BackgroundThis study provides biochemical and molecular genetic characteristics of P. multocida isolated from dead saigas in 1988, 2010–2015 on the territory of the Republic of Kazakhstan.ResultsBacteriological samples taken from carcasses of saiga antelope during mortality events recorded in West Kazakhstan in both 2010 and 2011 and in Kostanay in 2012 and 2015 confirmed the presence of P. multocida, according to morphological and biochemical characterisation. Only in the event of 2015 was the agent proven to be the causative agent of the disease observed, haemorrhagic septicaemia. In the other mortality events it is not certain if the organism was a primary aetiology or an incidental finding as confirmatory pathological investigation was not undertaken. The implemented phylogenetic analysis of ribosomal RNA 16S gene allowed us to identify Pasteurella strains isolated in 2010–2015 as P. multocida subspecies multocida. Capsular typing by PCR showed that the studied strains isolated from dead saiga in 2010, 2011, 2012 and 2015 belonged to serotype B. MLST analysis showed that these strains of P. multocida are of the capsule type B and form one clonal grouping with isolates ST64, ST44, ST45, ST46, ST44, ST47 which isolated from cases of hemorrhagic septicemia of animals in Hungary, Burma, Sri Lanka, Pakistan and Spain. Sixteen virulence genes of the five strains of P. multocida, isolated from saigas were studied using multiplex PCR. ptfA, ompA, ompH, oma87, plpB, fimA, hsf-2, pfhA, exbB, tonB, hgbA, fur, nanB, nanH and pmHAS genes were detected in all strains. The toxA gene was not identified in the studied strains. The phylogenies of these isolates is compared across saiga populations and years and the 2015 isolate was compared to that of an isolate from a disease outbreak in 1988 and the findings suggest that these isolated bacteria are stable commensals, opportunistically pathogenic, being phylogenetically uniform with very little genetic variation notable over the last 4 decades.ConclusionIsolation, phenotypic and genetic characterization of the P. multocida isolates inform understanding of the epidemiology of infection in saigas and predict virulent potential of these opportunistic bacteria.

Crimean–Congo hemorrhagic fever (CCHF) disease cases are registered annually in endemic regions of Kazakhstan. To study the prevalence of various Crimean–Congo hemorrhagic fever virus (CCHFV) genotypes, a total of 694 ticks were collected from southern regions of Kazakhstan in 2021. Hyalomma marginatum (n = 323) (46.5%), Hyalomma anatolicum (n = 138) (19.9%), Hyalomma asiaticum (n = 126) (18.2%), Hyalomma scupense (n = 80) (11.5%) and Ixodes ricinus (n = 27) (3.9%) were collected using the standardized flagging technique from the environment. All the tick samples were analyzed for the presence of CCHFV RNA by RT-PCR. The CCHF-positive samples were found within three Hyalomma asiaticum and one Ixodes ricinus tick sample. For the first time in Kazakhstan, infection of the Ixodes ricinus tick with CCHFV was detected. The results of sequencing and analysis of the S-gene fragment showed that the Asia 1 and Asia 2 CCHF genotypes circulate in the southern regions of Kazakhstan. Viruses isolated in the Zhambyl and Turkestan regions are assigned to the Asia-2 genotype, whereas the virus isolated in the Kyzylorda region to the Asia-1 genotype.

In this study, the ability of the combined vaccine against peste des petits ruminants (PPR) (Nigeria strain 75/1) and sheep pox (SPP) (NISKhI strain) to form a protective immune response for 12 months in Kazakh breed fine-fleeced sheep aged 6–12 months was demonstrated. The duration of the protective immunity of immunized sheep from PPR and from SPP was evaluated using a serum neutralization test (SNT), followed by testing of the resistance of vaccinated sheep to infection with the field strain Kentau-7 of the PPRV and the virulent strain A of the SPPV. The PPR antibody response was additionally measured by c-ELISA. A single immunization of sheep with a combined vaccine in a volume of 2.0 mL, containing the PPR and SPP vaccine viruses in the titers of 103.0 TCID50/mL, provided reliable protection of animals from two infections simultaneously for 12 months (observation period). At the same time, in sheep immunized with the combined vaccine, antibodies of PPRV persisted for up to 12 months, with slight fluctuations. The combined vaccine induced 100% clinical protection against the field strain of PPRV and the virulent strain of SPPV in immunized sheep for up to 12 months, while unvaccinated animals became ill with the manifestation of clinical signs specific to PPRV and SPPV.

The prevention of bluetongue is typically achieved with mono- or polyvalent modified- live-attenuated virus (MLV) vaccines. MLV vaccines typically elicit a strong antibody response that correlates directly with their ability to replicate in the vaccinated animal. They are inexpensive, stimulate protective immunity after a single inoculation, and have been proven effective in preventing clinical bluetongue disease. In this study, we evaluated the safety, immunogenicity, and efficacy of a bluetongue vaccine against Bluetongue virus serotypes 4 and 16 in sheep. All the animals remained clinically healthy during the observation period. The vaccinated animals showed no clinical signs except fever (>40.8 °C) for 2–4 days. Rapid seroconversion was observed in the sheep, with the accumulation of high antibody titers in the vaccinated animals. No animal became ill after the challenge, indicating that effective protection was achieved. Therefore, this vaccine, prepared from attenuated bluetongue virus strains, is safe, immunogenic, and efficacious.

The article presents the results of studies to determine the timing of the onset of immunity in sheep vaccinated with the associated vaccine against peste des petits ruminants (PPR) and sheep pox (SP). The timing of the onset of immunity in vaccinated animals against PPR and SP was evaluated by serum neutralization test (SNT) and by testing the withstood of vaccinated sheep to challenge infection with virulent strain "A" of SP virus. Protective tiers of virus neutralizing antibodies (VNA) to the PPRV virus were formed on 14 days with an average value of 2.8 log2 and reached up to 4.7 log2 on 21 days after vaccination, while immunity against the OO virus was formed on 7 days after vaccination with an average VNA titer of 1.8 log2, which increased to 4.3 log2 on 21 days after vaccination. All immunized sheep’s showed resistance to the virulent SP virus until the end of the experiment. Therefore, the experimental data obtained by us indicate a high degree of protection of animals immunized with the associated vaccine against PPR and SP, starting from day 7 from the SP virus and from day 14 from the PPR virus. Key words: combined vaccine, peste des petits ruminants, sheep pox, immunity.