Anti-noroviral effects of Lactobacillus sp. isolated from Korean population

Abstract

Norovirus gastroenteritis causes large health and economic costs, including at least 200,000 deaths annually. There is a difficulty of improve available vaccination program cause of limited cell culture system and effective treatment and prevention was not available until recently. Probiotics is live bacteria have potential health benefits on the host. It is known as playing the role of immune modulation in the human intestine. And previous studies said Probiotic bacteria have antiviral effects via various mechanism. In this study, we focused on the antiviral mechanism of the probiotics through activating innate immune response. Probiotics therapy could be an alternative method of antiviral prevention and modulation against norovirus infection. In this study, we isolated target strains of Lactobacillus spp. successfully in the feces of Korean infants. And we screened the anti-noroviral activity of isolated Lactobacillus strains. Lactobacillus reuteri SNUG50382 (LR50382) significantly inhibited murine norovirus infection in RAW264.7 cells with having highest probiotics potential. Both onset and resolution of disease symptoms are rapid, suggesting that components of the innate immune response are critical in norovirus control. To clarify the mechanism of norovirus inhibition of probiotics, we investigated gene expression of Interferon (IFN)-signaling components and IFN-inducible antiviral effectors. LR50382 increased IFN-α and IFN-β levels in RAW264.7 cells compared with the control. Gene expression of IFN regulating factor 7 (IRF7) and IFN-inducible antiviral effectors, Mx1 also increased. Overall, these results indicate that LR50382 efficiently inhibits norovirus replication in vitro due to its modulating capacity of the immune response through promoting type I IFNs, which are key regulators in IFN signaling pathway.