Inhibitory Effect of Curcumin on Norovirus Infection and its Mechanism

Abstract

Norovirus outbreak is a major public health burden across the world. In immunocompromised hosts, norovirus can establish chronic infection. Chronically infected hosts have potential to act as a reservoir of emergent norovirus strain. The safe and affordable therapeutic agents to control chronic norovirus infection are required. Phytonutrients have been used as supplements in traditional medicine to enhance immune responses or resistance to infectious diseases. In this study, the effect of curcumin on chronic norovirus infection was evaluated using mouse model. C57BL/6 mice were orally inoculated with curcumin daily for 34 days and infected with murine norovirus (MNoV) CR6 strain. Viral loads were quantified in stool and tissue samples by realtime PCR. Curcumin reduced MNoV in colon and mesenteric lymph nodes (MLN). Type I interferons (IFNs) were also enhanced in those tissues. Inhibition was not observed in ileum and peyers patch (PP). Microbial community was assessed using 16S rRNA sequencing to understand tissue-specific MNoV inhibition. Family Mogibacteriaceae was changed significantly only in colon. Family Mogibacteriaceae abundance and virus quantity showed a weak negative correlation using correlation analysis. These results suggest that curcumin enhanced type I interferons in large intestines resulting in inhibition of MNoV. Specific enteric bacteria may be related to control MNoV.