PREVALENCE OF ANTIBODY TO ALEUTIAN MINK DISEASE VIRUS IN EUROPEAN MINK (MUSTELA LUTREOLA) AND AMERICAN MINK (NEOVISON VISON) IN SPAIN

Molecular ecology of novel amdoparvoviruses and old protoparvoviruses in Spanish wild carnivorans

Wild carnivorans are key hosts of parvoviruses of relevance for animal health and wildlife conservation. However, the distribution and diversity of parvoviruses among wild carnivorans are under-investigated, particularly in Southern Europe. We evaluated the presence, spread, and diversity of multi-host protoparvoviruses (canine parvovirus type 2 (CPV-2), feline panleukopenia virus (FPV)), and amdoparvoviruses in 12 carnivoran species from Northern Spain to explore viral ecology. Broad-range PCRs were used to screen spleens (N = 157) and intestines (N = 116) from 171 road-killed mustelids, viverrids, and felids; identified viruses were molecularly characterized. We detected an Asian-like CPV-2c strain in the spleen of one wildcat (Felis silvestris, 1/40, 2.5 %), a globally distributed FPV strain in the spleen of one Eurasian badger (Meles meles, 1/35, 2.9 %), a novel amdoparvovirus (European mustelid amdoparvovirus 1), in the intestine and spleen of one stone marten (Martes foina, 1/16, 6.3 %) and in the spleen of one Eurasian badger (1/35, 2.9 %), the red fox fecal amdovirus (RFFAV) in the intestine and spleen of three wildcats (3/40, 7.5 %), and a novel amdoparvovirus closely related to RFFAV (European felid amdoparvovirus 1) in one wildcat (1/40, 2.5 %). We observed a correlation between the phylogeny of carnivorans and the one of amdoparvoviruses, possibly indicating virus-host co-evolution. Species originating from North America and Eurasia formed different clades, indicating local segregation in the absence of man-linked transboundary movements. In contrast, CPV-2 and FPV strains were internationally dispersed. Different parvovirus species co-occur in sympatric host populations, and higher viral diversity and additional hosts will likely be identified in future studies.

Drivers Shaping Spillover of Aleutian Mink Disease Virus Introduced With American Mink Among Native Mustelids

Invasive alien species pose a major threat to ecosystems by outcompeting native species for resources, altering habitats, enabling potential genetic hybridisation and introducing pathogens into the environment. An understanding of the factors that determine virus transfer between invasive and native species is crucial to the mitigation of the negative impact of the pathogens introduced. This study presents a comprehensive analysis of factors influencing Aleutian mink disease virus (AMDV) infection in native mustelids in Poland, following its introduction by feral American mink. AMDV seroprevalence in American mink varied spatially from 0 in the central and southern regions to 0.8 in the northern regions. Antibodies to AMDV were detected in all six studied mustelids, including a novel finding in weasels. AMDV seroprevalence in other mustelids correlated positively with its occurrence in American mink, and reached 0.54 in areas with the highest mink AMDV seroprevalence. Furthermore, in native mustelids, more closely phylogenetically related to mink, AMDV seroprevalence was higher (0.68 in polecats and weasels) compared to more distantly related species (0.37 in badgers). Over the 27-year study period, AMDV seroprevalence in mustelids has increased from 0.04 to 0.60, despite a decline in seroprevalence in feral mink in subsequent years. These findings suggest that the spread of viral infections as a result of the introduction of invasive species could affect mustelid species and may intensify over time.

Prevalence of Aleutian Mink Disease Virus (AMDV) in Free-Ranging American Mink from Biebrza and Narew National Parks (Poland)-An Epidemiological Concern

Aleutian Mink Disease Virus (AMDV) is the causative agent of Aleutian disease (AD). This progressive and chronic disorder significantly impacts the mink breeding industry, affecting farmed and free-ranging American and European mink. This study investigated AMDV variants isolated from free-ranging American mink in northeastern Poland. Between 2018 and 2019, 26 spleen samples were collected from mink in Narew National Park (NNP) and Biebrza National Park (BNP). DNA was extracted and subjected to PCR to amplify the NS1 gene, followed by sequencing and phylogenetic analysis. The NS1 gene was detected in 50% of samples from NNP minks and in 30% of samples from BNP minks, with an overall prevalence of 42.31%; these findings align with global data and indicate serious ecological and health concerns. Ten closely related AMDV variants and one distinct variant were identified. The grouped variants exhibited high genetic homogeneity, closely related to strains found in mink from the USA, Germany, Greece, Latvia, and Poland; meanwhile, the distinct variant showed similarities to strains found in mink from Finland, Denmark, China, Poland, and Latvia, suggesting multiple infection sources. These findings, consistent with data from Polish mink farms, indicate significant genetic similarity between farmed and wild mink strains, suggesting potential bidirectional transmission. This underscores the importance of a One Health approach, emphasizing the interconnectedness of human, animal, and environmental health. Continuous surveillance and genetic studies are crucial for understanding AMDV dynamics and mitigating their impacts. Measures to reduce transmission between farmed and wild mink populations are vital for maintaining mink health and ecosystem stability.

