A centrifugation-based method for extraction of norovirus from raspberries

A method was developed for extraction of noroviruses from raspberries. The method consists of removal of virus from fruit surfaces by alkaline extraction, then removal of residual food debris by centrifugation, followed by concentration of virus particles by ultracentrifugation. The efficiency of the extraction was estimated by comparison of reverse transcription PCR signals obtained from fruit extracts and the norovirus suspension that was used to contaminate the fruit. Noroviruses were recovered with at least 10% efficiency from 60-g raspberry samples (n = 10). The sample treatment reported here should be applicable for harnessing to any norovirus reverse transcription PCR and form the basis of a dependable method to detect noroviruses in raspberries.