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Background and Aim: The morbidity and mortality of Shigella infections remain a global challenge. Epitope-based vaccine development is an emerging strategy to prevent bacterial invasion. This study aimed to identify the ability of the 49.8 kDa pili subunit adhesin protein epitope of Shigella flexneri to induce an intestinal immune response in mice. Materials and Methods: Thirty adult male Balb/c mice were divided into a control group, cholera toxin B subunit (CTB) group, CTB+QSSTGTNSQSDLDS (pep_1) group, CTB+DTTITKAETKTVTKNQVVDTPVTTDAAK (pep_2) group, and CTB+ ATLGATLNRLDFNVNNK (pep_3). We performed immunization by orally administering 50 μg of antigen and 50 μl of adjuvant once a week over 4 weeks. We assessed the cellular immune response by quantifying T helper 2 (Th2) and Th17 using flow cytometry. In addition, we assessed the humoral immune response by quantifying interleukin (IL-4), IL-17, secretory immunoglobulin A (sIgA), and β-defensin using enzyme-linked immunoassay. Statistical analysis was performed using one-way analysis of variance and Kruskal–Wallis test. Results: Peptide oral immunization increases the cellular immune response as reflected by the increase of Th2 (p=0.019) and Th17 (p=0.004) cell counts, particularly in the CTB_pep_1 group. Humoral immune response activation was demonstrated by increased IL-4 levels, especially in the CTB+pep_3 group (p=0.000). The IL-17 level was increased significantly in the CTB+pep_1 group (p=0.042). The mucosal immune response was demonstrated by the sIgA levels increase in the CTB+pep_3 group (p=0.042) and the β-defensin protein levels (p=0.000). Conclusion: All selected peptides activated the cellular and humoral immune responses in the intestine of mice. Further studies are necessary to optimize antigen delivery and evaluate whether the neutralizing properties of these peptides allow them to prevent bacterial infection.

Tuberculosis is an infectious disease caused by the Mycobacterium tuberculosis. Mycobacterium tuberculosis will form the primary focus or Ghon focus in the lungs of infected people. The primary focus can break and get into the bloodstream and/or lymph to the entire body, including the central nervous system, especially the brain. Tuberculosis infection in the brain can cause microglia secrete inflammatory factors such as TNF-α and IL-1β is emerging as the body's immune response. The factors that can trigger microglia to secrete iNOS (Inducible Nitric Oxide Synthase) in order to protect the brain from attacking bacteria. iNOS is shown to have an important role in tuberculosis infection in the brain. TNF-α is a pro-inflammatory cytokine which is mostly produced by macrophages/microglia through several mechanisms. Therefore, to investigate how the expression of TNF-α and iNOS in the brain tissue of the mice is not infected with tuberculosis, tuberculosis infection with an incubation period of 8 weeks and 16 weeks. This study is a semiquantitative study by comparing the amount of expression of TNF-α and iNOS and all three groups of samples with treatment as has been mentioned. The expressions observation of TNF-α and iNOS in brain cell tissue of mice was conducted using immunohistochemical staining, and was seen in a microscope with a magnification of ×100. Brain cells that express TNF-α and iNOS are brown core, cytoplasm and cell walls. The results were obtained by the longer exposure to infection of the higher expression of TNF-α (r > 0688) and the expression of iNOS decreased (−0.993).