Long-term antibody production and viremia in American mink (Neovison vison) challenged with Aleutian mink disease virus.

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.

Urinary and plasma metabolome of farm mink (Neovison vison) after an intervention with raw or cooked poultry offal: a 1H NMR investigation.

The introduction of high amounts of cooked poultry offal in mink feed has been associated with health problems in growing mink. Cooking mink feed is a convenient way of reducing microbiological activity, but it may have a negative effect on raw material quality and animal welfare. This study investigates growth and health of mink fed raw or cooked poultry offal and describes urinary and blood plasma metabolic changes related to the feeding. A total of 65 male mink were divided in three feeding groups, two fed cooked offal and one group fed raw offal, and the plasma and urine samples were collected at 3 time points during the growth. Both bio-fluids and feed samples were measured by 1H NMR spectroscopy and resulted metabolomics data were analysed using univariate and multivariate statistical methods that revealed dominating effect of the mink growth stages and to a less extent the feeding regime. Metabolome differences in relation to low body mass index (BMI) and kidney lesions were observed in plasma. Disease and decrease in BMI was associated with high creatinine and dimethylglycine content in plasma. These molecules were also particularly indicative of the cooked feeds. Moreover, low urinary taurine levels were also associated with disease and low BMI. Individual mink appeared to show negative effects of the cooked feed diet, including impaired growth and gross pathological lesions involving the kidneys. This may be related to the absorption of essential metabolites such as amino acids and fats, necessary for mink growth, that are negatively impacted by the cooking process.

Low concentration of serum immunoglobulin G is associated with pre-weaning diarrhea in young mink kits (Neovison vison).

BACKGROUND: Pre-weaning diarrhea (PWD) is a severe syndrome, with world-wide occurrence, affecting farmed mink (Neovison vison) kits during the lactation period. Kits affected by PWD often display clinical signs such as: yellow-white diarrhea, greasy skin, and dehydration. In severe cases the kits eventually die. It is common practice to treat PWD using antimicrobials; however the effect is not well documented. Due to the multifactorial etiology of PWD vaccine development is not feasible. The role played by the immune status of the mink kits with respect to their susceptibility to PWD is not well studied. To elucidate the possible association between PWD and total IgG serum concentration in young kits we analyzed blood collected from kits from 100 litters on two mink farms during the same breeding period, one farm being a case farm with high prevalence of PWD, and the other being a control farm with no cases of PWD. RESULTS: Kits affected by PWD had a significantly reduced weight gain compared to unaffected control kits. Litters born later in the breeding period came down with PWD at an earlier age than litters born at the start of the breeding period. We found that PWD affected kits had significantly lower concentrations of serum IgG compared to unaffected kits at 13-15 days of age (the last blood sampling point of the study). CONCLUSION: The results in this study suggest that PWD affected kits less efficiently absorbed IgG from maternal milk or had a lower intake of maternal milk, potentially contributing to the exacerbation of disease. A lower intake of IgG and/or less absorption from maternal milk could also pre-dispose kits for PWD. Future studies will be needed to elucidate if the circulating level of IgG is directly related to protection against disease and to investigate if administration of IgG could be helpful in alleviating and/or preventing PWD in mink kits.

Severe Fever with Thrombocytopenia Syndrome Virus Infection in Minks in China.

We analyzed the seroprevalence of tick-borne severe fever with thrombocytopenia syndrome virus (SFTSV) in farm-raised minks using double antigen ELISA (enzyme-linked immunosorbent assay) kit and indicated that 8.4% (15/178) of the minks had antibodies to the nucleoprotein of SFTSV and 72.7% (8/11) of mink farms had minks positive to SFTSV. The ELISA results were further confirmed by presence of neutralization to SFTSV in the mink sera. Our results suggested that minks were widely infected with SFTSV in China.

Serology and protein electrophoresis for evidence of exposure to 12 mink pathogens in free-ranging American mink (Neovison vison) in Argentina.

