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1.
Health Secur ; 18(2): 83-95, 2020.
Article in English | MEDLINE | ID: mdl-32324068

ABSTRACT

We conducted a comprehensive, multi-phase laboratory evaluation of the Tularemia BioThreat Alert® (BTA) test, a lateral flow assay (LFA) for the rapid detection of Francisella tularensis. The study, conducted at 2 sites, evaluated the limit of detection (LOD) of this assay using the virulent SchuS4 strain and the avirulent LVS strain of F. tularensis. In 6-phase evaluation (linear dynamic range and reproducibility, inclusivity, near-neighbor, environmental background, white powder, and environmental filter extract), 13 diverse strains of F. tularensis, 8 Francisella near neighbors, 61 environmental background organisms, 26 white powders, and a pooled aerosol extract were tested. In the 937 tests performed, the Tularemia BTA demonstrated an LOD of 107 to 108 cfu/mL, with a sensitivity of 100.00%, specificity of 98.08%, and accuracy of 98.84%. These performance data are important for accurate interpretation of qualitative results arising from screening suspicious white powders in the field.


Subject(s)
Aerosols/analysis , Biological Assay/methods , Francisella tularensis/isolation & purification , Powders/analysis , Bioterrorism , Reproducibility of Results , Sensitivity and Specificity
2.
Health Secur ; 17(6): 439-453, 2019.
Article in English | MEDLINE | ID: mdl-31859568

ABSTRACT

We conducted a comprehensive, multiphase laboratory evaluation of the Plague BioThreat Alert® (BTA) test, a lateral flow immunoassay (LFA), for the rapid detection of Yersinia pestis. The study was conducted in 7 phases at 2 sites to assess the performance of the LFA. The limit of detection (LOD) was determined using both a virulent and avirulent strain of Y. pestis, CO99-3015 (105 CFU/ml) and A1122 (104 CFU/ml), respectively. In the other phases, 18 Y. pestis strains, 20 phylogenetic near-neighbor strains, 61 environmental background microorganisms, 26 white powders, and a pooled aerosol sample were also tested. A total of 1,110 LFA test results were obtained, and their analysis indicates that this LFA had a sensitivity of 97.65% and specificity of 96.57%. These performance data are important for accurate interpretation of qualitative results arising from testing suspicious white powders and aerosol samples in the field. Any positive specimen in this assay is considered presumptive positive and should be referred to the Centers for Disease Control and Prevention Laboratory Response Network for additional testing, confirmation, and characterization for an appropriate public health response.


Subject(s)
Bioterrorism/prevention & control , Immunoassay/methods , Plague/prevention & control , Yersinia pestis/isolation & purification , Humans , Sensitivity and Specificity
3.
Health Secur ; 17(4): 334-343, 2019.
Article in English | MEDLINE | ID: mdl-31433282

ABSTRACT

A comprehensive laboratory evaluation of the Tetracore RedLine Alert test, a lateral flow immunoassay (LFA) for the rapid presumptive identification of Bacillus anthracis, was conducted at 2 different test sites. The study evaluated the sensitivity of this assay using 16 diverse strains of B. anthracis grown on sheep blood agar (SBA) plates. In addition, 83 clinically relevant microorganisms were tested to assess the specificity of the RedLine Alert test. The results indicated that the RedLine Alert test for the presumptive identification of B. anthracis is highly robust, specific, and sensitive. RedLine Alert is a rapid test that has applicability for use in a clinical setting for ruling-in or ruling-out nonhemolytic colonies of Bacillus spp. grown on SBA medium as presumptive isolates of B. anthracis.


