Assuntos
Pelo Animal , Criação de Animais Domésticos , Pandemias , Pesquisadores , Zoonoses Virais , Animais , Humanos , Raposas/virologia , Vison/virologia , Pandemias/estatística & dados numéricos , Pandemias/veterinária , Pelo Animal/virologia , Zoonoses Virais/epidemiologia , Zoonoses Virais/transmissão , Zoonoses Virais/virologiaRESUMO
Animals such as raccoon dogs, mink and muskrats are farmed for fur and are sometimes used as food or medicinal products1,2, yet they are also potential reservoirs of emerging pathogens3. Here we performed single-sample metatranscriptomic sequencing of internal tissues from 461 individual fur animals that were found dead due to disease. We characterized 125 virus species, including 36 that were novel and 39 at potentially high risk of cross-species transmission, including zoonotic spillover. Notably, we identified seven species of coronaviruses, expanding their known host range, and documented the cross-species transmission of a novel canine respiratory coronavirus to raccoon dogs and of bat HKU5-like coronaviruses to mink, present at a high abundance in lung tissues. Three subtypes of influenza A virus-H1N2, H5N6 and H6N2-were detected in the lungs of guinea pig, mink and muskrat, respectively. Multiple known zoonotic viruses, such as Japanese encephalitis virus and mammalian orthoreovirus4,5, were detected in guinea pigs. Raccoon dogs and mink carried the highest number of potentially high-risk viruses, while viruses from the Coronaviridae, Paramyxoviridae and Sedoreoviridae families commonly infected multiple hosts. These data also reveal potential virus transmission between farmed animals and wild animals, and from humans to farmed animals, indicating that fur farming represents an important transmission hub for viral zoonoses.
Assuntos
Vison , Animais , Vison/virologia , Zoonoses/transmissão , Zoonoses/virologia , Cães Guaxinins/virologia , Zoonoses Virais/transmissão , Zoonoses Virais/virologia , Humanos , Coronavirus/isolamento & purificação , Coronavirus/genética , Coronavirus/classificação , Animais Domésticos/virologia , Especificidade de Hospedeiro , Reservatórios de Doenças/virologia , Reservatórios de Doenças/veterinária , Cães , Feminino , Vírus da Influenza A/isolamento & purificação , Vírus da Influenza A/fisiologia , Vírus da Influenza A/genética , Vírus da Influenza A/patogenicidade , Masculino , Filogenia , Pulmão/virologiaRESUMO
In late 2020, the focus of the global effort against the COVID-19 pandemic centered around the development of a vaccine, when reports of a mutated SARS-CoV-2 virus variant in a population of 17 million farmed mink came from Denmark, threatening to jeopardize this effort. Spillover infections of the new variant between mink and humans were feared to threaten the efficacy of upcoming vaccines. In this study the ensuing short-lived yet stringent lockdowns imposed in 7 of the countries 98 municipalities are analysed for their effectiveness to reduce SARS-CoV-2 infections. Synthetic counterfactuals are created for each of these municipalities using a weighted average combination of the remaining municipalities not targeted by the stringent measures. This allows for a clear overview regarding the development of test-positivity rates, citizen mobility behaviours and lastly daily infection numbers in response to the restrictions. The findings show that these targeted, short-term lockdowns significantly curtailed further infections, demonstrating a marked decrease, first in citizens mobility and then in daily cases when compared to their synthetic counterfactuals. Overall, the estimates indicate average reductions to infection numbers to be around 31%. This study underscores the potential of strict, yet severe lockdowns in breaking ongoing infection dynamics, by utilising a rare quasi-experimental design case that avoids bias introduced through treatment selection.