BACKGROUND: Basic pathologic characteristics for farmed minks were previously reported worldwide. However, its status in the wild has not been studied in detail. OBJECTIVE: Serology and electrophoresis were carried out for evidence of exposure to 12 mink pathogens on two different locations. ANIMALS AND METHODS: Serology was done in 87 wild minks by reference techniques against Toxoplasma gondii, Encephalitozoon cuniculi, Neospora caninum, Brucella abortus, Mycobacterium bovis, Leptospira interrogans, canine distemper virus (CDV), canine adenovirus (CAV), canine parvovirus (CPV), rabies virus (RV), Influenza A virus (FLUAV) and Aleutian disease virus (ADV). Hypergammaglobulinemia, the ADV main clinical feature, was determined by conventional electrophoresis. RESULTS: Seventy-one percent of the 87 sera had antibodies against one or more pathogens. ADV accounted for the highest seroprevalence (29%), followed by T. gondii (26%), L. interrogans (14%), M. bovis (12%), B. abortus (9%), N. caninum (3%), CPV (3%) and CDV (2%). Seroprevalence was influenced by location but not sex or age. Additionally, 16% of the seropositive samples for ADV had gammaglobulin levels >40.0 g/L. Antibody titers for CDV and CPV were low and difficult to interpret as almost all these cases had borderline concentrations. CONCLUSION: A cautious interpretation of the results is urged as the epidemiological role of the wild mink is largely unexplored for most of these agents. Nevertheless, the information may be clinically relevant..

[MORPHOLOGICAL FEATURES OF NEUTROPHILS AND EOSINOPHILS GRANULES IN SAPPHIRE MINKS].

It has been established that sapphire minks have abnormality of subcellular structure of blood and bone marrow neutrophils and eosinophils. The abnormality consists in forming of abnormal "giant" granules. The si- ze and the number of abnormal granules significantly change during maturation of leucocytes in bone marrow. We have found differences between abnormal granules forming in neutrophils and eosinophils that depend on the maturing stage and the cells life cycle duration as well as morphofunctional features of these granulocytes.

Metabolomic study of plasma from female mink (Neovison vison) with low and high residual feed intake during restrictive and ad libitum feeding.

Metabolite profiling may elucidate changes in metabolic pathways under various physiological or nutritional conditions. In the present study two groups of female mink characterised as having a high (16 mink) or low (14 mink) residual feed intake were investigated during restrictive and ad libitum feeding. Blood samples were collected three times during the experimental period; during restrictive feeding, and four days and three weeks after the change to ad libitum feeding. Plasma samples were subjected to liquid chromatography mass spectrometry non-targeted metabolomics. Subjecting data to principal component analysis showed that there was no grouping of the data according to the residual feed intake. In contrast, data were clearly grouped according to feeding level. Identification of the metabolites responsible for this grouping showed that the plasma level of metabolites related to mobilisation of energy was high during restrictive feeding, e.g. betaine, carnitine, and creatine. During ad libitum feeding the plasma level of metabolites that can be characterised as biomarkers of meat intake (creatinine, carnosine, 1- and 3 methylhistidine) was high. The plasma level of lysophosphatidylcholine species was highest after four days of ad libitum feeding suggesting a short term imbalance in the transport or metabolism of these metabolites when changing the feeding level.

The effects of feed restriction on physical activity, body weight, physiology, haematology and immunology in female mink.

The aim of the present study was to investigate if adult mink females characterised as having a high or low residual feed intake (RFI) differed in their response to feed restriction with regard to activity, body weight loss and physiological parameters. For RFI-High, the activity was higher prior to the expected feeding time both in the cases of restrictive and ad libitum feeding indicating a changed RFI-High feeding motivation and a higher risk of developing stereotypic activity. The body weight gain and the feed consumption were higher for RFI-High than for RFI-Low when feeding ad libitum indicating that RFI-High has a higher growth potential and/or a higher energy requirement than RFI-Low. Signs of immunosuppression were shown in connection with restrictive feeding compared to ad libitum feeding, and RFI-High females seemed to be more susceptible to immunosuppression than RFI-Low females. Based on the present results, mink characterised as RFI-Low would be preferable as breeders because they involve lower feed costs and seem to be less susceptible to immunosuppression. They also seem to have less risk of developing stereotypic activity, which is beneficial for the welfare.

Pregnancy detection in putatively unmated mink (Mustela vison) by serum progesterone level.

The aim of this study was to determine whether blood plasma progesterone is a reliable indicator of pregnancy in mink at an early stage of gestation. We also attempted to establish the threshold value of progesterone as a pregnancy indicator. The analysis was carried out at a production farm on 42 standard female mink aged 1 year, which were grouped both according to the observed success of mating ("mated" and "unmated") and the level of blood serum progesterone measured afterwards ("pregnant" and "nonpregnant"). It was next verified whether a particular female had been assigned to the proper group in the first place. An analysis of accuracy of mating success assessment within the group of unmated females revealed that more than one-third of decisions were wrong, since some females that had been considered unmated ultimately whelped. This suggests that mating supervision by farm workers lacks reliability. A progesterone test for verification of such management decisions should limit the risk of err,or. We suggest that progesterone tests could be carried out using the threshold values 1.9 ng/ml and 20 ng/ml in blood sampled on 25 March and 8 April, respectively, although some level of uncertainty should be taken into account.

