Brucellosis remains one of the most widespread zoonotic infections worldwide, causing serious veterinary, medical, and socio-economic consequences. The disease, caused by bacteria of the genus Brucella, affects a wide range of domestic and wild animals as well as humans, with global incidence potentially reaching 1.6–2.1 million new cases annually. The most effective approach to combating brucellosis is specific prevention through vaccination. Therefore, we conducted this review to summarize data from existing studies on modern strategies for brucellosis vaccination, types of vaccine platforms, their efficacy, safety, and applicability in veterinary and human medicine. We searched databases including PubMed, Scopus, and Web of Science to identify relevant scientific articles in English published from 1990 to 2025. The aim of this work is to conduct a systematic analysis of modern brucellosis vaccination strategies in livestock and humans, as well as to evaluate the prospects of new vaccine platforms. The review examines live attenuated, inactivated, subunit, vector, and DNA vaccines, as well as their immunological mechanisms of action, advantages, and limitations of application. This information allows for a better understanding of the mechanisms of protective immunity formation and challenges related to DIVA diagnostics (Differentiating Infected from Vaccinated Animals). The “One Health” concept demonstrated the interconnection between human, animal, and environmental factors, emphasizing the need for an interdisciplinary approach to brucellosis monitoring, prevention, and control. Vector vaccines based on influenza virus (Flu-BA), developed in Kazakhstan, have shown high promise, combining immunogenicity, protective efficacy, and a favorable safety profile. Promising directions remain mRNA vaccines, nanoparticles, CRISPR/Cas9 technologies, and mucosal vaccines.

Background/Objectives: Despite the availability of Newcastle disease (ND) vaccines, outbreaks have continued to occur for more than six decades, with significant economic consequences for the global poultry industry. The variability of the Newcastle disease virus requires constant monitoring, detection of new cases, and studies of the origin of the pathogen. The aim of this study was to develop an inactivated ND vaccine using a topical strain with different adjuvants and to compare them for stability, harmlessness, immunogenicity, and efficacy. Methods: A phylogenetic study of the F-gene of the ND strain isolated in Kazakhstan was conducted. The strain, which was selected to create a vaccine for the prevention of the disease, was revealed to belong to genotype VII class II and uploaded to GenBank (NCBI). Two different adjuvants, Montanide ISA 70 VG and Montanide ISA 78 VG, were used to create the vaccine. Birds were vaccinated intramuscularly. Results: Evaluations of antibody titers in the vaccinated groups during the experiment showed that the vaccines induced adequate levels of antibodies to provide protection against the virulent virus. High antibody titers were observed in the hemagglutination inhibition assay (HAI) in the vaccinated groups as early as 14 days post-vaccination in 100% of birds. The average antibody titer in both vaccinated groups exceeded 7 log2, sufficient to prevent clinical signs. None of the vaccinated birds exhibited clinical signs following control infection, whereas unvaccinated birds developed clinical manifestations within three days post-infection, leading to 100% mortality. Conclusions: The vaccine developed using the epizootic topical strain is stable, harmless, immunogenic, and effective when challenged with a virulent ND virus strain at a dose of 105 EID_50/mL.

Despite the availability of Newcastle disease (ND)vaccines, outbreaks have continued to occur for more than six decades, with huge economic consequences for the global poultry industry. The variability of the Newcastle disease virus requires constant monitoring, detection of new cases and study of the origin of the pathogen. The aim of the study was to develop an inactivated ND vaccine using a topical strain with different adjuvants and to compare them for stability, harmlessness, immunogenicity and efficacy. As a result of the phylogenetic study of the F-gene of the ND strain isolated in Kazakhstan, selected to create a vaccine for the prevention of this disease, it was revealed that this pathogen belongs to the genotype VII class II and was uploaded to GenBank (NCBI). Two different adjuvants were used to create the vaccine – Montanide ISA 70 VG and Montanide ISA 78 VG. The birds were vaccinated intramuscularly. Evaluation of antibody titers in the vaccinated groups during the experiment shows that the vaccines were able to induce adequate levels of antibodies to provide protection against the virulent virus. Vaccination provided high antibody titers in the HAI in the vaccinated groups as early as 14 days after vaccination in 100% of birds. When studying the effectiveness of vaccines, the average antibody titer in both vaccinated groups was above 7 log2, which is more than enough to protect birds from clinical signs. None of the vaccinated birds showed clinical signs after control infection. In groups of unvaccinated birds, clinical manifestations were observed as early as 3 days after infection with increasing severity, and eventually they all died (100% mortality). The vaccine from the epizootic topical strain developed by us is stable, harmless, immunogenic and effective when infected with a virulent strain of the ND virus at a dose of 100,000 EID50/cm³.

Background: Brucellosis remains a significant zoonotic infection affecting approximately 500,000 people worldwide annually, with no licensed human vaccine available. Recombinant influenza virus vectors expressing Brucella spp. antigens represent a promising vaccine platform. However, transitioning from laboratory constructs to clinical candidates requires validation of scalable purification methods compliant with Good Manufacturing Practice (GMP) standards. This study aimed to develop and optimize a pilot-scale purification protocol for these vectors. Methods: Recombinant influenza A viruses (H5N1) expressing Brucella spp. antigens (Omp16, Omp19, L7/L12, Cu-Zn SOD) were propagated in MDCK cell culture. The optimized purification process included: (1) clarification; (2) ultrafiltration/diafiltration (100 kDa MWCO); (3) two-step chromatography (anion-exchange Q-Sepharose^® Fast Flow and multimodal Capto™ Core 700); and (4) sterile filtration. Process validation was performed across three independent pilot-scale batches (20 L each). Results: The purification process demonstrated high reproducibility for all constructs. Final preparations met established quality criteria: infectious titer ≥ 5.2 log₁₀ TCID₅₀/mL, hemagglutination activity 7.33 ± 0.58–8.33 ± 0.58 log₂, total protein content 157–305 μg/mL, residual host cell DNA < 10 ng/dose, and bacterial endotoxin levels ≤ 0.15 IU/mL. The overall recovery of infectious virus was 20–24%, an optimal value for multi-stage bioprocessing. Preservation of the target genetic insert was confirmed in all final preparations by PCR and sequencing. Conclusions: The developed integrated purification protocol yields vectors with high purification efficiency, preserving biological activity and meeting regulatory quality requirements for residual host cell DNA and endotoxins. The technological platform demonstrated versatility, robustness (inter-batch coefficient of variation for yield did not exceed 10–12%), and scalability, establishing a foundation for preclinical and clinical studies of candidate brucellosis vaccines.