Assuntos
COVID-19 , Cidades , SARS-CoV-2 , COVID-19/epidemiologia , COVID-19/prevenção & controle , COVID-19/virologia , COVID-19/transmissão , Dinamarca/epidemiologia , Humanos , SARS-CoV-2/isolamento & purificação , SARS-CoV-2/genética , Animais , Quarentena , Vison/virologia , Controle de Doenças Transmissíveis/métodos , Pandemias/prevenção & controleRESUMO
In 2020, Denmark buried approximately four million culled, farmed mink in mass graves treated with slaked lime due to widespread SARS-CoV-2 infections. After six months, environmental concerns prompted the exhumation of these cadavers. Our analysis encompassed visual inspections, soil pH measurements, and gas emission assessments of the grave environment. Additionally, we evaluated carcasses for decay status, cadaverine content, and the presence of various pathogens, including SARS-CoV-2 and mink coronavirus. Our findings revealed minimal microbial activity and limited carcass decomposition. Although viral RNA from SARS-CoV-2 and mink coronavirus, along with DNA from Aleutian mink disease virus, were detected, the absence of infectious SARS-CoV-2 in cell culture assays suggests slow natural degradation processes. This study provides critical insights for future considerations in managing mass burial scenarios during outbreaks of livestock-associated zoonotic pathogens.
Assuntos
Sepultamento , COVID-19 , Vison , SARS-CoV-2 , Animais , Vison/virologia , COVID-19/epidemiologia , COVID-19/virologia , SARS-CoV-2/isolamento & purificação , Dinamarca , Pandemias , Cadáver , Humanos , RNA Viral/genética , Coronavirus/isolamento & purificação , Coronavirus/genéticaRESUMO
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) not only caused the COVID-19 pandemic but also had a major impact on farmed mink production in several European countries. In Denmark, the entire population of farmed mink (over 15 million animals) was culled in late 2020. During the period of June to November 2020, mink on 290 farms (out of about 1100 in the country) were shown to be infected with SARS-CoV-2. Genome sequencing identified changes in the virus within the mink and it is estimated that about 4000 people in Denmark became infected with these mink virus variants. However, the routes of transmission of the virus to, and from, the mink have been unclear. Phylogenetic analysis revealed the generation of multiple clusters of the virus within the mink. Detailed analysis of changes in the virus during replication in mink and, in parallel, in the human population in Denmark, during the same time period, has been performed here. The majority of cases in mink involved variants with the Y453F substitution and the H69/V70 deletion within the Spike (S) protein; these changes emerged early in the outbreak. However, further introductions of the virus, by variants lacking these changes, from the human population into mink also occurred. Based on phylogenetic analysis of viral genome data, we estimate, using a conservative approach, that about 17 separate examples of mink to human transmission occurred in Denmark but up to 59 such events (90% credible interval: (39-77)) were identified using parsimony to count cross-species jumps on transmission trees inferred using Bayesian methods. Using the latter approach, 136 jumps (90% credible interval: (117-164)) from humans to mink were found, which may underlie the farm-to-farm spread. Thus, transmission of SARS-CoV-2 from humans to mink, mink to mink, from mink to humans and between humans were all observed.
Assuntos
COVID-19 , Vison , Filogenia , SARS-CoV-2 , Vison/virologia , COVID-19/transmissão , COVID-19/virologia , COVID-19/epidemiologia , COVID-19/veterinária , SARS-CoV-2/genética , Animais , Dinamarca/epidemiologia , Humanos , Pandemias , Fazendas , Betacoronavirus/genética , Betacoronavirus/classificação , Genoma Viral , Infecções por Coronavirus/veterinária , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/virologia , Infecções por Coronavirus/transmissão , Glicoproteína da Espícula de Coronavírus/genéticaRESUMO
Morbillivirus canis (canine distemper virus (CDV)) is recognized as a multihost pathogen responsible for a transmissible disease affecting both domestic and wild animals. A considerable portion of wildlife populations remain unvaccinated due to a lack of safety and immunogenicity data on existing vaccines for the prevention of CDV infection in these species. This review aimed to assess the current state of CDV vaccination research for both domestic and wild animals and to explore novel vaccine candidates through in vivo studies. It also sought to synthesize the scattered information from the extensive scientific literature on CDV vaccine research, identify key researchers in the field, and highlight areas where research on CDV vaccination is lacking. A scoping review was conducted across four databases following the PRISMA-ScR protocol, with information analyzed using absolute and relative frequencies and 95% confidence intervals (CIs) for study number proportions. Among the 2321 articles retrieved, 68 met the inclusion criteria and focused on CDV vaccines in various animal species, such as dogs, ferrets, minks, and mice. Most of the scientific community involved in this research was in the USA, Canada, France, and Denmark. Various vaccine types, including MLV CDV, recombinant virus, DNA plasmids, inactivated CDV, and MLV measles virus (MeV), were identified, along with diverse immunization routes and schedules employed in experimental and commercial vaccines. Safety and efficacy data were summarized. Notably, 37 studies reported postimmunization CDV challenge, primarily in dogs, revealing the survival rates of vaccinated animals. In summary, CDV vaccines generally demonstrate an acceptable safety profile in dogs and show promise as a means of controlling CDV. However, significant gaps in vaccine research persist, particularly concerning wildlife reservoirs, indicating the need for further investigation.
