Field-Based cDNA-Biosensor for Accurate Detection of Canine Distemper Virus in Tissue Samples

Canine distemper, a viral disease with a global impact on various animals including dogs, foxes, wolves, lions, and leopards, requires early diagnosis for effective treatment and outbreak control. Common laboratory methods, such as enzyme-linked immunosorbent assay, polymerase chain reaction, and viral isolation, face challenges such as extended turnaround times, high costs, and the expertise required. This study has developed a field-based biosensor for detecting the canine distemper virus (CDV), utilising a screen-printed carbon electrode (SPCE) and a computer-assisted portable potentiostat. A 30-mer oligonucleotide capture probe, designed using Primer3 Plus software version 3.3.0, detected hybridisation with the CDV complementary strand through electrochemical analysis via differential pulsed voltammetry. The developed biosensor exhibited good linearity in quantifying the target analyte concentration (0.1 to 12.8 µM), with a detection limit of 0.05 µM, indicating high sensitivity. Specificity tests using complementary and non-complementary sequences confirmed the biosensor's accuracy. The electrode can be reused up to eight times with a residual capacity of 93.72 ± 5.45% after regeneration using a 50 mM NaOH solution. The developed biosensor was also used to detect CDV in biological samples after RNA extraction and amplification. Results from the biosensor aligned with those from reverse transcriptase polymerase chain reaction (RT-PCR) findings, showing 100% agreement. These findings support the potential development of a field-deployable portable device for effectively diagnosing canine distemper in biological samples.

Canine Distemper Virus in Sardinia, Italy: Detection and Phylogenetic Analysis in Foxes

Canine distemper virus (CDV) is the etiological agent of a highly prevalent viral infectious disease of carnivores, which could seriously lead to a threat to the conservation of the affected species worldwide [...].

Prevalence of canine distemper in minks, foxes and raccoon dogs from 1983 to 2023 in Asia, North America, South America and Europe

Canine distemper (CD) is a virulent disease caused by the canine distemper virus (CDV) in canines and mustelidaes with high mortality. The incidence of CDV is worldwide distribution and it has caused huge economic losses to multiple industries around the world. There are many studies investigating the prevalence of CD infection, but no comprehensive analysis of CDV infection in minks, foxes and raccoon dogs worldwide has therefore been carried out. The aim of this meta is to provide a comprehensive assessment of the prevalence of CDV infection in minks, foxes and raccoon dogs dogs through a meta-analysis of articles published from around the world. Data from 8,582 small carnivores in 12 countries were used to calculate the combined prevalence of CD. A total of 22.6% (1,937/8,582) of minks, foxes and raccoon dogs tested positive for CD. The prevalence was higher in Asia (13.8, 95% CI: 22.2-45.6), especially in South Korea (65.8, 95% CI: 83.3-95.8). Our study found that the incidence of CD was also associated with geographic climate, population size, health status, and breeding patterns. CD is more commonly transmitted in minks, foxes and raccoon dogs. However, the concentrated breeding as an economic animal has led to an increase in the prevalence rate. The difference analysis study recommended that countries develop appropriate preventive and control measures based on the prevalence in the minks, foxes, and raccoon dogs industries, and that reducing stocking density is important to reduce the incidence of CDV. In addition, CDV is more common in winter, so vaccination in winter should be strengthened and expanded to reduce the incidence of CD in minks, foxes and raccoon dogs.

Molecular Detection of Viral and Bacterial Pathogens in Red Foxes (Vulpes vulpes) from Italy

Animals, including wildlife, are part of One-Health concept since many infectious diseases can affect both humans and animals. In this study, 126 red foxes (Vulpes vulpes) from Northern Italy in 2022-2023 were tested by molecular assays for Protoparvovirus carnivoran 1 (PPVC-1), Canine adenovirus type 1 and 2 (CAdV-1 and CAdV-2), Circovirus canine (CanineCV), Canine distemper virus (CDV), and Leptospira spp. A total of 39 of 126 (30.9%) red foxes were infected with at least one pathogen and five of these were coinfected: 20/126 (15.9%) red foxes tested positive for PPVC-1, 3/126 (2.4%) for CAdV, 20/126 (15.9%) for CanineCV, and 2/126 (1.6%) for Leptospira spp. DNA. No foxes tested positive for CDV RNA. The pathogens identified were genetically analysed. New findings were reported such as a fox with multiple feline panleukopenia virus (FPV) and canine parvovirus type 2b (CPV-2b) infection associated with quasispecies dynamics, typical genetic characteristics of the identified CanineCV, and the first detection in red foxes of Leptospira ST198 related to L. interrogans serogroup Australis. Further studies are necessary to investigate the transmission between domestic animals and wildlife and to understand the role of red foxes in the maintenance of these pathogens not only in the wild but also in urban and peri-urban environments.

Analysis of a European general wildlife health surveillance program: Chances, challenges and recommendations

In a One Health perspective general wildlife health surveillance (GWHS) gains importance worldwide, as pathogen transmission among wildlife, domestic animals and humans raises health, conservation and economic concerns. However, GWHS programs operate in the face of legal, geographical, financial, or administrative challenges. The present study uses a multi-tiered approach to understand the current characteristics, strengths and gaps of a European GWHS that operates in a fragmented legislative and multi-stakeholder environment. The aim is to support the implementation or improvement of other GWHS systems by managers, surveillance experts, and administrations. To assess the current state of wildlife health investigations and trends within the GWHS, we retrospectively analyzed 20 years of wildlife diagnostic data to explore alterations in annual case numbers, diagnosed diseases, and submitter types, conducted an online survey and phone interviews with official field partners (hunting administrators, game wardens and hunters) to assess their case submission criteria as well as their needs for post-mortem investigations, and performed in-house time estimations of post-mortem investigations to conduct a time-per-task analysis. Firstly, we found that infectious disease dynamics, the level of public awareness for specific diseases, research activities and increasing population sizes of in depth-monitored protected species, together with biogeographical and political boundaries all impacted case numbers and can present unexpected challenges to a GWHS. Secondly, we found that even a seemingly comprehensive GWHS can feature pronounced information gaps, with underrepresentation of common or easily recognizable diseases, blind spots in non-hunted species and only a fraction of discovered carcasses being submitted. Thirdly, we found that substantial amounts of wildlife health data may be available at local hunting administrations or disease specialist centers, but outside the reach of the GWHS and its processes. In conclusion, we recommend that fragmented and federalist GWHS programs like the one addressed require a central, consistent and accessible collection of wildlife health data. Also, considering the growing role of citizen observers in environmental research, we recommend using online reporting systems to harness decentrally available information and fill wildlife health information gaps.

LISTERIA MONOCYTOGENES INFECTION IN FREE-RANGING RED FOXES (VULPES VULPES) AND EURASIAN LYNX (LYNX LYNX) IN SWITZERLAND

Listeria monocytogenes is an ubiquitous environmental saprophytic bacterium causing listeriosis in domestic animals, humans, and occasionally wildlife. In animals, this foodborne zoonotic disease mainly occurs in ruminants and it is rare in carnivores. Seven red foxes (Vulpes vulpes) and one Eurasian lynx (Lynx lynx) were diagnosed with listeriosis between 2010 and 2021 at the Institute for Fish and Wildlife Health, Bern, Switzerland. Necropsy and histopathology revealed meningitis (six of seven red foxes), hepatitis (six of seven red foxes), pneumonia (five of seven red foxes), splenitis (two of seven red foxes) and splenomegaly (the Eurasian lynx, two of seven red foxes). Listeria monocytogenes was isolated from either lung, spleen, liver, or kidney of all animals. Serotyping detected L. monocytogenes serotype 1/2a in five red foxes and the Eurasian lynx and serotype 4b in two red foxes. Six red foxes were positive for canine distemper virus (CDV) by polymerase chain reaction, whereas the Eurasian lynx and one red fox were negative. One red fox that was positive for CDV and listeriosis was also diagnosed with salmonellosis. The identified L. monocytogenes serotypes are among the three most frequently isolated serotypes (1/2a, 1/2b, and 4b) from food or the food production environment and those that cause most listeriosis cases in humans and animals. Coinfection with CDV in six red foxes questions the role of CDV as potential predisposing factor for septicemic listeriosis. The detection of listeriosis in the regionally endangered Eurasian lynx and in carnivores highly abundant in urban settings, such as red foxes, reinforces the importance of wildlife health surveillance in a One Health context and adds the Eurasian lynx to the list of carnivores susceptible to the disease. Further investigations are required to assess the prevalence and epidemiology of L. monocytogenes in free-ranging carnivores and its interaction with CDV.

