Biology subjects

Calmettes, C.

Publications and source records attributed to Calmettes, C..

4 recordsLinked to original sources

bioRxiv2025

Host range and zoonotic potential linked to P-like fimbrial adhesin specificity in avian pathogenic Escherichia coli

Fimbrial adhesins are surface-associated bacterial proteins that contribute to colonization, tissue tropism, and biofilm formation. Genomic analysis of the avian pathogenic Escherichia coli (APEC) strain QT598 identified a plasmid-localized fimbrial operon, termed plf which encodes P-like (PL) fimbriae. Herein, we investigated the role of P-like (PL) fimbriae, encoded on the ColV plasmid of APEC strain QT598, in a natural host turkey respiratory infection model. We determined that deletion of the plf genes reduced colonization in the lungs of turkeys. The PlfG class II fimbrial adhesin from APEC strain QT598 demonstrated species- and tissue-specific adherence, as adherence to turkey lung sections in vitro was more pronounced than adherence to chicken lung sections. In vivo, expression of plf was also found to be upregulated in the lungs of turkeys during infection, as determined by qRT-PCR. Glycan array analysis showed that the PlfG class II adhesin recognizes Lewis b, Lewis y, and H antigens as potential receptors that are present on human red blood cells and on the surface of turkey respiratory tissues, implicating specific -1,2-linked glycans as receptors. Structural modelling of Plf adhesin revealed conserved {beta}-sandwich folds with distinct binding pockets that predict receptor specificity differences between Plf adhesin variants and other fimbrial adhesins such as PapG II and the PlfG class I adhesin from UMEA 3703-1. These findings highlight the role of PL fimbriae in APEC virulence and suggest a potential zoonotic and foodborne risk from poultry to humans, demonstrating the common recognition of glycans present on both turkey and mammalian host cells and tissues. Author summaryFimbrial adhesins may play a role in bacterial attachment and colonization of host cells. We examined the role of new pap-like (PL) fimbriae in an Avian Pathogenic E. coli (APEC) strain originally isolated from a systemic infection in a young turkey poult using genetic, molecular, and cell culture methods, as well as a turkey infection model. Deletion of plf genes also decreased colonization in the turkeys lungs, and comparison between the wild-type APEC isolate and the plf-mutant showed that these fimbriae strongly promote adherence to turkey lung sections compared to chicken lung sections. The PL fimbrial adhesin of strain QT598 demonstrated receptor-specificity to fucose [a]-1,2-galactose containing glycans, including Lewis b, Lewis y, and H antigens or similar glycans as determined by carbohydrate inhibition and glycan array experiments. These findings highlight the role of PL fimbriae in APEC virulence and suggest a potential zoonotic and foodborne risk from poultry to humans, demonstrating the common recognition of glycans present on both turkey and mammalian host cells and tissues.

microbiology↗

bioRxiv2025

Rationally designed minimized TbpB confers broad protection against meningococcal infection

Transferrin binding protein B (TbpB), an iron acquisition protein, has long been recognized as a promising vaccine candidate targeting the pathogenic Neisseria species, including Neisseria meningitidis, the cause of meningococcal disease, and Neisseria gonorrhoeae, the cause of gonorrhea. A challenge to the development of this protein as a vaccine immunogen is the extent of antigenic variability it exhibits, which complicates the selection of a single variant to elicit a broadly cross-protective immune response. We have utilized structure-informed antigen engineering to develop a minimized version of TbpB consisting of the proteins carboxy-terminal lobe with its variable surface loops removed. Here, we reveal the effectiveness of this "loopless C-lobe" as an independent immunogen, with structural characterization and stability studies to demonstrate its integrity, and murine immunization and challenge studies that establish its ability to elicit robust protective efficacy by using N. meningitidis invasive infection and nasopharyngeal colonization models. The breadth of protection provided, as measured by both in vitro analysis and cross-protection mouse challenge studies, indicate that a single loopless C-lobe elicits a broadly cross-protective immune response against the diverse panel of meningococcal strains tested, and that the cross-reactivity is superior to that offered by the intact TbpB or the native C-lobe. Together, this study demonstrates the utility of structure-informed antigen engineering towards the development of broadly efficacious protein-based vaccines. ImportanceSurface-exposed proteins on bacterial pathogens are enticing candidate vaccine targets, however their exposure to the immune system frequently leads to high levels of antigenic variation, a factor that complicates the development of broadly protective vaccines. Here, we undertake an antigen engineering approach to develop a minimized version of a surface lipoprotein, transferrin binding protein B, where variable regions of the protein have been removed to focus the immune response to conserved regions of this antigen. We combine structural studies and mouse infection models of Neisseria meningitidis, the cause of meningococcal disease, and Neisseria gonorrhoeae, the causative agent of gonorrhea, to reveal that our strategic minimizing of the protein immunogen focuses the immune response to extend the resulting breadth of cross-reactivity and cross-protection.

