The article is devoted to the study of the adaptive capacity of bovine foamy virus to homologous continuous cell cultures, namely LEK and KST. In the process of integration of the causative agent of spumavirus infection in cattle into the continuous cultures LEK and KST, morphological changes in the state of the monolayer are observed on the principle of syncytium formation and vacuolization. It was found that LEK continuous cell culture is more suitable for pathogen replication and accumulation of viral mass. Studies on the possibility of integrating the field form of bovine foamy virus into the continuous cell culture KST showed low sensitivity of the latter to the virus of the Retroviridae family

The study aimed to evaluate the epizootic status of livestock in Ukraine concerning the prevalence of bovine immunodeficiency virus and bovine foamy virus infections. A literature review was conducted to analyze the epizootic status of livestock farming in various countries regarding bovine immunodeficiency and spumavirus infections. To investigate this issue in Ukrainian livestock, blood samples were collected from 10–15 cows with further DNA extraction and studies via PCR, according to the developers’ recommendations. The biological characteristics of bovine foamy virus and bovine immunodeficiency virus were studied by infecting bovine fetal lung (LEK) and calf coronary vessels (KST) cell cultures, with each passage being visually monitored and examined through light microscopy. PCR was performed on the third and fifth passages to detect the genetic material. The genetic material of bovine leukemia virus, bovine immunodeficiency virus, and bovine foamy virus was confirmed in 12 farms across 8 regions of Ukraine. It was demonstrated that bovine immunodeficiency virus and bovine foamy virus can integrate into homologous cell cultures derived from cattle. The immunosuppressive effects of bovine foamy virus and its capability to inhibit components of the non-specific immune system were established on laboratory animal models. Emphasis is placed on the necessity to develop domestic tools for the retrospective diagnosis of bovine immunodeficiency and spumavirus infections and to implement a national anti-epizootic program

According to the results of the survey of cattle in 13 regions of Ukraine, it was found that 33.8% of them had circulating herpesvirus type 1 (BHV-1), which is the causative agent of infectious rhinotracheitis (IRT). The respiratory form of IRT was found in 41.7% of farms, genital and keratoconjunctivitis in 8.3%, and asymptomatic and polysymptomatic in 25.0% and 16.7%, respectively. A significant percentage of farms with asymptomatic cases is due to the almost total use of IRT vaccination. Of particular concern is the use of vaccines containing live attenuated strains of herpesvirus type 1 in the surveyed farms (66.7% of all cases), which further complicates the epizootic situation

For the first time in Ukraine the presence of genetic material of bovine immunodeficiency virus and bovine foamy virus in cattle on Ukrainian farms was detected by scientists of the Laboratory of Leukemia Study and the Laboratory of Molecular Diagnostics of the National Scientific Center ‘Institute of Experimental and Clinical Veterinary Medicine’. The associative nature of animal infection with leukemia, immunodeficiency and spumavirus pathogens is recorded. In the future, it is planned to study the properties of pathogens, adaptation to homologous cell cultures and accumulation of viral material in order to develop domestic means of serological diagnosis of immunodeficiency and spumavirus infection

The aim of the study was to investigate the prevalence of minor cattle infections (leukemia, bovine immunodeficiency and spumavirus infection) using the polymerase chain reaction (PCR). Blood samples were collected from cows in conditionally leukemia-free farms in ten regions of Ukraine to determine the presence of these infections. The samples were examined via classical PCR to detect the genetic material of the specific fragment of the ENV gene of the leukemia virus using BLV-env-3/BLV-env-4 primers recommended by the OIE. To identify the proviral DNA of bovine foamy virus (BFV), primers Int 1-Int 2 and Int 3-Int 4 were used, and for the detection of bovine immunodeficiency virus (BIV) proviral DNA, a pair of primers RT_+(–) flanking the conservative domain of reverse transcriptase and a pair of primers flanking the pol gene of the BIV were selected. The situation concerning leukemia is most severe in Sumy and Kharkiv regions. A significant percentage of animals carrying the foamy virus was observed in farms in Kirovohrad, Kherson, Donetsk, and Kharkiv regions. Moreover, genetic material of the immunodeficiency virus was found in samples from Kirovohrad, Donetsk, and Kherson regions. These results indicate a significant prevalence of minor infections among cattle in Ukraine due to a lack of awareness among livestock workers, highlighting the necessity for comprehensive sanitary and preventive measures