Study of Canine Distemper Virus Presence in Catalonia's Wild Carnivores through H Gene Amplification and Sequencing

Canine distemper virus (CDV) is recognised worldwide as an important pathogen in both domestic and wild carnivores. Few data are available on its impact and spread on the wildlife/wildlife-domestic animal-environment interface. This study, aimed at developing a conservation-oriented control strategy, analysed 89 sick or deceased animals from 2019 to 2023 at the Wildlife Rehabilitation Centre in Torreferrussa. RT-PCR and sequencing of the partial H gene were used to detect and analyse CDV in tissues. The total positive percentage was 20.22% (18/89), comprising 13 red foxes (44.8%), 4 European badgers (28.6%), and 1 American mink (4.5%), while 24 Eurasian otters tested negative. Phylogenetic analysis indicated that all of the CDV strains belong to the European lineage. Geographically distant individuals and different species shared the same viral strain, suggesting a strong capacity of CDV for interspecies and long-distance transmission. This calls for further research, particularly focusing on potential impacts of CDV on endangered carnivores.

Survey of Common Infectious Diseases in Urban Foxes (Vulpes spp.) in Southeastern Iran

The red fox (Vulpes vulpes) is one of the most common species of wild Canidae and is relatively abundant in Iran. Foxes (Vulpes spp.) transmit many zoonotic diseases, the most important of which are visceral leishmaniasis, rabies, hydatidosis, toxocariasis, and trichinellosis. In this study, visceral leishmaniasis, rabies, ectoparasites, canine gastrointestinal helminths, dermatophytosis, distemper, parvovirus infection, and heartworm infections were evaluated among live-trapped and rescued foxes injured by traffic road accidents referred to the teaching hospital of Kerman, Iran, veterinary faculty. Skin scraping and direct microscopic examination were used to detect ectoparasites and dermatophytosis. Immunochromatography rapid kits were used to detect dirofilariasis, parvovirus infection, and distemper. Necropsy was used to check for gastrointestinal parasites. Rabies and visceral leishmaniosis were screened for with direct fluorescent antibody test and ELISA methods, respectively. Gastrointestinal helminth infections, including Toxocara canis, Taenia taeniaeformis, Dipylidium caninum, Joyeuxiella echinorhyncoids, Toxascaris leonina, Taenia hydatigena, Echinococcus granulosus, Rictolaria spp., Oxynema spp., Macracanthorhynchus hirudinaceus, and Physaloptera spp., were detected. Skin scrapings showed dermatophytosis and various ectoparasites, including Rhipicephalus sanguineus, Ctenocephalides canis and Ctenocephalides felis, and Sarcoptes scabiei, in foxes with dermal lesions. Distemper and parvovirus infection (26.66%) were the common viral diseases, and rabies infection rate was quite high (16.66%). Dirofilariasis and leishmaniasis were detected in 10% of the population. This study showed that urban foxes which often cohabit with humans and domestic animals are carriers of many different pathogens. This interaction may facilitate indirect cross-species transmission of zoonotic disease. Periodic health monitoring and multidisciplinary cooperation for the diagnosis, control, and prevention of these zoonoses is highly recommended.

Canine Distemper Virus Pathogenesis in the Ferret Model

Canine distemper virus (CDV) is a highly contagious pathogen within the morbillivirus genus infecting a wide range of different carnivore species. The virus shares most biological features with other closely related morbilliviruses, including clinical signs, tissue tropism, and replication cycle in the respective host organisms.In the laboratory environment, experimental infections of ferrets with CDV were established as a potent surrogate model for the analysis of several aspects of the biology of the human morbillivirus, measles virus (MeV). The animals are naturally susceptible to CDV and display severe clinical signs resembling the disease seen in patients infected with MeV. As seen with MeV, CDV infects immune cells and is thus associated with a strong transient immunosuppression. Here we describe several methods to evaluate viral load and parameters of immunosuppression in blood-circulating immune cells isolated from CDV-infected animals.

Serological and molecular survey of canine distemper virus in red foxes (Vulpes vulpes): Exploring cut-off values and the use of protein A in ELISA tests

The wide distribution and ecological plasticity of the red fox (Vulpes vulpes) make it a potential reservoir for many infectious diseases shared with domestic and wild carnivores. One of such diseases is canine distemper, which is caused by an RNA virus and its main domestic reservoir is the dog. However, other carnivores can also participate in its maintenance, as shown by the recent upsurge of reported cases in wildlife in many parts of the world, and by the fact that red foxes may act as true reservoirs for canine distemper virus (CDV). The lack of validated serological tests for wildlife or other non-target species may be a handicap for monitoring this virus. In this study, serological assays were compared in 147 red fox sera using a commercial ELISA validated for its use in dogs and a non-specific modified ELISA with Protein A peroxidase conjugate to detect bound antibodies. In addition, the presence of CDV RNA in brain, spleen, lung, and liver samples from 144 foxes was investigated by a RT-qPCR. Through the comparison of the results of both ELISAs and the use of a finite mixture model of the optical density values obtained by both techniques, we adjusted the cut-off point of the commercial ELISA to obtain the seroprevalence in foxes. The overall seroprevalence detected was 53.7% (79/147) and 57.1% (84/147) by the commercial and modified ELISA, respectively, with a moderate agreement according to Cohen's Kappa statistic (κ = 0.491, z = 5.97, p < 0.0001). CDV RNA was detected in 30 out of 144 foxes, which resulted in 20.8% of CDV-infected foxes. At individual level, the results obtained by relating the serological status and the presence/absence of RNA in different organs were explained in terms of the pathogenesis of the infection. Our results highlight the convenience of adjusting the cut-off point when using an ELISA assay developed in domestic dogs for its use in foxes. Moreover, Protein A is confirmed to be a good alternative to be used in red foxes, presenting a good reactivity towards its IgG.

Phenotypic Characterization of Encephalitis in the BRAINS of Badgers Naturally Infected with Canine Distemper Virus

Canine distemper virus (CDV) affects a huge diversity of domestic and wild carnivores, with increasing numbers of mortality events worldwide. The local cell-mediated immune response elicited against a natural infection is an important factor in determining the outcome of CDV infection. Therefore, the purposes of this study were to describe the local immune response within the central nervous systems (CNSs) of seven badgers naturally infected with CDV in Asturias (Atlantic Spain) and to determine the phenotype and distribution of microglial cells, T and B lymphocytes, and astrocytes in the foci of gliosis located in the thalamus and cerebellum using immunohistochemistry. The immunohistochemical assessment demonstrated the presence of Iba1-positive microglia and GFAP-positive astrocytes in the foci of gliosis, whereas T (CD3-negative) or B (CD20-negative) lymphocytes in those same lesions were absent. Our results also revealed that the badgers with natural CDV encephalitis presented lesions mostly located in the white matter of the thalamus and cerebellum, suggesting a CDV-specific tropism for the white matter of badger brains in those locations. The knowledge gained in the field of the immunopathogenesis of distemper disease affecting the CNSs of badgers could help to clarify CDV disease patterns in this species.

Case report: Canine distemper virus infection as a cause of central nervous system disease in a Eurasian lynx (Lynx lynx)

The Eurasian lynx (Lynx lynx) represents an endangered species with only small populations remaining in Central Europe. Knowledge about the threat posed by potential infectious agents to these animals is crucial for informing ongoing protection measures. Canine distemper virus (CDV) is known to have a wide host range with infection reported in many mammalian species including several lynx species (Lynx pardinus, Lynx canadensis, Lynx rufus), but is an extremely rare finding in the Eurasian lynx. The present report describes a case of a Eurasian lynx showing central nervous signs, including apathy and ataxia. A CT scan revealed multiple hypodense areas in different localizations within the brain as well as enlarged liquid filled areas, leading to the suspicion of a degenerative process. Due to clinical deterioration, the animal was euthanized and submitted for macroscopical and histological investigations. Histological investigations revealed multifocal demyelinations in the cerebellum, brain stem and cervical spinal cord as well as a multifocal, perivascular, lymphohistiocytic meningoencephalitis. A CDV infection was confirmed by immunohistochemistry and RT-PCR analyses. This CDV infection of a Eurasian lynx resembles a classical chronic manifestation of distemper in dogs and highlights the threat posed by canine distemper to this species.

Canine Distemper Virus Infection in the Free-Living Wild Canines, the Red Fox (Vulpes vulpes) and Jackal (Canis aureus moreoticus), in Croatia

The canine distemper virus (CDV), a paramyxovirus that is closely related to the human measles virus and rinderpest virus of cattle, is a highly contagious viral disease in dogs and wild carnivores worldwide. CDV represents a serious threat to domestic and wild animals, especially to the conservation of endangered wild carnivores. Our study aims to investigate the occurrence of CDV in free-living wild canines in Croatia. For this purpose, 176 red foxes and 24 jackal brain samples collected in the frame of the active surveillance of rabies during winter 2021/2022 were tested. This study provided the first comprehensive overview of the prevalence and spatial distribution of CDV in the wildlife of Croatia, including the molecular phylogenetic analysis of the H gene sequence of field CDV strains circulating in red fox and jackal populations of Croatia. The molecular characterization of hemagglutinin gene genomic regions confirmed the phylogenetic clustering of obtained sequences into the Europa 1 genotype. The obtained CDV red fox sequences were mutually very similar (97.60%). This study indicates the high genetic similarity of Croatian CDV red fox sequences and CDV red fox sequences from Italy and Germany, badger sequences from Germany, polecat sequences from Hungary, and dog sequences from Hungary and Germany.

