New flagellin gene for Salmonella enterica serovar Typhi from the East Indonesian archipelago

A potential mechanism of miana (Coleus scutellariodes) and quercetin via NF-κB in Salmonella typhi infection

Purpose

To prove the effect of Miana (M), Quercetin (Q), and the combination as an anti-inflammatory agent and Cefixime (C) as an antibiotic in Balb/c mice infected with Salmonella enterica serovar Typhi (S. Typhi) and related to the dynamics of NF-κB mRNA expression and NF-κB protein levels.

Methods

A cohort study on male Balb/c mice with subjects consisted of 8 groups with 5 each group by administration of M, Q, M + Q, M + C, Q + C, M + Q + C, C only and sterile distilled water group as negative control. The statistical significance of the difference group was defined as P values less than 0.05.

Results

Decreased mRNA expression of NF-κB, NF-κB protein levels, and bacterial load after administration of M + C, Q + C, or M + Q + C showed significant differences when compared to the negative control. The decline in NF-κB was stronger when M + Q + C was given compared to M, Q, M + Q, or C only.

Conclusion

The effects of NF-κB suppression appear to be the same between the administration of M, Q and the M + Q when C added. However, the suppression of NF-κB was not significant without adding C.

Immunogenicity Response of Mus musculus var. Balb/C after Immunization using Flagellin Salmonella typhi Serovar Semarang

<b>Background and Objective:</b> The flagellin of <i>Salmonella typhi</i> is potentially developed as an identifying antigen in a rapid diagnostic test instrument that may be more accurate than conventional serological tests. Therefore, this study aims to analyze the immunogenicity of flagellin <i>S. typhi</i> as the basis for developing a typhoid fever diagnostic. <b>Materials and Methods:</b> Flagellin was isolated from the bacterial culture of <i>S. typhi</i> serovar Semarang and used as the primary antigen for vaccine assembly. Native flagellin antigen was immunized in Balb/C mice with injection doses of 2, 3, 4, 5 and 6 g/100 L in each group (K0-K5), respectively, via intraperitoneal cavity. Blood serum was collected to ELISA based-measurement for IL-6 and TNF-a titers. Then, specific immunoglobulin (Ig) of anti-flagellin was detected using in-house ELISA and western blotting. <b>Results:</b> The findings in this study showed that immunization at the dose of 4-5 g/100 L significantly decreased the IL-6 titer, i.e., 8.33±0.87 pg mL<sup>1</sup>, compared to control. The antibody titer test analysis showed the highest Ig-G anti-flagellin was found in K4 mice after immunization using a dose of 5 g/100 L with an average absorbance of Ig-G reaching 1.19 ±0.32. <b>Conclusion:</b> The results indicated that the flagellin protein of <i>S. typhi</i> serovar Semarang induces adaptive immune responses and produces specific antibodies against flagellin. The immunogenic properties of the flagellin protein of <i>S. typhi</i> serovar Semarang potentially developed as a specific diagnostic marker. Further research may also focus on a beneficial feature of flagellin as a vaccine candidate.

Advances in Understanding Bacterial Pathogenesis Gained from Whole-Genome Sequencing and Phylogenetics

The development of next-generation sequencing as a cost-effective technology has facilitated the analysis of bacterial population structure at a whole-genome level and at scale. From these data, phylogenic trees have been constructed that define population structures at a local, national, and global level, providing a framework for genetic analysis. Although still at an early stage, these approaches have yielded progress in several areas, including pathogen transmission mapping, the genetics of niche colonization and host adaptation, as well as gene-to-phenotype association studies. Antibiotic resistance has proven to be a major challenge in the early 21(st) century, and phylogenetic analyses have uncovered the dramatic effect that the use of antibiotics has had on shaping bacterial population structures. An update on insights into bacterial evolution from comparative genomics is provided in this review.

Identification and Characterization of a Gene stp17 Located on the Linear Plasmid pBSSB1 as an Enhanced Gene of Growth and Motility in Salmonella enterica Serovar Typhi

The linear plasmid pBSSB1 mediates the flagellar phase variation in H:z66 positive Salmonella enterica serovar Typhi (S. Typhi). The gene named stp17 (S. Typhi plasmid number 17 gene) is located on pBSSB1 and encodes the protein STP17. The expression pattern at the protein-level and function of STP17 remains unknown. In this study, the recombinant protein STP17_His6 was expressed, purified and used to prepare the polyclonal anti-STP17 antibody. We detected protein-level expression of stp17 in S. Typhi and further investigated the protein expression characteristics of stp17 in different growth phases by western blot analysis. The effects of STP17 on bacterial growth and motility were analyzed. In addition, the structure of STP17 was predicted and the active site of STP17 was identified by site-directed mutagenesis. The results showed that STP17 was expressed stably in the wild type strain of S. Typhi. STP17 expression at the protein level peaks when cultures reach an OD₆₀₀ value of 1.2. The growth rate and motility of the Δstp17 strain were significantly decreased compared with the wild type strain (P < 0.05) and this phenotype was restored in the stp17 complementary strain. Moreover, the growth rate and motility of the stp17 over-expression strain was greater than the wild type strain. STP17 contains nine Helix segments, six Stand segments and some Coil segments in the secondary structural level. The top-ranked 3-D structure of STP17 predicted by I-TASSER contains a putative ATPase domain and the amino acid residues of GLY16, GLY19, LYS20, ASN133, LYS157, and LYS158 may be the active site residues of STP17. Finally, STP17 was able to catalyze the ATP to ADP reaction, suggesting that STP17 may be an ATPase. To our knowledge, this is the first report describing the protein expression characteristics of STP17 in S. Typhi, showing that STP17 promotes bacterial growth and motility, which may be associated with its potential ATPase activity.

Multi-locus variable-number tandem repeat profiling of Salmonella enterica serovar Typhi isolates from blood cultures and gallbladder specimens from Makassar, South-Sulawesi, Indonesia

Multi-locus variable-number tandem repeat analysis differentiated 297 Salmonella enterica serovar Typhi blood culture isolates from Makassar in 76 genotypes and a single unique S. Typhi genotype was isolated from the cholecystectomy specimens of four patients with cholelithiasis. The high diversity in S. Typhi genotypes circulating in Makassar indicates that the number of carriers could be very large, which may complicate disease prevention and control.