Creating an effective and safe vaccine is critical to fighting the coronavirus infection successfully. Several types of COVID-19 vaccines exist, including inactivated, live attenuated, recombinant, synthetic peptide, virus-like particle-based, DNA and mRNA-based, and sub-unit vaccines containing purified immunogenic viral proteins. However, the scale and speed at which COVID-19 is spreading demonstrate a global public demand for an effective prophylaxis that must be supplied more. The developed products promise a bright future for SARS-CoV-2 prevention; however, evidence of safety and immunogenicity is mandatory before any vaccine can be produced. In this paper, we report on the results of our work examining the safety, toxicity, immunizing dose choice, and immunogenicity of QazCoVac-P, a Kazakhstan-made sub-unit vaccine for COVID-19. First, we looked into the product’s safety profile by assessing its pyrogenicity in vaccinated rabbit models and using the LAL (limulus amebocyte lysate) test. We examined the vaccine’s acute and sub-chronic toxicity on BALB/c mice and rats. The vaccine did not cause clinically significant toxicity-related changes or symptoms in our toxicity experiments. Finally, we performed a double immunization of mice, ferrets, Syrian hamsters, and rhesus macaques (Macaca mulatta). We used ELISA to measure antibody titers with the maximum mean geometric titer of antibodies in the animals’ blood sera totaling approximately 8 log2. The results of this and other studies warrant recommending the QazCoVac-P vaccine for clinical trials.

Hyperimmune sera are a primary component of diagnostic test systems utilising enzyme immunoassay to identify specific antibodies against infectious disease pathogens. During diagnostic assay development, hyperimmune sera function as positive controls and enable the generation of standard curves for quantitative measurement of antibody levels. Furthermore, they can be used to assess the sensitivity and specificity of established test systems and to verify novel diagnostic approaches. The objective of this study was to produce hyperimmune serum against SARS-CoV-2. Purified and concentrated virus, in conjunction with adjuvants such as aluminium hydroxide or AddaS03, was employed to immunise animals. Consequently, specific sera exhibiting activity in ELISA at dilutions of 1:1600- 1:3200 and in the diffusion precipitation reaction (DPR) at 1:8–1:32 were acquired. The research demonstrated that the use of concentrated, pure SARS-CoV-2 for animal immunisation, supplemented with adjuvants, is a viable and efficacious approach for generating highly active antibodies.

The emergence and spread of coronavirus infections have created a necessity to develop serological methods for assessing population immunity. The enzyme-linked immunosorbent assay (ELISA) remains one of the most accessible and informative approaches for these purposes. The choice of recombinant proteins plays an important role in the sensitivity and specificity of the test system, and in this regard, the creation of a domestic ELISA based on the chimeric SM protein to the SARS-CoV-2 virus is relevant. In this work, a recombinant chimeric SM protein expressed in the E. coli system and purified using metal-affinity chromatography on Ni-NTA agarose was constructed and presented for the first time. An ELISA test system was developed and tested using panels of positive and negative sera, including samples obtained before the COVID-19 pandemic. The obtained sensitivity (90.48%) and specificity (93.65%) indicators with a ROC curve AUC = 0.9623 (OD450 = 0.213) indicate the diagnostic accuracy of the test system. The positive diagnostic ratio (LR+) = 14.25.0 indicates the reliability of a positive result. The domestically developed ELISA test system can be used for serological monitoring and assessment of the immune status of the population.

The development of viral vector vaccines against brucellosis requires strict control of the authenticity of recombinant strains used as vaccine candidates. One of the key stages in the molecular characterization of such strains is confirmation of the presence of heterologous genetic inserts encoding Brucella antigens. The aim of this study was to assess the authenticity of recombinant influenza strains by detecting brucellosis-related genetic inserts using reverse transcription polymerase chain reaction (RT-PCR). The study objects were recombinant influenza virus strains Flu-NS1-80-Omp16, Flu-NS1-80-L7/L12, Flu-NS1-80-Omp19, and Flu-NS1-80-Cu-Zn SOD, containing genes encoding immunodominant Brucella proteins. Analytical sensitivity was evaluated using serial tenfold dilutions of a positive control with a known RNA concentration. The specificity of the method was confirmed by the presence of amplicons of the expected size, approximately 1250–1300 bp for recombinant constructs and approximately 890 bp for the control virus, as well as by the absence of nonspecific amplification in negative controls. During the analysis of recombinant strains Flu-NS1-80-OMP16, Flu-NS1-80-OMP19, Flu-NS1-80-SOD, and Flu-NS1-80-L7/L12, target fragments were detected in all samples, indicating successful integration of Brucella spp. inserts into the viral genome. Reproducibility assessment showed 100% concordance of results in 10 independent replicates for all tested samples. The positive and negative controls demonstrated the expected results, confirming the correct performance of the reaction and the absence of contamination. The obtained results confirm the authenticity of the recombinant influenza strains and the presence of brucellosis-related genetic inserts in their genome, indicating the correctness of the viral vector constructs and their potential for further use in the development of vaccine preparations against brucellosis.

The global increase in antibiotic resistance, particularly among pathogens of the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae), highlights the urgent need for alternative antimicrobial approaches. One promising strategy is phage therapy, which involves the use of bacteriophages capable of specifically lysing bacterial cells. The aim of this study was to evaluate the quality parameters of experimental batches of the preparation “Bacteriophage against ESKAPE pathogens,” developed at the Research Institute for Biological Safety Problems LLP, Republic of Kazakhstan. Three experimental batches of the preparation (No. 0011224, No. 0021224, No. 0031224) were examined for appearance, extractable volume, hydrogen ion concentration (pH), sterility, and specific activity against ESKAPE test cultures in accordance with SK-ESKAPE-PR-23 requirements, the State Pharmacopoeia of the Republic of Kazakhstan, and regulatory guidelines of the Eurasian Economic Union for biological medicinal products. The results demonstrated that all batches met the established quality requirements, showing stable physicochemical properties, confirmed sterility, and high specific activity maintained at dilutions up to 10⁻⁷–10⁻¹⁰. These findings confirm the stability, quality, and biological efficacy of the investigated bacteriophage preparation and support its potential for further development and application in the prevention and treatment of infections caused by antibiotic-resistant ESKAPE pathogens.