Approaches to identify canine distemper virus with neurological symptoms on the basis of molecular characterization of hemagglutinin and fusion genes

Canine distemper virus (CDV), which causes severe infections in all domestic and wild carnivores, is transmitted by all secretions and excretions of infected animals. Despite the regular vaccination against it, CDV still manages to circulate in nature and is a worldwide problem in dogs. For many years in the world, the virus managed to circulate in nature. The current investigation aims to identify and characterize CDV in dogs with neurological symptoms and to determine whether CNS symptoms and phylogenetic data might be used to differentiate between CDV strains. The medical records of 35 dogs with central nervous system (CNS) symptoms were examined. An ELISA kit was used to identify CDV-specific IgG antibodies in all of the dogs' serum samples. RT-PCR confirmed the presence of CDV nucleic acid in 30 of these dogs. Of the RT-PCR-positive samples, 6 were randomly chosen for further sequencing, sequence comparisons, and phylogenetic reconstructions. Genes encoding the Hemagglutinin (H) and Fusion (F) proteins were partly sequenced and compared to other CDVs from throughout the world, including vaccine strains. The maximum likelihood method was used to build a phylogenetic tree using CDV H and F gene nucleotide sequences. According to phylogenetic analysis of partial H and F gene nucleotide sequences, the field CDVs in this investigation were unique and different from the vaccine strain. The phylogenetic analysis indicated that all Turkish CDV strains that induced CNS symptoms belonged to the European CDV clade. While the intricacy of the CNS and the complexities of glycosylation pathways may provide significant challenges to infections, future research will bring significant benefits by identifying evolutionarily conserved activities of N-glycosylation in CDV-infected dogs.

Biomolecular Analysis of Canine Distemper Virus Strains in Two Domestic Ferrets (Mustela putorius furo)

Canine distemper is a contagious and severe systemic viral disease that affects domestic and wild carnivores worldwide. In this study, two adult female ferrets (Mustela putorius furo) were evaluated for cutaneous lesions. Scab, fur, and swab samples from the external auditory canal, cutaneous lesions, and scrapings were analyzed. Canine distemper virus (CDV)-positive samples underwent RT-PCR/RFLP with the restriction enzyme PsiI, and the hemagglutinin gene sequence was obtained. According to the restriction enzyme and sequence analyses, the viral strains were typed as CDV field strains that are included within the Europe lineage and distinct from those including vaccinal CDV strains. The sequence analysis showed the highest nucleotide identity rates in older Europe lineage CDV strains collected from dogs and a fox in Europe. This study is the first to report on CDV infection in ferrets in southern Italy and contributes to the current knowledge about natural CDV infection in this species. In conclusion, vaccination remains crucial for preventing the disease and counteracting cross-species infection. Molecular biology techniques can enable the monitoring of susceptible wild animals by ensuring the active surveillance of CDV spread.

First Molecular Detection and Genetic Analysis of a Novel Porcine Circovirus (Porcine Circovirus 4) in Dogs in the World

A novel circovirus species was identified in farmed pigs and designated porcine circovirus 4 (PCV4); it has recently been proved to be pathogenic to piglets. However, little is known about its cross-species transmission, and there is no evidence of PCV4 in dogs. A total of 217 fecal samples were collected from diarrheal dogs in Henan Province, China, and tested for the presence of PCV4 using a real-time PCR assay. Among the 217 samples, the total positivity rate for PCV4 was 5.99% (13/217 samples), with rates of 7.44% and 4.17% in 2020 and 2021, respectively. PCV4 was detected in dogs in 6 of 10 cities, demonstrating that PCV4 could be detected in dogs in Henan Province, China. One PCV4 strain (HN-Dog) was sequenced in this study and shared high levels of identity (97.9% to 99.6%) with reference strains at the genome level. Phylogenetic analysis based on complete genome sequences of HN-Dog and 42 reference strains showed that the HN-Dog strain was closely related to 3 PCV4 reference strains (from pig, raccoon dog, and fox) but differed genetically from other viruses in the genus Circovirus. Three genotypes, i.e., PCV4a, PCV4b, and PCV4c, were confirmed by phylogenetic analysis of complete genome sequences of 42 PCV4 strains, and one amino acid variation in Rep protein (V239L) and three amino acid variations in Cap protein (N27S, R28G, and M212L) were considered conserved genotype-specific molecular markers. In conclusion, the present study is the first to report the discovery of the PCV4 genome in dogs, and the association between PCV4 infection and diarrhea warrants further study. IMPORTANCE This study is the first to report the presence of PCV4 in dogs worldwide, and the first complete genome sequence was obtained from a dog affected with diarrhea. Three genotypes of PCV4 strains (PCV4a, PCV4b, and PCV4c) were determined, as supported by specific amino acid markers (V239L for open reading frame 1 [ORF1] and N27S R28G and M212L for ORF2). These findings help us understand the current status of intestinal infections in pet dogs in Henan Province, China, and also prompted us to accelerate research on the pathogenesis, epidemiology, and cross-species transmission of PCV4.

Detection and genetic characterization of canine distemper virus isolated in civets in Vietnam

Canine distemper (CD), caused by the canine distemper virus (CDV), is a lethal systemic disease to a wide range of wild and domestic carnivorous hosts, including civets. In this study, a possible CD outbreak in a backyard farm with 32 diseased civets (Viverricula indica) in Hanoi, Vietnam, was investigated. The sick civets showed CD-like clinical signs such as anorexia, sedentary behavior, diarrhea, dermatitis, nasal, and footpad hyperkeratosis. Various tissue samples collected from the dead civets were utilized for molecular screening of CDV and histopathological examination. The genetic detection and characterization confirmed that samples collected from dead civets tested positive for CDV. The phylogenetic analysis based on the full-length H gene sequences indicated that all CDV strains isolated from civets belonged to the Asia-1 lineage and were closely related to the CDV strains previously reported from dogs in Thailand, China, and Vietnam. Histopathological examination showed severe interstitial pneumonia, hemorrhagic alveolar septa, necrotic alveolar epithelial cells, necrotic, degenerated, or lost Purkinje cells, eosinophilic intracytoplasmic inclusion bodies, edema, and perivascular cuff. This study confirmed the detection of CDV in civets for the first time in Vietnam.

Development and efficacy evaluation of remodeled canine parvovirus-like particles displaying major antigenic epitopes of a giant panda derived canine distemper virus

Canine parvovirus (CPV) and Canine distemper virus (CDV) can cause fatal diseases in giant panda (Ailuropoda melanoleuca). The main capsid protein of CPV VP2 can be self-assembled to form virus-like particles (VLPs) in vitro, which is of great significance for potential vaccine development. In the present study, we remodeled the VP2 protein of a giant panda-derived CPV, where the major CDV F and N epitopes were incorporated in the N-terminal and loop2 region in two combinations to form chimeric VLPs. The reactivity ability and morphology of the recombinant proteins were confirmed by Western blot, hemagglutination (HA) test and electron microscopy. Subsequently, the immunogenicity of the VLPs was examined in vivo. Antigen-specific antibodies and neutralizing activity were measured by ELISA, hemagglutination inhibition (HI) test and serum neutralization test (SNT), respectively. In addition, antigen specific T cell activation were determined in splenic lymphocytes. The results indicated that the VLPs displayed good reaction with CDV/CPV antibodies, and the heterologous epitopes do not hamper solubility or activity. The VLPs showed decent HA activity, and resembled round-shaped particles with a diameter of 22-26 nm, which is identical to natural virions. VLPs could induce high levels of specific antibodies to CPV and CDV, shown by the indication of neutralizing antibodies in both VP2N and VP2L VLPs group. In addition, splenic lymphocytes of mice immunized with VLPs could proliferate rapidly after stimulation by specific antigen. Taken together, the CPV VP2 VLPs or chimeric VLPs are highly immunogenic, and henceforth could function as CPV/CDV vaccine candidates for giant pandas.

Canine Distemper Virus in Endangered Species: Species Jump, Clinical Variations, and Vaccination

Canine morbillivirus (Canine distemper virus, CDV) is the cause of distemper in a large number of different species, some of which are endangered. The clinical outcome associated with infection is variable and based on many factors, including the host species, the immune response of the individual animal to the infection, and variation in virus tropism and virulence. Unfortunately, the viral characteristics associated with virulence versus attenuation are not fully characterized, nor are the specific mutations that allow this virus to easily move and adapt from one species to another. Due to its wide host range, this virus is difficult to manage in ecosystems that are home to endangered species. Vaccination of the domestic dog, historically considered the reservoir species for this virus, at dog-wildlife interfaces has failed to control virus spread. CDV appears to be maintained by a metareservoir rather than a single species, requiring the need to vaccinate the wildlife species at risk. This is controversial, and there is a lack of a safe, effective vaccine for nondomestic species. This review focuses on topics that are paramount to protecting endangered species from a stochastic event, such as a CDV outbreak, that could lead to extinction.

