title: Heterologous expression of antigenic peptides in Bacillus subtilis biofilms.
abstract: BACKGROUND
  Numerous strategies have been developed for the display of heterologous proteins in the surface of live bacterial carriers, which can be used as vaccines, immune-modulators, cancer therapy or bioremediation. Bacterial biofilms have emerged as an interesting approach for the expression of proteins of interest. Bacillus subtilis is a well-described, endospore-forming organism that is able to form biofilms and also used as a probiotic, thus making it a suitable candidate for the display of heterologous proteins within the biofilm. Here, we describe the use of TasA, an important structural component of the biofilms formed by B. subtilis, as a genetic tool for the display of heterologous proteins.
  
  
  RESULTS
  We first engineered the fusion protein TasA-mCherry and showed that was widely deployed within the B. subtilis biofilms. A significant enhancement of the expression of TasA-mCherry within the biofilm was obtained when depleting both tasA and sinR genes. We subsequently engineered fusion proteins of TasA to antigenic peptides of the E. granulosus parasite, paramyosin and tropomyosin. Our results show that the antigens were well expressed within the biofilm as denoted by macrostructure complementation and by the detection of the fusion protein in both immunoblot and immunohistochemistry. In addition, we show that the recombinant endospores of B. subtilis preserve their biophysical and morphological properties.
  
  
  CONCLUSIONS
  In this work we provide strong evidence pointing that TasA is a suitable candidate for the display of heterologous peptides, such as antigens, cytokines, enzymes or antibodies, in the B. subtilis biofilms. Finally, our data portray that the recombinant endospores preserve their morphological and biophysical properties and could be an excellent tool to facilitate the transport and the administration.
authors: Institute of Virology, University of Zurich, Winterthurerstrasse 266a, 8057, Zurich, Switzerland.
authors: Cédric M
authors: CM
authors: Vogt
authors: Institute of Virology, University of Zurich, Winterthurerstrasse 266a, 8057, Zurich, Switzerland.|Institute of Anatomy, University of Zurich, Zurich, Switzerland.
authors: Elisabeth M
authors: EM
authors: Schraner
authors: rqmicro Ltd, ETH, Otto-Stern-Weg 7, 8093, Zurich, Switzerland. aguilar@rqmicro.ch.
authors: Claudio
authors: C
authors: Aguilar
authors: Institute of Virology, University of Zurich, Winterthurerstrasse 266a, 8057, Zurich, Switzerland. ceichwald@vetvir.uzh.ch.
authors: Catherine
authors: http://orcid.org/0000-0003-0001-4843
authors: C
authors: Eichwald
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000235:genetics*; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics*; D018441:Biofilms; D048209:Echinococcus granulosus / Q000235:genetics* / Q000276:immunology; D015801:Helminth Proteins / Q000235:genetics* / Q000276:immunology; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000378:metabolism; D009876:Operon; D010446:Peptide Fragments / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D013171:Spores, Bacterial / Q000235:genetics; D014335:Tropomyosin / Q000235:genetics; D000097573:Red Fluorescent Protein
chemical_list: D000947:Antigens, Helminth; D001426:Bacterial Proteins; D015801:Helminth Proteins; D008164:Luminescent Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D014335:Tropomyosin; D000097573:Red Fluorescent Protein; C119938:TasA protein, Bacillus subtilis; C076733:FlaD protein, Bacteria
keywords: Antigen; Bacillus subtilis; Biofilm; E. granulosus; Endospores; Heterologous protein; Paramyosin; TasA; Tropomyosin; mCherry