title: DNA aptamers binding to multiple prevalent M-types of Streptococcus pyogenes.
abstract: This paper describes the selection of high affinity DNA aptamers binding to multiple M-types of the pathogenic species Streptococcus pyogenes (Group A Streptococcus or GAS). Unlike common aptamer selection techniques that use purified molecules of a monoclonal cell population as targets, this work has achieved the selection of aptamers against the various M-types of S. pyogenes. Cell mixtures containing equal numbers of the 10 most prevalent S. pyogenes M-types were incubated with 80-nucleotide DNA libraries, centrifuged, and washed to separate cell-bound from unbound DNA sequences. The DNA bound to the cells was amplified using the polymerase chain reaction, and the amplicons were tested for their binding to the target cells. The amplicons were also used as new DNA libraries for subsequent rounds of selection. Cloning, sequencing, and subsequent analysis of selected aptamers showed that they bind preferentially to GAS over other common and related bacteria. Resultant DNA aptamers showed strong and preferential binding to GAS, including the 10 most prevalent GAS M-types and another 10 minor M-types tested. Estimated K(d) values were in the range of 4 to 86 nM. Two aptamers, 20A24P and 15A3P (with estimated binding dissociation constants of 9 and 10 nM, respectively), are particularly promising. These aptamers could potentially be used to improve the detection of GAS, a pathogen that is the causative agent of many infectious diseases, most notably strep throat.
authors.affiliation: Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, 10-102 Clinical Sciences Bldg., Edmonton, Alberta, Canada T6G 2G3.
authors.forename: Camille L A
authors.initials: CL
authors.lastname: Hamula
authors.forename: X Chris
authors.initials: XC
authors.lastname: Le
authors.forename: Xing-Fang
authors.initials: XF
authors.lastname: Li
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D003001:Cloning, Molecular; D015723:Gene Library; D016133:Polymerase Chain Reaction; D052156:SELEX Aptamer Technique / Q000379:methods*; D017422:Sequence Analysis, DNA; D013297:Streptococcus pyogenes / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D052157:Aptamers, Nucleotide