Inhibitory Effects of Goishi Tea against Influenza Virus Infection

Abstract

We investigated the possible anti–influenza virus function of Goishi tea, which is a Japanese traditional microbial fermented tea, in in vitro and in vivo tests. We found that Goishi tea hot water extract (GTE) inhibited hemagglutination caused by influenza A/ Puerto Rico/ 8/ 34 (PR8, H1N1) and influenza A/ Guizhou/ 54/ 89 (Guizhou, H3N2) viruses, viral growth in Mardin-Darby canine kidney (MDCK) cells caused by PR8, and viral infection of mice caused by nasal inoculation of PR8. Furthermore, we investigated the functional fractions of GTE and found that a high-molecular-weight fraction of GTE inhibited viral adsorption to MDCK cells and that low-molecular-weight fractions inhibited subsequent stages of infection, such as viral invasion, genomic multiplication, and release, after adsorption. These results indicate that GTE exerts an inhibitory property against influenza virus infection by inhibiting various stages of infection.