Ginseng polysaccharide has been known to have multiple immunomodulatory effects. In this study, we investigated whether Panax ginseng polysaccharide (GP) would have a preventive effect on influenza infection. Administration of mice with GP prior to infection was found to confer a survival benefit against infection with H1N1 (A/PR/8/34) and H3N2 (A/Philippines/82) influenza viruses. Mice infected with the 2009 H1N1 virus suspended in GP solution showed moderately enhanced survival rates and lower levels of lung viral titers and the inflammatory cytokine (IL-6). Daily treatment of vaccinated mice with GP improved their survival against heterosubtypic lethal challenge. This study demonstrates the first evidence that GP can be used as a remedy against influenza viral infection.
Citation: Yoo D-G, Kim M-C, Park M-K, Park K-M, Quan F-S, Song J-M, et al. (2012) Protective Effect of Ginseng Polysaccharides on Influenza Viral Infection. PLoS ONE7(3): e33678. https://doi.org/10.1371/journal.pone.0033678
Editor: Leo L. M. Poon, University of Hong Kong, Hong Kong
Received: October 19, 2011; Accepted: February 14, 2012; Published: March 19, 2012
Copyright: © 2012 Yoo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was supported in part by National Institutes of Health (NIH)/National Institute of Allergy and Infections Diseases (NIAID) grant AI0680003 (RWC), the Korean Society of Ginseng (SMK), and NIH/NIAID grants AI093772 (SMK) and AI087782 (SMK). The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the funding agents. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding received for this study.
Competing interests: The authors have declared that no competing interests exist.
Influenza is a serious respiratory disease causing recurrent outbreaks significantly affecting human health, livestock, and the global economy. Diverse influenza A viruses with different combinations of hemagglutinin (H1 to H16) and neuraminidase (N1 to N9) subtypes have been identified . The new 2009 H1N1 influenza virus spread rapidly to over 74 countries around the world by early June 2009, when the World Health Organization raised the global outbreak alert level to the pandemic phase. –. Current vaccines are only effective if they are well matched with the predicted influenza strains that circulate during the next season. In addition, a number of influenza variants have evolved to develop resistance to antiviral drugs . A preventive measure that would have protective effects on influenza virus regardless of strain is highly desirable.
An acidic polysaccharide from Panax ginseng (ginseng polysaccharide) has been shown to display immunomodulatory effects either in an immuno-stimulatory or in an immuno-suppressive manner depending on timing of treatments and disease environments. Ginseng polysaccharide (GP) promoted the production of cytotoxic cells against tumors and stimulated macrophages to produce helper types 1 and 2 (Th1 and Th2) cytokines –. GP was also shown to modulate the antioxidant defense systems such as superoxide dismutase and glutathione peroxidase enzymes probably via inducing regulatory cytokines , . As an anti-inflammatory function, recent studies reported that pretreatment with GP suppressed acute inflammatory responses at an early phase resulting in the enhancement of antimicrobial activities and protection of mice from Staphylococcus aureus-induced sepsis , . However, the effects of GP on viral infection remain unknown.
In this study, we have investigated the potential effects of GP on survival outcomes after influenza viral infection in a mouse model. Also, the potential roles of GP in conferring protection to naïve mice and in improving cross-protection of vaccinated mice have been explored and discussed.
Materials and Methods
Cells, virus, and reagents
Spodoptera frugiperda sf9 insect cells purchased from the American Type Culture Collection (ATCC, CRL-1711) were used for the production of recombinant baculoviruses (rBVs) and virus-like particles (VLPs) as an influenza vaccine candidate, and were cultured in SF900-II serum-free medium (GIBCO-BRL) at 27°C in spinner flasks. The influenza subtype H1N1 A/PR/8/34 (A/PR8) and H3N2 A/Philippines/82 viruses were kindly provided by Dr. Huan Nguyen, and the new 2009 H1N1 influenza virus (A/California/04/2009) by Dr. Richard Webby. Influenza viruses were grown in 11-day old embryonated hen's eggs. Egg allantoic fluids were harvested and stored at −80°C until use. Madin-Darby canine kidney (MDCK) cells purchased from ATCC were maintained in Dulbecco's modified Eagle's medium (DMEM) and used to determine virus titers from egg allantoic fluids and mouse lung homogenates by a plaque assay . Mice were infected with serial dilutions of influenza virus and the 50% lethal dose (LD50) was determined. The ginseng polysaccharide (GP) reagent used in this study was obtained from the Korea Ginseng Corporation. Briefly, red ginseng (P. ginseng) was percolated with 5 volumes of 85% ethanol to extract off ethanol-soluble materials. The remaining residues were re-percolated with 5 volumes of distilled water, and the water-soluble extracts were concentrated with a vacuum evaporator. The concentrate was dialyzed against water to completely cut off small molecules of less than 15 kDa. Four volumes of absolute ethanol were added to precipitate the polysaccharide in the inner dialysate. The precipitate was dried in a vacuum drying oven, and was finally used as a red ginseng acidic polysaccharide (GP) as previously described , , . An active acidic polysaccharide moiety (Table 1, Fig. 1) present in GP was reported to be composed of a galactogalacturonan core such as α-D-Galacturonic acid-(1-4)-α-D-Galacturonic acid-(1-4)-α-D-Galacturonic acid-(1-6)-α-D-Galactose . GP is also known to contain sugars composed of α(1-6) glucopyranoside and β(2-6) fructofuranoside , . As a quality control, the endotoxin content in GP preparations was less than the threshold level (0.006 EU/mg) as determined by the Limulus amebocytes lysates assay (EndosafeJ, Charles River Laboratories, USA) according to the manufacturer's instructions , , .
