An Efficient Liposome‐Based Immunochromatographic Strip Assay for the Sensitive Detection of <scp><i>S</i></scp><i>almonella</i> <scp>T</scp>yphimurium in Pure Culture

Abstract

Abstract This study was aimed to develop specific antibody against S almonella T yphimurium ( S. Typhimurium) and to confirm the originality and sensitivity of a liposome‐based immunochromatographic strip assay. Liposomes were prepared through a reverse‐phase evaporation method and conjugated with goat anti‐ S almonella immunoglobulin G ( IgG ) in order to produce immunoliposomes. For the developed assay, a plastic‐backed nitrocellulose strip ( H i F low P lus HFB 09004, M illipore C orporation, B edford, MA ) was coated with two antibody zones. The lower zone (test line) of the strip was coated with 11.2 μg/μ L of laboratory‐produced rabbit anti‐ S . T yphimurium IgG , while the upper zone (control line) was coated with 1.2 μg/μ L of rabbit anti‐goat IgG . The prepared strips were allowed for capillary migration with wicking solution (mixture of diluted liposome and bacterial culture). S . T yphimurium was captured with surface bound immunoliposomes at lower zone, while the unbound liposomes migrated and bounded to the upper zone. The detection limit of the developed immunochromatographic strip assay was found to be 10 6 –10 7 cfu/m L with a total analysis time of 10 min. When the cross‐reactivity of the developed laboratory‐produced rabbit anti‐ S . T yphimurium IgG coated immunochromatographic strips were compared with commercial immunochromatographic detection kit and commercial antibody‐coated immunochromatographic strips, the developed test strips showed similar detection limit to commercial ones; however, they were specific to S . T yphimurium only. Practical Application S almonella pathogens have become major cause of food‐borne diseases worldwide, raising a great safety concern to consumers and public health. A number of S almonella serotypes responsible for severe foodborne outbreaks are found in various foods including fresh vegetables, dairy and meat products, as well as in human host. Such implications caused by these S almonella pathogens have sustained the demand for their on‐site detection using some advance techniques. In this context, we have developed an efficient liposome‐based immunochromatographic strip assay for the sensitive detection of S almonella T yphimurium ( S. Typhimurium) in pure cultures. This immunochromatographic strip prepared by using laboratory‐produced rabbit anti‐ S . T yphimurium IgG antibody was found specific to S . T yphimurium and showed better detection limit as compared with commercial immunochromatographic detection kit. Possible applications may be applied in food industry for the rapid and sensitive detection of S . T yphimurium in various food samples contaminated with this pathogenic bacterium.