Mohammad Sarwar Nasir

Fluorescence polarization (FP) assays for the determination of grain mycotoxins (fumonisins, DON vomitoxin and aflatoxins).

Successful use of fluorescence polarization assays (FPAs) in human clinical, infectious disease, and drug discovery fields has prompted us to extend its use to the grain mycotoxin field. An antibody specific to a mycotoxin and a mycotoxin-fluorophore conjugate are developed. Free toxin (extracted from the grains with a suitable solvent) competes with the toxin-fluorophore conjugate for the antibody and a change in FP relative to the quantity of free toxin occurs. This change is compared to a standard curve obtained by using known quantities of toxin. The use of FP and toxin-fluorophore conjugates for the quantification of fumonisins, deoxynivalenol and aflatoxins is described. These assays are field portable, simple to perform, rapid and require no washing steps.

The Use of Fluorescence Polarization Assays for the Detection of Infectious Diseases

Fluorescence Polarization Assays (FPAs) have been shown to have great utility in the detection of infectious diseases. Examples are presented of the use of O-polysaccharides (OPSs) for the detection of antibodies in serum, whole milk and whole blood to gram negative organisms (Brucella spp., Salmonella spp.). The use of proteins and peptides are also described for the detection of Mycobacterium bovis and Equine Infectious Anemia Virus. Fluorescence Polarization Inhibition Assays (FPIAs) are discussed for the specific and sensitive detection and quantitation of Salmonella spp. cells from culture. An example of the detection of enterohemorrhagic E. coli (EHECS) by Strand Displacement Amplification (SDA), coupled with FP, down to the single cell level, within thirty minutes, is described.

Serologic Detection of Experimental Salmonella enteritidis Infections in Laying Hens by Fluorescence Polarization and Enzyme Immunoassay

SUMMARY. Detection of infected poultry flocks is essential for controlling eggborne transmission of Salmonella enteritidis to humans. The present study evaluated the detection of antibodies in the sera of experimentally infected chickens by a fluorescence polarization assay with a tracer prepared from the O-polysaccharide of S. enteritidis and an enzyme-linked immunosorbent assay (ELISA) with an S. enteritidis flagellin antigen. In two trials, groups of specific-pathogen-free laying hens were infected orally with either 106 or 108 colony-forming units (CFU) of S. enteritidis (phage type 13a) or with 108 CFU of Salmonella typhimurium. Serum samples were collected before inoculation and at five subsequent weekly intervals. Both assays successfully detected the majority of hens infected with S. enteritidis at either dose level, but they also identified a substantial number of hens infected with S. typhimurium as seropositive. The fluorescence polarization test detected S. enteritidis infection significantly more often and cross-reacted with sera from hens infected with S. typhimurium significantly less often than the ELISA. The fluorescence polarization assay also offered advantages in terms of speed and methodologic simplicity.