Assuntos
Animais Domésticos , Animais Selvagens , Vírus da Cinomose Canina , Cinomose , Vacinação , Vacinas Virais , Animais , Animais Selvagens/virologia , Vírus da Cinomose Canina/imunologia , Vírus da Cinomose Canina/genética , Vacinas Virais/imunologia , Vacinas Virais/efeitos adversos , Vacinas Virais/administração & dosagem , Cinomose/prevenção & controle , Cinomose/imunologia , Cinomose/virologia , Vacinação/veterinária , Cães , Furões , Camundongos , Imunogenicidade da Vacina , Vison/virologia , Vison/imunologiaRESUMO
Introduction: Endogenous retroviruses (ERVs), which originated from exogenous retroviral infections of germline cells millions of years ago and were inherited by subsequent generations as per Mendelian inheritance patterns, predominantly comprise non-protein-coding sequences due to the accumulation of mutations, insertions, deletions, and truncations. Nevertheless, recent studies have revealed that ERVs play a crucial role in diverse biological processes by encoding various proteins. Methods: In this study, we successfully identified an ERV envelope (env) gene in a mink species. A phylogenetic tree of mink ERV-V env and reference sequences was constructed using Bayesian methods and maximum-likelihood inference. Results: Phylogenetic analyses indicated a significant degree of sequence conservation and positive selection within the env-surface open reading frame. Additionally, qRT-PCR revealed diverse patterns of mink ERV-V env expression in various tissues. The expression of mink ERV-V env gene in testicular tissue strongly correlated with the seasonal reproductive cycles of minks. Discussion: Our study suggests that the ERV-V env gene in mink may have been repurposed for host functions.
Assuntos
Retrovirus Endógenos , Vison , Filogenia , Retrovirus Endógenos/genética , Animais , Vison/virologia , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/metabolismo , Estações do Ano , Reprodução/genética , Masculino , Testículo/virologia , Teorema de BayesRESUMO
Highly pathogenic avian influenza (HPAI) has caused widespread mortality in both wild and domestic birds in Europe 2020-2023. In July 2023, HPAI A(H5N1) was detected on 27 fur farms in Finland. In total, infections in silver and blue foxes, American minks and raccoon dogs were confirmed by RT-PCR. The pathological findings in the animals include widespread inflammatory lesions in the lungs, brain and liver, indicating efficient systemic dissemination of the virus. Phylogenetic analysis of Finnish A(H5N1) strains from fur animals and wild birds has identified three clusters (Finland I-III), and molecular analyses revealed emergence of mutations known to facilitate viral adaptation to mammals in the PB2 and NA proteins. Findings of avian influenza in fur animals were spatially and temporally connected with mass mortalities in wild birds. The mechanisms of virus transmission within and between farms have not been conclusively identified, but several different routes relating to limited biosecurity on the farms are implicated. The outbreak was managed in close collaboration between animal and human health authorities to mitigate and monitor the impact for both animal and human health.
Assuntos
Animais Selvagens , Charadriiformes , Surtos de Doenças , Virus da Influenza A Subtipo H5N1 , Influenza Aviária , Filogenia , Animais , Influenza Aviária/virologia , Influenza Aviária/epidemiologia , Finlândia/epidemiologia , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/patogenicidade , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Animais Selvagens/virologia , Charadriiformes/virologia , Surtos de Doenças/veterinária , Fazendas , Infecções por Orthomyxoviridae/veterinária , Infecções por Orthomyxoviridae/virologia , Infecções por Orthomyxoviridae/mortalidade , Infecções por Orthomyxoviridae/epidemiologia , Raposas/virologia , Aves/virologia , Vison/virologiaRESUMO
Outbreaks of highly pathogenic H5N1 clade 2.3.4.4b viruses in farmed mink and seals combined with isolated human infections suggest these viruses pose a pandemic threat. To assess this threat, using the ferret model, we show an H5N1 isolate derived from mink transmits by direct contact to 75% of exposed ferrets and, in airborne transmission studies, the virus transmits to 37.5% of contacts. Sequence analyses show no mutations were associated with transmission. The H5N1 virus also has a low infectious dose and remains virulent at low doses. This isolate carries the adaptive mutation, PB2 T271A, and reversing this mutation reduces mortality and airborne transmission. This is the first report of a H5N1 clade 2.3.4.4b virus exhibiting direct contact and airborne transmissibility in ferrets. These data indicate heightened pandemic potential of the panzootic H5N1 viruses and emphasize the need for continued efforts to control outbreaks and monitor viral evolution.