Detection and sequence analysis of Canine morbillivirus in multiple species of the Mustelidae family

BACKGROUND

Canine morbillivirus (canine distemper virus, CDV) is a member of the Paramyxoviridae family. Canine distemper is a serious viral disease that affects many mammalian species, including members of the Mustelidae family. These animals have an elusive nature, which makes related virological studies extremely challenging. There is a significant knowledge gap about the evolution of their viruses and about the possible effects of these viruses to the population dynamics of the host animals. Spleen and lung tissue samples of 170 road-killed mustelids belonging to six species were collected between 1997 and 2022 throughout Hungary and tested for CDV with real-time RT-PCR.

RESULTS

Three species were positive for viral RNA, 2 out of 64 Steppe polecats (Mustela eversmanii), 1 out of 36 European polecats (Mustela putorius) and 2 out of 36 stone martens (Martes foina); all 18 pine martens (Martes martes), 10 least weasels (Mustela nivalis) and 6 stoats (Mustela erminea) tested negative. The complete CDV genome was sequenced in five samples using pan-genotype CDV-specific, amplicon-based Nanopore sequencing. Based on the phylogenetic analysis, all five viral sequences were grouped to the Europe/South America 1 lineage and the distribution of one sequence among trees indicated recombination of the Hemagglutinin gene. We verified the recombination with SimPlot analysis.

CONCLUSIONS

This paper provides the first CDV genome sequences from Steppe polecats and additional complete genomes from European polecats and stone martens. The infected specimens of various species originated from distinct parts of the country over a long time, indicating a wide circulation of CDV among mustelids throughout Hungary. Considering the high virulence of CDV and the presence of the virus in these animals, we highlight the importance of conservation efforts for wild mustelids. In addition, we emphasize the importance of full genomic data acquisition and analysis to better understand the evolution of the virus. Since CDV is prone to recombination, specific genomic segment analyses may provide less representative evolutionary traits than using complete genome sequences.

Detection and Molecular Characterization of Canine Distemper Virus in Wildlife from Northern Italy

Canine distemper virus (CDV) is a fatal, highly contagious disease found in wild and domestic carnivores. Several outbreaks have occurred in wildlife in Italy in recent years. This study aims to detect CDV in wildlife following the increasing mortality of foxes (Vulpes vulpes) in the Emilia-Romagna region (northern Italy) observed in 2021. Sixty-seven foxes and one badger (Meles meles) were subjected to necropsy followed by histological examination and were analyzed with molecular techniques to detect the presence of CDV. Of the tested animals, 16% (nine foxes and one badger) were positive for CDV. Phylogenetic analysis showed two different lineages based on complete H gene sequences. The Europe/South America-1 lineage was detected in one fox from Modena, which resembled the CDV variant associated with a previous outbreak in northern Italy in 2018, while the European Wildlife lineage was detected in animals from the Rimini province. Amino acid analysis highlighted a Y549H mutation in all sequences collected, which is commonly associated with increased virulence.

Neuropathologic and molecular aspects of a canine distemper epizootic in red foxes in Germany

In the last fifteen years, an epidemic of canine distemper virus (CDV) with marked neurotropism has occurred in Europe after a longer period of endemic transmission. Many wildlife species have been infected, with red foxes (Vulpes vulpes) being particularly affected. Given that this species is assumed to mediate cross-species CDV infections to domestic and wild animals, tissue samples from foxes with confirmed CDV infection in North-Western Germany were investigated to better understand the neurotropic aspects of the disease. This analysis included histopathology, virus distribution and cell tropism, phenotyping of inflammatory responses and determination of the genotype of the viruses based on the phylogeny of the hemagglutinin (H) gene. The predominant lesion type is gliosis in both gray and white matter areas associated with an accumulation of Iba1+ macrophages/microglia and upregulation of major histocompatibility complex class II molecules in the brain, while sequestration of CD3+ T and Pax5+ B cell in CDV-infected foxes is limited. Demyelination is found in few foxes, characterized by reduced myelin staining with loss of CNPase+ oligodendrocytes in the cerebellar white matter and brainstem. In addition, axonal damage, characterized by β-amyloid precursor protein expression, is found mainly in these brain regions. In situ hybridization reveals a primary infection of the cerebral and cerebellar gray matter and brain stem. Iba1+ cells and NeuN+ neurons represent the main CDV targets. Sequencing of the CDV H open reading frame from fox tissues reveals that the virus strains belongs to three different sub-lineages of the Europe-1/South America-1 genotype, suggesting independent transmission lines.

Canine morbillivirus (CDV): a review on current status, emergence and the diagnostics

The increasing host range of canine morbillivirus (CDV) affecting important wildlife species such as Lions, Leopard, and Red Pandas has raised the concern. Canine distemper is a pathogen of dogs affecting the respiratory, gastrointestinal, and nervous systems. Seventeen lineages of CDV are reported, and the eighteenth lineage was proposed in 2019 from India. Marked genomic differences in the genome of wild-type virus and vaccine strain are also reported.The variations at the epitope level can be differentiated using specific monoclonal antibodies in neutralization tests. Keeping in mind the current status of the emergence of CDV, genetic and molecular study of circulating strains of the specific geographical region are the essential components of the disease control strategy. New target-based diagnostics and vaccines are in need to counter the effects of the emerging virus population. Control of CDV is necessary to save the endangered, vulnerable, and many other wildlife species to maintain balance in the ecological system. This review provides an overview on emergence reported in CDV, diagnostics developed till today, and a perspective on the disease control strategy, keeping wildlife in consideration.

Retrospective Detection and Complete Genomic Sequencing of Canine morbillivirus in Eurasian Otter (Lutra lutra) Using Nanopore Technology

The Eurasian otter (Lutra lutra) is a piscivorous apex predator in aquatic habitats, and a flagship species of conservation biology throughout Europe. Despite the wide distribution and ecological relevance of the species, there is a considerable lack of knowledge regarding its virological and veterinary health context, especially in Central Europe. Canine morbillivirus (Canine distemper virus (CDV)) is a highly contagious viral agent of the family Paramyxoviridae with high epizootic potential and veterinary health impact. CDV is present worldwide among a wide range of animals; wild carnivores are at particular risk. As part of a retrospective study, lung-tissue samples (n = 339) from Eurasian otters were collected between 2000 and 2021 throughout Hungary. The samples were screened for CDV using a real-time RT-PCR method. Two specimens proved positive for CDV RNA. In one sample, the complete viral genome was sequenced using a novel, pan-genotype CDV-specific amplicon-based sequencing method with Oxford Nanopore sequencing technology. Both viral sequences were grouped to a European lineage based on the hemagglutinin-gene phylogenetic classification. In this article, we present the feasibility of road-killed animal samples for understanding the long-term dynamics of CDV among wildlife and provide novel virological sequence data to better understand CDV circulation and evolution.

An Integrated, Tentative Remote-Sensing Approach Based on NDVI Entropy to Model Canine Distemper Virus in Wildlife and to Prompt Science-Based Management Policies

Simple Summary

Canine distemper virus (CDV) is a pathogen that affects wildlife with particular regard to Canidae family such as red foxes, wolves, etc. In this study, we focus on CDV outbreaks in the Aosta Valley territory, an alpine region in the NW of Italy which was affected by important waves of this disease during the years 2015–2020 (hereinafter called τ). Ground data are collected on the entire territory at a municipality level. The detection of the canine distemper virus is performed by means of real-time PCR. By adopting satellite remote-sensing data, we notice that CDV trends are strongly related to anomalies in the NDVI entropy changes through (τ). A tentative local model is developed concerning on-the-ground data, helping veterinarians, foresters, and wildlife ecologists enforce management health policies in a One Health perspective.

Abstract

Changes in land use and land cover as well as feedback on the climate deeply affect the landscape worldwide. This phenomenon has also enlarged the human–wildlife interface and amplified the risk of potential new zoonoses. The expansion of the human settlement is supposed to affect the spread and distribution of wildlife diseases such as canine distemper virus (CDV), by shaping the distribution, density, and movements of wildlife. Nevertheless, there is very little evidence in the scientific literature on how remote sensing and GIS tools may help the veterinary sector to better monitor the spread of CDV in wildlife and to enforce ecological studies and new management policies in the near future. Thus, we perform a study in Northwestern Italy (Aosta Valley Autonomous Region), focusing on the relative epidemic waves of CDV that cause a virulent disease infecting different animal species with high host mortality. CDV has been detected in several mammalian from Canidae, Mustelidae, Procyonidae, Ursidae, and Viverridae families. In this study, the prevalence is determined at 60% in red fox (Vulpes vulpes, n = 296), 14% in wolf (Canis lupus, n = 157), 47% in badger (Meles meles, n = 103), and 51% in beech marten (Martes foina, n = 51). The detection of CDV is performed by means of real-time PCR. All the analyses are done using the TaqMan approach, targeting the chromosomal gene for phosphoprotein, gene P, that is involved in the transcription and replication of the virus. By adopting Earth Observation Data, we notice that CDV trends are strongly related to an altitude gradient and NDVI entropy changes through the years. A tentative model is developed concerning the ground data collected in the Aosta Valley region. According to our preliminary study, entropy computed from remote-sensing data can represent a valuable tool to monitor CDV spread as a proxy data predictor of the intensity of fragmentation of a given landscape and therefore also to monitor CDV. In conclusion, the evaluation from space of the landscape variations regarding the wildlife ecological corridors due to anthropic or natural disturbances may assist veterinarians and wildlife ecologists to enforce management health policies in a One Health perspective by pointing out the time and spatial conditions of interaction between wildlife. Surveillance and disease control actions are supposed to be carried out to strengthen the usage of geospatial analysis tools and techniques. These tools and techniques can deeply assist in better understanding and monitoring diseases affecting wildlife thanks to an integrated management approach.

