# Antiviral Activity of Marine Bacterium Paraliobacillus zengyii Against Enterovirus 71 In Vitro and In Vivo

## TL;DR

A marine bacterium called Paraliobacillus zengyii shows strong antiviral effects against Enterovirus 71 in both lab and animal studies.

## Contribution

This study identifies a new marine probiotic with antiviral activity against EV71 both in vitro and in vivo.

## Key findings

- P. zengyii reduces EV71 viral RNA levels and titers in cell cultures.
- Oral administration of P. zengyii decreases EV71 viral loads in mice.
- P. zengyii enhances IFN-I expression and ISG activity in EV71-infected cells and mice.

## Abstract

Enterovirus 71 (EV71) is the major causative agent of hand, foot, and mouth disease (HFMD), leading to a serious health threat to young children. Probiotics are effective at treating or preventing gastrointestinal infections, especially viral infections. Probiotics against EV71 are mainly traditional lactic acid-producing bacteria, and most of them have been proven to be effective only in vitro. Here, we report that the marine bacterium Paraliobacillus zengyii X-1125 (P. zengyii) has promising anti-EV71 activity. The antiviral effect of P. zengyii against EV71 was assessed in different cell lines, and the viral RNA levels and titers were obviously reduced after treatment with P. zengyii. Furthermore, we established an EV71-infected mouse model to evaluate its antiviral efficacy in vivo. The oral administration of P. zengyii significantly decreased the viral loads in the hindlimb muscles, spleens, and ileums. Further research revealed that P. zengyii enhances the expression of type I interferon (IFN-I) in EV71-infected cells. Similarly, transcriptome analysis indicated that the expression of interferon-stimulated genes (ISGs) in EV71-infected mice significantly increased after P. zengyii treatment. Taken together, the results of this study indicated that P. zengyii markedly reduces EV71 infection by regulating the IFN response both in vivo and in vitro, providing a potential means to work against EV71 infection.