STRATEGIES FOR THE DETECTION OF UNKNOWN BIOLOGICAL AGENTS Dr. Peter J. Stopa US Army Edgewood Chemical Biological Center Aberdeen Proving Ground, MD

OBJECTIVES FOR UNKNOWNS DETECTION Differentiate between natural and artificial events. Implement and maintain protective postures. Confirm whether forces have been attacked. Initiate treatment in the absence of a specific biological agent hazard.

Potential Classification Parameters Classify Pathogen/non-Pathogen Aerosol Additives Natural vs. Man-made Bacteria Encapsulants Virus Protein Peptide Toxin Non-Protein Toxin Bio/non-Bio

Natural vs. Man-made

Aerosol Additives

Bio/non-Bio Determination

Pathogen/non-pathogen Determination

Bacterial Specific Detection

Viral Specific Detection

Protein /Peptide Specific Detection

Non-Protein ToxinSpecific Detection

Determination of Appropriate Equipment How do you determine what you need? Need to identify: The end user. How they operate. Constraints. Performance Criteria. How important are each of these factors in determining the best equipment?) (Weighting Factors)

A Computer-based Approach Can identify each of the parameters and subsequent weighting factors and plug them into a statistical model. Identify appropriate candidate technologies and score them according to your criteria. Obtain the final results. See how they fared and why. Make purchasing decisions.

Biological Detection More difficult than chemical. No vapor pressure – sampling for detection is more difficult. Present in low concentrations. May be hard to discriminate an intentional release against background levels of similar “natural” biological materials. Technologies not as mature. Clinical personnel sometimes do not understand “the field”. Most confirmatory technologies are slow (i.e., culture). Microbiologists are reluctant to adopt instrumented methods (need to see it or smell it to believe it).

Biological Detection Process Collect samples Chemical Property Characterization Generic detection Biological agent characteristics Specific identification Identification kits Reference laboratory

Chemical Properties From July/August 2003 Homeland First Response

Chemical Properties From July/August 2003 Homeland First Response Premise: Biological materials can be viable only within a pH range of 5-9. Turbidity and density in water may give an indication of particle size and solubility. Presence of Protein may indicate a biological agent.

Chemical Tests

WHY GENERIC DETECTION? Rapidly provide the Incident Commander enough information to justify the response to a suspected biological terrorist threat. Minimize response resources to false threats. Evaluate if the sample can be further analyzed with immunoassay tickets on site or sent to a laboratory for confirmation. Should not rely on immunoassay tickets alone. Limited library - some materials that a terrorist may use are not on the threat list. For ticket results to be valid, the sample must be within certain concentration, pH, and ionic strength guidelines.

Biological Properties Generic detectors that detect biological properties are relatively rapid, inexpensive, and easy to use. More information than the chemical property test alone –i.e., is it LIVE? Confirmatory identification must be performed in the laboratory.

Generic Detection Strategy Use various properties to detect the presence of a biological material in a suspect sample. Luminescence – ATP – viability (cell battery). DNA – present in all biological materials. (blueprint). Protein – also present in all biological materials. (building block). Particle size/concentration.

Biological Detection Instruments Particle analyzer Fluorometer (DNA) Luminometer (ATP) Colorimeter (protein) Particle Analyzer Colorimeter Fluorometer Luminometers Integrated System

Expected Results for Generic Detection (1) Possibly from culture media. (2) If protein concentration is high enough (> 10 ug/ml), will probably see contaminating DNA from protein source.

Identification Immunoassay Tickets And Readers Biological Laboratory Field Instruments (PCR)

Comments Experience from Fall 2001 showed that no single technology was 100% accurate. Both IA platforms and PCR platforms missed samples for various reasons. Culture was able to detect in all of the samples – but TOO slow to be of value in the field. Need redundant capabilities.

CONCLUSIONS Tests and equipment exist for use by first responders for field screening of biological samples. Additional discussion is needed among the policy makers, field responders, and reference laboratories to develop or accept a workable system.