Genomic characterization and phylogenetic analysis of Aleutian mink disease virus identified in a sudden death mink case

Aleutian mink disease (AMD) is one of the most serious diseases in minks worldwide, it brings tremendous financial losses in mink farming. AMD virus (AMDV) has unusually high genetic diversity, its genomic structure remains unclear. In 2014, sudden death of breeding minks was occurred in northeast China. After clinical signs evaluation and virus isolation, AMDV was identified in all sudden death minks, we investigated the complete genomic sequence of AMDV-LM isolated from the sudden death case. The full-genome sequence of AMDV-LM was 7 nucleotides (nts) or 8 nts longer than isolates AMDV-BJ and AMDV-G. AMDV-LM contained two unique nucleotide changes in VP2 (G79T, T710C), which led to two amino acid changes G27W and L237S. For NS1, some unique point mutations, such as A374C, A428C, A463C, and T476A were found and resulted in four unique amino acid mutations at N24V, H125P, V143P, K155Q, and V159N, respectively. The predicted secondary structure of the 5' terminal of AMDV-LM formed a large bubble formation near the 5' end, which affected the stability of the U-shaped hairpin. Phylogenetic analysis demonstrated that AMDV-LM was closely related to Chinese isolates and confirmed that AMDV strains circulating in China had different origins of ancestors. This study was first to investigate the association of sudden death of adult breeding minks with AMDV infection. Our findings provide useful suggestions for evaluation of the pathogenic potential of AMDV, additional details on AMDV genome characterization were also presented. Future work should focus on the importance of AMDV-LM strain in mink infection.

Asymptomatic viral infection is associated with lower host reproductive output in wild mink populations

Many endemic viruses circulate in populations without hosts showing visible signs of disease, while still having the potential to alter host survival or reproduction. Aleutian Mink Disease Virus (AMDV) circulates in many American mink (Neogale vison) populations in its native and introduced ranges. In this study, we analysed how AMDV infection in female American mink affects the reproduction of a feral population. Females infected with AMDV delivered significantly smaller litters (5.8 pups) than uninfected females (6.3 pups), meaning their litter size was reduced by 8%. Larger females and yearling females had larger litters than smaller and older females. There were no significant differences in whole litter survival between infected and uninfected females; however, offspring survival until September or October within litters of infected females was 14% lower than that within those of uninfected females. This negative link between infection and reproductive output means that Aleutian disease could seriously affect the wild mink population. This study increases our understanding of the threats posed by the spread of viruses to wildlife from farm animals or humans, highlighting that viruses circulating in wildlife, even in the absence of clinical manifestation, can be important drivers of population dynamics in wildlife.

Seroprevalence and Molecular Epidemiology of Aleutian Disease in Various Countries during 1972-2021: A Review and Meta-Analysis

Simple Summary

Aleutian disease is caused by the Aleutian mink disease virus and is one of the most serious infectious diseases that affect the family Mustelidae, including the American mink, wild European mink, weasels, badgers and other animal species, such as skunks, raccoons, dogs, cats and mice, as well as humans. Effective treatments and vaccines against Aleutian disease have not been developed to date. Prophylactic programs that focus on the identification and elimination of infected mink are one of the methods of controlling the negative outcomes of Aleutian disease. This article analyses the seroprevalence of Aleutian mink disease virus infections in American and European mink and other species around the world, and reviews recent knowledge relating to the molecular epidemiology of the Aleutian mink disease virus.

