Dataset Information

Adaptive evolution of class 5 fimbrial genes in enterotoxigenic Escherichia coli and its functional consequences.

ABSTRACT: Class 5 fimbriae of enterotoxigenic Escherichia coli (ETEC) comprise eight serologically discrete colonization factors that mediate small intestinal adhesion. Their differentiation has been attributed to the pressure imposed by host adaptive immunity. We sequenced the major pilin and minor adhesin subunit genes of a geographically diverse population of ETEC elaborating CFA/I (n = 31), CS17 (n = 20), and CS2 (n = 18) and elucidated the functional effect of microevolutionary processes. Between the fimbrial types, the pairwise nucleotide diversity for the pilin or adhesin genes ranged from 35-43%. Within each fimbrial type, there were 17 non-synonymous and 1 synonymous point mutations among all pilin or adhesin gene copies, implying that each fimbrial type was acquired by ETEC strains very recently, consistent with a recent origin of this E. coli pathotype. The 17 non-synonymous allelic differences occurred in the CFA/I pilin gene cfaB (two changes) and adhesin gene cfaE (three changes), and CS17 adhesin gene csbD (12 changes). All but one amino acid change in the adhesins clustered around the predicted ligand-binding pocket. Functionally, these changes conferred an increase in cell adhesion in a flow chamber assay. In contrast, the two mutations in the non-adhesive CfaB subunit localized to the intersubunit interface and significantly reduced fimbrial adhesion in this assay. In conclusion, naturally occurring mutations in the ETEC adhesive and non-adhesive subunits altered function, were acquired under positive selection, and are predicted to impact bacteria-host interactions.

SUBMITTER: Chattopadhyay S

PROVIDER: S-EPMC3307271 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Adaptive evolution of class 5 fimbrial genes in enterotoxigenic Escherichia coli and its functional consequences.

Chattopadhyay Sujay S Tchesnokova Veronika V McVeigh Annette A Kisiela Dagmara I DI Dori Kathleen K Navarro Armando A Sokurenko Evgeni V EV Savarino Stephen J SJ

The Journal of biological chemistry 20120103 9

Class 5 fimbriae of enterotoxigenic Escherichia coli (ETEC) comprise eight serologically discrete colonization factors that mediate small intestinal adhesion. Their differentiation has been attributed to the pressure imposed by host adaptive immunity. We sequenced the major pilin and minor adhesin subunit genes of a geographically diverse population of ETEC elaborating CFA/I (n = 31), CS17 (n = 20), and CS2 (n = 18) and elucidated the functional effect of microevolutionary processes. Between the ...[more]

PMID: 22215679

Similar Datasets

Project description:Enterotoxigenic Escherichia coli (ETEC) is a leading diarrheagenic bacterial pathogen among travelers and children in resource-limited regions. Adherence to host intestinal cells mediated by ETEC fimbriae is believed to be a critical first step in ETEC pathogenesis. These fimbriae are categorized into related classes based on sequence similarity, with members of the class 5 fimbrial family being the best characterized. The eight related members of the ETEC class 5 fimbrial family are subdivided into three subclasses (5a, 5b, and 5c) that share similar structural arrangements, including a fimbrial tip adhesin. However, sequence variability among the class 5 adhesins may hinder the generation of cross-protective antibodies. To better understand functional epitopes of the class 5 adhesins and their ability to induce intraclass antibody responses, we produced 28 antiadhesin monoclonal antibodies (MAbs) to representative adhesins CfaE, CsbD, and CotD, respectively. We determined the MAb cross-reactivities, localized the epitopes, and measured functional activities as potency in inhibition of hemagglutination induced by class 5 fimbria-bearing ETEC. The MAbs' reactivities to a panel of class 5 adhesins in enzyme-linked immunosorbent assays (ELISAs) revealed several reactivity patterns, including individual adhesin specificity, intrasubclass specificity, intersubclass specificity, and class-wide cross-reactivity, suggesting that some conserved epitopes, including two conserved arginines, are shared by the class 5 adhesins. However, the cross-reactive MAbs had functional activities limited to strains expressing colonization factor antigen I (CFA/I), coli surface antigen 17 (CS17), or CS1, suggesting that the breadth of functional activities of the MAbs was more restricted than the repertoire of cross-reactivities measured by ELISA. The results imply that multivalent adhesin-based ETEC vaccines or prophylactics need more than one active component to reach broad protection.

Project description:Enterotoxigenic Escherichia coli (ETEC) strains that produce immunologically heterogeneous fimbriae and enterotoxins are the primary cause of neonatal diarrhea and postweaning diarrhea in young pigs. A multivalent vaccine inducing protective immunity against ideally all ETEC fimbriae and enterotoxins could be effective against diarrhea in young pigs. However, developing a vaccine to broadly protect against various ETEC virulence determinants has proven challenging. Recently developed structure- and epitope-based multiepitope fusion antigen (MEFA) technology that presents neutralizing epitopes of various virulence determinants at a backbone immunogen and that mimics epitope native immunogenicity suggests the feasibility of developing multivalent vaccines. With neutralizing epitopes from ETEC fimbria F18 and enterotoxins being identified, it becomes urgent to identify protective epitopes of K88 (F4) fimbriae, which play a major role in pig neonatal and postweaning diarrhea. In this study, we identified B-cell immunodominant epitopes in silico from the K88ac fimbrial major subunit (also adhesin) FaeG and embedded each epitope in a heterogeneous carrier for epitope fusions. We then immunized mice with each epitope fusion protein and examined epitope antigenicity and also neutralizing activities of epitope-induced antibodies. Data showed that while all nine FaeG epitope fusions induced antibodies to K88ac fimbria, anti-K88 IgG antibodies derived from epitopes MTGDFNGSVD (ep1), LNDLTNGGTK (ep2), GRTKEAFATP (ep3), ELRKPDGGTN (ep4), PMKNAGGTKVGAVKVN (ep5), and RENMEYTDGT (ep8) significantly inhibited adherence of K88ac fimbrial bacteria to porcine intestinal cell line IPEC-J2, indicating that these peptides were the neutralizing epitopes of K88ac fimbrial major subunit FaeG and suggesting the future application of FaeG epitopes in ETEC vaccine development.IMPORTANCE Enterotoxigenic Escherichia coli (ETEC) strains producing K88ac fimbriae and enterotoxins are a major cause of porcine neonatal diarrhea and postweaning diarrhea in the United States. Currently, there is no vaccine to induce broadly protective antiadhesin and antitoxin immunity against ETEC-associated diarrhea. To develop a broadly effective ETEC vaccine, we need to target the most important if not all ETEC virulence determinants. While conventional vaccinology approaches encounter difficulties at integrating or including heterogeneous ETEC fimbria and toxin antigens into a vaccine product, multiepitope fusion antigen (MEFA) structural vaccinology provides a new platform to combine neutralizing antigenic elements or epitopes from various heterogeneous virulence factors for broad immunity and protection. Identification of the neutralizing epitopes of K88ac fimbria from this study added the last antigens to an MEFA-based multivalent vaccine against ETEC-associated diarrhea in pigs. An effective vaccine against pig diarrhea can significantly improve swine health and well-being and reduce economic losses to the swine industry worldwide.

Dataset Information

Adaptive evolution of class 5 fimbrial genes in enterotoxigenic Escherichia coli and its functional consequences.

Publications

Adaptive evolution of class 5 fimbrial genes in enterotoxigenic Escherichia coli and its functional consequences.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets