Development of immunoliposome-based assay for the detection of Salmonella Typhimurium

Abstract

This study was aimed to produce a polyclonal antibody against Salmonella Typhimurium and to develop a liposome-based immunoassay to validate its detection. Formalin-killed cells of S. Typhimurium were subcutaneously injected as an antigen into rabbit to produce antibody. The optimum production of rabbit anti-Salmonella immunoglobulin G (anti-Salmonella IgG) antibody was reached to the highest level on 8 week. Purification of rabbit anti-Salmonella IgG from immunized rabbit sera was accomplished using caprylic acid and ammonium sulfate precipitation method. The purified anti-Salmonella IgG was used to conjugate with liposome to prepare anti-Salmonella IgG-tagged liposome (immunoliposome). Finally, an improved immunoassay method was developed using the immunoliposome for the detection of S. Typhimurium. As a result, sodium dodecyl sulfate-polyacrylamide gel electrophoresis produced two bands around 25 and 51 kDa, corresponding to a light and a heavy chain, respectively. The immunoliposome was successfully developed for the detection of S. Typhimurium in a 96-well microtiter plate, using purified anti-Salmonella IgG antibody. The improved technique was able to detect 103 cells/mL of Salmonellas. In the future, even better detection may be achieved by using this immunoliposome with some modifications or other detection methods.