This brief report pays tribute to Robert Eustace Montgomery (1880–1932) whose name is associated with the discovery of African swine fever (ASF). A hundred years ago, he published a major report on study of new highly dangerous disease carried out in 1900–1917 in the East Africa. The infection fundamentals have been established and described – the etiological, immunological  and nosological uniqueness  of the infection, fatal susceptibility of domestic  pigs, clinical sings and pathomorphology,  viral etiology, natural reservoir and source of the infection, survival of the virus outside the body, many specific epizootological aspects. Taking into account current high publication activity it has been concluded that there is a large body of multi-faceted  research focused on African swine fever. Gap analysis carried out by the large team of the European researchers and experts revealed the most challenging aspects – wild boars, ASF survival and transmission, biosecurity and surveillance. In addition to the gaps mentioned in these conclusions and recommendations there are serious gaps in African swine fever immunology, namely in protective immunity mechanisms, virus-macrophage interaction, in vitro virus phenotypic  signs correlating with its virulence, etc. Evidently, it is hardly possible to expect development of anti-ASF vaccines and particularly the vaccines capable of preventing and effectively protecting against ASF epizooty according to the general understanding without addressing these issues.

African swine fever (ASF) is a transboundary viral disease affecting all species of the Suidae family. It greatly undermines global pig industry and causes a significant damage to the ecology of the wild boar (Sus scrofa) which is a natural reservoir of the virus and is an intermediate  link in the epizootic process. Depopulation of wild boars is one of the measures taken to prevent spread of African swine fever in the Russian Federation. A threshold density of the wild boar population of 0.25 boars/1000 ha (0.025 boars/km²), according to the National Plan on the ASF Eradication in the Russian Federation, was achieved by 2020 in many RF Subjects. However, further analysis of the ASF epizootic situation shows that the measure has failed to eradicate the infection completely. A regression analysis showed statistically significant positive relationship between recurrent ASF outbreaks in the wild boar population and its density in a number of model subjects (N = 6). At the same time, there is no such dependence in other model subjects (N = 3), and  ASF outbreaks were recorded in wild boars at a density significantly lower than the recommended value. A review of foreign and national scientific publications has shown that such control methods as depopulation is just one part of the whole set of measures taken to eradicate African swine fever in the wild. The measure  is effective only when 70–80%  of animals are culled in a short time, which is practically impossible due to the high costs and some peculiarities of the population control and depopulation  process. Based on the results obtained, it can be concluded that a decrease in the number of wild boars does not guarantee to stop further spread of infection in the Russian Federation and it should be considered as just one part of the whole set of measures taken together with other anti-epizootic measures to eliminate and prevent ASF.

The African swine fever panzootic  is continuing  to spread,  and the number  of affected countries and material losses are increasing. In particular, India, Papua New Guinea, Malaysia, Greece and Bhutan joined the list of ASF infected countries in 2020–2021. The disease control is hindered  by the lack of commercially available and effective vaccines, which, in its turn, is attributable  to the insufficient knowledge of ASF pathogenesis  and immune defense against the disease. The use of attenuated virus variants enables a thorough  investigation of the factors influencing the virulence of African swine fever virus and the immune  response  to it. This involves the use of naturally attenuated virus variants, as well as of the variants attenuated by a long-term passaging of the virus in cell cultures. However, virulence heterogeneity characteristic of the ASF virus population, necessitates  the additional selection of infected cells for the virus cloning. Conventional culture-based techniques for virus particle cloning are rather time- and labour-consuming;  it is therefore appropriate  to use flow cytometry cell sorting for the selection and cloning of virus infected cells with a view of selecting  homologous  virus lineages.  The paper  presents  the results of sorting  of African green  monkey kidney cells (CV-1) and porcine bone marrow cells infected with African swine fever virus; the cells were sorted into the 96-well culture plates using a MoFlo  Astrios   EQ cell sorter in order to isolate a population of the virus originating from one infected cell. After the single cell sorting of the infected cell cultures into the 96-well plates, ASF positive cell detection  rates in the plate wells were 30% for porcine bone marrow cells and 20% for CV-1.

