Review of global use of licensed vaccines and development of new vaccines for the prevention of pneumococcal infection

Streptococcus pneumoniae infection is the most common cause of high morbidity and mortality among children under 5 years of age, immunocompromised people, and the elderly. Despite significant success, the approved pneumococcal conjugate and polysaccharide vaccines are of limited efficacy, providing protection against a small fraction of the known pneumococcal serotypes. The rapid spread of multidrug-resistant strains exacerbates the global challenge of treating infection caused by S. pneumoniae. At the same time, the emerging new strains dictate the need to include new serotypes into vaccines. In view of this, further improvement of vaccines for the prevention of pneumococcal infections is an urgent task. The aim of this study was to review advances in the development of polysaccharide, conjugate, whole-cell pneumococcal vaccines, as well as vaccines based on protein antigens and vaccines with an antigen delivery system. Genomics and proteomics data have helped to improve approaches to the creation of polysaccharide and protein-based vaccines, as well as whole-cell vaccines with the potential for population prophylactic coverage against various pneumococcal serotypes that are not included in the licensed pneumococcal vaccines. The method of antigen delivery to the cell is of great importance in the development of vaccines. The most promising strategy for improving pneumococcal vaccines is the creation of vaccines based on bacterium-like or synthetic particles carrying several antigens, including pneumococcal surface proteins. In conclusion, it should be noted that top-priority vaccines are those that provide a wide range of protection against circulating pneumococcal serotypes and, in addition to eliciting a systemic immune response, also induce local immunity.

Comparison of different technologies for producing recombinant adeno-associated virus on a laboratory scale

Adeno-associated virus vectors are among the most promising ones for the delivery of transgenes to various organs and tissues. Recombinant adeno-associated virus (rAAV) is able to transduce both dividing and non-dividing cells, has low immunogenicity, and is able to provide long-term expression of transgenes. Modern technologies make it possible to obtain rAAV for in vivo use, but they are not without drawbacks associated with laboriousness, scalability difficulties, and high cost, therefore, improvement of technological schemes for obtaining rAAV is an urgent issue. The aim of the study was to compare different technological approaches to rAAV production based on different conditions of the transfected HEK293 cell line cultivation on a laboratory scale. Materials and methods: HEK293 cell culture, AAV-DJ Packaging System, PlasmidSelect Xtra Starter Kit were used in the study. The technologies were compared using a model rAAV vector with a single-domain antibody transgene fused to the Fc-fragment of IgG1 specific to botulinum toxin. HEK293 cells were transfected with supercoiled plasmid DNA isolated by three-step chromatographic purification. The identity of the rAAV preparation was determined by electrophoresis, immunoblotting, and real-time polymerase chain reaction. Results: the study demonstrated the efficiency of the chromatographic method for obtaining a supercoiled form of plasmid DNA that can be used for efficient transfection of cell culture in order to produce rAAV. The study compared the following processes of rAAV production: using transient transfection and cultivation of the transfected HEK293 cell suspension in Erlenmeyer flasks, adherent culture in T-flasks, and adherent culture in a BioBLU 5p bioreactor on a matrix of Fibra-Cel disks. Conclusions: the data obtained showed the possibility of using the described approaches to purification of plasmid DNA, cell transfection, and cultivation of the transfected cells under various conditions to obtain rAAV samples that expresses the antibody gene. The BioBLU 5p reactor with Fibra-Cel discs was used for the first time to produce preparative quantities of rAAV on a laboratory scale, which increased the adherent surface area during cell culture and transfection, and, as a result, increased the yield of the target product.

Production of solid dosage forms of immunoglobulin products

At the moment, there are no scientific publications devoted to the technological aspects of production of immunoglobulin solid dosage forms. The aim of the study was to review Russian and foreign literature on production of immunoglobulin solid dosage forms, and present the results of the authors’ own research. The authors analysed data of the National Register of Medicines of the Russian Federation as of mid-2021 on the authorised medicines with a generic name ‘globulin in a solid dosage form’, and summarised their characteristics. They reviewed data on the qualitative and quantitative composition of excipients used in lyophilisation, preparation of tablets and capsules. A number of examples were used to illustrate the effect of technological parameters of immunoglobulin solid form production on the quality of the finished products. It was demonstrated that the production of solid forms of immunoglobulin products prevents aggregation and fragmentation of proteins during storage, which affect the product’s specific activity, and also help to preserve the product’s target characteristics for a longer period of time as compared to liquid dosage forms of immunoglobulins. The results of the study may be used as a basis for development of a manufacturing technology for solid forms of immunoglobulin products.

