Critical Review of Norovirus Surrogates in Food Safety Research: Rationale for Considering Volunteer Studies

The inability to propagate human norovirus (NoV) or to clearly differentiate infectious from noninfectious virus particles has led to the use of surrogate viruses, like feline calicivirus (FCV) and murine norovirus-1 (MNV), which are propagatable in cell culture. The use of surrogates is predicated on the assumption that they generally mimic the viruses they represent; however, studies are proving this concept invalid. In direct comparisons between FCV and MNV, their susceptibility to temperatures, environmental and food processing conditions, and disinfectants are dramatically different. Differences have also been noted between the inactivation of NoV and its surrogates, thus questioning the validity of surrogates. Considerable research funding is provided globally each year to conduct surrogate studies on NoVs; however, there is little demonstrated benefit derived from these studies in regard to the development of virus inactivation techniques or food processing strategies. Human challenge studies are needed to determine which processing techniques are effective in reducing NoVs in foods. A major obstacle to clinical trials on NoVs is the perception that such trials are too costly and risky, but in reality, there is far more cost and risk in allowing millions of unsuspecting consumers to contract NoV illness each year, when practical interventions are only a few volunteer studies away. A number of clinical trials have been conducted, providing important insights into NoV inactivation. A shift in research priorities from surrogate research to volunteer studies is essential if we are to identify realistic, practical, and scientifically valid processing approaches to improve food safety

Survival and fatty acid composition of UV-C treated Staphylococcus aureus

Ultraviolet irradiation (UV-C) is proven to be effective to inactivate microorganisms. The present study investigates the effect of sublethal UV-C rays on the membrane fatty acid profile of four Staphylococcus aureus strains isolated from air, patient, food and animal. Our results show that S. aureus isolated from patients and air are the most sensitive to UV-C rays and that their inactivation achieves a greater than 2-log reduction after a UV-C exposure of 210 mJ cm−2. However, the strain isolated from food is the most resistant one. The fatty acid analysis indicates that this strain (food) reveals a decrease of branched chain fatty acids (BCFA iso and anteiso) and an increase of straight chain saturated fatty acids (SCFA)