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1.  Gamma Irradiation Can Be Used To Inactivate Bacillus anthracis Spores without Compromising the Sensitivity of Diagnostic Assays▿  
Applied and Environmental Microbiology  2008;74(14):4427-4433.
The use of Bacillus anthracis as a biological weapon in 2001 heightened awareness of the need for validated methods for the inactivation of B. anthracis spores. This study determined the gamma irradiation dose for inactivating virulent B. anthracis spores in suspension and its effects on real-time PCR and antigen detection assays. Strains representing eight genetic groups of B. anthracis were exposed to gamma radiation, and it was found that subjecting spores at a concentration of 107 CFU/ml to a dose of 2.5 × 106 rads resulted in a 6-log-unit reduction of spore viability. TaqMan real-time PCR analysis of untreated versus irradiated Ames strain (K1694) spores showed that treatment significantly enhanced the detection of B. anthracis chromosomal DNA targets but had no significant effect on the ability to detect targets on the pXO1 and pXO2 plasmids of B. anthracis. When analyzed by an enzyme-linked immunosorbent assay (ELISA), irradiation affected the detection of B. anthracis spores in a direct ELISA but had no effect on the limit of detection in a sandwich ELISA. The results of this study showed that gamma irradiation-inactivated spores can be tested by real-time PCR or sandwich ELISA without decreasing the sensitivity of either type of assay. Furthermore, the results suggest that clinical and public health laboratories which test specimens for B. anthracis could potentially incorporate gamma irradiation into sample processing protocols without compromising the sensitivity of the B. anthracis assays.
PMCID: PMC2493171  PMID: 18515484
2.  Real-Time Reverse Transcription–Polymerase Chain Reaction Assay for SARS-associated Coronavirus 
Emerging Infectious Diseases  2004;10(2):311-316.
A real-time reverse transcription–polymerase chain reaction (RT-PCR) assay was developed to rapidly detect the severe acute respiratory syndrome–associated coronavirus (SARS-CoV). The assay, based on multiple primer and probe sets located in different regions of the SARS-CoV genome, could discriminate SARS-CoV from other human and animal coronaviruses with a potential detection limit of <10 genomic copies per reaction. The real-time RT-PCR assay was more sensitive than a conventional RT-PCR assay or culture isolation and proved suitable to detect SARS-CoV in clinical specimens. Application of this assay will aid in diagnosing SARS-CoV infection.
PMCID: PMC3322901  PMID: 15030703
SARS; Coronavirus; Real-Time PCR; RT-PCR
5.  First Case of Bioterrorism-Related Inhalational Anthrax in the United States, Palm Beach County, Florida, 2001 
Emerging Infectious Diseases  2002;8(10):1029-1034.
On October 4, 2001, we confirmed the first bioterrorism-related anthrax case identified in the United States in a resident of Palm Beach County, Florida. Epidemiologic investigation indicated that exposure occurred at the workplace through intentionally contaminated mail. One additional case of inhalational anthrax was identified from the index patient’s workplace. Among 1,076 nasal cultures performed to assess exposure, Bacillus anthracis was isolated from a co-worker later confirmed as being infected, as well as from an asymptomatic mail-handler in the same workplace. Environmental cultures for B. anthracis showed contamination at the workplace and six county postal facilities. Environmental and nasal swab cultures were useful epidemiologic tools that helped direct the investigation towards the infection source and transmission vehicle. We identified 1,114 persons at risk and offered antimicrobial prophylaxis.
PMCID: PMC2730309  PMID: 12396910
Anthrax; Bacillus anthracis; bioterrorism; nasal swab cultures; environmental cultures
6.  Bioterrorism-Related Anthrax Surveillance, Connecticut, September–December, 2001 
Emerging Infectious Diseases  2002;8(10):1078-1082.
On November 19, 2001, a case of inhalational anthrax was identified in a 94-year-old Connecticut woman, who later died. We conducted intensive surveillance for additional anthrax cases, which included collecting data from hospitals, emergency departments, private practitioners, death certificates, postal facilities, veterinarians, and the state medical examiner. No additional cases of anthrax were identified. The absence of additional anthrax cases argued against an intentional environmental release of Bacillus anthracis in Connecticut and suggested that, if the source of anthrax had been cross-contaminated mail, the risk for anthrax in this setting was very low. This surveillance system provides a model that can be adapted for use in similar emergency settings.
PMCID: PMC2730303  PMID: 12396919
7.  Detection of Bacillus anthracis DNA by LightCycler PCR 
Journal of Clinical Microbiology  2002;40(8):2897-2902.
