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INTRODUCTION: Oncolytic viruses are a promising approach for treating malignant brain tumors as part a of combination therapy. OBJECTIVE: To develop reporter influenza A viruses expressing NanoLuc luciferase and evaluate their safety following intracranial administration in rats. METHODS: Chemiluminescent reporter influenza A virus strains were obtained by reverse genetics. The NS genetic segment of the T_NS124-Luc and E_NS124-Luc strains encoded a fusion protein that combined NS1 124 and NanoLuc. In the T_NS124-2A-Luc and E_NS124-2A-Luc strains, the NS1 124 and NanoLuc sequences were separated by a 2A co-translational cleavage site. To enhance the tumor specificity of the viruses, the trypsin cleavage site (T) in the hemagglutinin (HA) protein was replaced with an elastase cleavage site (E) by introducing S342→P and R343→I substitutions in the HA region of the E_NS124-Luc and E_NS124-2A-Luc constructs. RESULTS: The obtained constructs demonstrated comparable reproductive and luminescent activity in MDCK cells. However, vectors containing the 2A site upstream of the transgene infected the glioma cell lines C6, A172, and T98G more effectively. Intracranial administration of a high dose of the virus was safe, causing no neurological or other pathological symptoms in rats. In addition, the luminescent reporter NanoLuc was expressed at the injection site without the formation of active viral progeny. CONCLUSION: This study demonstrated that a chemiluminescent influenza A virus strain can induce transgene expression at the site of intracranial injection without active viral replication.

Causing millions of cases worldwide every year, influenza is one of the most common respiratory infections. The effectiveness of influenza vaccination and the nature of the resulting immune response may vary depending on the vaccine composition and age group. Since children are at the highest risk of disease and act as the main carriers of influenza, the assessment of the immunological efficacy of vaccines in this group is crucial for controlling the epidemic. Therefore, this study aimed to evaluate the characteristics of the humoral immune response in children after immunization with various types of inactivated influenza vaccines. An observational study was conducted in the 2019-2020 season and involved 230 children (< 18 years old) and a comparison group of 87 adults aged 18 to 60 years. The subjects, who provided informed consent to participate, were vaccinated with one of three vaccines (Grippol Plus, Sovigripp, or Ultrix) in an open-label fashion. The humoral immune response was assessed by measuring the hemagglutination inhibition (HI) titer in the paired sera taken before and three weeks after vaccination. The immunogenicity of the vaccines in the age group under 18, met the CPMP criteria for the assessment of inactivated influenza vaccines in terms of the fold increase in antibody titers and the proportion of individuals with seroconversion to all three components (A/H1N1pdm09, A/H3N2, and B/Victoria). Although 6 to 18-year-old participants showed a more robust immune response to the B/Victoria component compared to the adult participants (aged 18 to 60), it was insufficient to ensure that 70% of the participants have a protective antibody titer. A comparative analysis of the vaccines’ immunogenicity was carried out for a subgroup of children aged 6-18 who had initially low antibody levels at the time of vaccination. The analysis showed that the split vaccine Ultrix outperformed the adjuvanted vaccine Grippol Plus in generating an antibody response to the component B/Victoria; however, the antibody responses to the A/H1N1pdm09 and A/H3N2 components did not differ between the two vaccines. The children under 6 years of age demonstrated a less pronounced humoral immune response to vaccination compared with the other age groups, which may be due to the age-related characteristics of the immune system in children of preschool age.

Recombinant viral vectors represent one of the most promising platforms for creating a new generation of vaccines against tuberculosis. We constructed a vaccine candidate based on a cold-adapted influenza vector with a truncated NS1 protein containing an insert of tuberculosis ESAT-6 and Ag85A antigens. The recombinant virus possessed a cold-adapted and temperature-sensitive phenotype and was attenuated for mice when administered intranasally. Immunofluorescent staining and Western blot showed the expression of ESAT-6 protein in MDCK cells infected by recombinant virus. After intranasal administration to mice, the recombinant virus stimulated a specific anti-tuberculosis CD4 + Th1-type response with the formation of polyfunctional antigen-specific T cells.