Discrimination between infectious and non-infectious human norovirus using porcine gastric mucin

Human noroviruses (NoVs) are known to bind to human histo-blood group antigens, as well as to chemically-similar porcine gastric mucins. Here, the binding ability of NoV to porcine mucin is shown to be substantially deficient after UV, thermal, and high pressure treatments. Using qRT-PCR, ≥ 68% of GI.1 NoV (Norwalk strain) bound to porcine gastric mucin-conjugated magnetic beads (PGM-MBs). Application of 600-MPa high pressure treatments reduced binding of the virus to PGM-MBs by 4.7-log₁₀, as determined by qRT-PCR, while a 300-MPa pressure treatment, reduced binding to PGM-MBs by only 0.45-log₁₀. This is consistent with a previously reported clinical trial (Leon et al., 2011. Appl. Environ Microbiol. 77:5476-5482.) which demonstrated inactivation of 4-log₁₀ of GI.1 NoV at 600-MPa. After thermal treatment, binding to PGM-MBs decreased when samples were heated from 0 to 80 °C. Ultraviolet treatments of 0.5 and 2 J/cm² reduced observed PGM-MB binding of norovirus to 33% and negligible levels, respectively, from an initially observed 84% binding for untreated NoV. Although thermal and UV treatments are generally recognized to inactivate viruses, verification of NoV inactivation by these treatments may require volunteer studies. In total, these results suggest the loss of NoV binding to porcine mucin as a potential means to preferentially exclude non-infectious virus particles from subsequent RT-PCR detection.