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Typhoid fever is an acute infectious disease caused by Salmonella enterica subsp. enterica serovar Typhi (S. Typhi), which is still extremely common in endemic low- and middle-income countries of Asia and Africa. Industrialised countries may also be affected by typhoid fever outbreaks due to booming international tourism, and natural disasters. Given S. Typhi progressive resistance to antibiotics, high epidemiological burden, and lack of adequate sanitation and hygiene in a number of regions, the introduction of new treatment protocols and the improvement of preventive vaccination are critical tasks in global healthcare. The aim of the study was to highlight the main historical aspects of the typhoid vaccine development, to summarise data on the licensed vaccines and promising approaches to the development of new typhoid vaccines. The paper describes the current epidemiological situation of typhoid fever globally and in the Russian Federation. It dwells upon the global experience in typhoid vaccine development from the production of an inactivated vaccine to the development of conjugated vaccines. The paper summarises data on Russian and foreign-made typhoid fever vaccines currently available in the global pharmaceutical market. It outlines the main trends in the development of vaccines against the disease caused by S. Typhi. The paper demonstrates the need for improving the efficacy of existing vaccines and development of new typhoid combination vaccines.

One of priority issues of the present-day healthcare system is development of new vaccines and improvement of existing ones due to decreasing immunocompetence of the population, emergence of new infections and reemergence of old ones which were previously thought to be under control. Adjuvants have proven to be integral and important components of modern vaccines, as they enhance immune response to the vaccine antigen. However, despite a lot of effort put into their development, only a small number of adjuvants are currently used in clinical practice.The aim of the study was to systematise literature data on the adjuvants’ mechanisms of action, their specific structure, composition, and stimulation effects that mediate their immunoadjuvant properties. The paper summarises data on adjuvants used as components in licensed vaccines, describes their characteristics, analyses molecular mechanisms of their action in order to establish correlation between their structure and activity, which is important for the development of more efficacious and safe adjuvants. The paper cites advanced developments aimed at enhancing stimulation effects of existing adjuvants. It concludes by stating that the key research area aimed at improving vaccination efficacy is the study of mechanisms that contribute to the development of effective protection against infectious agents, as well as analysis of how to use adjuvants to stimulate the body’s defensive mechanisms, primarily by impacting the innate immunity.

The review is devoted to specific aspects of the development of post-vaccination immunity following immunisation with different types of antiviral vaccines, as well as to ways of increasing immunogenicity of vaccines and effectiveness of preventive vaccination. Vaccines containing highly purified and recombinant antigens obtained using modern technologies have lower reactogenicity and a higher safety profile, but are less immunogenic compared to live vaccines. Effective vaccines have not been developed for many viral infections yet. Therefore, it is critical to search for ways to enhance immunogenic properties of vaccines in order to increase the efficiency of vaccination, and to develop new vaccine formulations that provide reliable protection of the body against infection. The aim of the paper was to analyse specific aspects of immune response development following immunisation with antiviral vaccines, and approaches to increasing their immunogenicity using adjuvants. It reviews different types of antiviral vaccines, as well as specific aspects of immune response development depending on the nature of a specific antigen. The paper substantiates the use of adjuvants to enhance and regulate the induced immune response. It analyses mechanisms that determine the stimulating effect of adjuvants and summarises data on the adjuvants used in the licensed vaccines for human use. The authors highlight the need for further research to increase the efficiency of vaccination and suggest that one of potential solutions is the use of adjuvants based on recombinant human cytokines.

Some scientific publications contain data suggesting the “return” or “resurgence” of pertussis. Prevention and elimination of pertussis can only be achieved by extensive immunisation of susceptible populations with a highly effective vaccine. The aim of the study was to characterise available whole-cell and acellular pertussis vaccines and to assess the feasibility of improving their quality, for instance, to demonstrate the role of lipooligosaccharide (LOS)—Bordetella pertussis cell wall antigen—in the induction of adaptive immunity. The paper summarises pathogenesis of pertussis, development of post-infection and post-vaccination immunity, and potential ways of improving pertussis vaccines. Improvement of quality of available vaccines can be achieved by reducing reactogenicity of whole-cell pertussis vaccines and enhancing immunogenic activity of acellular pertussis vaccines. One way to reduce reactogenicity of a whole-cell vaccine is to reduce the number of pertussis cells in the vaccine dose, provided that this does not affect the immunogenic activity of the product. Another possible way of reducing reactogenicity is to select vaccine strains based on the LOS endotoxin content. Improvement of acellular vaccine quality involves addressing many issues, such as identification and isolation of new protective antigens. Literature review demonstrated that LOS is a key antigen, because it is involved in the body’s immune response and ensures Th1 and Th17 cell responses to pertussis, which is crucial for protection from B. pertussis bacteria. Considering the evolutionary stability of the LOS structure, this antigen (i.e. its non-toxic oligosaccharide part) can be considered as a candidate for acellular pertussis vaccine.

