The optimal effect was induced by the Flu-L7/L12-Omp16-MontanideGel01 vaccine and the commercial B. abortus S19 vaccine. Furthermore, the viral construct vaccine formulations were able to induce a humoral immune response (IgG) to Brucella antigens after booster vaccination. Although the humoral immune response in the experimental groups was significantly lower than that of the positive control group vaccinated PCI-32765 clinical trial with the B. abortus S19 vaccine, a prevalence of IgG2a isotype antibodies (relative to IgG1) was observed

in the experimental animals, indicative of a predominantly Th1-mediated immune response [38]; this effect was especially pronounced in the group of animals vaccinated with vaccine Flu-L7/L12-Omp16-MontanideGel01. The effects observed in the cellular immune response assays were reflected in experiments to determine the protectiveness of the vaccines in cattle. It should be noted that unlike other similar studies, the protectiveness of the vaccines in cattle was not only

evaluated by isolation of virulent strain B. abortus 544 from the most sensitive lymph nodes, but also by evaluating parameters such as the effectiveness of vaccination and index of infection (or index generalization of infection). In our opinion, these indicators in combination provide a more comprehensive and objective characterization of AT13387 in vivo the protectiveness of vaccines. To estimate the number of cultured Brucella in the organs of the cattle after challenge with B. abortus 544, we sampled the retropharyngeal and right subscapular lymph nodes. These lymph nodes were selected for study as Brucella MTMR9 is mainly cultured

(in 20–100% of cases) from these organs. As expected, the highest level of protectiveness was achieved with Flu-L7/L12-Omp16-MontanideGel01; the viral construct vaccine formulation only also demonstrated good results, with all tested parameters of protectiveness comparable to the commercial B. abortus S19 vaccine. Interestingly, inclusion of chitosan as an adjuvant in the viral construct vaccines did not contribute and in fact, even slightly reduced their efficiency. This can be explained by the fact that according to Wang et al. [39], chitosan can significantly decrease the infectivity of the viral vector in cattle corneal epithelial cells. In respect of the vaccines tested in this study, the infectivity of the viral vectors in corneal epithelial cells appears to be very critical process, as penetration of the recombinant influenza viruses into the cells is required for expression of the brucellosis L7/L12 and Omp16 proteins and induction of the immune response in cattle. We attribute the strong cellular immune response and high level of protectiveness for the viral construct vaccine samples with several factors. The first is the method of vaccine administration.