Anthrax is a zoonotic disease that is also well recognized as a potential agent of bioterrorism. Routine culture and biochemical testing methods are useful for the identification of Bacillus anthracis, but a definitive identification may take 24 to 48 h or longer and may require that specimens be referred to another laboratory. Virulent isolates of B. anthracis contain two plasmids (pX01 and pX02) with unique targets that allow the rapid and specific identification of B. anthracis by PCR. We developed a rapid-cycle real-time PCR detection assay for B. anthracis that utilizes the LightCycler instrument (LightCycler Bacillus anthracis kit; Roche Applied Science, Indianapolis, Ind.). PCR primers and probes were designed to identify gene sequences specific for both the protective antigen (plasmid pX01) and the encapsulation B protein (plasmid pX02). The assays (amplification and probe confirmation) can be completed in less than 1 h. The gene encoding the protective antigen (pagA) was detected in 29 of 29 virulent B. anthracis strains, and the gene encoding the capsular protein B (capB) was detected in 28 of 29 of the same strains. Three avirulent strains containing only pX01 or pX02, and therefore only pagA or pagB genes, could be detected and differentiated from virulent strains. The assays were specific for B. anthracis: the results were negative for 57 bacterial strains representing a broad range of organisms, including Bacillus species other than anthracis (n = 31) and other non-Bacillus species (n = 26). The analytical sensitivity demonstrated with target DNA cloned into control plasmids was 1 copy per μl of sample. The LightCycler Bacillus anthracis assay appears to be a suitable method for rapid identification of cultured isolates of B. anthracis. Additional clinical studies are required to determine the usefulness of this test for the rapid identification of B. anthracis directly from human specimens.
PMCID: PMC120654  PMID: 12149348
8.  Detection of Smallpox Virus DNA by LightCycler PCR 
Journal of Clinical Microbiology  2002;40(6):1985-1988.
A 300-bp plasmid fragment of the hemagglutinin gene was used as target DNA to develop a rapid real-time LightCycler (Roche Applied Science, Indianapolis, Ind.) PCR assay for laboratory detection of smallpox virus. PCR primers and probes were designed specifically for detection of smallpox virus DNA, but all viruses of the genus Orthopoxvirus tested could be detected by use of the hemagglutinin gene target sequence. Base pair mismatches in the 204-bp amplicon allowed discrimination of cowpox virus (melting temperature [Tm], 56.40°C), monkeypox virus (Tm, 56.24°C), and vaccinia virus (Tm, 56.72°C), including the Dryvax vaccine strain, from smallpox virus (Tm, 62.45°C) by melting curve analysis. The analytical sensitivity was 5 to 10 copies of target DNA per sample. The assay was specific for members of the genus Orthopoxvirus; the DNAs of herpes simplex virus and varicella-zoster virus were not detected by the smallpox virus LightCycler PCR.
PMCID: PMC130682  PMID: 12037052
9.  Enzyme-Linked Immunosorbent Assays for Detection of Antibodies to Ebola and Marburg Viruses Using Recombinant Nucleoproteins 
The full-length nucleoprotein (NP) of Ebola virus (EBO) was expressed as a His-tagged recombinant protein (His-EBO-NP) by a baculovirus system. Carboxy-terminal halves of NPs of EBO and Marburg virus (MBG) were expressed as glutathione S-transferase-tagged recombinant proteins in an Escherichia coli system. The antigenic regions on the NPs of EBO and MBG were determined by both Western blotting and enzyme-linked immunosorbent assay (ELISA) to be located on the C-terminal halves. The C-terminal 110 and 102 amino acids of the NPs of EBO and MBG, respectively, possess strong antigenicity. The full-length NP of EBO was strongly expressed in insect cells upon infection with the recombinant baculovirus, while expression of the full-length NP of MBG was weak. We developed an immunoglobulin G (IgG) ELISA using His-EBO-NP and the C-terminal halves of the NPs of EBO and MBG as antigens. We evaluated the IgG ELISA for the ability to detect IgG antibodies to EBO and MBG, using human sera collected from EBO and MBG patients. The IgG ELISA with the recombinant NPs showed high sensitivity and specificity in detecting EBO and MBG antibodies. The results indicate that ELISA systems prepared with the recombinant NPs of EBO and MBG are valuable tools for the diagnosis of EBO and MBG infections and for seroepidemiological field studies.
PMCID: PMC87670  PMID: 11136739

Results 1-9 (9)