The problem of the intrauterine  infection of fetus is one of the most critical ones in veterinary obstetrics and in perinatology due to the high level of infection in pregnant  cows, the risk of developmental disorder of fetus and the birth of sick calves. Complications of pregnancy occur in case of viral, bacterial and protozoal infections, when the pathogen  enters the uterus in an ascending or descending way with further transplacental  infection of the fetus. Morphological studies of placenta  of Black Pied cattle infected with bovine viral diarrhea, chlamydia and neosporosis were carried out. The presence of the pathogen was confirmed by serological and molecular genetic methods. The material used for histological studies was the fetal part of placenta. After sampling, the material was fixed in a 10% neutral formalin solution, then xylene-free method  for histological preparation  was used. Afterwards, samples were embedded in paraffin. In order to study morphological structures, samples were sectioned at 5–6 µm, and stained with hematoxylin and eosin. Histological sections were analyzed using a Leica DM 1000 light microscope at a magnification of 100×,  200×,  400×,  630×.  On the basis of the conducted studies, it was established that bovine viral diarrhea-associated morphofunctional changes in the “mother – placenta – fetus” system are characterized by involutive-dystrophic changes with microcirculation disorders and the development of an immunity-associated inflammatory process. Chlamydia abortus intrauterine  infection in the “mother – placenta – fetus” system in cows causes a complex of destructive morphological and functional changes of an infectious and toxic nature with a pronounced inflammatory reaction, involvement of blood vessels in the pathological process, and endothelial dysfunction development,  alongside with tissue necrosis in case of a chronic process. The presence of cellular structures in the placenta and the inner part of the umbilical cord is a pathognomonic sign of chlamydia. The role of transplacental transmission of Neospora caninum in cattle was confirmed, the Neospora parasites subjected to basophilic staining were detected not only in the tissues of the placenta, but also in histological sections of the fetus heart and liver. The main characteristic diagnostic sign is the presence of basophilic stained Neospora parasites  in the organs of the mother  and fetus, placenta, and intervillous space. As part of the study morphological features of placenta, one of the most unique histohematic barriers and the basic element of the intrauterine infectious process, were determined.

The global economy dictates more and more stringent  requirements  for the quality and volumes of products consumed. Veterinary professionals have to look for medicinal products that have a sparing effect on the animal body and, at the same time, are capable of eliminating  disease causes. The paper presents  the results of tests of Kutikulin, a product made at the Vologda Branch of the FSC VIEV, which consists of chicken gizzard cuticle containing a keratoid secretion and a number of biologically active enzymes. It is a non-toxic, water-insoluble, odourless yellow-green powder with a bitterish taste. When Kutikulin was used to treat newborn calves with a mild dyspepsia resulting from various alimentary causes, the disease duration averaged 2.9 days, recovery rates in the groups were approximately the same (96.6–96.9%). Kutikulin treatment of older calves allowed to reduce the duration of treatment by almost a day, to increase recovery rates by 4.8% and to decrease the number of deaths by 1.6 times.When used for preventive purposes in weaned piglets, Kutikulin helped to decrease morbidity in groups 1, 3 and 5 (test groups) by 2.7, 8.9 and 1.8 times, respectively, as compared with control groups. Its preventive effectiveness was found to be the highest in group 3 (test) piglets that received Kutikulin on a group basis with a liquid feed at a dose of 1.0 g once a day during 3 consecutive days. Along with a shorter disease duration, test group animals also demonstrated  less pronounced clinical symptoms. Thus, the use of Kutikulin reduces gastrointestinal disease morbidity and mortality in calves and piglets.

Global warming results in increased extreme weather  events, including heatwaves,  droughts and floods, which exceed plants’and animals’tolerance thresholds, thus posing a threat to the economy and agriculture. Under these conditions, heat stress becomes a vital problem for animal husbandry. The paper presents the study results of biochemical blood parameters and endogenous intoxication in cows suffering from hepatopathies  under heat stress. Based on the calculated temperature-humidity  index, it was established that during the summer season in the conditions of the Krasnodar  Krai lowlands, cows are under heat stress. Using the method of paired comparisons, two groups of animals (n = 10) were formed: the first group was a healthy livestock; and the second group consisted of animals suffering from hepatic pathologies.  Blood was sampled from all cows at the beginning of the experiment (the first decade of May) and at the end (the last decade of July). Laboratory tests of blood revealed that as the heat stress develops healthy cows show the increase in the protein concentration in blood, and, on the contrary, animals with hepatic pathologies demonstrate the inhibition of protein synthesis. The higher activity of aminotransferases and alkaline phosphatase in the bovine serum in the summer season when compared to the spring season was established. The study of the endogenous intoxication level dynamics in cattle during the development of heat stress, showed that in both groups the concentrations of middle molecules (ММ) increased relative to the background data: in the first group (healthy cows) MM 237 – by 11.8%,  MM 254 – by 14.4%,  MM 280 – by 16.9%; in the second group (cattle with liver pathology)  MM 237 – by 16.9%,  MM 254 – by 20.3%,  MM 280 – by 33%. Thus, under heat stress, the endogenous intoxication in healthy livestock was almost 1.5 times less intense as compared to the animals suffering from hepatopathies.

