title: Detection of anthrax toxin by an ultrasensitive immunoassay using europium nanoparticles.
abstract: We developed a europium nanoparticle-based immunoassay (ENIA) for the sensitive detection of anthrax protective antigen (PA). The ENIA exhibited a linear dose-dependent pattern within the detection range of 0.01 to 100 ng/ml and was approximately 100-fold more sensitive than enzyme-linked immunosorbent assay (ELISA). False-positive results were not observed with serum samples from healthy adults, mouse plasma without PA, or plasma samples collected from mice injected with anthrax lethal factor or edema factor alone. For the detection of plasma samples spiked with PA, the detection sensitivities for ENIA and ELISA were 100% (11/11 samples) and 36.4% (4/11 samples), respectively. The assay exhibited a linear but qualitative correlation between the PA injected and the PA detected in murine blood (r=0.97731; P<0.0001). Anthrax PA was also detected in the circulation of mice infected with spores from a toxigenic Sterne-like strain of Bacillus anthracis, but only in the later stages of infection. These results indicate that the universal labeling technology based on europium nanoparticles and its application may provide a rapid and sensitive testing platform for clinical diagnosis and laboratory research.
authors.affiliation: Laboratory of Molecular Virology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA. Shixing.tang@fda.hhs.gov
authors.forename: Shixing
authors.initials: S
authors.lastname: Tang
authors.forename: Mahtab
authors.initials: M
authors.lastname: Moayeri
authors.forename: Zhaochun
authors.initials: Z
authors.lastname: Chen
authors.forename: Harri
authors.initials: H
authors.lastname: Harma
authors.forename: Jiangqin
authors.initials: J
authors.lastname: Zhao
authors.forename: Haijing
authors.initials: H
authors.lastname: Hu
authors.forename: Robert H
authors.initials: RH
authors.lastname: Purcell
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Leppla
authors.forename: Indira K
authors.initials: IK
authors.lastname: Hewlett
mesh_terms: D000328:Adult; D000818:Animals; D000881:Anthrax / Q000175:diagnosis*; D000942:Antigens, Bacterial / Q000032:analysis*; D001427:Bacterial Toxins / Q000032:analysis*; D005063:Europium / Q000378:metabolism*; D005189:False Positive Reactions; D006801:Humans; D007118:Immunoassay / Q000379:methods; D051379:Mice; D053758:Nanoparticles / Q000032:analysis*; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; C030325:anthrax toxin; D005063:Europium