Assuntos
Furões , Virus da Influenza A Subtipo H5N1 , Vison , Infecções por Orthomyxoviridae , Animais , Vison/virologia , Furões/virologia , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/patogenicidade , Infecções por Orthomyxoviridae/virologia , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/veterinária , Medição de Risco , Humanos , Mutação , Proteínas Virais/genética , Proteínas Virais/metabolismo , Feminino , Surtos de Doenças/veterinária , Masculino , Influenza Humana/virologia , Influenza Humana/transmissãoRESUMO
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects various mammalian species, with farmed minks experiencing the highest number of outbreaks. In Spain, we analyzed 67 whole genome sequences and eight spike sequences from 18 outbreaks, identifying four distinct lineages: B.1, B.1.177, B.1.1.7, and AY.98.1. The potential risk of transmission to humans raises crucial questions about mutation accumulation and its impact on viral fitness. Sequencing revealed numerous not-lineage-defining mutations, suggesting a cumulative mutation process during the outbreaks. We observed that the outbreaks were predominantly associated with different groups of mutations rather than specific lineages. This clustering pattern by the outbreaks could be attributed to the rapid accumulation of mutations, particularly in the ORF1a polyprotein and in the spike protein. Notably, the mutations G37E in NSP9, a potential host marker, and S486L in NSP13 were detected. Spike protein mutations may enhance SARS-CoV-2 adaptability by influencing trimer stability and binding to mink receptors. These findings provide valuable insights into mink coronavirus genetics, highlighting both host markers and viral transmission dynamics within communities.
Assuntos
COVID-19 , Genoma Viral , Vison , Mutação , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , COVID-19/virologia , COVID-19/epidemiologia , COVID-19/transmissão , Animais , SARS-CoV-2/genética , SARS-CoV-2/fisiologia , Espanha/epidemiologia , Vison/virologia , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo , Adaptação ao Hospedeiro/genética , Humanos , Surtos de Doenças , Pandemias , Filogenia , Sequenciamento Completo do GenomaRESUMO
ABSTRACTRapid evolution of highly pathogenic avian influenza viruses (HPAIVs) is driven by antigenic drift but also by reassortment, which might result in robust replication in and transmission to mammals. Recently, spillover of clade 2.3.4.4b HPAIV to mammals including humans, and their transmission between mammalian species has been reported. This study aimed to evaluate the pathogenicity and transmissibility of a mink-derived clade 2.3.4.4b H5N1 HPAIV isolate from Spain in pigs. Experimental infection caused interstitial pneumonia with necrotizing bronchiolitis with high titers of virus present in the lower respiratory tract and 100% seroconversion. Infected pigs shed limited amount of virus, and importantly, there was no transmission to contact pigs. Notably, critical mammalian-like adaptations such as PB2-E627 K and HA-Q222L emerged at low frequencies in principal-infected pigs. It is concluded that pigs are highly susceptible to infection with the mink-derived clade 2.3.4.4b H5N1 HPAIV and provide a favorable environment for HPAIV to acquire mammalian-like adaptations.
