The use of polyvinyl alcohol glutaraldehyde antigen coated discs for laser induced fluorescence detection of plague

F1-antigen purified from Yersinia pestis was covalently linked to polyvinyl alcohol (PVA) glutaraldehyde cross-linked discs synthesized by acid catalysis. This derivative was incubated with fluorescein labeled antibody against F1-antigen and excited at 4880 Angstrom by either an argon laser or a dye laser. The fluorescence was detected at 5200 Angstrom. The appearance of the transition at 5200 Angstrom was indicative of positive complex formation, since PVA-glutaraldehyde does not fluoresce at this wavelength. The observed fluorescence was compared with samples treated with patient sera. A positive response was indicated by a decrease in the fluorescence at 5200 Angstrom. An additional series of experiments was carried out by first treating the F1-antigen-PVA-glutaraldehyde disc with patient sera, followed by fluorescein labeled goat anti-human IgG conjugate. A positive response was indicated by an increase in the observed fluorescence. Both approaches were equally capable of detecting antibodies in patient sera. However, the first technique was more rapid. When these data are compared against the standard passive hemagglutination assay presently used in Brazil, it has been found to have far greater sensitivity for the detection of plague.