Influenza is an acute respiratory illness caused by the influenza A virus, which causes economic losses and social disruption mainly by increasing hospitalization and mortality rates among the elderly and people with
chronic diseases.
Influenza vaccines are the most effective means of preventing seasonal
influenza, but can be completely ineffective if there is an antigenic mismatch between the seasonal
vaccine virus and the virus circulating in the community. In addition, influenza viruses resistant to
antiviral drugs are emerging worldwide. Thus, there is an urgent need to develop new
vaccines and
antiviral drugs against these viruses. In this study, we conducted in vitro and in vivo analyses of the
antiviral effect of Panax notoginseng root (PNR), which is used as an herbal medicine and nutritional supplement in Korea and China. We confirmed that PNR significantly prevented influenza virus
infection in a concentration-dependent manner in mouse macrophages. In addition, PNR pretreatment inhibited
viral protein (PB1, PB2, HA, NA, M1, PA, M2, and NP) and viral
mRNA (NS1, HA, PB2, PA, NP, M1, and M2) expression. PNR pretreatment also increased the secretion of pro-inflammatory
cytokines [
tumor necrosis factor alpha and
interleukin 6] and
interferon (IFN)-beta and the phosphorylation of type-I IFN-related
proteins (TANK-binding kinase 1, STAT1, and IRF3) in vitro. In mice exposed to the
influenza A H1N1 virus, PNR treatment decreased mortality by 90% and prevented
weight loss (by approximately 10%) compared with the findings in untreated animals. In addition, splenocytes from PNR-administered mice displayed significantly enhanced natural killer (NK) cell activity against YAC-1 cells. Taking these findings together, PNR stimulates an
antiviral response in murine macrophages and mice that protects against
viral infection, which may be attributable to its ability to stimulate NK cell activity. Further investigations are needed to reveal the molecular mechanisms underlying the protective effects of PNR and its components against influenza virus A
infection.