Determination of T-cell immune response to SARS-CoV-2 is important both for diagnosis of the disease in symptomatic patients, and for determination of the total number of people who have had the disease, including its asymptomatic form. In addition, these assays are efficient for assessing the immune response after vaccination, as well as immunity levels in risk groups and in convalescent patients. The most promising method of T-cell immune response assessment is an ELISPOT-based assay measuring the release of interferon-gamma (IGRA) after stimulation with coronavirus-specific antigens. The present review analyses the prospects for using the ELISPOT technological platform in the clinical laboratory setting when dealing with the new coronavirus infection COVID-19, given specific aspects of the immune response. The review summarises data from articles published in peer-reviewed journals, preprints of articles available at arXiv resources, and information that some leading immunologists shared with the authors during private discussions. It has been shown that the introduction of B- and T-cell ELISPOT assays will make it possible to monitor the immunological status of patients, select a treatment strategy, identify the most vulnerable populations, carry out comprehensive assessment of vaccines during the development, clinical trials and implementation stages. The paper discusses the issues of maintaining T-cell immunity in the blood of people who have had HCoV, SARS, MERS, and COVID-19 coronavirus infections. It also discusses the advantages of the T-cell ELISPOT assay over serological tests as regards epidemiological assessment of the prevalence of the new coronavirus infection, and clinical trials of COVID-19 vaccines. Biotechnology companies have a ready-made technological platform for the development and industrial-scale production of ELISPOT kits, and this platform is easily adaptable to specific types of assays and pathogens. The paper supports the need to develop vaccines that would stimulate both cellular and humoral immune responses, and raises the question of the protective potential of cross-immunity acquired before the COVID-19 pandemic.

The cell line is one of the necessary components of a biomedical cell product (BMCP) which can include only viable human cells. In addition, human, animal, insect, or bacterial cell lines can be used as a substrate for the production of some biological drugs. The list of quality parameters and test methods for medicinal products quality control are specified in the State Pharmacopoeia of the Russian Federation, but it contains only a few general monographs on blood products and a few requirements for cell lines as substrates for the production of biological drugs (which cover all types of cells). Currently, there is no regulatory document comparable to the State Pharmacopoeia of the Russian Federation that would contain requirements and test methods for BMCP quality control in the Russian Federation. Thus, one of the issues that arises both during quality control and approval of BMCPs is the lack of a regulatory document defining requirements for BMCP quality parameters and test methods. However, some general monographs of the Russian Pharmacopoeia and other pharmacopoeias can be used for quality control of both cell lines and non-cellular components. The aim of the study was to analyse and compare different pharmacopoeial requirements for the quality of cell lines used as components in human cell- and tissue-based products (comparable to BMCPs), which could be used in BMCP quality control. The paper analyses general monographs of the United States Pharmacopoeia (USP), European Pharmacopoeia (Ph. Eur.), Japanese Pharmacopoeia, Pharmacopoeia of the Republic of Belarus, including general monographs on biological/biotechnological products, because their requirements apply to human cell lines included as components in products similar to BMCPs. The analysed approaches and methods of quality control of cell- and tissue-based products described in the USP and Ph. Eur. could form the basis for elaboration of general monographs for the Russian Pharmacopoeia, including identification, potency, viral safety, and mycoplasma tests that are based on the nucleic acid amplification technology and other tests for cell lines as components of BMCPs.

Vaccination remains the only way to prevent tick-borne encephalitis (TBE). All TBE vaccines are based on strains of the Far Eastern and European subtypes of TBE virus. Currently, the Siberian subtype of the virus, which differs from the vaccine strains, accounts for 80–100% of the genetic population of TBE virus in most of Russia. The proportion of TBE vaccinated patients among those infected was different from year to year in Russia, e.g. 3.9% in 2012 and 1.5% in 2018, there were also some fatal cases registered among vaccinated patients. In this regard, evaluation of the effectiveness of vaccination against various genetic subtypes of TBE is a promising area of research. The purpose of this study was to summarise the results of studies investigating effectiveness of specific prevention of TBE as regards various genetic subtypes of the virus. The paper analyses data on the effectiveness of TBE vaccination in experimental settings and in real life. It was demonstrated that the use of vaccines for prevention of TBE is effective, provided the vaccination coverage is not less than 80%. The paper cites the data from a long-term study of the stability and protective activity of vaccine immunity against TBE virus strains isolated in highly endemic territories. It was established that TBE vaccines have high immunogenic activity and contribute to the production of stable protective antibodies against the strains of the three genetic subtypes of the virus. Protective efficacy of vaccination depends on the number of vaccinations received, the vaccination scheme, gender and age of those vaccinated. The paper concludes by saying that further studies are needed to assess TBE vaccine efficacy in order to improve vaccination tactics, to better understand causes of morbidity and mortality among vaccinated individuals.

