study/life balance, reduced their stress levels, and enabled a more efficient use of their time when studying, compared to the flipped classroom approach in 2022. Surveying student perceptions was integral to maximizing their learning experience. Data clearly demonstrates that students will mix-and-match how they interact with available options provided via flexible delivery on an individualized basis. This teaching method offers veterinary educators an innovative and efficient approach to veterinary student education in anatomy and physiology while enhancing student well-being.

Are Pathogenic Leptospira Species Ubiquitous in Urban Recreational Parks in Sydney, Australia?

Leptospirosis is a zoonotic disease caused by the spirochete bacteria Leptospira spp. From December 2017 to December 2023, a total of 34 canine leptospirosis cases were reported in urban Sydney, Australia. During the same spatio-temporal frame, one locally acquired human case was also reported. As it was hypothesised that human residents and companion dogs might both be exposed to pathogenic Leptospira in community green spaces in Sydney, an environmental survey was conducted from December 2023 to January 2024 to detect the presence of pathogenic Leptospira DNA in multipurpose, recreational public parks in the council areas of the Inner West and City of Sydney, Australia. A total of 75 environmental samples were collected from 20 public parks that were easily accessible by human and canine visitors. Quantitative PCR (qPCR) testing targeting pathogenic and intermediate Leptospira spp. was performed, and differences in detection of Leptospira spp. between dog-allowed and dog-prohibited areas were statistically examined. The global Moran's Index was calculated to identify any spatial autocorrelation in the qPCR results. Pathogenic leptospires were detected in all 20 parks, either in water or soil samples (35/75 samples). Cycle threshold (Ct) values were slightly lower for water samples (Ct 28.52-39.10) compared to soil samples (Ct 33.78-39.77). The chi-squared test and Fisher's exact test results were statistically non-significant (p > 0.05 for both water and soil samples), and there was no spatial autocorrelation detected in the qPCR results (p > 0.05 for both sample types). Although further research is now required, our preliminary results indicate the presence of pathogenic Leptospira DNA and its potential ubiquity in recreational parks in Sydney.

Production and Immunogenicity of FeLV Gag-Based VLPs Exposing a Stabilized FeLV Envelope Glycoprotein.

The envelope glycoprotein (Env) of retroviruses, such as the Feline leukemia virus (FeLV), is the main target of neutralizing humoral response, and therefore, a promising vaccine candidate, despite its reported poor immunogenicity. The incorporation of mutations that stabilize analogous proteins from other viruses in their prefusion conformation (e.g., HIV Env, SARS-CoV-2 S, or RSV F glycoproteins) has improved their capability to induce neutralizing protective immune responses. Therefore, we have stabilized the FeLV Env protein following a strategy based on the incorporation of a disulfide bond and an Ile/Pro mutation (SOSIP) previously used to generate soluble HIV Env trimers. We have characterized this SOSIP-FeLV Env in its soluble form and as a transmembrane protein present at high density on the surface of FeLV Gag-based VLPs. Furthermore, we have tested its immunogenicity in DNA-immunization assays in C57BL/6 mice. Low anti-FeLV Env responses were detected in SOSIP-FeLV soluble protein-immunized animals; however, unexpectedly no responses were detected in the animals immunized with SOSIP-FeLV Gag-based VLPs. In contrast, high humoral response against FeLV Gag was observed in the animals immunized with control Gag VLPs lacking SOSIP-FeLV Env, while this response was significantly impaired when the VLPs incorporated SOSIP-FeLV Env. Our data suggest that FeLV Env can be stabilized as a soluble protein and can be expressed in high-density VLPs. However, when formulated as a DNA vaccine, SOSIP-FeLV Env remains poorly immunogenic, a limitation that must be overcome to develop an effective FeLV vaccine.

The Raccoon (Procyon lotor) as a Neozoon in Europe.

The raccoon (Procyon lotor) is a North American half-bear that is present in much of Europe and Asia as a result of both accidental and planned releases. In Europe, raccoons were introduced primarily as a source of fur for the fur industry. In the 1930s, raccoons were released into the wild in Central Europe. At the same time, animals from fur farms and private holdings continued to enter the wild. In the following decades, the raccoon spread over large parts of Europe. In addition to the invasive spread of the Central European initial population, individual releases of raccoons occurred frequently, mainly in Southern Europe. The high adaptability of the raccoon favors its expansion into new habitats. It has a high reproductive rate, is very mobile, and encounters few predators in Europe. Raccoons have recently become a topic of interest when large raccoon populations have colonized suburban and urban areas. Despite the proximity of raccoons and humans, however, there have been hardly any conflicts to date, unlike in North America. A significant negative impact on the native fauna has been suspected but not proven. Raccoons have been identified as vectors of zoonotic diseases. Nevertheless, monitoring of the increasing numbers of raccoons in Europe seems advisable.

Field Performance of a Rapid Test to Detect Progressive, Regressive, and Abortive Feline Leukemia Virus Infections in Domestic Cats in Australia and Germany.

Different feline leukemia virus (FeLV) infection outcomes are possible in cats following natural exposure, such as progressive infections (persistent viremia), regressive infections (transient or no viremia followed by proviral persistence) and abortive infections (presence of only antibodies). Laboratory-based testing is currently required for categorization of infection outcomes in cats. The aim of this study was to evaluate the field performance of a novel, rapid, combination point-of-care (PoC) test kit commercially available in Europe (v-RetroFel®Ag/Ab; 2020-2021 version) to determine different FeLV infection outcomes by concurrent detection of FeLV antigen (p27) and antibodies against FeLV transmembrane envelope protein (p15E). A secondary aim was to evaluate the performance of the same test kit (v-RetroFel®FIV) to determine positive/negative feline immunodeficiency virus (FIV) infection status by the detection of antibodies to FIV capsid protein (p24) and transmembrane glycoprotein (gp40). Two cohorts of domestic cats were recruited and tested with v-RetroFel® using plasma or serum, including cats in Australia (n = 200) and cats in Germany (n = 170). Results from p27 antigen PoC testing, proviral DNA PCR, and neutralizing antibody testing or testing for antibodies against non-glycosylated surface unit envelope protein (p45) were used to assign cats to groups according to different FeLV infection outcomes. Testing with a laboratory-based FeLV p15E antibody ELISA was also performed for comparison. In the first cohort, v-RetroFel®Ag/Ab correctly identified 89% (109/122) FeLV-unexposed cats and 91% (21/23) progressive infections, but no regressive (0/23) or abortive (0/32) infections. In the second cohort, v-RetroFel®Ag/Ab correctly identified 94% (148/158) FeLV-unexposed cats and 100% (4/4) progressive infections, but no regressive (0/2) and only 17% (1/6) abortive infections. There was test agreement between v-RetroFel®Ab and the p15E laboratory ELISA in 58.9% of samples. As a secondary outcome of this study, the sensitivity and specificity of v-RetroFel®FIV testing in cohort 1 were 94.7% (18/19) and 98.3% (178/181), and in cohort 2, 30.0% (3/10) and 100.0% (160/160), respectively. Prior history of FIV vaccination did not produce any false-positive FIV results. In conclusion, v-RetroFel®Ag/Ab (2020-2021 version) was unable to accurately determine different FeLV infection outcomes in the field. Improvements of the test prior to application to field samples are required.