Limitations of molecular biological techniques for assessing the virological safety of foods

Enteric viruses, including hepatitis A, Norwalk, and Snow Mountain viruses, Hawaii agent, and rotaviruses have been associated with outbreaks of foodborne illness. Classical culturing procedures are available for poliovirus; however, hepatitis A, Norwalk, and many of the other viruses and agents cannot be propagated in cell culture, therefore, molecular biological tools have emerged as a possible means to detect enteric viruses in foods and environmental samples. There are limitations however in the application of polymerase chain reaction and reverse transcription polymerase chain reaction that restrict their usefulness for measuring the virological safety of foods. The most serious limitation is that molecular techniques fail to discriminate between viable and inactivated viruses even though inactivated viruses pose no threat to the consumer and may be present at levels substantially higher than the virulent forms. Other disadvantages include a lack of assay sensitivity and specificity, high assay costs, and a level of technical expertise not available in most food-testing laboratories. Overall, scientific advances in the development of molecular biological tools have outpaced the demonstration of their validity in assessing the virological safety of foods.