Purpose: To identify the factors other than intrinsic properties that contribute to the strength of virus adhesion onto a substrate.
Methods: MS2 coliphage or murine norovirus was grown and purified via a multi-step foam fractionation and filtrations. AFM probes were coated with a linker and virions were conjugated to the probes. A force-distance curve from which the strength of adhesion can be directly measured was generated for each measurement. Multiple locations on glass and PVC surfaces were examined to derive adhesive forces at >100 data per sample.
Results: The adhesive force of MS2 to glass substrates showed a narrow data distribution. With the same probe and virus preparation, the force measured for PVC was consistently and statistically higher than glass (P<0.01), but had a much broader distribution. When the substrate surface was imaged, glass was found to be smooth and homogeneous, whereas numerous pores of 75-250 nm in diameter with random distribution were present on PVC surfaces. The median force measured at porous regions of PVC was 2 to 3 times higher than that at smooth areas (P<0.01). Thus, both intrinsic material properties and surface porosity/heterogeneity attributed to the variation in the virus adhesion force measurements. In addition, variation was also attributed to differences in AFM probe modification, possibly due to variation in the number of virions conjugated on the probes.
Significance: Both the material type (e.g., glass vs. PVC) and heterogeneity (porous vs. non-porous) should be considered when developing strategies for minimizing virus attachment and transmission via food-contact surfaces.