Abstract
Background
Plague is a severe, highly communicable bacterial disease caused by Yersinia pestis. It is still endemic in more than 20 countries worldwide. Although known as a devastating disease for centuries, laboratory confirmation of clinical suspected cases is still problematic. No standardized and internationally approved test system is commercially available. The aim of this study was the introduction and evaluation of a combination of immunomagnetic separation and flow cytometry for the serodiagnosis of human plague.
Methods
Paramagnetic polystyrene beads were coated with purified F1 capsular antigen (F1 CA) and reacted with sera from plague patients, from 26 laboratory personnel vaccinated against plague and from 102 healthy blood donors (HBD). After incubation with fluorescein isothiocyanate–conjugated anti‐human rabbit IgG, particle‐associated fluorescence was detected by flow cytometry.
Results
Anti‐F1 CA antibodies could be demonstrated in all patients with bacteriologically confirmed plague and in 22 sera (84.6%) from vaccinees. Only one serum in the HBD group showed a weakly positive reaction. The total assay time was less than 2 h.
Conclusions
Compared with a recently published combination of an anti‐F1 CA enzyme‐linked immunosorbent assay (ELISA) and immunoblot, the new assay showed the same sensitivity as the ELISA and almost the same specificity (99.0 versus 100%) as the immunoblot. Allowing a rapid, reliable, and quantitative analysis, immunomagnetic separation combined with flow cytometry might replace both conventional immunoassays. Cytometry Part A 53A:88–96, 2003. © 2003 Wiley‐Liss, Inc.