The industrial reference standard of tuberculosis (BCG) vaccine (IRS), certified and registered by the Federal State Budgetary Institution “Scientific Centre for Expert Evaluation of Medicinal Products” of the Ministry of Health of the Russian Federation (OSO 42-28-420), is used as a reference product in quality control of tuberculosis vaccines BCG and BCG-M. The IRS is a useful means of quality control of these products, as the stability of its proper ties helps to minimise errors during quality evaluation. The shelf life of the BCG vaccine IRS is not more than 2 years if stored at 2–8 °C. It is likely that a vaccine batch could be used as the IRS for a longer period of time. The literature data suggest that the shelf life of a BCG vaccine can be prolonged if it is stored at low temperatures. However, due to significant phenotypic and genotypic differences between BCG sub-strains, the extrapolation of these data to the vaccine produced from the Russian Mycobacterium bovis BCG-I sub-strain requires appropriate testing. The aim of the study was to analyse the possibility of increasing the shelf life of the tuberculosis vaccine IRS by changing the storage temperature. Materials and methods: the effect of low temperatures on the stability of OSO 42-28-420 was studied in commercial batches of tuberculosis vaccine which met all the quality requirements for candidate IRSs. Samples from 6 IRS batches produced from 2014 through 2019 were stored at –(20 ± 1) °С. The stability of their quality characteristics, namely “Specific activity (viability)”, “Total bacterial count”, and “Dispersibility”, was monitored according to the recommendations of the World Health Organization. The obtained data were evaluated relative to the baseline data obtained during certification of each batch. Results: it was demonstrated that there was more than 95 percent probability that the tested parameters would not differ from the initial data if OSO 42-28-420 samples were stored at a low temperature for 5 years. Conclusions: the results obtained support the prolongation of the OSO 42-28-420 shelf life up to 4 years under the recommended storage conditions at –(20 ± 1) °С.

Assessment of specific activity of Russian and foreign-made filgrastim products by biological in vitro methods is performed using different types of dyes. It is important to choose one cell staining dye in order to align the procedure of filgrastim specific activity assessment using cell culture. The aim of this study was to perform comparative assessment of tetrazolium and resazurin dyes in tests determining filgrastim ability to activate proliferation of sensitive cells. Materials and methods: NFS-60 (mouse myelogenous leukemia) cell line, 2nd International Standard for Granulocyte Colony Stimulating Factor (IS), as well as МТТ, MTS, WST-1, and alamarBlue dyes were used in the study. Proliferative activity of cells was assessed in vitro. The level of cell proliferation was assessed by fluorescence or absorbance intensity. Origin Pro 9.1. and Microsoft Excel applications were used for statistical processing of the obtained results. Results: the paper compares characteristics of the most widely used dyes. It describes the procedure for choosing optimal test conditions for some of the studied dyes. The authors analysed the potential of some factors, such as duration of cell suspension incubation with IS and with a dye, composition of the lysis buffer (for MTT staining), and different readout modes, to influence the final results. Despite the fact that all the studied dyes gave reproducible dose–response curves under the given test conditions, 50% effective concentrations showed no statistically significant differences in tests with only three dyes: МТТ, MTS, and alamarBlue (р > 0.05). Conclusions: better reproducibility of results was obtained in tests using МТТ and alamarBlue. The test procedure using alamarBlue is easier to perform and less time-consuming, it does not include the cell lysis stage and does not require additional reagents, therefore this dye may be recommended for harmonisation of the test procedure to be elaborated for the Russian Pharmacopoeia.

The European Pharmacopoeia requires that the transportation and storage of human plasma for fractionation should be carried out at –20 °C or below, while allowing for some deviations in the temperature regime. The current Russian regulatory documentation requires the transportation and storage of plasma intended for the production of labile protein preparations (blood clotting factors) at  –30 °C or lower. However, acceptable deviations from the temperature regime are not specified, which creates certain difficulties in their assessment by an authorised person during plasma batch release. The main tool in risk assessment is in-process control of factor VIII activity in plasma stored at inadequate temperature, which entails significant financial costs. The aim of the study was to assess stability of factor VIII activity in human plasma for fractionation when modeling deviations in the storage and transportation temperature regime and to assess the possibility of amending the regulatory documentation requirements. Materials and methods: only full individual doses of plasma obtained by apheresis were used in the experiments. The tests were performed under simulated high temperature conditions with accurate continuous recording of temperature by a measuring system. An automatic coagulation analyser was used to determine factor VIII activity. Quantitative evaluation of the results was carried out by comparing factor VIII activity in the plasma before freezing and in the tested plasma. Statistical processing of data was performed by descriptive statistics methods using Microsoft Excel 2007 applications. Results: no significant effect of short-term deviations in the storage temperature on the stability of factor VIII activity in human plasma for fractionation was observed. Conclusions: the obtained data can be used as a rationale for introducing changes in the official requirements for the storage and transportation temperature regime for human plasma for fractionation, as well as for including details of acceptable short-term deviations of the storage and transportation temperature regime in the regulatory documentation.