Potential antiviral effects of the marine probiotic Paraliobacillus zengyii on the respiratory syncytial virus.

Probiotics can reduce the incidence of respiratory syncytial virus (RSV) disease in premature infants; this approach is resource-intensive and less expensive than other strategies and easier to implement than most current methods worldwide. Traditional lactic acid-producing bacteria are the main probiotics that have been studied for RSV treatment. Marine probiotics promote the survival, immunity, and disease resistance of aquatic plants and animals. However, relatively little research has been conducted on viral infections in humans. Here, we report a slightly halophilic and extremely halotolerant marine bacterium, Paraliobacillus zengyii, which has antiviral activity and grows at a relatively low temperature (28°C). We found that P. zengyii inhibited RSV infection by regulating the interferon (IFN) response both in vitro and in vivo. P. zengyii significantly increased the RSV-induced phosphorylation of TBK1 and IRF3 and the expression of antiviral factors interferon-induced transmembrane protein 1 (IFITM1) and interferon-induced transmembrane protein 3 (IFITM3). Furthermore, P. zengyii upregulated Sendai virus (SeV)- and poly(I:C)-induced IFN-β expression. These results indicate that the marine bacterium P. zengyii inhibits RSV infection and increases IFN-β production in response to RSV, SeV infection, or poly(I:C) stimulation. Consequently, P. zengyii has potential as a broad-spectrum anti-RNA virus probiotic.