Subject(s)
Anthrax , Bacillus anthracis/isolation & purification , Diagnostic Tests, Routine , Immunoassay , Animals , Anthrax/diagnosis , Anthrax/microbiology , Humans , Sensitivity and Specificity , Sheep
4.
Health Secur ; 14(5): 351-65, 2016.
Article in English | MEDLINE | ID: mdl-27661796

ABSTRACT

We conducted a comprehensive, multiphase laboratory evaluation of the Anthrax BioThreat Alert(®) test strip, a lateral flow immunoassay (LFA) for the rapid detection of Bacillus anthracis spores. The study, conducted at 2 sites, evaluated this assay for the detection of spores from the Ames and Sterne strains of B. anthracis, as well as those from an additional 22 strains. Phylogenetic near neighbors, environmental background organisms, white powders, and environmental samples were also tested. The Anthrax LFA demonstrated a limit of detection of about 10(6) spores/mL (ca. 1.5 × 10(5) spores/assay). In this study, overall sensitivity of the LFA was 99.3%, and the specificity was 98.6%. The results indicated that the specificity, sensitivity, limit of detection, dynamic range, and repeatability of the assay support its use in the field for the purpose of qualitatively evaluating suspicious white powders and environmental samples for the presumptive presence of B. anthracis spores.


Subject(s)
Bacillus anthracis/isolation & purification , Bioterrorism/prevention & control , Immunoassay/methods , Spores, Bacterial/isolation & purification , Civil Defense/methods , Immunoassay/instrumentation , Powders , Reagent Strips , Reproducibility of Results , Sensitivity and Specificity
5.
Biosecur Bioterror ; 12(1): 49-62, 2014.
Article in English | MEDLINE | ID: mdl-24552362

ABSTRACT

Abrin is a heterodimeric toxin present in the seeds of the Abrus precatorius plant. The easily obtainable seeds can yield a highly toxic product that can be used in various types of biocrimes and terrorism-related activities, including "white-powder" letters. Although the vast majority of these threats are hoaxes, the lack of rapid and reliable detection assays for abrin, such as lateral flow assays (LFAs), can be an impediment to accurate and rapid hazard assessment. One of the complicating factors associated with LFAs is the use of antibodies of poor affinity and specificity that cross-react with near neighbors or that bind to plant lectins, which are capable of nonspecifically cross-linking the capture and detector antibodies. Because of the critical need to promote public safety and public health, we conducted a comprehensive laboratory evaluation of a commercial LFA for the rapid detection of abrin. This study was conducted using comprehensive inclusivity and exclusivity panels of abrin and near-neighbor plant materials, along with panels of lectins, related proteins, white powders, and environmental background material, to determine the sensitivity, specificity, limit of detection, dynamic range, and repeatability of the assay for the specific intended use of evaluating suspicious white powders and environmental samples for the presumptive presence of abrin.


Subject(s)
Abrin/isolation & purification , Powders/chemistry , Reagent Kits, Diagnostic/standards , Chemical Terrorism , Powders/poisoning , Reagent Strips , Sensitivity and Specificity , United States
6.
Biosecur Bioterror ; 11(4): 237-50, 2013 Dec.
Article in English | MEDLINE | ID: mdl-24320219

ABSTRACT

Ricin, a heterodimeric toxin that is present in the seeds of the Ricinus communis plant, is the biothreat agent most frequently encountered by law enforcement agencies in the United States. Even in untrained hands, the easily obtainable seeds can yield a highly toxic product that has been used in various types of threats, including "white-powder" letters. Although the vast majority of these threats are hoaxes, an impediment to accurate hazard assessments by first responders is the unreliability of rapid detection assays for ricin, such as lateral flow assays (LFAs). One of the complicating factors associated with LFAs is the incorporation of antibodies of poor specificity that cross-react with near-neighbors or with plant lectins that are capable of nonspecifically cross-linking the capture and detector antibodies. Because of the compelling and critical need to promote the interests of public safety and public health, the Department of Homeland Security conducted a comprehensive laboratory evaluation study of a commercial LFA for the rapid detection of ricin. This study was conducted using comprehensive inclusivity and exclusivity panels of ricin and near-neighbor plant materials, along with panels of lectins and "white-powders," to determine the specificity, sensitivity, limits of detection, dynamic range, and repeatability of the assay for the specific intended use of evaluating suspicious white powders and environmental samples in the field.


