Probiotic lactic acid bacteria are live microorganisms that provide health benefits when administered in adequate amounts and may exhibit antiproliferative effects on various cancer cell lines, including colon cancer. This study investigates the cytotoxic effects of three Lactobacillus strains - Limosilactobacillus (L.) reuteri VA 102, Ligilactobacillus (L.) animalis VA 105, and Limosilactobacillus (L.) reuteri KCTC 3594 (ATCC 23272) - on mouse colon carcinoma cells (CT-26). Live cells, heat-killed cells, and cell-free supernatant (CFS) of Lactobacillus sp. were prepared and used to treat CT-26 cells at different concentrations. The cytotoxic effect was assessed using the MTT assay. The results indicated that the CFS of all strains significantly reduced the viability of CT-26 cells in a dose-dependent manner, with the VA 102 strain showing the most pronounced effect. Heat-killed cells of L. reuteri VA 102 and L. reuteri KCTC 3594 (ATCC 23272) also reduced cell viability. These findings suggest the potential anticancer properties of these Lactobacillus strains and indicate that CFS and heat-killed cells may offer a safer and more effective alternative to live bacteria for therapeutic applications. Our study contributes to the understanding of the potential of Lactobacillus strains, particularly L. reuteri VA 102, L. reuteri KCTC 3594 (ATCC 23272), and L. animalis VA 105, as possible candidates for cancer treatment and control.

The primary therapeutic approach for Brucella species infections has mainly been based on antibiotic treatment. However, the development of vaccines for brucellosis control remains controversial. Furthermore, there is currently no licensed vaccine available for human brucellosis. This study aims to evaluate the effect of a combination of recombinant protein vaccines against Brucella (B.) abortus infection using a mouse model. Two B. abortus genes, namely dapB and gpm, were cloned and expressed in competent Escherichia (E.) coli DH5α using the pCold-TF vector. Successfully cloned vectors were subjected to PCR amplification using specific primer pairs. The apparent sizes of dapB and gpm were detected at 807 bp and 621 bp, respectively. Besides, the purified recombinant proteins dapB and gpm were detected using SDS-PAGE electrophoresis with correct sizes of 82.86 kDa and 87.61 kDa, respectively. These recombinant proteins were used to immunize mice as a combined subunit vaccine (CSV) to elicit host immunity against B. abortus infection. Mice immunized with CSV exhibited increased proliferation of CD4+ and/or CD8+ T cells at week 7th and 9th before sacrifice, in comparison to the control group. Notably, CSV immunization showed a significant decrease in bacterial burden in the spleen compared to the control group. Altogether, CSV using dapB and gpm induced host adaptive immune response against Brucella infection, suggesting its potential as an effective new subunit vaccine candidate.

Extensive research and testing continue to be conducted for the development of vaccines targeting zoonotic diseases such as brucellosis. In this study, the potential of the DapB as a recombinant protein vaccine to effectively combat Brucella abortus 544 infection in BALB/c mice was evaluated. Western blotting assay results showed that recombinant protein DapB reacted with Brucella-positive serum, indicating its potential immunoreactivity. In vivo results showed that the peripheral blood CD4+ and CD8+ T cell population significantly increased in the DapB-immunized mice group after the first, second and third blood collection, compared to the control group that received PBS. Additionally, at the fourth blood collection, an increase in CD4+ T cell activation was observed in three vaccination groups compared to PBS negative control group. These results indicate the potential of DapB in stimulating cellular immunity. Fourteen days after infection, the bacterial load in the spleen was evaluated. The reduction in bacterial replication in the spleen by both DapB and RB51 highlights their protective efficacy against Brucella infection. These findings contribute to the ongoing efforts in developing effective vaccines against brucellosis and provide valuable insights for further research in this field.