In vitro digestion of SARS-CoV-2 contaminated berries reveals high inactivation of infectious virus during gastrointestinal passage

Abstract

ABSTRACT Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infectivity was shown to be stable on frozen berries for at least a month; however, whether the virus on berries remains infectious as it passes through the gastrointestinal tract is unknown. Here, the stability of SARS-CoV-2 infectivity on berries under in vitro digestion was investigated. The INFOGEST (an international network of excellence on the fate of food in the gastrointestinal tract) and the biorelevant fast- and fed-state models were used. SARS-CoV-2 (~7 log 50% tissue culture infective dose [TCID 50 ]/mL) infectivity was assessed in blueberry and strawberry homogenates at 4°C and 37°C, and following consecutive oral (2 min), gastric (10 and 60 min), and intestinal (15 and 120 min) digestion at 37°C. SARS-CoV-2 infectivity was quantified on Vero-E6 cell line using the TCID 50 assay. SARS-CoV-2 infectivity in berry homogenates was stable for 120 min at 4°C; however, the virus was completely inactivated at 37°C within 60 min. The biorelevant fed-state model closely mimicked the INFOGEST model. In the oral phase, SARS-CoV-2 infectivity decreased by ~1 log, which did not change during the 10-min gastric digestion. By 60 min of gastric digestion, strawberries had a protective effect on SARS-CoV-2, showing less inactivation (~2 log) in comparison to blueberries (~3–3.4 log). The viruses entering the intestinal phase showed a 2.6–3.3 log inactivation within 15 min. In contrast, SARS-CoV-2 in the fast-state model showed high inactivation at the 10- and 15-min gastric and intestinal time points (2.5 and 4 log, respectively). Therefore, under high levels of SARS-CoV-2 contamination of berries, it is possible for the virus to infect the oral cavity but less likely to infect the intestine. IMPORTANCE During the pandemic, news outlets occasionally reported on the detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RNA on various foods, raising concerns over contaminated foods initiating infections. Coronavirus disease 2019 (COVID-19) patients often experience gastrointestinal symptoms and shed SARS-CoV-2 RNA in their feces. In addition, active virus replication in the gastrointestinal tract was shown; however, infectious viruses were rarely detected in feces. We previously showed that SARS-CoV-2 remained infectious on frozen berries for at least a month. Here, in vitro digestion models showed that SARS-CoV-2 on berries exhibits minimal inactivation at the oral phase and the virus may escape gastric inactivation early during feeding. However, high intestinal inactivation of the virus on berries suggested that SARS-CoV-2 was less likely to initiate infection in the small intestine. In contrast, the oral cavity is a potential site where infection might be initiated, providing more input for the gastrointestinal tract. High intestinal inactivation might explain the difficulty of detecting infectious SARS-CoV-2 in feces but not of virus RNA.