Aleutian mink disease: the effectiveness of immunocorrective therapy

Aleutian mink disease is one of the main problems of fur farming, since it causes colossal losses to the industry due to the mass death of animals and due to the lack of effective means of treatment and prevention. In the presented work the results of using an antiviral agent based on alloferon Allokin-alpha in Aleutian mink disease are reported for the first time, an effective scheme of drug use has been developed, differences in clinical signs, blood biochemical parameters, morphological changes in internal organs have been established for animals with and without the peptide. The objective of our work was to evaluate the effectiveness of the use of the drug Allokin-alpha in Aleut mink disease and to investigate the effects of the drug as a means of immune correction, ensuring the maintenance of the body condition of sick minks. The experiments were performed in compliance with the requirements of the European Convention for the Protection of Vertebrate Animals used for experiments or for other scientific purposes. The research was conducted from May to December 2019 in one of the fur farms of the Northwestern region of the Russian Federation on the mink ( Neovison vison Schreber, 1777) of the sapphire breed of 30-day age. The control and experimental groups included 5 males and 25 female mink each. All individuals in the experiment were intraperitoneally injected with Aleutian Mink disease virus (Sapphire isolate) at a dose of 2 cm3. The experimental minks were twice injected subcutaneously with the drug Allokin-alpha (0.5 mg per animal) with a 6-day interval. The control animals were injected subcutaneously with sterile saline solution (0.9 % NaCl) in the same dosage regimen. Clinical, laboratory and economic indicators were assessed in both groups over 6 months of the experiment. Minks' mobility, coordination, appetite, color of the mucous membrane, fur condition and response to external stimuli were recorded. Animal mortality in both groups was checked daily, and all minks were weighed at the beginning of each month. Biochemical blood parameters were determined after 1, 3 and 6 months. Macroscopic, microscopic and chemical studies of feces were performed 3 days after repeated use of the drug Allokin alpha. At the end of the experiment, animals were subjected to diagnostic slaughter, the kidneys, spleen, ovaries of females and testes of males were collected. The biomaterial was fixed, dried, and poured into paraffin. Sections (5-7 microns thick) were stained with hematoxylin and eosin and examined under a microscope (LOMO Micromed-5, JSC LOMO, Russia). Our research data show that in the test group the minks were strong and had a proportional physique, the animals were very mobile and responded vividly to external stimuli compared to the control group, in which individuals exhibited reduced reactions, lethargy and drowsiness. The experimental minks had their digestion normalized. After receiving Allokin-alpha, the average bodyweight was 19.7 % higher in females and 15.6 % higher in males compared to control. The mortality in the test group was 0 % vs. 20 % in the control. The control animals had a high level of urea (84.05±4.22 mmol/l), creatinine (142.06±2.62 mmol/l), and transaminase activity (73.60±5.84 IU/l for ALT and 286.60±3.36 IU/l for AST). In contrast, in the experimental minks, the indicators were significantly lower, the 9.88±3.88 mmol/l for urea, 97.71±1.47 mmol/l for creatinine, 130.73±4.43 IU/l for ALT and 184.88±3.22 IU/l for AST. The use of Allokin-alpha caused a decrease in pH from 8.7±0.25 to 6.8±0.18 in feces. Intestinal epithelial cells, blood pigments, and soluble protein were not found in the feces of the experimental minks, but they appeared in the control minks, which indicated the normalization of digestion. Internal organs' morphology showed the signs of glomerulonephritis and foci of lymphoplasmacytic infiltration of kidneys, spleen, liver and ovaries of female and testes of males. Ne