Effects of heat-killed Lactobacillus plantarum against influenza viruses in mice.

The potential use of dietary measures to treat influenza can be an important alternative for those who lack access to influenza vaccines or antiviral drugs. Lactobacillus plantarum (Lp) is one of many lactic acid bacteria that grow in 'kimchi', an essential part of Korean meal, and several strains of Lp reportedly show protective effects against influenza. Using heat-killed Lp (nF1) isolated from kimchi, which is known for its immunomodulatory effects, we investigated whether regular oral intake of nF1 could influence the outcome of influenza virus infection in a mouse model. In a lethal challenge with influenza A (H1N1 and H3N2 subtypes) and influenza B (Yamagata lineage) viruses, daily oral administration of nF1 delayed the mean number of days to death of the infected mice and resulted in increased survival rates compared with those of the non-treated mice. Consistent with these observations, nF1 treatment also significantly reduced viral replication in the lungs of the infected mice. Taken together, our results might suggest the remedial potential of heatkilled Lactobacillus probiotics against influenza.