A proposed partial structure of polysaccharides present in GP was suggested in a previous study . A proposed active component of GP comprises a galactogalacturonan core such as α-D-Galacturonic acid-(1-4)-α-D- Galacturonic acid-(1-4)-α-D- Galacturonic acid-(1-6)-α-D-Galactose as the acidic moiety .
Ginseng polysaccharide pretreatment of mice and influenza virus infection
A powder form of GP was dissolved in phosphate-buffered saline (PBS, pH 7.4), filtered through 0.4 µm Millipore membranes. For animal experiments, 8–10 weeks old BALB/c mice (Harlan Laboratories, Indianapolis, IN) were lightly anesthetized with isoflurane inhalation and then GP was administered intranasally or intravenously in a dose ranging from 12.5 to 50 mg/kg weight. To determine the effects of GP treatment on influenza infection, mice (n = 6 to 10 per group) were anesthetized by isoflurane inhalation and intranasally infected by mouse-adapted pathogenic strains of A/PR8 or A/Philippines/82. Mice were monitored daily to record weight changes and mortality. All animal experiments and husbandry involved in the studies presented in this manuscript were conducted under the guidelines of the Emory University Institutional Animal Care and Use Committee (IACUC). Emory IACUC operates under the federal Animal Welfare Law (administered by the USDA) and regulations of the Department of Health and Human Services. Emory University IACUC specifically approved full details of this study as proposed by the approved IACUC DAR-2000161-081313.
Lung viral titers and cytokine assays
Lung viral titers were performed using MDCK cells as previously described . Lungs were collected at day 4 post infection. Briefly, serially diluted lung extracts were added to six-well plates containing confluent MDCK cell monolayers, and incubated at 37°C for 1 h. Overlay medium containing DEAE dextran, nonessential amino acids, glutamine, and trypsin were added and incubated for 2 or 3 days. After fixing with 0.25% glutaraldehyde and staining with 1% crystal violet, the plaques were counted. Cytokine ELISA was performed as described previously . Ready-Set-Go interferon (IFN) γ and interleukin (IL)-6)- kits (eBioscience, San Diego, CA) were used for detecting cytokine levels in lung extracts following the manufacturer's recommended procedures.
In vivo infection with mixtures of ginseng polysaccharide and virus
Different concentrations of ginseng polysaccharide (25 µl) or PBS buffer control were mixed with influenza virus (25 µl with 3 LD50) and incubated at room temperature for 30 min. The virus and ginseng polysaccharide mixtures were administered to naïve mice, and body weight changes and survival rates were monitored daily.
Treatment of vaccinated mice with GP and heterosubtypic challenge
To vaccinate mice, influenza VLPs containing hemagglutinin (HA) and matrix (M1) proteins from H1N1 A/PR8 virus were prepared as described previously . Mice were intramuscularly vaccinated with influenza VLPs (8 µg total protein per mouse) one time followed by daily administration with GP (0.1 mg) intranasally for 12 days from the day 1 post vaccination. On day 13 post vaccination, vaccinated mice were challenged with a lethal dose of H3N2 heterosubtypic virus (A/Philippines/82, 6 LD50). Body weight changes and survival rates were monitored daily.
Antibody determination and hemagglutination activity assay
Influenza virus-specific total IgG antibodies were determined using standard methods as described previously , . Briefly, inactivated influenza virus was used as an antigen on 96 well microtiter plates (Nunc, Rochester, NY) in coating buffer (0.1 M sodium carbonate, pH 9.5). Serially diluted serum samples were added and incubated for 1 hr at 37°C, and then horseradish peroxidase (HRP) -conjugated goat anti-mouse IgG antibody was used as secondary antibody and O-phenylenediamine as a substrate. Antibody levels are presented based on optical spectrophotometer readings at 450 nm (OD450).