Comparative analysis of existing platforms for the development of vaccines against dangerous and extremely dangerous viral infections with pandemic potential

The main triggers of new infectious diseases, including those with pandemic potential, are: spontaneous emergence of infectious strains which are more virulent for humans and contribute to transmission of pathogenic microorganisms, environmental changes, social and economic factors, increased contact rates between different regions. A successful pandemic response requires mass immunisation against a specific disease, aimed at the development of herd immunity which is based on the concept of indirect protection of the whole of the population by immunising a part of it. A well-grounded choice of the vaccine platform is central to dealing with this problem. The aim of the study was to compare characteristics of vaccine platforms (attenuated, inactivated, subunit, recombinant vector, DNA, and RNA vaccines) intended for mass immunisation against dangerous and extremely dangerous viral infections with pandemic potential. The study focused on the members of Poxviridae, Orthomyxoviridae and Coronaviridae families as potential pathogens. The vaccine platforms were compared in terms of the following parameters: capability of producing a robust immune response; protective efficacy; time required for vaccine development and testing; ability to produce vaccine in volumes required for mass immunisation; potential obstacles associated with the intended use of the vaccine. It is expected that in the next few decades DNA and RNA vaccine platforms will be most widely used for development of products against dangerous and extremely dangerous viral infections with pandemic potential, regardless of taxonomic groups of pathogens.

Estimation of production consistency of diphtheria, tetanus, and pertussis components of the DTP vaccine using Shewhart charts

The Russian Federation puts special emphasis on vaccination-related issues, in accordance with the WHO recommendations. The fact that vaccination, in particular with the diphtheria, tetanus, and pertussis vaccine (DTP vaccine), covers large population groups, accounts for the relevance of research aimed at improving the quality of vaccines. One of the ways to produce vaccines of assured quality is to maintain consistent manufacturing processes that ensure consistency of product characteristics. The stability of the technological processes may be assessed using Shewhart charts. The aim of the study was to assess the production consistency of diphtheria, tetanus, and pertussis components of DTP vaccine using Shewhart control charts. Materials and methods: the study used data from 60 batch summary protocols of a Russian-produced DTP vaccine that were submitted to the Testing Centre of the Scientific Centre for Expert Evaluation of Medicinal Products from September 2017 until April 2020. The study assessed one of the main vaccine quality characteristics—specific (protective) activity of diphtheria, tetanus, and pertussis components. Shewhart charts for the diphtheria and tetanus components were constructed based on the manufacturer’s summary protocols, while Shewhart charts for the pertussis component were constructed based on both summary protocols and the results obtained by the Testing Centre during certification of the product batches. The Shewhart charts were used in accordance with the national standards GOST R 50779.42-99 and GOST R ISO 7870-2-2015. Results: a retrospective analysis of R- and X-charts covering a 2.5-year period revealed some characteristic trends in special-cause criteria. The most alarming situation was observed for the production of the diphtheria component. The technological processes were somewhat safer in the case of the tetanus and pertussis components. The production process lacked due statistical control, which is confirmed by the lack of correlation between the results of the pertussis component activity assessment obtained by the manufacturer and the Testing Centre. Conclusions: during the analysed period, the production of the diphtheria, tetanus, and pertussis components of the DTP vaccine was not always consistent. This highlights the need to conduct research aimed at standardisation of both production processes and control test conditions.