immunology↗

bioRxiv2022

Interaction mechanism between the HSV-1 glycoprotein B and the antimicrobial peptide Amyloid-β

Unravelling the mystery of Alzheimers Disease (AD) requires urgent resolution given the worldwide increase of the aging population. There is a growing concern that the current leading AD hypothesis, the amyloid cascade hypothesis, does not stand up to validation with respect to emerging new data. Indeed, several paradoxes are being discussed in the literature, for instance, both the deposition of the Amyloid-Beta peptide (A{beta}) and the intracellular neurofibrillary tangles (NFTs) could occur within the brain without any cognitive pathology. Thus, these paradoxes suggest that something more fundamental is at play in the onset of the disease and other key and related pathomechanisms have to be investigated. The present study follows our previous investigations on the infectious hypothesis, which posits that some pathogens are linked to late onset AD. Our studies also build upon the shattering finding that A{beta} is a powerful antimicrobial agent capable of inhibiting pathogens as observed in in vitro experiments. Herein, we ask what are the molecular mechanisms in play when A{beta} neutralizes infectious pathogens? To answer this question, we probed at nanoscale lengths with FRET (Forster Resonance Energy Transfer), the interaction between A{beta} peptides and glycoprotein B (responsible of virus-cell binding) within the HSV-1 virion. We concluded that there is indeed a close interaction, likely nonspecific or semi-specific, between the two types of molecules, which participate in virus neutralization.

neuroscience↗

bioRxiv2022

Bacterial outer-membrane polysaccharide export (OPX) proteins occupy three structural classes with selective β-barrel porin requirements for polymer secretion

Secretion of high-molecular-weight polysaccharides across the bacterial envelope is ubiquitous as it enhances prokaryotic survival in (a)biotic settings. Such polymers are often assembled by Wzx/Wzy- or ABC transporter-dependent schemes that implicate outer-membrane (OM) polysaccharide export (OPX) proteins in polymer translocation to the cell surface. In the social predatory bacterium Myxococcus xanthus, exopolysaccharide (EPS)-pathway WzaX, major spore coat (MASC)-pathway WzaS, and biosurfactant polysaccharide-pathway WzaB were herein found to be truncated OPX homologues of Escherichia coli Wza lacking OM-spanning -helices. Comparative genomics across all bacteria, complemented with cryo-electron tomography cell- envelope analyses, revealed WzaX/S/B architecture to be the most common amongst three defined OPX-protein structural classes independent of periplasmic thickness. Fold-recognition and deep- learning analyses revealed the conserved M. xanthus proteins MXAN_7418/3226/1916 (encoded adjacent to WzaX/S/B) to be integral OM {beta}-barrels, with structural homology to the poly-N-acetyl-D- glucosamine synthase-dependent pathway porin PgaA. Such porins were identified in bacteria near numerous genes for all three OPX-protein classes. Interior MXAN_7418/3226/1916 {beta}-barrel electrostatics were found to match known properties of their associated polymers. With MXAN_3226 essential for MASC export, and MXAN_7418 absence shown herein to compromise EPS translocation, these data support a novel secretion paradigm for Wzx/Wzy-dependent pathways in which those containing an OPX component that cannot span the OM instead utilize a {beta}-barrel porin to mediate polysaccharide transport across the OM.

microbiology↗