Based on the analysis of OIE data and world scientific literature, the spread of spumavirus infection and bovine immunodeficiency in livestock production worldwide, and on the basis of our own research in Ukrainian livestock production was studied. The adaptive ability of field isolates of minor infections to homologous cell cultures for cattle, genetic characteristics of pathogens isolated in different regions of Ukraine, the effect of field isolates of the pathogen when inoculated into the body of laboratory animal models at the hematological, molecular genetic and biochemical levels have been studied

The article contains materials from literary reports on the influence of minor infections, namely bovine leukemia, bovine immunodeficiency and bovine spumavirus infection on the immune status of animals, antigenic affinity of pathogens. Emphasis is placed on the biological properties of the causative agent of bovine immunodeficiency, its spread and pathogenesis, and disease diagnosis

Biological properties of field isolates of bovine immunodeficiency virus and bovine foamy virus on homological cell cultures (fetal bovine lung and bovine coronary artery endothelial cells) were investigated. Pathogens of bovine slow infections, namely bovine immunodeficiency virus and bovine foamy virus, are able to integrate into cell cultures of homologous to cattle type, which is confirmed by the results of PCR. There has been determined the presence of genetic material of pathogens of bovine immunodeficiency (BIV) and spumavirus infection (BFV) in the cultivation of lymphocytes of field isolates in the culture of bovine coronary artery endothelial cells (BCAEC) at the level of 5th passage, and in the cell culture of fetal bovine lung (FBL) — at the level of 10th passage. In the process of integration of pathogens of immunodeficiency and spumavirus infection of cattle in continuous cell cultures FBL and BCAEC, morphological changes in the state of the monolayer by the principle of syncytiation and vacuolation are observed

Genetic material of the field isolate of bovine foamy virus was inoculated subcutaneously in rabbits (5 experimental and 5 intact animals). The influence of genetic material on the organism of experimental animals was studied at the molecular-genetic, cellular, and biochemical levels. It has been established that the persistence of the causative agent of spumavirus infection according to the results of molecular and genetic research (PCR) is 60 days. Redistribution of cells of leukocyte fraction towards lymphocytosis (80–88%) was recorded. Decrease in the concentration of circulating immune complexes by 22.2% (p ≤ 0.05) and a tendency to decrease in the seromucoid concentration (by 6.5%) were found on 60th day after infection compared with control indicators. At the end of the experiment it was established a statistically significant decrease in the concentration of circulating immune complexes and an increase in seromucoid level by 21.5% and 17.6% respectively, as well as a tendency to decrease in the level of globulins, which was 15.5%. The results of hematological and biochemical analysis indicate the development of immunosuppressive state under the influence of the inoculated material

Comparative hematological and biochemical studies in heifers at the age of 6–8 months with different epizootic background revealed that the persistence of the association of viruses (causative agents of bovine leukemia, infectious bovine rhinotracheitis, bovine parainfluenza-3, and bovine viral diarrhea) negatively affect the status of immunocompetent cells. As the cell number of the macrophage-neutrophil group increases by 25–37%, their functional activity decreases. Significant shifts in the state of protein metabolism, the development of immunosuppression, and intensification of lipid peroxidation processes occur in the bodies of the infected animals, indicating a decrease in the natural resistance of these animals. Significant difference in the intensity of the specific immune response in the vaccinated against pneumoenteritis of the viral etiology animals from BLV-free and BLV-positive farms has not been established.