Complete genomic sequencing of canine distemper virus with nanopore technology during an epizootic event

Canine distemper virus (CDV) endangers a wide range of wild animal populations, can cross species barriers and therefore representing a significant conservational and animal health risk around the globe. During spring to autumn 2021, according to our current estimates a minimum of 50 red foxes (Vulpes vulpes) died of CDV in Hungary, with CDV lesions. Oral, nasal and rectal swab samples were RT-PCR screened for Canine Distemper Virus from red fox carcasses. To investigate in more detail the origins of these CDV strains, 19 complete genomes were sequenced with a pan-genotype CDV-specific amplicon-based sequencing method developed by our laboratory and optimized for the Oxford Nanopore Technologies platform. Phylogenetic analysis of the complete genomic sequences and separately the hemagglutinin gene sequences revealed the role of the Europe lineage of CDV as a causative agent for the current epizootic. Here we highlight the growing importance of fast developing rapid sequencing technologies to aid rapid response activities during epidemics or epizootic events. We also emphasize the urgent need for improved surveillance of CDV, considering the epizootic capability of enzootic strains as reported in the current study. For such future efforts, we provide a novel NGS protocol to facilitate future genomic surveillance studies.

Molecular and pathological screening of canine distemper virus in Asiatic lions, tigers, leopards, snow leopards, clouded leopards, leopard cats, jungle cats, civet cats, fishing cat, and jaguar of different states, India

The present investigation was conducted to rule out canine distemper (CD) diseases in Indian wild felids (Asiatic lions, tigers, leopards, snow leopards, clouded leopards, leopard cats, jungle cats, civet cats, fishing cat, and jaguar). The collected samples were screened for CD virus (CDV) by histopathology (HP), immunohistochemistry (IHC) and reverse transcriptase-polymerase chain reaction (RT-PCR) targeting H gene and N gene. The HP and IHC of suspected samples portrayed that 22 [11 leopards, 6 lions, 3 tigers, 1 snow leopard and 1 civet cat] out of 129 (17.05%) wild felids were positive for CD. The major pathological consequences were observed in spleen, lung, kidney and brain. The syncytia and intranuclear as well as intracytoplasmic eosinophilic inclusion bodies were seen in CDV infected cells. Although the histopathological lesions in spleen were more specific and consistent, however, the severe demyelinated leukoencephalitis (usually expected in CD infected dog) was not observed in the brain of any Indian wild felids. Conversely, the CDV antigen has been portrayed via IHC in pancreatic islets of Langerhans of tiger species for the first time in this study. Moreover, the concurrent CD and babesiosis has also been observed in a lioness without a usual coffee-coloured urine. The N gene and H gene of CDV isolates were amplified, sequenced and subsequently constructed the phylogenetic tree. The phylogenetic analysis of H gene revealed that the CDV isolates from Indian lion formed separate clade with CDV isolates from Indian dog and Indian palm civet cat. Furthermore, two CDV isolates from Indian tigers formed clade with Onderstepoort vaccine strain and CDV isolates from dogs of Uttar Pradesh, USA and UK. Evidently, CDV is circulating in Indian wild felids and causing diseases in them.

Management of Suspected Cases of Feline Immunodeficiency Virus Infection in Eurasian Lynx (Lynx lynx) During an International Translocation Program

The Eurasian lynx (Lynx lynx) population in Switzerland serves as a source for reintroductions in neighboring countries. In 2016–2017, three lynx from the same geographical area were found seropositive for feline immunodeficiency virus (FIV) in the framework of an international translocation program. This novel finding raised questions about the virus origin and pathogenicity to lynx, the emerging character of the infection, and the interpretation of serological results in other lynx caught for translocation. Archived serum samples from 84 lynx captured in 2001–2016 were retrospectively tested for FIV antibodies by Western blot. All archived samples were FIV-negative. The three seropositive lynx were monitored in quarantine enclosures prior to euthanasia and necropsy. They showed disease signs, pathological findings, and occurrence of co-infections reminding of those described in FIV-infected domestic cats. All attempts to isolate and characterize the virus failed but serological data and spatiotemporal proximity of the cases suggested emergence of a lentivirus with antigenic and pathogenic similarities to FIV in the Swiss lynx population. A decision scheme was developed to minimize potential health risks posed by FIV infection, both in the recipient and source lynx populations, considering conservation goals, animal welfare, and the limited action range resulting from local human conflicts. Development and implementation of a cautious decision scheme was particularly challenging because FIV pathogenic potential in lynx was unclear, negative FIV serological results obtained within the first weeks after infection are unpredictable, and neither euthanasia nor repatriation of multiple lynx was acceptable options. The proposed scheme distinguished between three scenarios: release at the capture site, translocation, or euthanasia. Until April 2021, none of the 40 lynx newly captured in Switzerland tested FIV-seropositive. Altogether, seropositivity to FIV was documented in none of 124 lynx tested at their first capture, but three of them seroconverted in 2016–2017. Diagnosis of FIV infection in the three seropositive lynx remains uncertain, but clinical observations and pathological findings confirmed that euthanasia was appropriate. Our experiences underline the necessity to include FIV in pathogen screenings of free-ranging European wild felids, the importance of lynx health monitoring, and the usefulness of health protocols in wildlife translocation.

Canine distemper virus in wildlife in south-western Europe

Multi-host pathogens emerging and re-emerging at the wildlife-domestic animal interface affect wildlife management and conservation. This is the case of canine distemper virus (CDV), a paramyxovirus closely related to human measles virus and rinderpest virus of cattle. With an area of 10,603 km² , Asturias region in Atlantic Spain is a hotspot of carnivore diversity, which includes the largest Eurasian brown bear (Ursus arctos arctos) population and one of the largest wolf (Canis lupus) populations in south-western Europe. In 2020-2021, we recorded mortality due to distemper in four carnivore species including three mustelids (Eurasian badger Meles meles, European marten Martes martes and European polecat Mustela putorius) and one canid (red fox, Vulpes vulpes). Clinical signs and pathology were similar across species and consistent with the emergence of a highly pathogenic viral strain, with CDV antigen mainly located in the central nervous system, lungs, spleen and lymph nodes. A molecular study in eight wild carnivore species, also including the Iberian wolf, Eurasian brown bear, American mink (Neovison vison) and stone marten (Martes foina), revealed 19.51% (16/82) of positivity. Phylogenetic analysis demonstrated that CDV belonged to the previously described European lineage. A retrospective serosurvey (2008-2020) showed a high seroprevalence of CDV antibodies (43.4%) in 684 analyzed badgers, indicating a long-term though not stable viral circulation in this multi-host community. The possible triggers of the 2020-2021 outbreak and the implications for carnivore management and conservation are discussed.

Sylvatic Canine Morbillivirus in Captive Panthera Highlights Viral Promiscuity and the Need for Better Prevention Strategies

Canine Distemper Virus (CDV) is a multi-host morbillivirus that infects virtually all Carnivora and a few non-human primates. Here we describe a CDV outbreak in an exotic felid rescue center that led to the death of eight felids in the genus Panthera. Similar to domestic dogs and in contrast to previously described CDV cases in Panthera, severe pneumonia was the primary lesion and no viral antigens or CDV-like lesions were detected in the central nervous system. Four tigers succumbed to opportunistic infections. Viral hemagglutinin (H)-gene sequence was up to 99% similar to strains circulating contemporaneously in regional wildlife. CDV lesions in raccoons and skunk were primarily encephalitis. A few affected felids had at least one previous vaccination for CDV, while most felids at the center were vaccinated during the outbreak. Panthera sharing a fence or enclosure with infected conspecifics had significantly higher chances of getting sick or dying, suggesting tiger-tiger spread was more likely than recurrent spillover. Prior vaccination was incomplete and likely not protective. This outbreak highlights the need for further understanding of CDV epidemiology for species conservation and public health.