Subject(s)
Chemical Warfare Agents/analysis , Chromatography, Affinity/methods , Ricin/analysis , Air Filters , Environment , Humans , Laboratories , Limit of Detection , Plant Extracts/analysis , Plant Lectins/analysis , Powders/chemistry , Reproducibility of Results
7.
Cancer Res ; 63(8): 1834-7, 2003 Apr 15.
Article in English | MEDLINE | ID: mdl-12702570

ABSTRACT

The cytotoxicity of a diphtheria toxin-human epidermal growth factor fusion protein (DAB(389)EGF) was tested against 14 human glioma cell lines. After cells were cultured for 48 h with various concentrations of DAB(389)EGF, the percentage reduction in thymidine incorporation was determined. For 13 of 14 cell lines, potent cytotoxicity was observed, with IC(50)s of 0.4-50 pM. The epidermal growth factor receptor (EGFR) density of these cell lines was determined by immunofluorescence microscopy, flow cytometry, and radioligand binding. These assays correlated well with each other and demonstrated EGFR levels of 15,000-230,000/cell for 13 of 14 cell lines. The cell line U138MG, which lacked EGFR, was the only cell line insensitive to DAB(389)EGF. Linear regression analysis showed a good correlation between EGFR density and DAB(389)EGF sensitivity (P < 0.001) and between results of flow cytometry and radiolabeled binding assays of EGFR density (P = 0.01). DAB(389)EGF may have potential for intracranial therapy of EGFR-positive glioblastomas.


Subject(s)
Brain Neoplasms/drug therapy , Diphtheria Toxin/pharmacology , Epidermal Growth Factor/pharmacology , Glioblastoma/drug therapy , Recombinant Fusion Proteins/pharmacology , Brain Neoplasms/metabolism , Carcinoma, Squamous Cell/drug therapy , Carcinoma, Squamous Cell/metabolism , Diphtheria Toxin/genetics , Diphtheria Toxin/metabolism , Drug Screening Assays, Antitumor , Epidermal Growth Factor/genetics , Epidermal Growth Factor/metabolism , ErbB Receptors/metabolism , Flow Cytometry , Glioblastoma/metabolism , Humans , Inhibitory Concentration 50 , Kinetics , Microscopy, Fluorescence , Recombinant Fusion Proteins/genetics , Tumor Cells, Cultured
8.
Leuk Res ; 27(1): 79-84, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12479856

ABSTRACT

Diphtheria fusion proteins are a novel class of agents for the treatment of chemotherapy resistant acute myelogenous leukemia (AML). We prepared diphtheria toxin/urokinase fusion protein (DTAT) composed of the amino terminal fragment of the urokinase-type plasminogen activator (uPA) fused to the catalytic and translocation domains of diphtheria toxin (DT) and assessed its activity on leukemic cell lines. The number of uPA receptors (uPAR or CD87) was measured using a phycoerythrin conjugated monoclonal antibody to CD87 and flow cytometry. Seven of 23 cell lines (30%) showed CD87 expression (> or =5000 receptors/cell). DTAT cytotoxicity (IC(50)< or =30pM) was observed in all seven of these samples and none of the 16 samples with low or absent CD87 expression. There was a significant correlation between DTAT sensitivity and CD87 density (P=0.0007). These results show that specific CD87 binding is one factor important in the sensitivity of patient's leukemic blasts to DTAT and demonstrate for the first time that the CD87/uPAR can be used as a target for fusion protein therapy of AML.


Subject(s)
Antineoplastic Agents/pharmacology , Leukemia, Myeloid/pathology , Neoplasm Proteins/drug effects , Neoplastic Stem Cells/drug effects , Oncogene Proteins, Fusion/pharmacology , Receptors, Cell Surface/drug effects , Acute Disease , Antineoplastic Agents/chemistry , Blast Crisis/pathology , Burkitt Lymphoma/pathology , Flow Cytometry , HL-60 Cells/drug effects , Humans , Jurkat Cells/drug effects , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology , Leukemia-Lymphoma, Adult T-Cell/pathology , Multiple Myeloma/pathology , Neoplasm Proteins/physiology , Neoplastic Stem Cells/metabolism , Protein Structure, Tertiary , Receptors, Cell Surface/physiology , Receptors, Urokinase Plasminogen Activator , Recombinant Fusion Proteins/pharmacology , U937 Cells/drug effects
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