[Effect of mutations affecting coat color on the blood lymphocyte structure in the American mink (Mustela vison Schreber, 1777)].

American minks with different genotypes containing the Aleutian coat color allele in the homozygous state, including the single recessive Aleutian (a/a); double recessive sapphire (a/a p/p) and lavender (m/m a/a); triple recessive violet (m/m a/a p/p); and dominant-recessive cross sapphire (S/+ a/a p/p), sapphire leopard (S(K)/+ a/a p/p), and shadow sapphire (S(H)/+ a/a p/p) minks, as well as American minks without the Aleutian allele, including the standard (+/+); single recessive silver-blue (p/p) and hedlund-white (h/h); double recessive pearl (k/k p/p), Finnish topaz (t(S)/t(S) b/b); incompletely dominant royal silver (S(R)/+), standard leopard (S(K)/+), and black crystal (C(R)/+); and dominant-recessive snowy topaz (C(R)/+ t(S)/t(S) b/b) and Kujtezhy-spotted (S(K)/+ b/b) minks have been studied. Homozygosity for the a allele has been found to disturb the subcellular structure of leukocyte, namely the formation of abnormally large granules.

[Morphology and cytochemistry of abnormal cytoplasmic granules in blood leukocytes in sapphire minks (cytological and cytochemical study)].

Detailed morphological and cytochemical investigation of blood leukocytes was performed in minks of three genotypes: dark-brown minks (n=10), which had the color resembling that of the wild type, mutant silver-blue (p/p) minks (n=10), and sapphire minks (a/a p/p) (n=10). The sapphire minks were demonstrate to have a hereditary defect of leukocyte granules containing peroxidase, nonspecific esterases and non-enzymatic cationic protein. These granules have abnormally large size, the neutrophil cytoplasm contains one to several abnormal granules, they are numerous in eosinophil and basophil cytoplasm and rare in lymphocytes and monocytes. Morphological and cytochemical features indicate the similarity of hereditary leukocytes pathology of sapphire mink with that one found in human Chediak-Higashi syndrome.

Chronic oral exposure to bunker C fuel oil causes adrenal insufficiency in ranch mink (Mustela vison).

Animals living in the near-shore marine environment are predisposed to contact with chemical contaminants through land- and ocean-based activities. The release of petroleum hydrocarbons into the marine environment is a stressor to this environment and its resident wildlife. The stress response to chemical threats is dependent on an intact hypothalamic-pituitary-adrenal axis, which also may be a target to the effects of these chemicals. Ranch mink (Mustela vison) were used as surrogates for sea otters (Enhydra lutris) to examine the development of adrenal hypertrophy after chronic, oral exposure to low concentrations of bunker C fuel oil. Animals were fed three different concentrations of fuel oil (48, 520, and 908 ppm) or mineral oil (control) for 60-62 days. At the end of the exposure, blood and fecal samples were collected and organs were weighed and examined microscopically. In all fuel oil groups, exposure resulted in adrenal hypertrophy, an adaptation suggestive of adrenal activation. However, concentrations of serum and fecal glucocorticoids and serum progesterone were not elevated over control values. Hematologic parameters and serum chemistries showed no changes consistent with increased adrenal activity. In addition, adrenal glands from animals fed the higher concentrations of fuel oil contained large numbers of heavily vacuolated cells. We conclude that petroleum hydrocarbons are inducing an adrenal insufficiency that leads to the adaptive enlargement of the gland. This would increase the susceptibility of fuel oil-exposed animals to the deleterious effects of other environmental stressors.

Monitoring blood glucose levels in female mink during the reproductive cycle: 1. Prevention of hyperglycemia during the nursing period.

Nursing sickness, the largest cause of death in female adult mink, is a metabolic disorder characterized by hyperglycemia. The impacts of body condition, dietary supplements, and reproductive status on the blood glucose concentration in female mink during the reproductive cycle were investigated. Mink dams on 3 farms were assigned to receive either herring oil (HerO) or chromium picolinate (CrPic) or to be in a control group, receiving only the basal diet, for 6 wk at the onset of lactation. Hyperglycemia was observed throughout the reproductive cycle. Significant differences in blood glucose levels were observed between farms, emphasizing the importance of herd genetics and of animal management and feeding practices in glycemic regulation. Female mink exhibiting hyperglycemia early in the reproductive cycle tended to remain hyperglycemic and to have poorer health and fewer kits. Glucose levels > 7 mmol/L can be considered critical in this regard. Supplementing the diet with CrPic reduced the blood glucose concentration. Results from this study suggest that a diet containing high-quality n-3 polyunsaturated fatty acids, high levels of carbohydrate, and CrPic supplementation may help the nursing mink dam maintain a normal blood glucose concentration during lactation.