Abstract

Aleutian disease (AD) poses a serious threat to both free-ranging and farmed mink around the world. The disease is caused by the Aleutian mink disease virus (AMDV), which also poses a health risk for other members of the family Mustelidae, including wild mink, weasels, badgers and other animal species. This article analyses the seroprevalence of AMDV infections in mink and other species around the world, and reviews recent knowledge relating to the molecular epidemiology of the AMDV. Depending on the applied diagnostic technique and the country, the prevalence of anti-AMDV antibodies or AMDV DNA was established at 21.60–100.00% in farmed American mink, 0.00–93.30% in free-ranging American mink and 0.00–25.00% in European mink. Anti-AMDV antibodies or AMDV DNA were also detected in other free-living fur-bearing animals in Europe and Canada, where their prevalence was determined at 0.00–32.00% and 0.00–70.50%, respectively. This may indicate a potential threat to various animal species. AMDV strains are not clustered into genotypes based on the geographic origin, year of isolation or pathogenicity. The isolates that were identified on mink farms around the world originated from North America because American mink were introduced to Europe and Asia for breeding purposes and to restock natural populations.

Surrounded by challenges: The simulated presence of competitors and predators modulates perianal secretion marking behaviour in the European mink (Mustela lutreola)

Animals face a variety of daily challenges to their reproduction and survival that can detect in time through to the environment cues. By using an individual focal sampling, we evaluated the variations in the time devoted to the perianal secretion marking behaviour (PSMB) of European mink when they were exposed to the simulated presence of conspecifics and two potential predators. Model results indicated that males and adult individuals dedicated more time to PSMB than females and subadults. The presence of conspecifics increased PSMB time only in adult and males, probably as an intrasexual territorial competence response. The heightened decrease in PSMB time in presence of a dog suggests an innate response due to the detection of volatile substances from faeces of carnivorous. In addition, simulated conspecific presence increased PSMB in absence of odours (control) and with owl faeces. However, when facing dog faeces, the simulated conspecific presence had no effects on PSMB. Thus, minks seem to prioritize the imminent risk of predation to avoid being detected. The stimulation of PSMB in captivity by simulated cues from conspecifics and potential predators could be useful to facilitate the reintroduction of individuals into nature, as well as their adaptation and survival.

Aleutian mink disease: Spatio-temporal variation of prevalence and influence on the feral American mink

Pathogens are one of the factors driving wildlife population dynamics. The spread of pathogens in wildlife is currently highly related to the transmission of pathogens from farmed animals, which has increased with the constant development of farming. Here, we analysed the spatio-temporal variation in the prevalence of Aleutian mink disease virus (AMDV) antibodies in feral American mink (Neovison vison) populations in Poland (1,153 individuals from nine sites) in relation to mink farming intensity. AMDV was detected in feral mink at all study sites and the prevalence ranged from 0.461 in the northern region to 0.826 in the western region. Mink males and adults were infected more often than females and subadults; the infection was also more frequent during the mink breeding season than during non-breeding. The prevalence of AMDV changed non-linearly in consecutive years and the peak of prevalence was every 3-4 years. The predicted AMDV prevalence was low at sites where the number of farmed mink was also low and increased linearly with the increase in the number of mink kept on farms. The predicted AMDV prevalence at sites with low mink farming intensity strongly varied between years, whereas at sites with high mink farming intensity, the predicted prevalence did not change significantly. AMDV infection affected the mink's body condition and caused an increase in the size of the spleen, liver and kidneys. This study shows that Aleutian mink disease strongly affects feral mink but the spatio-temporal variation of its prevalence is complex and partly related to the transmission of the virus from farmed mink to feral populations. The study highlights the complexity of AMDV circulation in feral mink populations and implicates a potential spillover of the virus to native species.

Estimation of the Age and Reproductive Performance of Wild-Born and Escaped Mink (Neovison vison) Caught in the Wild in Denmark

Simple Summary

Previous studies of wild caught mink in Denmark showed that 30–80% had recently escaped from farms. Therefore, it is debated whether a self-sustaining feral mink population is established in Denmark or whether the population rests upon a continuous contribution of captive-born farm mink. Knowledge regarding the reproduction and mortality of mink adapted for living in the wild is important for the management of feral mink. In this study, we separated wild-born from captive-born mink caught in the wild in Denmark. To be able to age the mink in this study, an age determination model for mink was developed based on the width of the pulp cavity. The mean litter size of wild-born female mink was 7.6 (range: 5–11 kits). The annual turnover of mink caught in the wild was estimated to be 66%, and the yearly mortality was 69%; thus, the population of wild-born mink is slightly declining. The results confirmed that the wild-born mink population in Denmark is reproducing and self-sustaining without a continuous influx of captive-born mink escaped from farms. The effect of escaped mink on the wild mink population will depend on the currently unknown ability of captive mink to survive in the wild.

