Comparative recovery of foodborne viruses from fresh produce.

Abstract

A large percentage of foodborne outbreaks are caused by viruses, and outbreaks associated with fresh produce have increased over the past decade within the United States. Virus recovery from food is of the utmost importance in determining the cause of viral outbreaks. While there are many experimental studies investigating viruses on fruits and vegetables, there is a lack of standard techniques concerning the initial inoculation and recovery of viruses. This study investigates the efficiency of methodology in the recovery of three viruses, hepatitis A virus (HAV), Aichi virus, and feline calicivirus, on three different produce surfaces (lettuce, green onions, and strawberries). To do so, three common times of virus inoculation were examined (0.5, 4, and 12 h) along with two routes of inoculation (immersion and spot inoculation), and then two recovery methods were compared (physical removal and chemical extraction/blending) utilizing three different recovery eluents (2% media, beef extract, and phosphate-buffered saline). Results suggested that incubation time did not significantly affect the survival of the viruses on green onions and strawberries, while a significant decrease (p <or= 0.05) was observed after 4 or 12 h of incubation on lettuce. In general, media containing 2% fetal bovine serum had more efficient recovery of the three viruses, and spot inoculation was observed to be more efficient than inoculation by immersion. A significantly higher percent recovery was observed for HAV compared to the other viruses on lettuce and green onions. Comparison of virus recovery by physical removal or chemical extraction/blending showed no significant differences (p > 0.05); however, the percent recovery was greater by extraction/blending methodology.