The Center for Disease Control and Prevention (CDC) has developed a list of pathogens that have potential as a biological warfare weapon. These are classified into three categories: A, B, and C. It is important from a national security perspective to develop a means of identifying these organisms. A key element in developing defenses against uses of such agents by rogue entities is the ability to quickly and accurately detect the presence of these organisms in samples or environment. DNA-based diagnostic methods are only valuable if they are highly specific to the target organism, otherwise, they may give rise to false positive results. False positives are particularly an issue when analyzing complex environmental samples where nontarget microbes cross-react with the target organism. A reliable and specific DNA-based diagnostic method is thus needed for the detection of bio-weapons.


LLNL researchers have discovered unique DNA signatures that can be used to identify, with high specificity, three such organisms with bio-weapon potential, including Yersinia pestis and Francisella tularensis (both Category A agents), and Brucella species (Category B agent). The DNA sequence information of a desired region of an organism unique to that organism is recorded, a DNA primer is used to amplify the target fragment using the polymerase chain reaction (PCR), and then a hybridization probe is used to increase the specificity of the detection process by marking the target. Combined, this process uniquely identifies a DNA signature of an organism.

  • Simple and accurate DNA-based diagnostics
  • Specific diagnostic results even with complex environmental samples
Potential Applications
  • Accurate detection of select agents belonging to Category A (Yersinia pestis and Francisella tularensis) and category B (Brucella species) in environmental samples for surveillance purpose
  • Identification of unique regions which may be targets for protein-based diagnostics and research
Development Status

LLNL currently holds patents 7,494,772 "Nucleotide sequences specific to Yersinia pestis and methods for the detection of Yersinia pestis," 7,494,778 "Nucleotide sequences specific to Francisella tularensis and methods for the detection of Francisella tularensis," and 7,494,773 "Nucleotide sequences specific to Brucella and methods for the detection of Brucella" for these methods (LLNL internal #s IL-11030, IL-11031, and IL-11032 respectively).

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