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Pilot method developer studies for PCR-based detection of B. anthracis in aerosol collection filters or liquids and for ricin hand-held assays (HHAs) have been completed, and data were reviewed by the Stakeholder Panel on Agent Detection Assays (SPADA) in March 2011. For PCR-based assays to detect B. anthracis, method developer studies included inclusivity/exclusivity, environmental interference, upper and lower LODs of DNA, matrix testing with live spores, method robustness, between-instrument variability and consistency, and stability of the test kit. Data showed that the system passed all of the studies. The assay was specific, reliable at the acceptable minimum detection level (AMDL), free from interference by the soils, powders, and chemicals tested, and robust. In addition, results of the stability study supported the shelf-life of the product, and performance was consistent from instrument to instrument. In summary, of 1372 samples tested during validation, 1370 (99.8%) gave expected results. It was suggested by stakeholders that inhibition controls should be included in PCR methods for environmental sample testing. As a result, SPADA approved the establishment of a working group to examine assay and system controls. AOAC is identifying working group members, who will present a report to SPADA in September 2011 during the AOAC Annual Meeting in New Orleans, Louisiana, USA. For the ricin method developer validation, studies included a matrix study [probability of detection (POD) at the AMDL] which included laboratory and intended user studies (data was highly reproducible from laboratory to intended user); inclusivity/exclusivity (near neighbors)/antibody characterization; environmental interference; product consistency and stability (examines lot-to-lot and shelf-life, for informational purposes only); and robustness (introducing small changes to the method). Results showed that the study met requirements. There were no unexpected results for inclusivity/exclusivity. However, there were study design issues with product consistency and stability and robustness, so these parts of the study are being repeated. Independent validation studies for B. anthracis and ricin are underway at MRI Global. The next SPADA meeting is scheduled for September 2011 during the AOAC Annual Meeting in New Orleans, Louisiana, USA. For more information, contact Deborah McKenzie, senior director, methods development and approval processes, at dmckenzie@aoac.org or Scott Coates, chief scientific officer, at scoates@aoac.org.
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