Endocrine and metabolic alterations in the mink (Mustela vison) due to chronic phytoestrogen exposure.

Phytoestrogens are natural components of plant-based food items with beneficial health effects. The aim of the present study was to investigate the chronic effects of dietary phytoestrogens, genistein (8 mg kg(-1) day(-1)) and beta-sitosterol (50 mg kg(-1) day(-1)), on the weight regulation of the mink (Mustela vison). The parental generation was exposed from August 2002 to May-June 2003 to either beta-sitosterol or genistein, while the kits were exposed through gestation and lactation. Food consumption and body masses were monitored monthly. Plasma lipid, glucose, total protein and hormone (ghrelin, leptin, triiodothyronine and thyroxine) concentrations were measured from the parents in August 2002, January 2003 and at the end of the experiment in May-June 2003 when the kits were 21 days of age. Relative food intake was higher in the beta-sitosterol-exposed minks than in the control or genistein minks in September 2002. Plasma leptin and total protein concentrations were lower in the beta-sitosterol kits compared to the control kits. Furthermore, plasma ghrelin levels and liver phosphorylase activities of the mink kits were higher due to genistein exposure. In mink kits, exposure to both phytoestrogens reduced the plasma thyroxine concentrations. The kidney glycogen concentrations and the muscle phosphorylase activities of phytoestrogen-treated adult minks were elevated. The results of this study suggest that minks are sensitive to perinatal phytoestrogen exposure.

A diet rich in phosphatidylethanolamine increases plasma homocysteine in mink: a comparison with a soybean oil diet.

The effects of high dietary levels of phosphatidylethanolamine (PE) on plasma concentrations of homocysteine (tHcy) have not previously been studied. Eighteen mink (Mustela vison) studied were fed one of three diets during a 25 d period in a parallel-group design. The compared diets had 0, 17 and 67 % extracted lipids from natural gas-utilising bacteria (LNGB), which were rich in PE. The group with 0 % LNGB was fed a diet of 100 % soyabean oil (SB diet). Phospholipids are the main lipid components in LNGB and Methylococcus capsulatus is the main bacteria (90 %). The fasting plasma concentration of tHcy was significantly higher when the mink consumed the diet with 67 % LNGB than when they consumed the SB diet (P=0.039). A significantly lower glutathione peroxidase activity was observed in mink consuming the 17 % LNGB diet or the 67 % LNGB diet than was observed in mink fed the SB diet. The lack of significant differences in the level of plasma PE due to the diets indicates that most of the PE from the 67 % LNGB diet was converted to phosphatidylcholine (PC) in the liver. It has previously been hypothesised that phosphatidylethanolamine N-methyltransferase is an important source of tHcy. The present results indicate that plasma tHcy is at least partly regulated by phospholipid methylation from PE to PC. This methylation reaction is a regulator of physiological importance.

Radiographic evaluation of destructive periodontal disease in blue mink in relation to age and blood morphology.

In this study, blood samples and jaws were collected from 2 genotypes of blue mink (n = 289) in order to examine phenotypic expression of specific characteristics of Chediak-Higashi Syndrome (C-HS). Blood samples were subjected to differential counts to assess the proportion of abnormal polymorphonuclear leukocytes characteristic for CH-S (C-HS-leukocytes). Abnormal leukocytes with characteristic signs of C-HS were found in blood smears from all mink included in this study. Four teeth in one half of the mandible (P3, P4, M1, M2) were subjected to quantitative radiographic evaluation of alveolar bone loss and tooth loss. There was a high prevalence of destructive periodontal disease among blue mink included in this study. Mild to moderate periodontal disease (defined by less than 50% alveolar bone loss related to 1 or more teeth) affected 73.7% of young mink (age = 7 mo) and 67.9% of older animals (age > or = 19 mo). Severe periodontal disease (defined by more than 50% bone loss related to one or more teeth) was not detected in mink aged 7 mo, but affected 15.3% of mink aged 19 mo and 39.6% of mink aged 31 mo. The positive relationship between age and periodontal disease was statistically significant (P < 0.01). The prevalence of tooth loss was found to be high among blue mink aged > 19 mo (21.6%) and was also significantly related to age (P < 0.01). A significant positive interaction between alveolar bone loss and tooth loss (P < 0.01), implies that the highly prevalent tooth loss in the mink was related to and possibly caused by destructive periodontal disease. There was no significant difference in the prevalence of periodontal disease between the 2 genotypes and age was found to be the only statistical predictor of poor production results (P < 0.01) in blue mink.

