Expression of a functional single-chain Fv antibody on the surface of Streptococcus gordonii.
Gram-positive bacterium Streptococcus gordonii, a human oral commensal, was engineered to display a single-chain Fv (scFv) antibody fragment at the cell surface. The previously developed host-vector system allowed expression of the Guy's 13 scFv as a fusion with the streptococcal surface protein M6. Surface expression of the 515-amino acid M6/scFv fusion protein was confirmed by Western blot analysis on cellular fractions and flow cytometric analysis. Guy's 13 scFv was derived from the Guy's 13 monoclonal antibody, which was raised against streptococcal antigen I/II (SA I/II), the major adhesin of the caries-producing bacterium Streptococcus mutans. Surface plasmon resonance was used to test binding of scFv-expressing S. gordonii to SA I/II. Whole cells of recombinant S. gordonii were found to specifically bind to immobilised SA I/II and binding was inhibited by fluid-phase SA I/II in a dose-dependent manner. Production of a functional scFv in S. gordonii is the first step towards the development of genetically engineered commensal bacteria that, by colonizing mucosal surfaces, may provide the host with sustained delivery of recombinant antibodies.
LAMMB Department of Molecular Biology, University of Siena, 53100 Siena, Italy.
Barbara
B
Giomarelli
Tiziana
T
Maggi
Justine
J
Younson
Charles
C
Kelly
Gianni
G
Pozzi
D018829:Adhesins, Bacterial / Q000737:chemistry; D000906:Antibodies / Q000737:chemistry*; D000911:Antibodies, Monoclonal / Q000737:chemistry; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D007135:Immunoglobulin Variable Region / Q000737:chemistry*; D008024:Ligands; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013291:Streptococcus / Q000737:chemistry* / Q000276:immunology; D013295:Streptococcus mutans / Q000378:metabolism; D013347:Subcellular Fractions; D020349:Surface Plasmon Resonance; D013997:Time Factors
D018829:Adhesins, Bacterial; D000906:Antibodies; D000911:Antibodies, Monoclonal; D007135:Immunoglobulin Variable Region; D008024:Ligands