Kim Y., Kwon J., Ju H., Gwon G., Song C.
Konkuk university, South Korea

Avian influenza has high impact in public health areas. For improved therapies and preventive measures against influenza, there has been an increased tendency in modern medicine involving the use of probiotics. Lactic acid bacteria (LAB) stimulate mucosal immunity which is important to prevent influenza virus infection. However, many of recent studies are focused on screening LAB which has potent protective ability against single virus used in single experiment. There is only few articles dealing with effective LAB selection against multiple viruses. It is required to check the capability of selected LAB inducing broadly protective immunity against various influenza subtypes.

In this study, we compared the protective efficacy of selected LAB (Lactobacillus sakei) which isolated from Kimchi against challenge with different HA type of Influenza in mice according to the intranasal administration route. Animals were assigned to seven experimental groups; three virus (H1N1, H3 and H5N2) challenge groups after 6 times Lactobacillus sakei administration via intranasal route, positive control of each virus and a negative control. All mice except negative control were challenged with a lethal dose of AI viruses intranasally. After challenge with influenza virus at day 0 post-infection (p.i.), survival rate, weight loss and clinical signs were observed daily for 14 days p.i.
In addition, to understand the underlying mechanism behind this clinical protective effect, we performed immunologic assays including determination of lung virus titers, examination of IgA levels and cytokine profiles in the lung with two viruses which have shown difference in protective efficacy from the former experiment. The level of total and virus-specific IgA in lung homogenates was assayed using ELISA mice from each group on days 0, 2, 4, and 6 p.i. Quantitation of cytokine also measured in the same manner. To find out lung virus titers, MDCK cells were used with homogenized lung supernatants which were 10-fold serially diluted.

The survival rate of mice receiving intranasal administration of LAB was higher than only virus challenged control. There were differences in protective efficacy of various influenza subtypes. All of mice of LAB administration group showed enhancement of secretory IgA production and down-regulation of pro-inflammatory cytokines in the respiratory immune system.

Intranasal administration route of lactic acid bacteria produced marked antiviral activity against influenza virus and activated host immune system. We found that protective effects induced by single LAB strain were distinct against various subtype of influenza infection. Therefore, for better clinical applications, selection of effective strains could be including evaluation of protection efficiency against multiple viruses.

Keywords: Influenza, Lactobacillus sakei, Lactic acid bacteria(LAB), Intranasal administration, Immune response, Probiotic

Kim Y., et al. (2016). Evaluation of the intranasal administration of live Lactobacillus sakei protection against different subtype influenza virus infection in mice. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 36.). IPC2016

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