Development of immunoaffinity based detection platforms for food pathogens

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2016
Çam, Dilek
Salmonella and E.coli, food pathogens, are among the very important pathogens threating the health. Rapid and easy detection of these pathogens is crucial. In this context, lateral flow assay (LFA) platform prepared by gold nanoparticles (GNPs) based on antibody for Salmonella and E.coli O157:H7 was developed in the first part of this study. In second part, single chain variable fragments (scFv) and SNAP-Tagged full IgG (fusion protein) of se155-4 antibody specific to Salmonella were genetically produced. Target capturing potential of the antibodies was examined by conventional and immunomagnetic ELISA. HF180 and 36nm GNPs were ideal membrane and dimension, respectively in the developed LFA. The best recognized species were S. enteritidis and S. infantis. E.coli were also specifically captured by developed strips. 5x105 S. typhimurium and 3x104 E.coli cells were determined as limit of detection by strips. scFv captured 2.8x104 and 2.8x105 target cells alone and in bacterial mixture, respectively. To our knowledge, recognition of whole cells by scFv and fusion protein of se155-4 were the first records in the literature. Produced antibodies showed strong affinity to S. typhimurium LPS, live and killed S. typhimurium. With the recombinant production of se155-4 known as specific to serogroup B cells, its high affinity to Salmonella serogroup D LPS was indicated as the first, in this work. LPS was the best antigen with high affinity. 1.4x101 S. typhimurium cells were the minimum pathogens detected by immunomagnetic ELISA.

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Citation Formats
D. Çam, “Development of immunoaffinity based detection platforms for food pathogens,” Ph.D. - Doctoral Program, Middle East Technical University, 2016.