text: APDS monitors air and water for the three types of biological threat agents: bacteria, viruses, and toxins. The autonomous detection system is capable of (1) rapidly processing and accurately analyzing aerosol or water samples with a high level of confidence; (2) automating and integrating the major system functions into the detector, including sample collection, preparation, analysis, and analytical results reporting; (3) operating in its intended indoor and outdoor environments; and (4) disseminating and archiving analysis results and system operational data via the C3 network, known as the BioWatch Gen-3 Operations Support Service.
  APDS operates continuously; the system can detect low concentrations of bioagents that might go undetected by a system that is triggered only when the overall number of particles in the air is high. APDS collects samples, prepares them for analysis, and tests for multiple biological agents. This automation reduces the cost and staffing that would be required to manually analyze samples.
  As APDS collects air or water samples, it first runs them through an immunoassay detector. If that detector returns a positive result, APDS performs a second assay based on nucleic-acid amplification and detection. Having two different assay systems increases system reliability and minimizes the possibility of false positives.
  The immunoassay detector incorporates liquid arrays, a multiplexed assay that uses small-diameter polystyrene beads (microbeads) coated with thousands of antibodies. Each microbead is colored with a unique combination of red- and orange-emitting dyes. The number of agents that can be detected in a sample is limited only by the number of colored bead sets. When the sample is exposed to the beads, a bioagent, if present, binds to the bead with the appropriate antibody. A second fluorescently labeled antibody is then added to the sample, resulting in a highly fluorescent target for flow analysis. Preparing the sample and performing this first analysis takes less than 30 minutes.
  Nucleic acid assays require amplification of one or more target sequences of nucleic acid. Short strands of single-stranded DNA are synthesized in known sequences and attached to spots in the array in a predetermined way Detection of these spots that contain hybridized target DNA allows one to the sequence of DNA in the unknown target. RNA readily hybridizes to form double-stranded structures to its complementary sequence (A-T, C-G, G-C, U-A). Thus, arrays of single-stranded DNA can be used to detect RNA via hybridization.
  TABLE 1.1 Centers for Disease Control and Prevention (CDC) Prioritized List of Biological Threat Agents
  Research Internationals sells standalone and portable systems for use in mailrooms, called ASAP II. ASAP II gives real time detection of bio-warfare agents, chemical agents and toxic industrial chemicals, explosives in particulate and vapor form and nuclear materials. The system can be customised according to the need of the mailroom.
  ASAP II is an automated chemical, biological and nuclear detection and identification system. The system can detect and identify from four (RAPTOR module) to eight (BioHawk module) bio-agents in real time. Periodically or on demand, a concentrated sample is sent to the modules and within fifteen minutes these systems will identify the presence of any bioagents and notify the operator if a hazardous agent is detected.
  The systems need to be in a negative pressure room on a downward draft table. An air sampling module within the systems draws air into the downward draft table for analysis. Sampling is continuous until the batch of mail is complete, which may take a few minutes, hours or days. The systems are able to handle thousands of pieces of mail per hour.