The purpose of the work was to determine the effectiveness of different approaches to the recovery of cattle population from leukemia, and their impact on cattle productivity and profitability of livestock farming. The choice of measures to ensure the safety of a particular farm was determined by indicators of herd infection, number of livestock population in the holding, availability of conditions for isolated keeping of animals, availability of herd replacements. Two methods of serological testing were used during the work, namely ID and ELISA. The methodological basis of the work was the regular serological examination of conditionally safe concerning leukemia livestock in the ID — once every 20–30 days, or by ELISA — with an interval of 45–50 days. According to the results of each study, depending on the approach of farm recovery, infected with leukemia animals were slaughtered or isolated from the herd in an isolated group. Improvement of farms by detecting and slaughtering infected animals is economically justified only in the case of livestock infections up to 5–10 %. In other cases, it is advisable to carry out rehabilitation by the method of gradual replacement of the infected livestock, which allows to ensure the safety of the farms during 2–4 years while saving the population and productivity of the livestock

The purpose of the work was to carry out comparative analysis of the positive and negative on leukemia cattle blood sera in ELISA kits of different constructions. Research was carried out using “DIA®-BLV-Ab” kit, in which the reaction had been performed in the indirect ELISA, and “ID Screen® BLV Competition” kit in a competitive format. There were used 15 cattle blood sera for testing, in which antibodies to BLV were confirmed in the ID and the ELISA “Bovine leukemia virus antibody test kit” (IDEXX), as well as 10 positive cattle blood sera confirmed in ID, 10 weak positive sera tested in ID and 10 sera with a weak line of precipitate in ID, 34 negative for leukemia blood sera tested in ID, from which 24 were also tested in the ELISA “Bovine leukemia virus antibody test kit”. The “DIA®-BLV-Ab” kit and “ID Screen® BLV Competition” kit determined positive 25 blood sera with antibodies to BLV, which were positive in ID, and 15 samples were also confirmed in IDEXX test kit. When analyzing 10 sera, that were weak positive in ID, the “DIA®-BLV-Ab” kit determined 8 sera as positive and 2 samples as negative. The “ID Screen® BLV Competition” kit detected specific antibodies to all sera. When analyzing 14 sera with a weak precipitate line in ID, the “DIA®-BLV-Ab” kit determined 9 samples as positive and 5 as negative. The “ID Screen® BLV Competition” determined specific antibodies in 11 samples When analyzing 3 sera, the test result was negative in both ELISA kits. The “DIA®-BLV-Ab” kit determined as negative all 34 sera, which were negative in ID, 24 samples from them were negative in IDEXX test kit. In the “ID Screen® BLV Competition” kit 5 false positive results were received. Studies have shown that both test kits have a high diagnostic capacity and detect antibodies to BLV at different concentrations in all positive sera. The “DIA®-BLV-Ab” kit determined 34 sera as negative, in which specific antibodies were absent, and the “ID Screen® BLV Competition” kit identified 5 samples with a false positive result

One of the most common and dangerous cattle diseases of oncogenic origin is leukemia. An effective technological step to control animal leukemia and to prevent the possibility of its further spread is milk pasteurization. We have studied the quality of dairy raw materials and equipment used in the pasteurization of milk. The resistance of pasteurized milk was compared after using various methods of its processing (storage in a refrigerator at a temperature of 4–5°C). The comparative characteristics and specific energy consumption of the most popular pasteurizer models with ‘UOM’ milk pasteurizer-disinfectant were described. We studied the specific energy consumption of the ‘UOM’ units. It was established that pasteurization of milk in cattle leukemia is an integral stage in the overall complex of veterinary and sanitary measures. For pasteurization in livestock farms and milk processing plants, it is necessary to install modern, energy-saving, highly efficient pasteurizers using infrared heating. When using infrared equipment for pasteurization-disinfection of milk (‘UOM’), the disinfection of milk occurs at 79.5°C in a stream (without exposure). This mode of milk processing completely destroys the leukemia virus in it and does not affect its nutritional qualities

As a representative of RNA-containing viruses, the causative agent of bovine leukemia (BLV) is characterized by the signifi cant level of genetic variability which results in considerable information content of phylogenic studies of its populations. Aim. This study is aimed at exploring the sequence of 440 bp long fragment of the pol gene of BLV in three farms in the Eastern Ukraine. Methods. The polymerase chain reaction, sequencing and standard methods of isolating nucleic acids have been used. Results. The sequencing and the sequence analysis of the pol gene demonstrated the presence of three variants of sequences, corresponding to the isolates, identifi ed in Kharkiv and Sumy regions and the sample of the proviral DNA from the FLK-BLV culture. Con- clusions. The genetic homology of the sequences of the characterized isolates to the populations of viruses, circulating in the territory of Europe and the European part of the Russian Federation, has been established.