For determination of hemagglutination activity as a measure of viral growth, virus culture supernatants were diluted, mixed with 0.5% chicken red blood cells, and then incubated for 1 hour at room temperature. The dilutions showing a blood cell precipitated spot were used as an endpoint as described previously , .
Ginseng polysaccharide protects mice from lethal infection with H1N1 influenza virus
We have investigated the effects of ginseng polysaccharide (GP) on conferring protection against lethal infection with influenza virus in a mouse model. Mice (BALB/c) were intranasally administered 25 mg GP/kg body weight. At six hours after treatment with GP, the treated or naïve mice were intranasally infected with a lethal dose (3 LD50) of influenza H1N1 virus A/PR/8/34 (LD50: 50% lethal dose) and monitored daily for morbidity (body weight changes) and mortality (survival rates). As shown in Fig. 2A, naïve (untreated) mice showed severe body weight loss over 25% and died or were euthanized by day 8 post infection with A/PR/8/34. GP treated mice exhibited a significant delay in body weight loss although these mice also showed approximately 20–25% loss in body weight (Fig. 2A). Importantly, the GP treated mice all survived lethal infection (Fig. 2B). When mice were treated with GP at an earlier time point 24-hr before infection, 30% of GP treated mice were protected while none of the naïve control group survived challenge infection with A/PR/8/34 (3 LD50).
A) Changes in body weight (%). B) Survival rates (%). BALB/c mice (n = 10, 12 weeks old) were pretreated once intranasally with ginseng polysaccharide (25 mg/kg weight) 6 hours prior to infection with 150 plaque-forming units (pfu) of A/PR/8/34 virus (3 LD50). Mock: mice treated with PBS, GP: mice treated ginseng polysaccharide. * p<0.05 between mock and GP groups as determined by Student's t-test.
To determine the dosage effects of GP, different doses of GP were similarly tested in mice with the same challenge dose (3 LD50) as summarized in the Table 2. The lowest dose of GP (12.5 mg/kg) provided only partial protection of 60% of the treated mice indicating less protective efficacy (Table 2). The higher dose (50 mg GP/kg) provided 80–100% protection following severe body weight loss, which indicates no improved protection with the higher dose of GP.
Ginseng polysaccharide confers protection against lethal infection with H3N2 influenza virus
To test if the protective effects of GP extended to a different subtype influenza virus, the A/Philippines/82 (H3N2 subtype) was used as a challenge virus (Fig. 3). The GP treated or naïve mice were challenged with a sub-lethal dose of A/Philippines/82 virus (2 LD50). Less body weight loss (15–20%) was observed in the GP treated compared to naïve mice that showed 25% average body weight loss (Fig. 3A). Also, the survival rates of GP-administered and naïve mice were 100% and 33% respectively (Fig. 3B). To better understand the effects of GP on improving protection, we determined viral loads at an early stage of infection and host responses in the surviving mice. 2.5 fold lower lung viral titers were observed in the GP-treated mice compared to the naïve control (Fig. 3C, p<0.05).
A) Changes in body weight (%). B) Survival rates (%). C) Lung viral titers at day 4 post infection (n = 4 out of 10 infected mice). BALB/c mice (n = 10 , 12 weeks old) were once pretreated intranasally with ginseng polysaccharide (25 mg/kg) 6 hours prior to infection with H3N2 subtype A/Philippines/82 virus (3 LD50). * p<0.05 between mock and GP groups.
As an alternative route of delivery, different doses (10, 25 mg/kg) of GP were administered to mice intravenously 6 hr before infection with A/Philippines/82 virus (3 LD50). The low dose 10 mg/kg group showed 100% survival rate whereas a partial protection of 66% was observed in the 25 mg/kg group (Fig. 4). Nonetheless, the surviving mice in both groups showed severe body weight loss (Fig. 4A). All naïve mice died after infection with the same dose of A/Philippines/82 virus (3 LD50). Thus, GP might be partially effective in conferring protection through intravenous administration but high doses of GP would not enhance the survival protection. The results suggest that an optimal dose of GP administration confers the host with improved capacity to protect against lethal infection with H3N2 influenza strain.
