Design of an oral vaccine using Lactococcus lactis against brucellosis: an in vitro and in vivo study

Abstract

Brucellosis is regarded as one of the world’s most severe zoonotic diseases. This study aimed to investigate the possibility of using recombinant Lactococcus lactis (L. lactis) as a live vector to produce recombinant Brucella abortus (B. abortus) Omp10. The gene sequences were obtained from GenBank. The proteins’ immunogenicity was assessed using Vaxijen. After confirming the cloning of the Omp10 gene in the pNZ8148 vector by enzymatic digestion and PCR, transformation into L. lactis was done. SDS-PAGE and western blot methods evaluated omp10 protein expression. Mice received oral recombinant L. lactis vaccines. IgG antibodies against Omp10 were tested using ELISA. Real-time PCR and ELISA were used to analyze cytokine responses. Survival rate and histopathological changes were evaluated after the challenge. Omp10 was chosen for its 1.5524 antigenicity score. Enzymatic digestion and PCR identified a 381-bp gene fragment. A 10 kDa band indicated the success of L. lactis transformation. Mice administered the L. lactis-pNZ8148-Omp10-Usp45 vaccination 14 days after priming showed significantly higher Omp10-specific total IgG and IgG1 (P < 0.001) than the PBS control group. The mice who received the L. lactis-pNZ8148-Omp10-Usp45 and IRBA vaccines had significantly elevated levels of IFN-γ, TNFα, IL-4, and IL-10 in samples collected on days 14 and 28 (P < 0.001). Inflammatory response, morphological damage, alveolar edema, and lymphocyte infiltration were reduced in the target group. A recombinant L. lactis expressing the Omp10 protein was constructed as an oral Lactococcus-based vaccine and compared to live attenuated vaccines for future brucellosis investigations.

Targeted Bioimaging of Microencapsulated Recombinant LAB Vector Expressing Fluorescent Reporter Protein: A Non-invasive Approach for Microbial Tracking

“…Therefore, if a sustained effect from a non-commensal probiotic bacterium, such as L. lactis , is desired, higher doses with repeated administration will likely be the solution. In contrast, if modified or recombinant probiotics are intended for prophylactic use, one must consider the risk of bacterial colonization and the chance of high-dose antigen-induced immunotolerance. ,, To this end, using bioengineered LAB vectors such as L. lactis as a live vector-based vaccine delivery as well as a biotherapeutic platform warrants a tunable approach to maintain the delicate balance between bioavailability and optimal immune activation at the mucosal surface. ,,,,− Therefore, knowledge of the precise location and duration of gut transit of non-commensal LAB vectors is pivotal for determining the dose, frequency, and length of probiotic administration to achieve the intended benefits.…”