Chronic fuel oil toxicity in American mink (Mustela vison): systemic and hematological effects of ingestion of a low-concentration of bunker C fuel oil.

Petroleum oil enters the coastal marine environment through various sources; marine mammals such as sea otters that inhabit this environment may be exposed to low concentrations of petroleum hydrocarbons through ingestion of contaminated prey. The inability to perform controlled studies in free-ranging animals hinders investigations of the effects of chronic petroleum oil exposure on sea otter morbidity and mortality, necessitating the development of a reliable laboratory model. We examined the effects of oral exposure to 500 ppm bunker C fuel oil over 113-118 days on American mink, a species phylogenetically related to the sea otter. Hematological parameters and organs were examined for fuel oil-associated changes. Hepatic cytochrome P4501A1 mRNA expression and fecal cortisol concentrations were also measured. Ingestion of fuel oil was associated with a decrease in erythrocyte count, hemoglobin concentration (Hgb), hematocrit (HCT), and an increase in mean corpuscular volume (MCV). Total leukocytes were elevated in the fuel oil group from increases in neutrophils, lymphocytes, and monocytes. Significant interactions between fuel oil and antigen challenge were found for erythrocyte parameters, monocyte and lymphocyte counts. Liver and adrenal weights were increased although mesenteric lymph node weights were decreased in the fuel oil group. Hepatic cytochrome P4501A1 mRNA was elevated in the fuel oil group. Fecal cortisol concentration did not vary between the two groups. Our findings show that fuel oil exposure alters circulating leukocyte numbers, erythrocyte homeostasis, hepatic metabolism and adrenal physiology and establish a framework to use mink as a model for sea otters in studying the systemic effects of marine contaminants.

Serum amyloid P component in mink, a non-glycosylated protein with affinity for phosphorylethanolamine and phosphorylcholine.

Experimental AA amyloidosis in the mink is used as a model for the amyloid disease process. In that context it is important to characterize the different proteins involved in the amyloid formation. In the present work, we have characterized the serum amyloid P component (SAP) in mink. SAP was purified from serum by affinity chromatography using phosphorylethanolamine-coupled ECH-sepharose 4B. SDS-PAGE showed one major protein band (approximately 26 kDa) together with one minor band (10% of the major band) with a higher molecular mass (approximately 30 kDa) corresponding to a non-glycosylated and a glycosylated variant. All SAP molecules elucidated so far have at least one major subunit that is heavily glycosylated. It is therefore the first time that a non-glycosylated SAP protein is found in a mammalian species. The amino acid sequence was established using Edman degradation and mass spectrometry. As expected, the protein showed high homology with the other mammalian SAP molecules, ranging from 73% (human) to 63% (mouse). The SAP protein showed affinity for phosphorylcholine and thus expressed CRP-like properties.

Immunophenotypic and functional effects of bunker C fuel oil on the immune system of American mink (Mustela vison).

The relationship between exposure to environmental contaminants and immunotoxicity in vulnerable marine species is unknown. In this study, we used American mink (Mustela vision) as a surrogate species for the sea otter to examine the immunotoxic effects of chronic exposure to a low concentration of bunker C fuel oil (500 ppm admixed in the feed for 113-118 days). The mink immune system was monitored over time by flow cytometric analysis for alterations in the immunophenotype of blood lymphocytes and monocytes and by mitogen-stimulated proliferation assays for changes in peripheral blood mononuclear cell function. Fuel oil exposure caused a mild, yet significant (P < 0.05) increase in the absolute numbers of specific peripheral blood lymphocyte subsets (CD3+T cells) and monocytes, an increase in the level of expression of functionally significant cell surface proteins (MHC II, CD18), and an increase in mitogen-induced mononuclear cell proliferative responses. This heightened state of cellular activation along with the increase in specific cell surface protein expression on both the innate and adaptive immune cells is similar to the pro-inflammatory or "adjuvant-like" effect described in laboratory models of polycyclic aromatic hydrocarbon exposure in other species. These results show the benefits of using a controlled laboratory model for detecting and characterizing subtle petroleum oil-induced perturbations in immune responses. In addition this study establishes a framework for studying the effects of environmental petroleum oil exposure on the immune system of free-ranging marine mammals. Expansion of these studies to address biolgical significance is warranted.