Abstract Title
Evaluating Stability of Tulane Virus, a Human Norovirus Surrogate, and an Indicator of Human Fecal Contamination on Fresh Strawberries
Presenter
Cameron Boerner, Food and Drug Administration
Co-Author(s)
Cameron Boerner, Human Foods Program/FDA; Efstathia Papafragkou, Human Foods Program/FDA
Abstract Category
Food & Environmental Virology-I (Food)
Abstract
Background and Purpose:
Norovirus, the leading cause of gastroenteritis in the United States, is frequently linked to contaminated food. Understanding its persistence on high-risk foods of epidemiological significance and developing sensitive detection methods are critical for assessing infection risk. Tulane calicivirus, a culturable norovirus surrogate, aids in optimizing viral isolation techniques, while crAssphage serves as a human fecal contamination indicator. Developing sensitive methods to recover these viruses from fresh strawberries, a commodity previously associated with enteric virus outbreaks, will ultimately provide tools to study the stability of infectious norovirus throughout the product’s expected shelf-life.
Methodology:
This study examined the stability and RNA persistence of Tulane virus and crAssphage on strawberries stored at 4°C for two weeks. Fifty-gram strawberry samples were surface-inoculated with high concentrations of either a cell culture lysate of Tulane virus or a crAssphage fecal suspension. Samples were then processed for virus/phage elution, concentration, and detection of infectious titer via TCID50 assay (Tulane virus) or genetic material via RT-qPCR (Tulane virus and crAssphage) at days 0, 1, 5, 8, 11, and 15.
Results:
Infectious Tulane virus was detectable up to twelve days post-inoculation, and virus RNA titer, as estimated by RT-qPCR, remained stable on average. Additionally, crAssphage DNA was consistently detected during the same two-week sampling period with an approximate two-log decrease.
Conclusion:
This study optimized methods for evaluating the stability of Tulane virus and crAssphage on strawberries. These techniques can be refined to recover infectious norovirus in additional FDA-regulated foods, supporting efforts to prevent foodborne illnesses.
Norovirus, the leading cause of gastroenteritis in the United States, is frequently linked to contaminated food. Understanding its persistence on high-risk foods of epidemiological significance and developing sensitive detection methods are critical for assessing infection risk. Tulane calicivirus, a culturable norovirus surrogate, aids in optimizing viral isolation techniques, while crAssphage serves as a human fecal contamination indicator. Developing sensitive methods to recover these viruses from fresh strawberries, a commodity previously associated with enteric virus outbreaks, will ultimately provide tools to study the stability of infectious norovirus throughout the product’s expected shelf-life.
Methodology:
This study examined the stability and RNA persistence of Tulane virus and crAssphage on strawberries stored at 4°C for two weeks. Fifty-gram strawberry samples were surface-inoculated with high concentrations of either a cell culture lysate of Tulane virus or a crAssphage fecal suspension. Samples were then processed for virus/phage elution, concentration, and detection of infectious titer via TCID50 assay (Tulane virus) or genetic material via RT-qPCR (Tulane virus and crAssphage) at days 0, 1, 5, 8, 11, and 15.
Results:
Infectious Tulane virus was detectable up to twelve days post-inoculation, and virus RNA titer, as estimated by RT-qPCR, remained stable on average. Additionally, crAssphage DNA was consistently detected during the same two-week sampling period with an approximate two-log decrease.
Conclusion:
This study optimized methods for evaluating the stability of Tulane virus and crAssphage on strawberries. These techniques can be refined to recover infectious norovirus in additional FDA-regulated foods, supporting efforts to prevent foodborne illnesses.