A Canine Distemper Virus Retrospective Study Conducted from 2011 to 2019 in Central Italy (Latium and Tuscany Regions)

Canine distemper virus (CDV) is a highly lethal contagious viral pathogen mainly found in domestic and wild canids and mustelids. Although, in Italy, circulating strains of Europe 1, Europe wildlife and Arctic type are reported, data relating to Latium and Tuscany regions are limited. In view of this, through passive surveillance, we investigated the presence of CDV and which strains were circulating in these Regions. From March 2017 to October 2019, a group of 122 subjects were tested for CDV using a PCR protocol described in the literature, with 12 detected positive; analyses were carried out on a set of target samples (brain and lung, conjunctival, nasal and rectal swabs, urine or swab from bladder and intracardiac clot) that was defined for the detection of CDV in both live and dead animals. The rectal swab, easily collected also from live animals, represented the most suitable sample for CDV diagnosis, with 9 positive of the 11 (81.82%) tested. In addition, brain and lung of 15 subjects out of 181 susceptible animals collected between 2011 and 2018, during post mortem investigations in routine diagnostic activity, were CDV positive. Molecular analyses of all positive samples, using a 287 bp fragment located within the conserved N terminus of the morbillivirus nucleoprotein gene, detected the circulation of strain CDV599/2016 (KX545421.1) belonging to the “Europe wildlife” lineage, and of strain CDV12254/2015 (KX024709.1), belonging to the Arctic-lineage, thus confirming the co-circulation of the two lineages, as already noted in previous studies.

Mink SLAM V-Region V74I Substitutions Contribute to the Formation of Syncytia Induced by Canine Distemper Virus

The Signal lymphatic activation molecule (SLAM, also known as CD150) as the cellular receptor of canine distemper virus (CDV) plays an important role in the virus-host interaction. However, it is still unknown whether amino acid differences in the SLAM variable (V) region affect the formation of syncytia. Here, using raccoon dog SLAM (rSLAM) and mink SLAM (mSLAM), we performed SLAM-V homologous modeling, site-directed mutagenesis, and surface expression analysis, as well as a cell fusion assay, to study the interaction between SLAM and CDV. More specifically, our investigation focused on two amino acid residues (74 and 129) of SLAM, previously predicted to play a relevant role in receptor-ligand interaction. Our results indicated that only residues at position 60, 74, and 129 were different between rSLAM and mSLAM among the 29 amino acids that might interact with CDV H, and residues 74 and 129 were located in the interface region interacting with CDV H. The amino acid substitution at the positions of 74 have a significant effect on the expression of mSLAM. The SLAM-V74I mutation in mink significantly improved the cell fusion efficiency of CDV. In contrast, the SLAM-I74V mutation in the raccoon dog significantly decreased cell fusion efficiency. We conclude that residue 74 of SLAM plays an important role during the the formation of syncytia. Only when implementing CDV infection analysis, the rSLAM-Q129R can significantly decreased the mean number of syncytia, but the mSLAM-R129Q can't. Additionally, residue 60 show variability between rSLAM and mSLAM. We believe that our study makes a significant contribution to the literature because we provide molecular data, partially accounting for the differences in host membrane and virus interaction laying the foundation for further molecular work.

Canine Distemper Outbreaks in Wild Carnivores in Northern Italy

Canine distemper (CD) is a fatal, highly contagious disease of wild and domestic carnivores. In the Alpine territory, several outbreaks have occurred in the past few decades within wild populations. This study investigated the presence of canine distemper virus (CDV) infections in wild carnivores in Lombardy, relating to the different circulating genotypes. From 2018 to 2020, foxes, badgers, and martens collected during passive surveillance were subjected to necropsy and histological examination, showing classical signs and microscopic lesions related to CDV. Pools of viscera from each animal were analysed by molecular methods and immunoelectron microscopy. Total prevalences of 39.7%, 52.6%, and 14.3% were recorded in foxes, badgers, and stone martens, respectively. A phylogenetic analysis showed that the sequences obtained belonged to the European 1 lineage and were divided into two different clades (a and b) according to the geographical conformation of alpine valleys included in the study. Clade a was related to the European outbreaks originating from Germany in 2006–2010, while clade b was closely related to the CDV sequences originating from northeastern Italy during the 2011–2018 epidemic wave. Our results suggest that CDV is currently well adapted to wild carnivores, mostly circulating with subclinical manifestations and without severe impact on the dynamics of these populations.

Multi-targeted gene silencing strategies inhibit replication of Canine morbillivirus

BACKGROUND

Canine morbilivirus (canine distemper virus, CDV) is a highly contagious pathogen associated with high morbidity and mortality in susceptible carnivores. Although there are CDV vaccines available, the disease poses a huge threat to dogs and wildlife hosts due to vaccine failures and lack of effective treatment. Thus, the development of therapeutics is an urgent need to achieve rapid outbreak control and reduce mortality in target species. Gene silencing by RNA interference has emerged as a promising therapeutic approach against different human and animal viruses. In this study, plasmid-based short hairpin RNAs (shRNAs) against three different regions in either CDV nucleoprotein (N), or large polymerase (L) genes and recombinant adenovirus-expressing N-specific multi-shRNAs were generated. Viral cytopathic effect, virus titration, plaque-forming unit reduction, and real-time quantitative RT-PCR analysis were used to check the efficiency of constructs against CDV.

RESULTS

In CDV-infected VerodogSLAM cells, shRNA-expressing plasmids targeting the N gene markedly inhibited the CDV replication in a dose-dependent manner, with viral genomes and titers being decreased by over 99%. Transfection of plasmid-based shRNAs against the L gene displayed weaker inhibition of viral RNA level and virus yield as compared to CDV N shRNAs. A combination of shRNAs targeting three sites in the N gene considerably reduced CDV RNA and viral titers, but their effect was not synergistic. Recombinant adenovirus-expressing multiple shRNAs against CDV N gene achieved a highly efficient knockdown of CDV N mRNAs and successful inhibition of CDV replication.

CONCLUSIONS

We found that this strategy had strong silencing effects on CDV replication in vitro. Our findings indicate that the delivery of shRNAs using plasmid or adenovirus vectors potently inhibits CDV replication and provides a basis for the development of therapeutic strategies for clinical trials.

Animal morbilliviruses and their cross-species transmission potential

Like measles virus (MV), whose primary hosts are humans, non-human animal morbilliviruses use SLAM (signaling lymphocytic activation molecule) and PVRL4 (nectin-4) expressed on immune and epithelial cells, respectively, as receptors. PVRL4's amino acid sequence is highly conserved across species, while that of SLAM varies significantly. However, non-host animal SLAMs often function as receptors for different morbilliviruses. Uniquely, human SLAM is somewhat specific for MV, but canine distemper virus, which shows the widest host range among morbilliviruses, readily gains the ability to use human SLAM. The host range for morbilliviruses is also modulated by their ability to counteract the host's innate immunity, but the risk of cross-species transmission of non-human animal morbilliviruses to humans could occur if MV is successfully eradicated.

Assessing the health risks of reintroduction: The example of the Amur leopard, Panthera pardus orientalis

Translocation of wildlife as a means of reintroducing or reinforcing threatened populations is an important conservation tool but carries health risks for the translocated animals and their progeny, as well as wildlife, domestic animals and humans in the release area. Disease risk analyses (DRA) are used to identify, prioritize and design mitigation strategies to address these threats. Here, we use a DRA undertaken for Amur leopards (Panthera pardus orientalis) to illustrate how specific methodology can optimize mitigation strategy design. A literature review identified a total of 98 infectious hazards and 28 non-infectious hazards. Separate analyses were undertaken for disease risks in leopards from hazards of source origin (captive zoo collections and the transit pathway to the Russian Far East), or of destination origin (in breeding enclosures and wider release areas); and for disease risks in other wildlife, domesticated species or humans, similarly from hazards of source or destination origin. Hazards were assessed and ranked as priority 1, priority 2, priority 3 or low priority in each of the defined scenarios. In addition, we undertook a generic assessment of stress on individual leopards. We use three examples to illustrate the process: Chlamydophila felis, canine distemper virus (CDV) and feline immunodeficiency virus (FIV). We found that many potentially expensive screening procedures could be performed prior to export of leopards, putting the onus of responsibility onto the zoo sector, for which access to diagnostic testing facilities is likely to be optimal. We discuss how our methods highlighted significant data gaps relating to pathogen prevalence in the Russian Far East and likely future unpredictability, in particular with respect to CDV. There was emphasis at all stages on record keeping, meticulous planning, design, staff training and enclosure management, which are relatively financially inexpensive. Actions to minimize stress featured at all time points in the strategy and also focussed on planning, design and management.

An Eight-Year Survey for Canine Distemper Virus Indicates Lack of Exposure in the Endangered Darwin's Fox (Lycalopex fulvipes)

No evidence of exposure to canine distemper virus (CDV) was detected in 70 samples corresponding to 58 wild-trapped Darwin's foxes (Lycalopex fulvipes) in Chile. Given its current endangered status and it being immunologically naïve, in the event of a CDV spillover from dogs to foxes, high population mortality is expected.

Spatiotemporal spread of sarcoptic mange in the red fox (Vulpes vulpes) in Switzerland over more than 60 years: lessons learnt from comparative analysis of multiple surveillance tools

BACKGROUND

Sarcoptic mange is a contagious skin disease of wild and domestic mammals caused by the mite Sarcoptes scabiei. Reports of sarcoptic mange in wildlife increased worldwide in the second half of the 20th century, especially since the 1990s. The aim of this study was to provide new insights into the epidemiology of mange by (i) documenting the emergence of sarcoptic mange in the red fox (Vulpes vulpes) in the last decades in Switzerland; and (ii) describing its spatiotemporal spread combining data obtained through different surveillance methods.