Within the framework of the Rosselkhoznadzor measures aimed at control of highly dangerous  diseases and development of timely recommendations for disease prevention and control, 36,986 serum samples to be tested for the presence of avian influenza virus antibodies and 30,325 serum samples to be tested for the presence of Newcastle disease virus antibodies were submitted to the FGBI “ARRIAH” Reference Laboratory for Avian Viral Diseases  in 2020. The samples were collected from domestic, wild and synanthropic birds in 60 Subjects of the Russian Federation. As a result of the laboratory diagnosis, antibodies against type A influenza virus were found in vaccinated chickens from two poultry farms in the Primorsky Krai. Typing of sample sera using hemagglutination inhibition test showed that the detected antibodies were specific to the haemagglutinin subtype of the vaccine antigen  (A/H9). Antibodies to the H9 subtype  avian influenza  virus were detected in sera of non-vaccinated geese from two poultry farms in the Kurgan Oblast and from one poultry farm in the Republic of Bashkortostan. As for the  backyards where  scheduled  vaccination  against  avian influenza  A/H5 is carried out, a low level of immunity  was seen in the Republics of Adygea and Chechnya (0 and 15%, respectively), while a high immunity level was observed in the Rostov Oblast (74%). High seroprevalence  of Newcastle disease virus was found in adult poultry in indoor industrial farms, which was associated with mass vaccination against the disease. In broiler chickens, post-vaccination antibodies were observed, on average, in 44% of the tested sera samples. The antibodies  against  Newcastle  disease  virus and avian influenza  virus subtype  H5 detected in wild and synanthropic birds indicate the circulation of these viruses in the Russian Federation. The insufficient level of post-vaccination antibodies suggests that the risk of epidemic among poultry in industrial poultry farms and backyards remains.

Classical swine  fever  (CSF) is a highly dangerous porcine disease. CSF outbreaks are annually notified in several countries. Despite the availability of specific prevention tools, the disease spread risk still persists both at country level and at world level. Hence, the disease surveillance and eradication require highly sensitive methods for early diagnosis of the infection and for tests for the virus circulation in the environment.  Development of up-to-date  diagnostic methods is based on well-established  virus cultivation system; therefore, CSF virus reproduction enhancement,  tests of new cell lines without  endogenous  contamination  for their possible use are still of current importance. The said study was aimed at testing of primary and continuous cell cultures for their susceptibility to classical swine fever virus (vaccine virus strains and some field virus isolates recovered in the Russian Federation) and detection of the virus reproduction dynamics with real-time polymerase chain reaction with fluorescent hybridization probes used for detection. Virus replication intensity in primary and continuous cell cultures was also analyzed. The CSF virus was found incapable of replicating in some cell cultures without  its preliminary adaptation.  Primary porcine and lamb testicle cell cultures grown in minimal essential medium supplemented  with 10% normal CSFV-negative porcine serum instead  of fetal bovine serum were shown to be useful for the virus accumulation, both for vaccine strains and field isolates. Cultivation parameters and optimal minimal essential medium composition contributing to the 4–10-fold  increase in the virus accumulation  both in primary and continuous  cell cultures were determined.

The growth properties of the nutrient medium for the cultivation of pathogenic mycoplasmas depend on the type of blood serum it is supplemented with. Comparative tests of two cell-free nutrient media supplemented with bovine and porcine blood sera for the cultivation of strains “S6” Mycoplasma gallisepticum and “WVU 1853” Mycoplasma synoviae were performed. Growth properties of the tested nutrient media were assessed by determining the activity of the resulting biomass in the hemagglutination and agglutination assays, as well as by determining  the concentration of viable cells after the 9th passage. It has been shown that a cell-free nutrient medium supplemented with the porcine blood serum is optimal for the cultivation of pathogenic mycoplasma species causing infectious diseases in birds. The hemagglutinating activity of the Mycoplasma gallisepticum culture reached 5 HAU log₂ after 72 hours of cultivation, the agglutinating activity of Mycoplasma synoviae reached 5 AU log₂  during the 88-hour incubation period, the concentration  of viable cells of both strains was 10⁶ CFU/cm³. The low growth properties of the medium  prepared  with the addition  of bovine blood serum are most likely associated with its biochemical composition, which contains 5–20 times more provitamin A than the porcine blood serum, and high density lipoprotein cholesterol. On the contrary, in the porcine blood serum, most of the lipoproteins have a low density, containing a large amount of fatty acids and cholesterol, which are the main structural elements of mycoplasma cells. The obtained test results are of practical value and can be used in the technology of cultivation of pathogenic  species of avian mycoplasmas in the production of diagnostic and preventive tools.

