Biological properties of the African swine fever (ASF) virus isolates originating from various regions of the Russian Federation (2013–2018) were studied in a series of experimental infections. Comparative analysis allowed us to establish the differences in the key characteristics of the infection, such us the duration of the incubation periods, disease, and the onset of death. The incubation period averaged 4.1 days, varying from 1 to 13 days. An average duration of the disease was 6.3 days and varied from 0 to 18 days. Overall case fatality was 94.5%, and antibodies were detected only in 19.3% of the animals. The biological properties of isolates Odintsovo 02/14 and Lipetsk 12/16 were significantly different from others. For this two, the presence of antibodies to the virus was detected in 71.4% and 75% of animals respectively and mortality levels were of 87.5% and 50%.

One of the measures used to control and prevent African swine fever spread in the Russian Federation involves testing pig and boar sera using inter alia serological tools based on enzyme-linked immunosorbent assay (ELISA) for anti-viral antibody detection. However, there is no unified regulatory document specifying storage conditions for sera used in the ELISA for anti-ASFV antibody detection. There are also lack of published data on the maximum admissible shelf life of the pig sera, and the effect of storage conditions on the serological status of the pig sera as for ASF is understudied. The paper demonstrates results of the experiment aimed at the determination of the effect of storage temperatures and shelf life on the serological status of ASFV seropositive and seronegative pig sera when tested by INgezim PPA Compac (Ingenasa, Spain) ELISA as well as on the possibility of false results. During the experiment and analysis of its results, the new data were obtained, and they indicated from none to non-significant effect of the simulated storage conditions on the serological status of sera used for ASFV detection, while hemolyzed sera demonstrated more significant changes proportional to hemolysis degree and storage duration. Although the results of detection of antibodies against the agents of some diseases cannot be used in case of other pathogens, this study has a substantial applied significance as it allows to specify the dependence of the valid results of ASF serodiagnosis on the storage conditions of the samples.

INTRODUCTION. Bioanalytical techniques are characterised by greater variability and lower stability than physicochemical methods because live test systems are inherently labile. Since regulatory standards do not establish a unified approach, the selection of system suitability criteria and acceptance criteria for test results is based on validation studies.AIM. This study aimed to validate an analytical procedure for evaluating the biological activity of a medicinal product based on the investigational tocilizumab biosimilar GNR-087 and determine the quantitative limits for system suitability criteria and acceptance criteria for test results.MATERIALS AND METHODS. The biological activity of the investigational tocilizumab biosimilar was assessed by the inhibition of IL-6-induced secreted embryonic alkaline phosphatase (SEAP) expression by HEK-Blue™ IL-6 cells. Statistical processing of the obtained results was performed using Prism 6.0 software.RESULTS. The specificity of the analytical procedure was confirmed by the dose-dependent inhibition of IL-6-induced SEAP expression by cells observed with tocilizumab. The analytical procedure was linear, with a coefficient of determination R²≥ 0.99. The precision of the analytical procedure was satisfactory; its repeat ability varied from 2 to 9%, and its intermediate precision was 14%. The recovery coefficients (Rc) for spiked samples simulating activity levels of 60–140%, including blinded samples, ranged from 80 to 120%. The theoretical values of relative potency (RP) were within the confidence intervals of the mean relative potency estimates, which confirmed the accuracy of the analytical procedure. The validation confirmed the robustness of the analytical procedure to controlled variations, including the use of reporter cells at different passages (with a coefficient of variation for relative potency estimates (CV_RP) of 10%), different IL-6 lots (with a CV_RP of 1%), and different SEAP detection reagent lots (with a CV_RP of 3%); the Rc remained in the range of 80–120% of the nominal RP value.CONCLUSIONS. The analytical procedure for evaluating the biological activity of the investigational tocilizumab biosimilar meets the validation criteria, including accuracy, linearity, precision, specificity, and robustness. The study established system suitability criteria and acceptable limits for biological assay results. This analytical procedure can be used both for routine biological activity control and for demonstrating the biosimilarity of new medicinal products to the original (reference) tocilizumab-based medicinal product.

Laboratory diagnosis is a crucial component in implementation of the set of anti-epidemic measures aimed at contagious animal disease control. The need for unswerving trust in the quality of laboratory performance is a matter of importance not only for service providers and customers, but also for inspecting organiza­tions, accreditation bodies, etc. that establish performance requirements for diagnostic laboratories. Incorrect laboratory test results can lead to a misdiagnosis and, therefore, to grave consequences. One of the forms of experimental verification of a laboratory’s performance with a view to determine the laboratory’s competence and to verify its compliance with accreditation criteria as part of inspection control of the laboratory’s activities is interlaboratory comparison. The laboratory can prove its competence at a particular time, as well as clearly demonstrate how stable the quality of its test results is by summarizing and analyzing the results of its participation in interlaboratory comparisons. The analysis of the results of the interlaboratory comparisons (programmes for detection of causative agents or antibodies to the causative agents of avian influenza, Newcastle disease, rabies, classical swine fever, African swine fever, bluetongue, lumpy skin disease) organized by the FGBI “ARRIAH” for the veterinary laboratories of the Russian Federation in 2018–2019 is presented. The results showed that most of the laboratories had passed the tests successfully. The results submitted by participants were unsatisfactory in some interlaboratory comparison programmes (rabies virus detection using fluorescent antibody technique; detection of avian influenza, classical swine fever and lumpy skin disease viruses using polymerase chain reaction). That highlights the need for those participants who failed the tests to improve their laboratory testing quality.