One of the major public health challenges today is development of new vaccines and technologies to optimize the vaccination process. There is a growing scientific interest in vaccine adjuvants that enhance vaccine immunogenicity. At present, numerous studies are underway to develop COVID-19 vaccines, including inactivated and subunit vaccines which contain adjuvants for efficient induction of immune response and solid immunity. The aim of the study was to systematise literature related to the analysis of the structure, mechanisms of action and stimulating properties of vaccine adjuvants (synthetic oligodeoxynucleotides, virosomes, polyoxidonium, sovidone), as well as to summarise data on the effects of adjuvants used in SARS-CoV, MERS-CoV, and SARS-CoV-2 vaccine development studies. The paper analyses the prospects for enhancing the stimulating effect of the adjuvants when used in combination with compounds having a different mechanism of action. It also analyses the results of studies of adjuvanted vaccines against SARS-CoV and MERS-CoV, which may be useful when selecting adjuvants with optimal efficacy and safety profiles to be used in SARS-CoV-2 vaccines under development. It was concluded that understanding of the mechanisms of action of adjuvants that mediate their stimulating effect on the body’s immune system will contribute to safe and effective use of adjuvants to enhance the immunogenicity of both authorised and new vaccines.

Rotavirus infection is a widespread cause of severe gastroenteritis in children in low-income countries. Specific prophylaxis in young children has become the most important means of combating severe rotavirus gastroenteritis. The review presents current data on the molecular biology and genetic diversity of rotaviruses, interaction of viral proteins with host cell receptors, molecular aspects of infectivity and pathogenesis of rotavirus infection, and the development of immunity. It addresses a new approach to the epidemiology of rotavirus infection which regards it as a manageable infection, it illustrates the specificity of the epidemic process based on data gained from extensive experience in vaccination, and summarises relevant information on the introduction of rotavirus vaccines into the international healthcare practice. The paper summarises risks associated with the use of vaccines based on the analysis of WHO statistics, scientific publications on the epidemiology of rotavirus infection, and the results of vaccination. It analyses approaches of the competent authorities of some countries to the tactics of vaccination against rotavirus infection and the WHO stance on the use of existing vaccines for the prevention of rotavirus infection. A conclusion was made that it is necessary to further improve the tactics of vaccine prevention of rotavirus infection in Russia, to study the incidence of idiopathic intussusception, and to conduct further studies aimed at characterisation of existing and newly emerging genotypes of rotavirus.

The manufacturer (developer) has to prepare a specification for each newly developed biomedical cell product (BCP) that has passed the stage of preclinical studies. The specification is included into the registration dossier when applying for marketing authorisation of a BCP. In accordance with the Order of the Ministry of Health of the Russian Federation No. 14n of 19 January 2017 «On approval of the specification format for a biomedical cell product» the specification should contain information about authenticity of the cell line used in the BCP, namely: morphological characteristics, expression of specific markers, expression of specific genes, expression of specific proteins, as well as markers of cell line stability. At present Russia has no practical experience in BCP quality evaluation. The aim of the study was to substantiate methodological approaches to authentication of cell lines used in BCPs as illustrated by quality evaluation of the DF-2 model cell line using test methods that allow for characterisation of the morphological, genetic, immunophenotypic, and cytogenetic profile of the cell line. Materials and methods: the study analysed the DF-2 cell line — human dermal fibroblasts (mesenchymal stem cells) obtained from the Institute of Cytology of the Russian Academy of Sciences (St. Petersburg). The following analytical test methods were used in the study: morphological analysis; flow cytometry for immunophenotyping of the DF-2 model cell line; short tandem repeats for creating an allelic profile of the model cell line; cytogenetic analysis — differential DAPI staining of metaphase chromosomes. Results: the paper summarises methodological approaches to identification testing of medicines containing living human cells (BCP analogues) currently used in international practice, and presents the results of authentication of the model cell line. Conclusions: methods used for BCP identification testing should ensure unambiguous authentication of the cell line according to its specification. The study performed helped to work out the procedure of authentication of a model cell line.