Approaches to quality control, preclinical and clinical studies of live recombinant viral vector vaccines

At present, there are not much data on the clinical use of live recombinant viral vector vaccines. Characteristics of new vaccines should be factored into requirements/recommendations for quality control, preclinical and clinical studies of vaccines in order to enable further risk/benefit assessment. The aim of this study was to analyse current approaches to quality control, preclinical and clinical studies of live recombinant viral vector vaccines. The paper provides an overview of the licensed live viral vector vaccines and those at various stages of clinical trials. The authors analysed Russian, European, American, and Japanese guidelines related to quality issues, preclinical and clinical studies of live viral vector vaccines. The analysis demonstrated that the regulatory requirements for live recombinant viral vector vaccines include assessment of a detailed rationale for vaccine development, including information on the choice of the vector, the origin of the heterologous antigen gene(s), elements related to the transgene(s) expression, as well as assessment of the genetic and phenotypic stability of the recombinant virus, the risk of reversion to virulence or recombination with wild type strains, the potential for virus genome integration into the host cell chromosome, the pre-existing immunity to the vector, the intensity of the immune response elicited by the vector, and the reusability of the vector. The choice and number of applicable toxicological and pharmacological models will depend on these aspects. The results of the analysis of approaches to quality control, preclinical and clinical studies of live recombinant viral vector vaccines may be used in the development of Russian regulatory guidelines harmonised with the international norms and regulations.

Vaccine interchangeability: problems and prospects

Vaccines by different manufacturers are available for most of the vaccine-preventable infections covered by the National Immunisation Schedule of the Russian Federation. Determination of the possibility of replacing a vaccine in the case of routine or emergency vaccination still remains a challenging issue. The aim of the study was to substantiate the problem of vaccine interchangeability, outline specific challenges and ways of solving them, analyse criteria underlying evaluation of vaccine interchangeability in Russia, and international experience in this area. The procedure for determining the interchangeability of biological products, including vaccines, was established in the Decree of the Government of the Russian Federation of 5 September 2020, No. 1360 “On the procedure for determination of interchangeability of medicinal products for human use”. The paper analyses the applicability of the official criteria for interchangeability of biological products, including vaccines. It outlines the main problems of performing evaluation of vaccine interchangeability in accordance with the established criteria. It is concluded that the vaccine interchangeability criteria need to be clarified in order to allow for assessment of comparability of active substances, and comparison of efficacy, safety, and immunogenicity of vaccines, taking into account vaccination schedules for different age groups. The possibility of evaluating interchangeability based on the results of post-authorisation studies also needs clarification. It is also necessary to align patient information leaflets for interchangeable vaccines.

Development of the technology for preparation of enzymatic hydrolysate of waste chick embryos

The development of technologies for preparation of protein nutritional bases for microbiological nutrient media, from production waste of mainly readily available or non-food products, is a promising area in biotechnology. Researchers of Vyatka State Agrotechnological University assume that non-food secondary raw materials, such as waste chick embryos (WCEs) used in the production of anti-influenza products, could be used for these purposes, after removal of the virus-containing allantoic fluid. The aim of the study was to develop a technology for preparation of WCE enzymatic hydrolysate (WCEEH), and to evaluate growth properties of the hydrolysate-based solid nutrient medium, using Escherichia coli M-17 and Pseudomonas alcaligenes IP-1 test strains. Materials and methods: the authors offer methodological approaches to obtaining WCEEH and substantiate hydrolysis parameters. The obtained WCEEH was characterised in terms of physico-chemical properties: pH, amine nitrogen, total nitrogen, sodium chloride, degree of protein cleavage. The growth properties of the hydrolysate-based nutrient medium were studied using E. coli M-17 and Ps. alcaligenes IP-1 test strains. Results: the experiments demonstrated the feasibility of performing enzymatic hydrolysis of WCEs, and assessed physico-chemical properties of the prepared WCEEH batches. The study demonstrated the possibility of using the prepared hydrolysate as a component of solid nutrient media for growing the selected test strains. Conclusions: the study substantiated the optimal technological parameters for WCE enzymatic hydrolysis: pH (7.6 ± 0.3), duration (48 ± 2 h), temperature (49 ± 1) °C. The loading of hydrolysis components was optimised: mass fraction of the substrate—500 g/L, mass fraction of the hydrolysing agent—100 g/L. The physico-chemical properties of WCEEH make it suitable for preparation of microbiological media; the hydrolysate-based solid nutrient medium consistently ensures the growth of E. coli M-17 and Ps. alcaligenes IP-1 test strains with standard properties. The growth properties of the experimental medium are comparable to those of the meat-peptone broth-based nutrient medium.

