This article describes the results of a preclinical safety and immunogenicity study of QazCovid-in®, the first COVID-19 vaccine developed in Kazakhstan, on BALB/c mice, rats, ferrets, Syrian hamsters and rhesus macaques (Macaca mulatta). The study’s safety data suggests that this immunobiological preparation can be technically considered a Class 5 nontoxic vaccine. The series of injections that were made did not produce any adverse effect or any change in the general condition of the model animals’ health, while macroscopy and histology studies identified no changes in the internal organs of the BALB/c mice and rats. This study has demonstrated that a double immunization enhances the growth of antibody titers as assessed by the microneutralization assay (MNA) and the enzyme-linked immunosorbent assay (ELISA) in a pre-clinical immunogenicity test on animal models. The best GMT results were assessed in MNA and ELISA 7 days after re-vaccination; however, we noted that GMT antibody results in ELISA were lower than in MNA. A comparative GMT assessment after the first immunization and the re-immunization identified significant differences between model animal groups and a growth of GMT antibodies in all of them; also, differences between the gender groups were statistically significant. Moreover, the most marked MNA immune response to the QazCovid-in® vaccine was seen in the Syrian hamsters, while their SARS-CoV-2-specific antibody activity as assessed with ELISA was the lowest.

Bovine leukemia virus (BLV) remains a major concern for cattle industries worldwide due to its persistent nature, economic impact, and challenges in control. In this study, we conducted a comprehensive nationwide survey of BLV in Kazakhstan between 2014 and 2024, utilizing serological diagnostics to assess prevalence and characterize viral genotypes (2024). A total of 433,537 serum samples were screened by agar gel immunodiffusion (AGID), revealing an overall seroprevalence of 5.87%, with the highest rates observed in the North Kazakhstan, Kostanay, and East Kazakhstan regions. In 2024, a targeted analysis of 3736 serum and 536 whole blood samples across 17 regions was performed using AGID, ELISA, real-time PCR, and nested PCR. ELISA demonstrated higher sensitivity than AGID (10.4% vs. 8.2%), confirmed by statistical correlation (r = 0.97, p < 0.001) and a Wilcoxon signed-rank test (p = 0.026). Real-time PCR detected BLV DNA in 4.7% of samples, with the highest positivity in the East Kazakhstan and Abai regions, confirming active viral circulation. Validation of a domestically developed AGID diagnostic kit showed full concordance with commercial assays (IDEXX, IDvet), supporting its use in national surveillance programs. These findings highlight the endemic status of BLV in Kazakhstan. Molecular analysis of sequenced isolates revealed the presence of genotype G-7, consistent with strains circulating in neighboring countries. Together, these results underscore the importance of integrated serological and molecular approaches for effective monitoring and control.

Background. Enzootic bovine leukosis (EBL) remains a significant problem in cattle production. Agar gel immunodiffusion (AGID) is widely used for screening; however, diagnostic performance depends on test-kit manufacturing parameters. Aim. To develop and optimize manufacturing conditions for an AGID test system for serological diagnosis of EBL, ensuring reproducibility and compliance with World Organisation for Animal Health (WOAH) recommendations. Methods. BLV antigen was produced on a persistently infected FLK cell line and standardized to gp51 using WOAH reference serum E05. We optimized agarose concentration (0.8–2.0% in 0.2 M Tris, pH 7.2, with 8.5% NaCl), antigen dilutions (1:2–1:64), and control sera dilutions. Plates were incubated in a humid chamber at 20–27 °C with readings at 24–72 h. Validation was performed on bovine sera (positive/weak-positive/negative) and compared with commercial kits. Results. An agarose concentration of 1.0–1.2% provided clear, stable precipitin lines within 24–72 h, balancing diffusion rate and line quality. Optimal antigen dilutions were 1:4 (eliminating nonspecific lines with negative serum while maintaining high sensitivity) and 1:8. Positive control serum was optimal at 1:4–1:8; weak-positive control at 1:32 yielded a reproducible faint line suitable for sensitivity assessment. Negative serum produced no lines. Stable performance was achieved under specified storage and operating conditions; diagnostic characteristics were comparable to those of commercial tests. Conclusions. The optimized AGID test system demonstrates high reproducibility, specificity, and adequate sensitivity, aligns with international requirements, and is suitable for broad implementation in veterinary laboratories in Kazakhstan. Accounting for regional features further enhances its practical value.

Bovine Viral Diarrhea Virus (BVDV) is a globally important cattle pathogen causing substantial economic losses. In Kazakhstan, BVDV’s epidemiological status remains poorly characterized due to the absence of systematic surveillance. We carried out a cross-sectional study of cattle herds across Kazakhstan, using ELISA to detect anti-BVDV antibodies and RT-PCR to identify active infections. Positive samples underwent sequencing for phylogenetic analysis of circulating strains. Additionally, a standard reference serum panel was developed to measure virus neutralization titers (ND₅₀) and to evaluate cross-neutralization with Border Disease virus (BDV). Antibodies against BVDV were prevalent, with seropositivity ranging from 28.89% to 96.13% across surveyed regions. Active BVDV infection was confirmed by RT-PCR in 17 animals. Phylogenetic analysis with 2 samples from Mangystau region classified the virus as BVDV2 genotype. The reference serum panel exhibited high neutralizing titers ND₅₀ up to 1:286 against the local BVDV-1 isolate. Notably, these sera also neutralized BDV, albeit at lower titers ND₅₀ 1:45. These findings provide crucial baseline epidemiological data and enhanced diagnostic tools for BVDV in Kazakhstan. They highlight the need for improved surveillance and will inform strategic control measures against this economically significant cattle disease.