METHODS

Retrospective analysis of archived material together with prospective data collection delivered a large dataset from the 19th century to 2018. Methods included: (i) a review of historical literature; (ii) screening of necropsy reports from general health surveillance (1958-2018); (iii) screening of data on mange (1968-1992) collected during the sylvatic rabies eradication campaign; (iv) a questionnaire survey (<1980-2017) and (v) evaluation of camera-trap bycatch data (2005-2018).

RESULTS

Sarcoptic mange in red foxes was reported as early as 1835 in Switzerland. The first case diagnosed in the framework of the general health surveillance was in 1959. Prior to 1980, sarcoptic mange occurred in non-adjacent surveillance districts scattered all over the country. During the period of the rabies epidemic (1970s-early 1990s), the percentage of foxes tested for rabies with sarcoptic mange significantly decreased in subregions with rabies, whereas it remained high in the few rabies-free subregions. Sarcoptic mange re-emerged in the mid-1990s and continuously spread during the 2000-2010s, to finally extend to the whole country in 2017. The yearly prevalence of mange in foxes estimated by camera-trapping ranged from 0.1-12%.

CONCLUSIONS

Sarcoptic mange has likely been endemic in Switzerland as well as in other European countries at least since the mid-19th century. The rabies epidemics seem to have influenced the pattern of spread of mange in several locations, revealing an interesting example of disease interaction in free-ranging wildlife populations. The combination of multiple surveillance tools to study the long-term dynamics of sarcoptic mange in red foxes in Switzerland proved to be a successful strategy, which underlined the usefulness of questionnaire surveys.

CANINE DISTEMPER VIRUS AS AN EMERGING MULTIHOST PATHOGEN IN WILD CARNIVORES IN NORTHWEST ITALY

Canine distemper (CD) may pose a serious threat to Alpine wild carnivores and affect their population dynamics. Since 2006, the strain Europe Wildlife 2006-09, a distinct CD virus subgroup within viral lineage Europe 1 (EU1) characterized by increased virulence and host range expansion, has been linked to multiple CD outbreaks in Alpine wild carnivores. The aim of this study was to fill knowledge gaps about ongoing Alpine outbreaks of CD. To do this, we report on the circulation of canine distemper virus (CDV) and outbreaks of CD in Alpine wild carnivores in northwest Italy. A specific diagnostic protocol applied to a sample of 548 wild carnivores collected between January 2013 and December 2015 revealed the circulation of CDV belonging to the EU1 lineage. All isolates were carriers of amino-acid mutations defining the cluster Europe Wildlife 2006-09. A self-maintained multihost pathogen system may have developed in northwest Italy in which interspecies transmission from red foxes (Vulpes vulpes) to other noncanid species enhanced pathogen maintenance in the system.

Histopathological Characteristics and Expression of CDV-NP Antigen in the Brain of Serologically Positive Spontaneously Infected Red Foxes (Vulpes Vulpes) In Western Serbia

Canine distemper virus (CDV) is a worldwide distributed RNA virus that can cause severe disease in carnivore and non-carnivore species. Red foxes are highly susceptible and may act as a reservoir of the virus. As in other wild species, distemper in red foxes can manifest as acute, systemic and chronic nervous form. In the present study, we detected antibodies against CDV among red foxes in Western Serbia, and analyzed histopathologically and immunohistochemically for CDV nuclear protein antigen (CDV-NP) brain samples derived from seropositive animals. Seroprevalence of CDV antibodies was 36.8%. Histopathological changes included gliosis, neuronal degeneration, satellitosis, mononuclear inflammation, demyelination and presence of inclusion bodies. Immunostaining showed a diffuse presence of CDV-NP antigen, mainly in the cytoplasm of astrocytes and neurons. Results of this work contribute to the opinion that red foxes act as a potential reservoir of CDV and underline the importance of routine vaccination of dogs that could come in close contact with these animals. Potential active surveillance program would give a better insight in the degree of CDV infection in wildlife.

RECENT CHANGES IN INFECTIOUS DISEASES IN EUROPEAN WILDLIFE

Many infectious diseases originating from, or carried by, wildlife affect wildlife conservation and biodiversity, livestock health, or human health. We provide an update on changes in the epidemiology of 25 selected infectious, wildlife-related diseases in Europe (from 2010-16) that had an impact, or may have a future impact, on the health of wildlife, livestock, and humans. These pathogens were selected based on their: 1) identification in recent Europe-wide projects as important surveillance targets, 2) inclusion in European Union legislation as pathogens requiring obligatory surveillance, 3) presence in recent literature on wildlife-related diseases in Europe since 2010, 4) inclusion in key pathogen lists released by the Office International des Epizooties, 5) identification in conference presentations and informal discussions on a group email list by a European network of wildlife disease scientists from the European Wildlife Disease Association, or 6) identification as pathogens with changes in their epidemiology during 2010-16. The wildlife pathogens or diseases included in this review are: avian influenza virus, seal influenza virus, lagoviruses, rabies virus, bat lyssaviruses, filoviruses, canine distemper virus, morbilliviruses in aquatic mammals, bluetongue virus, West Nile virus, hantaviruses, Schmallenberg virus, Crimean-Congo hemorrhagic fever virus, African swine fever virus, amphibian ranavirus, hepatitis E virus, bovine tuberculosis ( Mycobacterium bovis), tularemia ( Francisella tularensis), brucellosis ( Brucella spp.), salmonellosis ( Salmonella spp.), Coxiella burnetii, chytridiomycosis, Echinococcus multilocularis, Leishmania infantum, and chronic wasting disease. Further work is needed to identify all of the key drivers of disease change and emergence, as they appear to be influencing the incidence and spread of these pathogens in Europe. We present a summary of these recent changes during 2010-16 to discuss possible commonalities and drivers of disease change and to identify directions for future work on wildlife-related diseases in Europe. Many of the pathogens are entering Europe from other continents while others are expanding their ranges inside and beyond Europe. Surveillance for these wildlife-related diseases at a continental scale is therefore important for planet-wide assessment, awareness of, and preparedness for the risks they may pose to wildlife, domestic animal, and human health.

Serosurvey of rabies virus, canine distemper virus, parvovirus, and influenza virus in military working dogs in Korea

Rabies virus (RABV), canine distemper virus (CDV), canine parvovirus type-2 (CPV-2), and canine influenza A virus (CIV) are important contagious pathogens in canine populations. To assess post-vaccination immunity against RABV, CDV and CPV-2, and serological evidence of exposure to influenza A virus in military working dogs (MWDs) in Korea, we tested blood samples of 78 MWDs by fluorescent antibody virus neutralization (FAVN) for RABV, and by commercially available enzyme-linked immunosorbent assay (ELISA) for CDV, CPV-2, and CIV. Korean MWDs had high antibody-positive rates against RABV (97.4%, ≥0.5 IU/ml), CDV (94.8%), and CPV (100%). All dogs tested seronegative (0/78; 0%) for influenza A virus. Two 1-year-old dogs stationed in known rabies outbreak areas (Gangwon and Gyeonggi) exhibited VNA titers below the protective level (0.06 and 0.29 IU/ml, respectively). The breed and sex of MWDs were not significantly associated with antibody titers for RABV, CDV, or CPV; however, age was significantly associated with CPV antibody titers, while region of residence was associated with CDV antibody titer. Taken together, the data presented here provide important insights necessary for post-vaccination management and control of infectious diseases in MWDs.

Serosurvey of rabies virus, canine distemper virus, parvovirus, and influenza virus in military working dogs in Korea

Rabies virus (RABV), canine distemper virus (CDV), canine parvovirus type-2 (CPV-2), and canine influenza A virus (CIV) are important contagious pathogens in canine populations. To assess post-vaccination immunity against RABV, CDV and CPV-2, and serological evidence of exposure to influenza A virus in military working dogs (MWDs) in Korea, we tested blood samples of 78 MWDs by fluorescent antibody virus neutralization (FAVN) for RABV, and by commercially available enzyme-linked immunosorbent assay (ELISA) for CDV, CPV-2, and CIV. Korean MWDs had high antibody-positive rates against RABV (97.4%, ≥0.5 IU/ml), CDV (94.8%), and CPV (100%). All dogs tested seronegative (0/78; 0%) for influenza A virus. Two 1-year-old dogs stationed in known rabies outbreak areas (Gangwon and Gyeonggi) exhibited VNA titers below the protective level (0.06 and 0.29 IU/ml, respectively). The breed and sex of MWDs were not significantly associated with antibody titers for RABV, CDV, or CPV; however, age was significantly associated with CPV antibody titers, while region of residence was associated with CDV antibody titer. Taken together, the data presented here provide important insights necessary for post-vaccination management and control of infectious diseases in MWDs.

