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  1. A 35 kDa antigenic protein from Shigella flexneri: in silico structural and functional studies
    Yung-Hung RL, Ismail A, Lim TS, Choong YS
    Biochem Biophys Res Commun, 2011 Nov 18;415(2):229-34.
    PMID: 21982766 DOI: 10.1016/j.bbrc.2011.09.116
    Shigella flexneri serotype 2a is a major public health concern in the developing and under-developed countries which contributes to shigellosis endemic and mortality. Thus, there is an urgent need for a rapid diagnostic test for effective therapy and disease management. Previous study showed that a ∼35 kDa antigenic protein from S. flexneri is a potential biomarker. We therefore modelled the three-dimensional structure of the antigen to probe its functionality which could aid in the development of an antigen-based diagnostic. Results showed that the antigen is a transmembrane protein consists of OmpA and OmpA-like domains. The OmpA domain is a beta-barrel embedded in the outer membrane with four surface-exposed extracellular loops. The OmpA-like domain is linked to the OmpA domain with a 17 amino acids linker and located in the periplasmic. Docking of peptidoglycan into the groove of OmpA-like domain might help in catalyzing the bacterial cell wall formation. Both domains are expected to be involved in the virulence, structural stability, pathogenesis and survival of Shigella thus made the 35 kDa protein a suitable shigellosis diagnostic biomarker. This structural elucidation will also enable a better identification of the epitope regions for the development of specific binders to the 35 kDa antigen.
    Matched MeSH terms: Shigella flexneri/immunology*
  2. Fulltext Shigella flexneri serotype 1c derived from serotype 1a by acquisition of gtrIC gene cluster via a bacteriophage
    Tang SS, Carlin NI, Talukder KA, Cam PD, Verma NK
    BMC Microbiol, 2016 Jun 27;16(1):127.
    PMID: 27349637 DOI: 10.1186/s12866-016-0746-z
    BACKGROUND: Shigella spp. are the primary causative agents of bacillary dysentery. Since its emergence in the late 1980s, the S. flexneri serotype 1c remains poorly understood, particularly with regard to its origin and genetic evolution. This article provides a molecular insight into this novel serotype and the gtrIC gene cluster that determines its unique immune recognition.

    RESULTS: A PCR of the gtrIC cluster showed that serotype 1c isolates from different geographical origins were genetically conserved. An analysis of sequences flanking the gtrIC cluster revealed remnants of a prophage genome, in particular integrase and tRNA(Pro) genes. Meanwhile, Southern blot analyses on serotype 1c, 1a and 1b strains indicated that all the tested serotype 1c strains may have had a common origin that has since remained distinct from the closely related 1a and 1b serotypes. The identification of prophage genes upstream of the gtrIC cluster is consistent with the notion of bacteriophage-mediated integration of the gtrIC cluster into a pre-existing serotype.

    CONCLUSIONS: This is the first study to show that serotype 1c isolates from different geographical origins share an identical pattern of genetic arrangement, suggesting that serotype 1c strains may have originated from a single parental strain. Analysis of the sequence around the gtrIC cluster revealed a new site for the integration of the serotype converting phages of S. flexneri. Understanding the origin of new pathogenic serotypes and the molecular basis of serotype conversion in S. flexneri would provide information for developing cross-reactive Shigella vaccines.

    Matched MeSH terms: Shigella flexneri/immunology
  3. Designing and evaluation of an antibody-targeted chimeric recombinant vaccine encoding Shigella flexneri outer membrane antigens
    Kazi A, Hisyam Ismail CMK, Anthony AA, Chuah C, Leow CH, Lim BH, et al.
    Infect Genet Evol, 2020 06;80:104176.
    PMID: 31923724 DOI: 10.1016/j.meegid.2020.104176
    Shigellosis is one of the most common diseases found in the developing countries, especially those countries that are prone flood. The causative agent for this disease is the Shigella species. This organism is one of the third most common enteropathogens responsible for childhood diarrhea. Since Shigella can survive gastric acidity and is an intracellular pathogen, it becomes difficult to treat. Also, uncontrolled use of antibiotics has led to development of resistant strains which poses a threat to public health. Therefore, there is a need for long term control of Shigella infection which can be achieved by designing a proper and effective vaccine. In this study, emphasis was made on designing a candidate that could elicit both B-cell and T-cell immune response. Hence B- and T-cell epitopes of outer membrane channel protein (OM) and putative lipoprotein (PL) from S. flexneri 2a were computationally predicted using immunoinformatics approach and a chimeric construct (chimeric-OP) containing the immunogenic epitopes selected from OM and PL was designed, cloned and expressed in E. coli system. The immunogenicity of the recombinant chimeric-OP was assessed using Shigella antigen infected rabbit antibody. The result showed that the chimeric-OP was a synthetic peptide candidate suitable for the development of vaccine and immunodiagnostics against Shigella infection.
    Matched MeSH terms: Shigella flexneri/immunology*
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