Assuntos
Virus da Influenza A Subtipo H5N1 , Vison , Infecções por Orthomyxoviridae , Doenças dos Suínos , Animais , Vison/virologia , Infecções por Orthomyxoviridae/virologia , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/veterinária , Suínos , Virus da Influenza A Subtipo H5N1/patogenicidade , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/fisiologia , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Doenças dos Suínos/virologia , Doenças dos Suínos/transmissão , Espanha , Proteínas Virais/genética , Proteínas Virais/metabolismo , Eliminação de Partículas ViraisRESUMO
BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease. SFTS virus (SFTSV) is transmitted by tick bites and contact with the blood or body fluids of SFTS patients. Animal-to-human transmission of SFTS has been reported in Japan, but not in China. In this study, the possible transmission route of two patients who fed and cared for farm-raised fur animals in a mink farm was explored. METHOD: An epidemiological investigation and a genetic analysis of patients, animals and working environment were carried out. RESULTS: It was found that two patients had not been bitten by ticks and had no contact with patients infected with SFTS virus, but both of them had skinned the dying animals. 54.55% (12/22) of the farm workers were positive for SFTS virus antibody. By analyzing the large, medium and small segments sequences, the viral sequences from the two patients, animals and environments showed 99.9% homology. CONCLUSION: It is suspected that the two patients may be directly infected by farm-raised animals, and that the virus may have been transmitted by aerosols when skinning dying animals. Transmission by direct blood contacts or animal bites cannot be ignored.
Assuntos
Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Animais , Humanos , Anticorpos Antivirais/sangue , China/epidemiologia , Fazendeiros , Fazendas , Vison/virologia , Phlebovirus/genética , Phlebovirus/isolamento & purificação , Phlebovirus/classificação , Filogenia , RNA Viral/genética , Febre Grave com Síndrome de Trombocitopenia/transmissão , Febre Grave com Síndrome de Trombocitopenia/virologia , Febre Grave com Síndrome de Trombocitopenia/epidemiologiaRESUMO
In this report, a multiplex PCR method was developed for the detection of three diarrhea-associated viruses in mink, including circovirus (MCV), bocavirus (MBoV), and enteritis virus (MEV). Three compatible sets of primers specific for each virus were designed respectively based on their conserved sequences. After optimization of the crucial factors such as primer concentration and annealing temperature in single and multiple amplification, three specific fragments were simultaneously amplified with the highest sensitivity and specificity in one PCR reaction. The fragments amplified were 259â¯bp (MCV)ï¼455â¯bp (MBoV) and 671â¯bp (MEV). The sensibility of this one-step multiplex PCR is about 10 times lower than that of regular singleplex PCR. There were no cross-reactions with some relevant pathogens like mink coronavirus, canine distemper virus, and aleutian mink disease virus. In our study we analyzed viral DNA in mink fecal samples by multiplex PCR assay from China, which revealed the occurrence of MCV, MBoV, and MEV as 3.1â¯%, 5.7â¯%, and 9.8â¯%, respectively. The testing results of multiplex PCR agreed with the singleplex PCR results with a coincidence rate of 100â¯%. These results indicated that the method could provide technical support for rapid detection of the three diarrhea-associated viruses, and epidemiological investigation of mink viral diarrhea.
Assuntos
Primers do DNA , Diarreia , Fezes , Vison , Reação em Cadeia da Polimerase Multiplex , Sensibilidade e Especificidade , Animais , Vison/virologia , Reação em Cadeia da Polimerase Multiplex/métodos , Reação em Cadeia da Polimerase Multiplex/veterinária , China , Diarreia/virologia , Diarreia/veterinária , Diarreia/diagnóstico , Primers do DNA/genética , Fezes/virologia , Circovirus/genética , Circovirus/isolamento & purificação , Bocavirus/genética , Bocavirus/isolamento & purificação , Vírus da Enterite do Vison/genética , Vírus da Enterite do Vison/isolamento & purificação , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Diagnóstico Molecular/veterináriaRESUMO
We isolated severe fever with thrombocytopenia syndrome virus (SFTSV) from farmed minks in China, providing evidence of natural SFTSV infection in farmed minks. Our findings support the potential role of farmed minks in maintaining SFTSV and are helpful for the development of public health interventions to reduce human infection.
Assuntos
Surtos de Doenças , Vison , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Phlebovirus/genética , Phlebovirus/isolamento & purificação , Phlebovirus/classificação , China/epidemiologia , Febre Grave com Síndrome de Trombocitopenia/epidemiologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Animais , Vison/virologia , Filogenia , Humanos , FazendasRESUMO
In late 2022 and early 2023, SARS-CoV-2 infections were detected on three mink farms in Poland situated within a few km from each other. Whole-genome sequencing of the viruses on two of the farms showed that they were related to a virus identified in humans in the same region 2 years before (B.1.1.307 lineage). Many mutations were found, including in the S protein typical of adaptations to the mink host. The origin of the virus remains to be determined.