Causes of mortality and morbidity in free-ranging mustelids in Switzerland: necropsy data from over 50 years of general health surveillance

BACKGROUND

Although mustelids occur worldwide and include a wide range of species, little is known about the diseases affecting them. Mustelids have regularly been submitted for post mortem investigation in the framework of the program for general wildlife health surveillance in Switzerland, which has been in place for nearly 60 years. We performed a retrospective analysis of the necropsy reports on mustelids submitted to the diagnostic service of the University of Bern. The aims of this study were to present an overview of the causes of mortality and morbidity observed in these carnivores, to assess differences among species, to assess changes in disease detection over the study period, and to describe the pathology of selected diseases.

RESULTS

Five hundred and sixty-six reports from 1958 to 2015 were analyzed. Most animals were stone martens (Martes foina, 46%) and badgers (Meles meles, 44%); the remaining species were polecats (Mustela putorius, 4.7%), pine martens (Martes martes, 2%), stoats (Mustela erminea, 1.4%), weasels (Mustela nivalis, 0.8%) and otters (Lutra lutra, 0.3%). Infectious diseases (n = 262) were frequent and were mostly bacterial or viral; non-infectious conditions (n = 169) were less common and were mostly traumatic or due to metabolic disorders. The most frequent diagnoses included distemper (75% were badgers), amyloidosis (96% were martens), bacterial respiratory infections (all mustelids), biting lice (badgers only) and pulmonary and gastro-intestinal helminths (all species). Less frequent diseases included histoplasmosis (badgers only), aspergillosis, toxoplasmosis, hepatozoonosis, and sarcoptic mange. Lesions due to infection with distemper virus were primarily appreciated in the respiratory tract and central nervous system; they presented species-specific characteristics such as necrosis in the ependyma in badgers and absence of syncytia in stone martens. Amyloidosis in martens was multisystemic in most cases and included both AA and AL amyloidosis; the main macroscopic change was severe splenomegaly.

CONCLUSION

Infectious diseases were the most frequent causes of morbidity and mortality of mustelids, with marked species-specific differences. Lung and skin were the most commonly affected organs. Contagious diseases such as canine distemper, sarcoptic mange and rabies in mustelids showed a similar temporal pattern as in red foxes (Vulpes vulpes), suggesting pathogen spillovers from foxes to mustelids.

Detection of morbillivirus infection by RT-PCR RFLP analysis in cetaceans and carnivores

Morbillivirus genus comprises several members related to specific hosts, such as canine distemper virus (CDV) and cetacean morbillivirus (CeMV) in which the dolphin morbillivirus (DMV) is included. Both CDV and DMV are able to cause serious outbreak associated with high morbidity and mortality representing an important conservation threat for terrestrial and aquatic mammalian species. This paper describes a new RT-PCR RFLP technique based on a RT-PCR with degenerate primers targeting a 287 bp fragment located on the conserved N terminus of the morbillivirus NP gene, followed by MseI RFLP, in order both to confirm the detection of the virus and to distinguish DMV from CDV. Both carnivores and cetaceans tissues (brain, lung and lymph node) presenting evidence of morbillivirus infection (MI) were analyzed. RT-PCR positive samples were typed by RFLP analysis and then sequenced to confirm the RFLP results. This method was applied during the last morbillivirus cetacean die-off occurred in the Mediterranean basin in 2013, when there was the urgent need of a rapid and economic method to investigate among causes of death on stranded cetaceans. This new technique has proved to be a valuable, reliable, simple and relatively inexpensive diagnostic tool easily applicable also in limited-resource laboratories.

Canine distemper virus in the Serengeti ecosystem: molecular adaptation to different carnivore species

Was the 1993/1994 fatal canine distemper virus (CDV) epidemic in lions and spotted hyaenas in the Serengeti ecosystem caused by the recent spillover of a virulent domestic dog strain or one well adapted to these noncanids? We examine this question using sequence data from 13 'Serengeti' strains including five complete genomes obtained between 1993 and 2011. Phylogenetic and haplotype network analyses reveal that strains from noncanids during the epidemic were more closely related to each other than to those from domestic or wild canids. All noncanid 'Serengeti' strains during the epidemic encoded: (1) one novel substitution G134S in the CDV-V protein; and (2) the rare amino acid combination 519I/549H at two sites under positive selection in the region of the CDV-H protein that binds to SLAM (CD 150) host cell receptors. Worldwide, only a few noncanid strains in the America II lineage encode CDV-H 519I/549H. All canid 'Serengeti' strains during the epidemic coded CDV-V 134G, and CDV-H 519R/549Y, or 519R/549H. A functional assay of cell entry revealed the highest performance by CDV-H proteins encoding 519I/549H in cells expressing lion SLAM receptors, and the highest performance by proteins encoding 519R/549Y, typical of dog strains worldwide, in cells expressing dog SLAM receptors. Our findings are consistent with an epidemic in lions and hyaenas caused by CDV variants better adapted to noncanids than canids, but not with the recent spillover of a dog strain. Our study reveals a greater complexity of CDV molecular epidemiology in multihost environments than previously thought.

Lethal distemper in badgers (Meles meles) following epidemic in dogs and wolves

Canine distemper virus (CDV) represents an important conservation threat to many wild carnivores. A large distemper epidemic sustained by an Arctic-lineage strain occurred in Italy in 2013, mainly in the Abruzzi region, causing overt disease in domestic and shepherd dogs, Apennine wolves (Canis lupus) and other wild carnivores. Two badgers were collected by the end of September 2015 in a rural area of the Abruzzi region and were demonstrated to be CDV-positive by real time RT-PCR and IHC in several tissues. The genome of CDV isolates from badgers showed Y549H substitution in the mature H protein. By employing all publicly available Arctic-lineage H protein encoding gene sequences, six amino acid changes in recent Italian strains with respect to Italian strains of dogs from 2000 to 2008, were observed. A CDV strain belonging to the European-wildlife lineage was also identified in a fox found dead in the same region in 2016, proving co-circulation of an additional CDV lineage.

Application of xenogeneic anti-canine distemper virus antibodies in treatment of canine distemper puppies

OBJECTIVE

The clinical feasibility of passive immunotherapy has not been demonstrated in dogs naturally infected with canine distemper. In this study, porcine anti-canine distemper virus IgG and F(ab')₂ antibody fragments were used to treat infected puppies.

METHODS

A total of 41 naturally infected puppies (age Äsix months) exhibiting severe respiratory signs, but lacking neurological signs, were enrolled in the study. Twenty-five puppies were treated with a combination of IgG or F(ab')₂ antibody fragments (Group 1) and supportive therapy and 16 puppies received routine supportive care only (Group 2).

RESULTS

The survival rate of dogs in Group 1 (19/25; 76%) was significantly higher than that in Group 2 (5/16; 31·3%) (P<0·05). During the therapy, 8 of the 25 dogs (32%) in Group 1 developed neurological signs versus 12 of the 16 dogs (75%) in Group 2 (P<0·05). Adverse reactions were limited to elevated body temperature in dogs that received IgG antibodies.

CLINICAL SIGNIFICANCE

Porcine anti-canine distemper virus antibodies improved survival in puppies affected with canine distemper with minimal adverse effects. Therefore, this therapy could be considered for treatment of endangered animal species infected with canine distemper virus.

Screening red foxes (Vulpes vulpes) for possible viral causes of encephalitis

Background

Next to various known infectious and non-infectious causes, the aetiology of non-suppurative encephalitis in red foxes (Vulpes vulpes) often remains unclear. Known causes in foxes imply rabies, canine distemper, toxoplasmosis, Aujeszky’s disease, as well as parvovirus, adenovirus, circovirus and flavivirus infections. In this study, particular attention was paid on bornaviruses, since red foxes are predators of bicoloured white-toothed shrews, a reservoir of Borna disease virus 1 (BoDV-1). In addition, foxes are known to be highly susceptible for viruses of the order Mononegavirales.

Methods

Analyses for the presence of anti-BoDV-1 antibodies, BoDV-1-RNA and antigen were performed on 225 blood and 59 brain samples, from a total of 232 red foxes. Foxes originated from BoDV-1 endemic and non-endemic German areas. Additional investigations for the presence of rabies, canine distemper, toxoplasmosis, Aujeszky’s disease, parvovirus, adenovirus and flavivirus infections were carried out on 16 red foxes with non-suppurative (meningo-) encephalitis. A metagenomic analysis was used on three representative brain samples displaying encephalitis.

Results

Among 225 foxes, 37 displayed anti-BoDV-1 antibodies with titres ranging between 1:40 and 1:2560, regardless of geographic origin. In 6 out of 16 foxes with encephalitis, canine distemper virus was detected. No evidence of any of the other investigated agents was found in the 16 fox brains with encephalitis. Metagenomics revealed no infectious agents, except for one already known canine distemper case.

Conclusion

Red foxes can exhibit BoDV-1 specific antibodies without association with geographic origin or encephalitis due to bornavirus infection. The encephalitis pattern was highly conspicuous for a viral infection, but remained unclear in 10 out of 16 foxes. Thus, presently unknown infectious and non-infectious causes need to be considered and further investigated, especially since foxes also tend to occur in human proximity.