Cryopreservation is the optimal way to store cells at ultra-low temperatures. Cryoprotectants are added to cell culture suspension to reduce cell death due to exposure to low temperatures. Cryoprotective media contain combinations of various cryoprotectants. Ethylene glycol, glycerin, dimethyl sulfoxide, sucrose, dextran, propylene  glycol, albumin, polyvinylpyrrolidone and blood serum can be used as cryoprotectants. For cryopreservation it is necessary  to select a cryoprotectant that ensures the highest survival of cells after storage and thawing. The paper presents  the results of experiments  on comparing the effectiveness of dimethyl sulfoxide, ethylene  glycol and glycerin in cryopreservation  of primary trypsinized chicken embryo fibroblasts. As a result of cell suspension  equillibration  (incubation  at room temperature) with serum and the specified cryoprotectants at different concentrations, the suspension variants containing different cryoprotectant and serum ratios were selected for freezing. Previously, it was found that after 12 months of observation, when using dimethyl sulfoxide as a cryoprotectant,  the largest number of surviving cells (46%) was observed in a suspension  containing  20% fetal serum and 10% dimethyl sulfoxide. The amount of surviving  cells if 10% fetal serum  and 5% ethylene  glycol were included in the cryoprotective mixture was slightly lower and amounted  to 36% after 12 months of observation. Glycerin is shown  to have weak protective properties as regards chicken embryo fibroblast cells. After 8 months of storage, the amount of surviving cells in a suspension containing 10% serum and 5% glycerin was 22%, no live cells were found in this mixture if stored longer. The proliferative properties of cells and their sensitivity to viruses remained within the 12 months  of the experiment.

Mycoplasmoses of cattle and small ruminants,  pigs and poultry are widely spread and the infection process is frequently associated with other diseases. Mycoplasma spp. cause inflammatory respiratory diseases, diseases of joints and meninges, keratoconjunctivitis, mastitis and endometritis,  abortion and stillbirths. Etiotropic therapy of mycoplasmal infections consists in prescribing antibiotics: enrofloxacin, difloxacin, oxytetracycline, chlortetracycline, doxycycline, tylosin, tilmicosin, tylvalosin, tiamulin, florfenicol, lincomycin, spectinomycin, tulathromycin. The results of studies described in different publications show high sensitivity of Mycoplasma synoviae and Mycoplasma gallisepticum to tetracyclines, tiamulin and tylvalosin. Isolates with increased resistance to tilmicosin are also resistant to tylosin and lincomycin. Treatment of respiratory infections in lambs, the main causative agents  of which are Mannheimia haemolytica and Mycoplasma, has been successful with the use of fluoroquinolones, tilmicosin, tulathromycin, chlortetracycline, enrofloxacin, doxycycline, and oxytetracycline. Isolates of Mycoplasma bovis are largely sensitive to oxytetracycline, florfenicol and tulathromycin.  Enrofloxacin has a less pronounced therapeutic effect. Tilmicosin and oxytetracycline are effective in the treatment of respiratory diseases of young cattle, associated with Mycoplasma spp. Tulathromycin and tilmicosin have a significant therapeutic effect in the treatment of pneumonia in weaned piglets experimentally infected with Mycoplasma hyopneumoniae. Multiple (course) use of enrofloxacin significantly increases the therapeutic effect. Tilmicosin is effective in the control of other bacterial infections of pigs (pasteurellosis, streptococcosis, hemophilic polyserositis, infectious atrophic rhinitis).The general prophylaxis of mycoplasmal infections is to comply with veterinary and sanitary standards and to implement quarantine measures in the infection outbreak.

Coronavirus induced diseases can cause significant damage to agriculture that is associated with high (up to 100%) lethality in young animals. Members of the family Coronaviridae are characterized by the fact that they infect a wide range of animals and birds with expressed species-limited  pathogenicity.  One more coronavirus specificity involves their ability to simultaneously affect more than one organ. The disease severity is also strongly correlated with the age of the susceptible animal and degree of pathology. Thus, the coronavirus induced diseases are most often acute in newborn and young animals, while such diseases often develop into chronic and latent forms in adult animals. The general property of all coronavirus-induced diseases involves acute impairement of capillary circulation in the affected organ thus leading to the development of further pathology. The proposed review demonstrates  brief overview of the history of discovery and examination of the viruses of Coronaviridae family and describes the coronavirus taxonomy. The paper reviews the virus structure, physico-chemical and biological properties; it describes specific features  of their cultivation in vitro, some biochemical aspects of the virus replication and analyses the process of their propagation  in the sensitive cells. Some data on the virus antigen structure and immunogenicity, on the presence of related antigens in the coronaviruses infecting humans, animals and birds are demonstrated as well. The paper provides data on the significant role the coronaviruses play in the pathology of farm animals and stresses their economic relevance, in particular for the commercial pig and poultry production.