Effect of aerosolization and surface deposition on the infectivity of bacteriophages suspended in artificial gastric fluid as a model of HuNoV transmission

Human norovirus (HuNoV) is the leading cause of viral gastroenteritis, at an estimated 680 million cases per year worldwide. Although its transmission via the fecal-oral route is well documented, some research has suggested involvement of aerosol, a route that remains poorly understood. The possible role of aerosol produced during emesis is examined here using bacteriophages MS2 and ΦX174 in a sealed chamber designed to model spread through air and via surfaces including foods exposed to aerosol. Phages suspended in buffer or artificial gastric fluid (INFOGEST 2.0 protocol) were nebulized into the chamber containing 10 stainless steel discs and 10 apple peel squares. Air and surfaces were sampled at 2 h or 24 h after nebulization. The amount of phage thus collected was determined using the double-layer method and RT-qPCR. At the 2 h point, infectious phage was detected in air and on all surfaces, regardless of the suspension medium. At 24 h, phage was not found in the air but was found in infectious state on steel and peel. Artificial gastric fluid had no protective effect on the infectivity of the phages in the air or on the surfaces. Our data indicate nonetheless that aerosol can contaminate surfaces and foods with infectious phage, which could represent a secondary route of transmission of viral gastroenteritis. This study suggests that measures suitable for reducing the aerosol load of ambient air should be implemented when and where emesis has occurred and HuNoV may be involved. • ΦX174 and MS2 phages persisted in the air for at least 2 hours. • No increase in phage infectivity was observed with simulated gastric fluid. • There was a deposit of phage aerosols on apple peels and stainless-steel discs. • The solution had no effect on deposit and infectivity.