Assuntos
COVID-19 , Reservatórios de Doenças , Vison , SARS-CoV-2 , Animais , Humanos , COVID-19/transmissão , COVID-19/veterinária , Fazendas , Vison/virologia , Polônia/epidemiologia , SARS-CoV-2/genética , Reservatórios de Doenças/veterinária , Reservatórios de Doenças/virologia , Mutação , Sequenciamento Completo do GenomaAssuntos
Virus da Influenza A Subtipo H5N1 , Vírus da Influenza A , Infecções por Orthomyxoviridae , Animais , Sítios de Ligação , Surtos de Doenças/veterinária , Glicoproteínas de Hemaglutininação de Vírus da Influenza , Virus da Influenza A Subtipo H5N1/genética , Vison/virologia , Ácido N-Acetilneuramínico , Neuraminidase/genética , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/veterináriaAssuntos
Virus da Influenza A Subtipo H5N1 , Infecções por Orthomyxoviridae , Animais , Sítios de Ligação , Surtos de Doenças/veterinária , Glicoproteínas de Hemaglutininação de Vírus da Influenza , Vison/virologia , Ácido N-Acetilneuramínico , Neuraminidase/genética , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/veterináriaAssuntos
Aves , Surtos de Doenças , Vison , Infecções por Orthomyxoviridae , Zoonoses Virais , Animais , Humanos , Aves/virologia , Surtos de Doenças/prevenção & controle , Surtos de Doenças/estatística & dados numéricos , Surtos de Doenças/veterinária , Influenza Aviária/virologia , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Influenza Humana/transmissão , Influenza Humana/virologia , Vison/virologia , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/prevenção & controle , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/veterinária , Zoonoses Virais/epidemiologia , Zoonoses Virais/prevenção & controle , Zoonoses Virais/transmissão , Zoonoses Virais/virologiaRESUMO
Big outbreak at a Spanish farm reignites fears of an H5N1 influenza pandemic.
Assuntos
Virus da Influenza A Subtipo H5N1 , Influenza Aviária , Vison , Animais , Humanos , Aves , Surtos de Doenças , Influenza Aviária/epidemiologia , Vison/virologia , EspanhaRESUMO
BACKGROUND: Selecting American mink (Neovison vison) for tolerance to Aleutian mink disease virus (AMDV) has gained popularity in recent years, but data on the outcomes of this activity are scant. The objectives of this study were to determine the long-term changes in viremia, seroconversion and survival in infected mink. Mink were inoculated intranasally with a local isolate of Aleutian mink disease virus (AMDV) over 4 years (n = 1742). The animals had been selected for tolerance to AMDV for more than 20 years (TG100) or were from herds free of AMDV (TG0). The progenies of TG100 and TG0, and their crosses with 25, 50 and 75% tolerance ancestry were also used. Blood samples were collected from each mink up to 14 times until 1211 days post-inoculation (dpi) and were tested for viremia by PCR and for anti-AMDV antibodies by counter-immunoelectrophoresis (CIEP). Viremia and CIEP status were not considered when selecting replacements. Low-performing animals were pelted and the presence of antibodies in their blood and antibody titer were measured by CIEP, and viremia and viral DNA in seven organs (n = 936) were tested by PCR. RESULTS: The peak incidences of viremia (66.7%) and seropositivity (93.5%) were at 35 dpi. The incidence of viremia decreased over time while the incidence of seroconversion increased. The least-squares means of the incidence of PCR positive of lymph node (0.743) and spleen (0.656) were significantly greater than those of bone marrow, liver, kidneys, lungs and small intestine (0.194 to 0.342). Differences in tolerant ancestry were significant for every trait measured. Incidences of viremia over time, terminal viremia, seropositivity over time, AMDV DNA in organs and antibody titer were highest in the susceptible groups (TG0 or TG25) and lowest in the tolerant groups (TG100 or TG75). CONCLUSION: Previous history of selection for tolerance resulted in mink with reduced viral replication and antibody titer. Viremia had a negative effect and antibody production had a positive effect on survival and productivity.