P-045. Optimization of an Elution and Concentration Method for the Detection of Enteric Viruses in Fresh Strawberries and Lettuces

S. Cheong, C. Lee, W. Choi, S-J. Kim;
Seoul Natl. Univ., Seoul, REPUBLIC OF KOREA.

Enteric viruses are a frequent cause of foodborne outbreaks worldwide, and fresh vegetables and fruits can be considered as a vector of transmission for viruses from the contaminated water, airborne droplets, and soil. To select the most efficient elution-concentration method for the detection of noroviruses (NVs), coxsackieviruses (CVs), adenoviruses (AdVs), and rotaviruses (RVs) in contaminated fresh strawberries and lettuces, we optimized an elution buffer and concentration method by the use of RT-PCR and cell-culture analysis, and tested the efficiency of second concentration step to apply a large volume of food samples. We found that the combination of a 0.05M glycine-100mM Tris elution buffer (pH 9.5) and a PEG precipitation resulted in the best efficiency for the detection of viruses and additional second concentration step using ultra-filtration devices could be applied to a large volume of food sample without a decrease of detection efficiency. Using this optimized method, norovirus detection was possible at levels as low as 4.8 RTPCRU/5 g in strawberries and 48 RTPCRU/25 g in lettuces. The average recoveries were approximately 100% in strawberries and 69.4% in lettuces. Also CVs, AdVs, and RVs could be recovered in lettuce in an efficiency of 11.4%, 9.05%, and 11.3%, respectively. It is indicated that this method could be the rapid, useful and sensitive for the detection of enteric viruses in fresh foods.