Purpose: The objective of this study was to compare the extraction and detection methodologies of enteric viruses in soft fruit using the ISO/DIS 15216-1 horizontal method for determination of HAV and NoV in food and the FDA validated soft fruit protocol.
Methods: For the ISO/DIS 15216-1 protocol, 25g of fresh blackberries and fresh blueberries were spiked with HAV in high (>10 PFU/g) and low (<5 PFU/g) concentrations. FDA validated methods utilized 50g of fresh blackberries and fresh blueberries spiked with HAV in high (>10 PFU/g) and low (<5 PFU/g) concentrations. Murine norovirus (MNV) was used as an extraction control for both protocols.
Results: With the ISO/DIS 15216-1 protocol, HAV was detected in fresh blackberries at the high (>10 PFU/g) levels but not in the low (<5 PFU/g) levels. In fresh blueberries, HAV was detected in both the high and low levels. With the FDA protocol, HAV was detected in fresh blackberries and fresh blueberries at both the high (>10 PFU/g) and low (<5 PFU/g) levels. The average extraction efficiency of MNV with the ISO/DIS 15216-1 protocol was 15% due to PCR inhibition and the average was 59% with the FDA protocol.
Significance: Rapid, sensitive methods to accurately detect viral pathogens in food samples are an integral part of outbreak and surveillance investigations. Extraction and detection of HAV in soft fruit utilizing the FDA validated method yields accurate results at high and low levels with minimal inhibition.