Abstract

The feral mink population in Denmark consists of two groups of animals: mink born in the wild and mink that have recently escaped from farms. The aims of this study were to: (1) estimate the reproductive performance and mortality of the Danish mink born in the wild (wild-born) and mink escaped from farms (captive-born); (2) discuss the likelihood of a self-sustaining population of wild-born mink in Denmark; and (3) model the relationship between the pulp cavity width and the age of mink. During 2018, 247 wild caught mink were sent for necropsy at the Danish National Veterinary Institute. Based on body length, 112 were determined as captive-born and 96 as wild-born. The mean litter size ± SE of wild-born females was 7.6 ± 0.9 (range: 5–11 kits) and for captive-born females 5.9 ± 0.9 (range: 1–10 kits). The relationship between age (in months) of mink and pulp cavity width was highly significant. Individuals with a pulp cavity width of >35% were younger than one year. Based on fecundity, the turnover of the mink population was estimated to be 66%, and the yearly mortality was estimated at 69%. Hence, the population is slightly declining. In conclusion, a feral reproducing mink population in Denmark persists without a continuous influx of captive-born mink from farms.

Molecular epidemiology of Aleutian mink disease virus causing outbreaks in mink farms from Southwestern Europe: a retrospective study from 2012 to 2019

BACKGROUND

Aleutian mink disease virus (AMDV) causes major economic losses in fur-bearing animal production. The control of most AMDV outbreaks is complex due to the difficulties of establishing the source of infection based only on the available on-farm epidemiological data. In this sense, phylogenetic analysis of the strains present in a farm may help elucidate the origin of the infection and improve the control and biosecurity measures.

OBJECTIVES

This study had the following aims: characterize the AMDV strains from most outbreaks produced at Spanish farms between 2012-2019 at the molecular level, and assess the utility of the combined use of molecular and epidemiological data to track the possible routes of infection.

METHODS

Thirty-seven strains from 17 farms were partially sequenced for the NS1 and VP2 genes and analyzed phylogenetically with other strains described worldwide.

RESULTS

Spanish AMDV strains are clustered in four major clades that generally show a good geographical correlation, confirming that most had been established in Spain a long time ago. The combined study of phylogenetic results and epidemiological information of each farm suggests that most of the AMDV outbreaks since 2012 had been produced by within-farm reservoirs, while a few of them may have been due to the introduction of the virus through international trade.

CONCLUSIONS

The combination of phylogenetic inference, together with epidemiological data, helps assess the possible origin of AMDV infections in mink farms and improving the control and prevention of this disease.

Neoplasms and novel gammaherpesviruses in critically endangered captive European minks (Mustela lutreola)

The European mink (Mustela lutreola) is a riparian mustelid, considered one of the most endangered carnivores in the world. Alpha, beta and gammaherpesviruses described in mustelids have been occasionally associated with different pathological processes. However, there is no information about the herpesviruses species infecting European minks. In this study, 141 samples of swabs (oral, conjunctival, anal), faeces and tissues from 23 animals were analysed for herpesvirus (HV) using a pan-HV-PCR assay. Two different, potentially novel, gammaherpesvirus species were identified in 12 samples from four animals (17.3%), and tentatively named Mustelid gammaherpesvirus-2 (MUGHV-2) and MuGHV-3. Gross examination was performed on dead minks (n = 11), while histopathology was performed using available samples from HV-positive individuals (n = 2), identifying several neoplasms, including B-cell lymphoma (identified by immunohistochemistry) with intralesional syncytia and intranuclear inclusion bodies characteristic of HV (n = 1), pulmonary adenocarcinoma (n = 1), and biliary (n = 1) and preputial (n = 1) cystadenomas, as well as other lesions (e.g., axonal vacuolar degeneration [n = 2] and neuritis [n = 1]). Viral particles, consistent with HVs, were observed by electron microscopy in the mink with neural lymphoma and inclusion bodies. This is the first description of neoplasms and concurrent gammaherpesvirus infection in European minks. The pathological, ultrastructural and PCR findings (MuGHV-2) in the European mink with lymphoma strongly suggest a potential role for this novel gammaherpesvirus in its pathogenesis, as it has been reported in other HV-infected species with lymphoma. The occurrence of neural lymphoma with intralesional syncytia and herpesviral inclusions is, however, unique among mammals. Further research is warranted to elucidate the potential oncogenic properties of gammaherpesviruses in European mink and their epidemiology in the wild population.