Red Ginseng-containing diet helps to protect mice and ferrets from the lethal infection by highly pathogenic H5N1 influenza virus

Abstract

The highly pathogenic (HP) H5N1 influenza virus is endemic in many countries and has a great potential for a pandemic in humans. The immune-enhancing prowess of ginseng has been known for millennia. We aimed to study whether mice and ferrets fed with Red Ginseng could be better protected from the lethal infections of HP H5N1 influenza virus than the infected unfed mice and ferrets. We fed mice and ferrets with Red Ginseng prior to when they were infected with HP H5N1 influenza virus. The mice and ferrets fed with a 60-day diet containing Red Ginseng could be protected from lethal infections by HP H5N1 influenza virus (survival rate of up to 45% and 40%, respectively). Interferon-α and -γ antiviral cytokines were significantly induced in the lungs of mice fed Red Ginseng, compared to mice fed an unsupplemented diet. These data suggest that the diet with the immune-enhancing Red Ginseng could help humans to overcome the infections by HP H5N1 influenza virus.

Keywords: H5N1; Panax ginseng; influenza; interferon; pandemic.

Fig. 1

Survival rate and body changes of mice fed with Red Ginseng against highly pathogenic (HP) H5N1 influenza virus. (A) Mice (n = 20) fed with Red Ginseng extract (50 mg/kg) for 80 d were intranasally (i.n.) challenged with HP H5N1 influenza virus [10 mouse lethal dose (10 MLD) 50/mL] and were observed for the survival rate for 14 d. (B, C) Mice (n = 20) fed with Red Ginseng extract (50 mg/kg) for 60 d were i.n. challenged with HP H5N1 influenza virus (10 MLD 50/mL) and were observed for (B) body-weight change and (C) survival for 14 d. Groups were compared using repeated measures analysis of variance (ANOVA). *p < 0.05. **p < 0.001.

Fig. 2

Viral titers in the lungs and brains of mice fed with Red Ginseng and challenged with highly pathogenic (HP) H5N1 influenza virus. Mice fed with Red Ginseng extract (50 mg/kg) for 60 d were intranasally (i.n.) challenged with HP H5N1 influenza. The surviving mice (n = 5) were euthanized prior to when (A) the tissues of lungs and (B) brains were collected, homogenized, and suspended in phosphate buffered saline (PBS). The tissue supernatants were serially diluted and were inoculated into the fertilized eggs prior to when viral titers were determined by log₁₀ egg infectious dose (EID) 50/mL. Groups were compared using repeated measures analysis of variance (ANOVA). ¹⁾ We could not detect viruses on 9 d and 14 d post challenge (d.p.c.) because all control mice died. *p < 0.05. **p < 0.001.

Fig. 3

Evaluation of pathological damage to the lungs of mice fed with Red Ginseng following viral challenge. Mice fed with Red Ginseng extract (50 mg/kg) for 60 d were intranasally (i.n.) challenged with highly pathogenic (HP) H5N1 influenza virus and the surviving mice were euthanized on 5 d postinfection (d.p.i.), and the lungs were collected. Lung tissues were cut and stained with hematoxylin and eosin (H&E) stain. Lung tissues of (A) control uninfected mice, (B) mice fed with Red Ginseng and infected with HP H5N1 influenza virus, and (C), and control mice infected with HP H5N1 influenza virus are shown.

Fig. 4

Evaluation of cytokine induction in the lungs of mice fed with Red Ginseng. Mice fed with Red Ginseng extract (50 mg/kg) for 60 d were intranasally (i.n.) challenged with highly pathogenic (HP) H5N1. The surviving mice (n = 3) were euthanized on 3 d, 5 d, or 7 d postinfection (d.p.i.), and the lungs were collected. The collected lungs were homogenized in phosphate buffered saline (PBS) and the induced amount of cytokines of (A) tumor necrosis factor-alpha (TNF-α), (B) interferon-α (IFN-α), and (C) IFN-γ were detected. Groups were compared using repeated measures analysis of variance (ANOVA). *p < 0.05. d.p.c., days post challenge.

Fig. 5

Body-weight change and survival rate of ferrets fed with Red Ginseng. Ferrets (n = 10) fed with Red Ginseng extract (50 mg/kg) for 60 d and intranasally (i.n.) challenged with 10 ferret lethal dose (FLD) 50/mL of highly pathogenic (HP) H5N1 influenza virus were observed for (A) body-weight change and (B) survival rate for 14 d. Groups were compared using repeated measures analysis of variance (ANOVA). *p < 0.05. **p < 0.001. d.p.c., days post challenge.