Introduction. Newcastle disease (ND) is classified as especially dangerous pathogen. Its primary source is an infected or recovered bird. The virus shedding begins just in a day after infection, and virus remains in the body for another 2-4 months after the recovery. The complexity of the final elimination of the causative agent of the disease lies in its ability for long-term preservation in the external environment and the possibility of constant circulation in one complex between groups of birds of different sex and age. Therefore, the main element of protecting birds from ND is immunoprophylaxis that is based on vaccines containing an inactivated ND virus (NDV). The aim of the work ‒ is to optimize the parameters of inactivation of the NDV actual strain H with formaldehyde at final concentrations of 0.01, 0.025, 0.05, and 0.1% under temperature conditions of 20 2 and 37 0.5 C. Materials and methods. We used a virus-containing suspension of the NDV strain H with an initial biological activity of 10.75 lg EID50/cm3 grown by cultivation in 10-day-old developing chick embryos. Results. On the 16th day after the administration of the tested suspensions of NDV inactivated at different temperatures and concentrations of the inactivant , the geometric mean titers of antibodies to NDV in sera of vaccinated birds were at least 1 : 63 in the hemagglutination inhibition reaction, indicating that the studied inactivated suspensions were antigenically active. Conclusion. The optimal parameters of the inactivation mode (final concentration, temperature and time of inactivation) of the NDV strain H were established. The inactivation process at 37 0.5 C with inactivant concentrations of 0.01, 0.025, 0.05, and 0.1% lasts up to 72, 22, 18, and 12 hours, respectively. The inactivation process at 20 2 C with inactivant concentrations of 0.05 and 0.1% lasts up to 22 and 18 hours, respectively.

Background/Objectives: Brucellosis remains a widespread zoonosis, yet no licensed human vaccine exists and the live attenuated vaccines used in animals are unsuitable for people because of residual virulence and the risk of accidental infection. Recombinant platforms are attractive alternatives, but direct head-to-head comparisons within a single study are scarce. We compared the safety, immunogenicity and protective efficacy of three recombinant candidates: the AddaS03-adjuvanted subunit vaccine BruVac-Pro, the capripoxvirus-vectored BruVac-CPX and the influenza virus-vectored BruVac-FLU. Methods: Inbred BALB/c mice (n = 355) received a prime-boost immunization, except for the single-dose Rev-1 reference group. A subgroup of 10 animals per group was monitored serologically from day 0 and subsequently challenged intraperitoneally with virulent Brucella melitensis 16M, and the remaining animals were assigned to safety, vector-detection and cellular-immunity read-outs. The timing and prospective nature of allocation to the challenge cohort could not be documented; selection bias in the efficacy endpoint therefore cannot be excluded. Safety was assessed from clinical observation, body weight and early serum clinical chemistry; antigen-specific IgG to Omp16, Omp19, L7/L12 and SodC was measured by indirect ELISA; and protection was quantified from splenic bacterial load (Y), the protective index (PI) and the proportion of animals with no splenic recovery (n = 10 per group). Immunogenicity was assessed as humoral (IgG) responses only; antigen-specific cellular responses were measured in separate subsets of the same experiment and are reported separately. Results: Mortality during the immunization phase was confined to the three sublingually dosed viral-vector and stabilizer groups (CPX/CPX 4/50, CCFLU/CCFLU 3/55, FLU/FLU 1/55), with no deaths in the Pro/Pro, AddaS03/AddaS03, Rev-1 or PBS/PBS groups (8/160 versus 0/195); surviving animals showed no overt clinical signs. Influenza-vector RNA was not detected in serum or spleens at days 3 and 6 by a qualitative assay of undetermined sensitivity. Seroconversion to Omp16 and Omp19 was confined to the Pro-containing group; no animal in any group seroconverted to SodC, and responses to L7/L12 were confined to isolated single animals without a group-level pattern. Splenic burden differed across groups (Kruskal–Wallis, p = 4 × 10⁻⁷). BruVac-Pro gave the strongest protection (Y 2.32; PI 2.62; 70.0% with no recovery; p = 0.028 for splenic burden and adjusted p = 0.015 for the proportion of animals with no recovery, both versus the phosphate-buffered saline (PBS) control). BruVac-CPX showed only a non-significant trend towards reduced burden (PI 1.54; p = 0.57 after correction for multiple comparisons) without increasing clearance (20.0%), and BruVac-FLU did not prevent colonization. Rev-1 confirmed model validity (PI 3.15; 80.0%). Conclusions: Under the non-equivalent, formulation-specific regimens tested, BruVac-Pro was the only experimental formulation with no mortality and no overt clinical signs, produced the most consistent antigen-specific IgG response, and was the only experimental candidate to reduce day-14 splenic burden significantly relative to the PBS and adjuvant-only controls. These findings support further dose, mechanism and durability studies of this formulation, but do not establish platform superiority, sterile protection or suitability for human use.