Optimization of methods for detecting norovirus on various fruit.

Methods for detecting norovirus (NoV) in food are crucial for investigation and prevention of outbreaks caused by NoV-contaminated food. However, current NoV detection methods have not been well examined or optimized. In this study, the effectiveness of various methods for eluting NoV from various fruit, concentrating the virus using polyethylene glycol (PEG), and extracting the viral RNA for subsequent assay by RT-PCR was optimized. First, six different buffers previously described for eluting NoV from fruit surfaces were evaluated. A known amount of NoV was spiked onto the surface of grapes, strawberries, and raspberries, and the virus was recovered with distilled water, 0.05 M glycine-0.14 M NaCl (pH 7.5), 2.9% tryptose phosphate broth-6% glycine, 100 mM Tris-HCl (pH 9.5), 50 mM glycine-50 mM MgCl(2) (pH 9.5), or 3% beef extract. Quantitation of the recovered virus using RT-PCR revealed that the most effective elution buffer was 3% beef extract. Secondly, to optimize a method for concentrating the recovered NoV, the key parameters of PEG precipitation, a typical method for concentrating enteric virus, were investigated. The influence of PEG molecular weight and the duration and temperature of the precipitation procedure were examined. NoV was concentrated most efficiently by precipitation when PEG (10,000) was used for 4h at room temperature. Finally, five different methods for nucleic acid extraction were evaluated. Among RNA extraction methods examined, QIAamp Viral RNA Mini kit showed the best recovery efficiency. Using the optimized method, approximately 6-80% of the seeded NoV was recovered from the various fruit.

Effects of repeated short-term skin contact with proteolytic enzymes.

The objective was to investigate effects on the hand of protease used in dishwashing liquids (DWL). A group of 30 Koreans (normal skin) and 24 Japanese (12 atopic and 12 normal) were employed for two different studies, respectively. The 30 Koreans were divided into three groups. Each group immersed their hands for 15 min a day for 9 days into DWL containing 0.005% protease, 0.02% protease, or non-enzyme DWL. The 24 Japanese immersed their hands for 15 min a day for 4 days into 0.005% protease-containing or a non-enzyme DWL. The hand skin was evaluated by measuring overall and dry skin grades, estimated before and after exposures to the test products. The Korean study shows that 0.005% and 0.02% protease-containing DWL are less irritating to the skin than non-enzyme control, as measured by better overall skin grades and less dry skin. The Japanese study shows that 0.005% protease-containing DWL are less irritating to the skin than non-enzyme control in both atopic and normal subjects. The 0.005% protease use did not cause any adverse dermatological effects to atopic subjects compared with non-enzyme control. Both studies indicate that 0.005% and 0.02% protease resulted in better skin mildness profile, without causing adverse dermatological complications to the subjects.