title: Virus-based assay for antigen detection using infective growth as signal transduction mechanism.
abstract: Viruses have the ability to infect and thereby confer new phenotypes on host cells. E. coli, for example, if infected by viruses containing antibiotic resistance genes, can benefit by surviving in the presence of the corresponding antibiotics to grow into colonies observable by the naked eye. Using this concept as a signal transduction mechanism for our immunoassay, we have engineered ampicillin resistant virions to display a dimer of the z domain from Protein A. This zz-domain selectively binds to the conserved heavy domain of IgG across various species. As commercially available antibodies are in no short supply, this engineered virion can be used modularly with existing antibodies for converting the presence of target antigen into a visually detectable colony forming unit. Here we demonstrate that this scheme for zz-phage transfection and selective growth of infected E. coli can facilitate sub-nanomolar detection limits for target antigen. Moreover, this phage infectivity assay works over a range of concentrations competitive with existing ELISA techniques. Because this system is derived from self-regenerating components (i.e., virus and bacteria) and furthermore obviates the need for chromogenic substrates or spectroscopic equipment, we find it particularly suitable for use in regions where cost effective detection is a necessity.
authors.affiliation: Department of Chemical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea.
authors.forename: Hui Shan
authors.initials: HS
authors.lastname: Cheok
authors.affiliation: Department of Chemical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea; Institute of Nanoscience and Technology, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea. Electronic address: justynj@hanyang.ac.kr.
authors.forename: Justyn
authors.initials: J
authors.lastname: Jaworski
mesh_terms: D000941:Antigens / Q000032:analysis* / Q000276:immunology*; D001435:Bacteriophages / Q000276:immunology*; D001681:Biological Assay / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli / Q000276:immunology / Q000821:virology*; D007118:Immunoassay / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000295:instrumentation
chemical_list: D000941:Antigens
keywords: Antibody; Infection; Phage; Visual detection; Z Domain