title: Development of a DNA aptamer that binds specifically to group A Streptococcus serotype M3.
abstract: Group A streptococcus (GAS) is an important Gram-positive pathogen that causes various human diseases ranging from peripheral lesions to invasive infections. The M protein is one of the main virulence factors present on the cell surface and is associated with invasive GAS infections. Compared with other M types, serotype M3 has a predominant role in lethal infections and demonstrates epidemic behaviors, including streptococcal toxic shock syndrome, bacteremia, and necrotizing fasciitis. Traditional methods for M typing are time-consuming, tedious, contradictory, and generally restricted to reference laboratories. Therefore, development of a new M-typing technique is needed. Aptamers with the ability to detect their target with a high degree of accuracy and specificity can be ideal candidates for specific M-typing of Streptococcus pyogenes. In this study DNA aptamers with a high binding affinity towards S. pyogenes serotype M3 were selected through 12 iterative rounds of the Systematic Evolution of Ligands by EXponential (SELEX) enrichment procedure using live cells as a target. We monitored the progress of the SELEX procedure by flow cytometry analysis. Of several aptamer sequences analyzed, 12L18A showed the highest binding efficiency towards S. pyogenes type M3, with an apparent dissociation constant (Kd) of 7.47 ± 1.72 pmol/L being the lowest. Therefore the isolated aptamer can be used in any tool, such as a biosensor, for the detection of S. pyogenes and can be used in the development of a novel M-typing system.
authors.affiliation: a Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran.
authors.forename: Hanif
authors.initials: H
authors.lastname: Alfavian
authors.affiliation: a Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran.
authors.forename: Seyed Latif
authors.initials: SL
authors.lastname: Mousavi Gargari
authors.affiliation: a Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran.
authors.forename: Samaneh
authors.initials: S
authors.lastname: Rasoulinejad
authors.affiliation: b GENEXIR Biopharma, a knowledge-based company at Pasteur Institute of Iran Health Technology Park, Tehran, Iran.
authors.forename: Arvin
authors.initials: A
authors.lastname: Medhat
mesh_terms: D052157:Aptamers, Nucleotide / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D052156:SELEX Aptamer Technique; D065288:Serogroup; D013297:Streptococcus pyogenes / Q000145:classification / Q000302:isolation & purification*
chemical_list: D052157:Aptamers, Nucleotide
keywords: Cell-SELEX; SELEX cellulaire; Streptococcus pyogenes; aptamers; aptamère; cytométrie en flux; flow cytometry; serotyping; sérotypage