Assessment of T-cell immunity to SARS-CoV-2 in COVID-19 convalescents and vaccinated subjects, using TigraTest® SARS-CoV-2 ELISPOT kit

With the onset of the COVID-19 pandemic, a number of molecular-based tests have been developed to diagnose SARS-CoV-2 infection. However, numerous available serological tests lack sufficient sensitivity or specificity. They do not detect specific antibodies in a significant proportion of patients with PCR-confirmed COVID-19. There is evidence that some convalescents have a relatively short-lived humoral immunity. In contrast, a number of publications have shown that T-cell response to human coronaviruses, including SARS-CoV-1, MERS, and SARS-CoV-2, can be strong and long-term. Assessment of T-cell immunity to SARS-CoV-2 is important not only for stratification of risks and identification of potentially protected populations with immunity acquired as a result of previous infection, but also for determining immunogenicity and potential efficacy of vaccines under development. The existing methods of quantitative or semi-quantitative assessment of specific T-cell response are mainly used in scientific research and are not standardised. The aim of the study was to develop and verify experimentally a test kit to be used in a standardised procedure for in vitro determination of T-cells specific to SARS-CoV-2 antigens, in human peripheral blood. Materials and methods: the TigraTest® SARS-CoV-2 kit developed by GENERIUM, which determines the number of T-cells secreting interferon gamma in vitro, was tested in the study. Samples of venous blood of volunteers from three different groups were analysed in the study: presumably healthy volunteers; COVID-19 convalescents; individuals vaccinated against SARS-CoV-2. Results: the authors developed the TigraTest® SARS-CoV-2 kit for in vitro determination of T-cells specific to SARS-CoV-2 antigens in human peripheral blood, demonstrated its specificity and performed preliminary assessment of its sensitivity. The study analysed the range and magnitude of the T-cell response in convalescent and vaccinated individuals. A pronounced T-cell response was also shown in some individuals with no symptoms or with unconfirmed diagnosis. It was discovered that the mean T-cell response to peptides of the spike protein (S-protein) was higher in the vaccinated individuals than in the convalescent patients. A correlation was determined between the severity of the disease and the level of T-cell response. Specific contributions of various groups of antigens to the T-cell response after COVID-19 infection were also determined. Conclusions: the TigraTest® SARS-CoV-2 kit is a specific and sensitive tool for the assessment of T-cell immunity to the SARS-CoV-2 virus, which can also be used for vaccinated individuals. The kit may be used in clinical practice for comprehensive assessment of immunity to SARS-CoV-2.

World practice of providing scientific advice on the development and authorisation of innovative medicines

Current challenges to healthcare, i.e. the emergence of new diseases, lack of therapies for known diseases and life-threatening conditions, identification of patients who do not respond to standard treatment, on the one hand, and the evolution of scientific understanding of disease processes, medicines, therapies, causes of treatment failures, and implementation in clinical practice of innovations related to molecular biology and genetic engineering, on the other hand, create conditions and opportunities for the development of innovative medicinal products. A relatively new class of medicines is based on human cells and tissues (the term used in Russian legislation is biomedical cell products, BCP). However, the inability to accurately predict the efficacy and financial rewards of such medicines for pharmaceutical companies, as well as significant labour and financial costs associated with their development and clinical use, hinder their entry into the market. The aim of the study was to analyse the foreign regulatory setting for the development and launch of human cell- and tissue-based products, as well as approaches of foreign regulatory authorities to scientific advice, which can be drawn upon by the Russian expert authority when providing advice to BCP developers. The paper summarises the results of analysis of regulations establishing the procedure for providing scientific advice by EU, USA, and Russian regulatory authorities, and analyses the advice provided for the human cell- and tissue-based products which are now authorised in the EU and USA. The analysis of advice provided by foreign regulatory authorities shows that the largest number of consultations were given for medicinal products based on genetically modified cells for the treatment of cancer and genetic diseases. The questions were mainly related to the contents of specifications for finished pharmaceutical products, safety evaluation, curtailing of preclinical studies due to the lack of relevant animal/disease models, the number of subjects and efficacy endpoints in clinical studies, assessment of the appearance of replication-competent retroviruses.