Phylogenetic analysis of prospective M. bovis antigens with the aim of developing candidate vaccines for bovine tuberculosis

BACKGROUND

Bovine Tuberculosis is a respiratory disease caused by the pathogen Mycobacterium bovis (M. bovis) that infects cattle. Though rare, this disease can also affect humans, as well as domestic and wild animals, making it a serious concern. Therefore, searching for alternative and new vaccines with high efficiency and safety is the main goal in bovine tuberculosis prophylaxis. New vaccines, known as vector vaccines, have the potential to become safe and effective alternatives to the traditional BCG vaccine. In this study, two major immunodominant proteins of M. bovis Esat-6 and TB10.4 were utilized to create a vector vaccine for bovine tuberculosis.

METHODS

The Esat-6 and TB10.4 genes were amplified by PCR. The amplified and purified PCR products were sequenced by the Sanger method. Assembly and multiple alignments of amplicon nucleotides were carried out in the MEGA 11 software.

RESULT

Two genes of the local strain 0078-M. bovis-8/RIBSP were sequenced. The nucleotide sequences were deposited in the GenBank database. Comparative analysis of the nucleotide sequences of the ESAT-6 and TB10.4 genes established 100% identity of the compared strains of Mycobacterium.

CONCLUSION

Through the use of phylogenetic analysis, it has been confirmed that the amplified genes are related to the mycobacteria genus. This discovery allows the development of a vector vaccine against bovine tuberculosis utilising these genes.

Duration of Protective Immunity in Sheep Vaccinated with a Combined Vaccine against Peste des Petits Ruminants and Sheep Pox

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 10^3.0 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.

Biological characterization of Pasteurella multocida present in the Saiga population

Background

This 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.

Results

Bacteriological 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.

Conclusion

Isolation, 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.

Duration of protective immunity after a single vaccination with a live attenuated bivalent bluetongue vaccine

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.