AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Evaluation of an Ion Capture Device for Determination of Aerosolized Venezuelan Equine Encaphailitis Virus and a Novel Method for Absolute Particle Count Determination
Abstract Number: 35 Working Group: Portable and Inexpensive Sensor Technology for Air Quality Monitoring
Abstract Ionic capture devices have had widespread use for air cleaning. We are exploring the use of a miniature device (cICD) for capture and detection of allergens, bacteria and viruses. Here we present data for its use in detection of gamma-irradiated inactivated Venezuelan Equine Encephalitis Virus. Samples are collected on removable silk envelopes covering the entire electrode. As references, data was obtained by extraction from the electrodes directly, and with a sampling filter run in parallel. Capture was quantitated by q-RT-PCR. Controlled aerosols were released into an environmental chamber and particle size and concentration were held constant during 30 minutes. There is a possibility that irradiation damage to the viral RNA rendered it un-amplifiable. An alternative method of evaluation was devised based on limiting dilution conditions where amplification occurred in some, but not all, PCR reactions. The occurrence of amplification is a stochastic event determined by Poisson distribution. We make the approximation that, when the proportion of reactions giving amplification was less than 50%, there was either 0 or 1 amplifiable particle per reaction. From that, the average number of amplifiable molecules may be calculated. Using this metric, the LOD for the sampler is 0.06 amplifiable particles per liter and for the reference filter it is 1.4. The higher LOD for the reference filter is simply accounted for by the fact that the extraction is done in 10 times the volume compared with the electrodes. Capture efficiencies and LOD’s from the disposable and the entire electrode were equivalent. The number of amplifiable particles is considerably lower than the number calculated from the calibration based on the original PFU. The method provides a method for determining an absolute amplifiable particle count, independent of any calibration. The cICD offers a simple, low cost, silent method of efficiently determining airborne viruses.