A) Changes in body weight (%). B) Survival rates (%). Groups of mice (n = 5) intravenously administered ginseng polysaccharide (10 or 25 mg/kg) were infected with A/Philippines/82 virus (3 LD50), and survival rates monitored daily for 14 days. Mock: mice treated with PBS, GP 10 mg: mice treated with 10 mg/kg ginseng polysaccharide, GP 25 mg: mice treated with 25 mg/kg ginseng polysaccharide.
Ginseng polysaccharide contributes to protective immunity
To better understand the potential role of GP in conferring protection against influenza viral infection, we tested the direct effects of GP on viral infection in naïve mice. Mixtures of a lethal dose (3 LD50) of the 2009 H1N1 virus (A/California/04/2009) and GP were used to intranasally infect naïve mice. Naïve mice that were infected with a mixture of virus and PBS buffer showed severe body weight loss and all died (Fig. 5). In contrast, 2.5 mg/kg and 25 mg/kg GP provided 33% and 66% protection to naïve mice that were infected with a lethal dose of the 2009 H1N1 virus mixed with GP although the surviving mice showed a visible body weight loss similar to the infection in the PBS control (Mock). Therefore, these results suggest that GP may have a direct effect on improving the survival against influenza infection.
Mixtures of virus (A/California/2009, 3 LD50) and different amounts of ginseng polysaccharide (2.5 mg/kg, 25 mg/kg) were used to infect mice intranasally (n = 6). The body weight changes (A) and survival rates (B) were monitored daily for 14 days. Mock: naïve mice infected with virus in PBS, GP 2.5 mg: naïve mice infected with a mixture of virus and 2.5 mg/kg of ginseng polysaccharide, GP 25 mg: naïve mice infected with a mixture of virus and 25 mg/kg of ginseng polysaccharide.
Lungs were collected at day 4 post infection to determine lung viral titers and cytokine levels (Fig. 6). The GP treated group showed lower lung viral titers by 2.5 fold compared to that of the control group without GP (Fig. 6A). Also, the levels of inflammatory cytokine IL-6 was found to be lower in the GP treated group compared to the untreated control after lethal infection (Fig. 6B). In contrast, interferon (IFN)-γ was moderately higher in lungs of GP-treated mice compared to the infected naïve control mice (Fig. 6C). These results imply that GP-mediated protection might be partially due to inhibiting lung viral replication and inflammatory cytokines, and stimulating antiviral cytokine IFN-γ production.
Lung viral titers (A), interleukin (IL)-6 (B), and interferon (IFN)-γ levels (C) were determined at day 4 post infection with a mixture of ginseng polysaccharide and virus (A/California/2009, 3 LD50) (n = 5). Mock: naïve mice infected with virus in PBS, GP 25 mg: naïve mice infected with a mixture of virus and 25 mg/kg of ginseng polysaccharide. * p<0.05 between mock and GP 25 mg/kg groups as determined by Student's t-test.
Ginseng polysaccharide improves cross protection by influenza vaccines
Immunization with inactivated viral vaccine usually induces good protective immunity against the homologous virus infection but not against a heterosubtypic influenza A virus. Influenza virus-like particles (VLPs) have been suggested to be a promising candidate vaccine , . Here, we determined the effects of GP pretreatment on induction of heterosubtypic protection in mice vaccinated with influenza VLPs containing HA and M1 derived from H1N1 A/PR8 virus (Fig. 7). Mice were intranasally immunized with influenza VLPs (8 µg total protein). From day 1 post vaccination, groups of naïve and vaccinated mice were treated daily with GP (5 mg/kg daily) via the intranasal route for 12 days. At day 13 post vaccination, mice were challenged with a lethal dose (6 LD50) of H3N2 subtype A/Philippines virus. All naïve mice became very sick, rapidly lost body weight below 75% and died or were euthanized. Also, all mice in the A/PR8 VLP vaccinated group died although the vaccinated mice showed a delay in mortality (Fig. 7A, 7B). The group of unvaccinated mice with GP treatment daily for 12 days exhibited severe loss in body weight similar to that of vaccinated mice without GP and showed 25% survival (data not shown). Importantly, 80% of mice that were vaccinated with A/PR8 VLPs and treated with GP daily for 12 days were survived lethal challenge with A/Philippines virus. Daily GP treatment did not increase the immune responses to the viral antigen (Fig. 7C). Also, daily treatment of a higher dose (25 mg/kg body) did not improve the cross protective efficacy (data not shown). These results suggest that daily GP treatment has the potential to improve the cross protective vaccine efficacy.
(A) Body weight changes. (B) Survival rates. Mice (n = 5) that were intranasally vaccinated with influenza VLPs (H1 VLP, 8 µg total protein) were intranasally treated with ginseng polysaccharide (5 mg/kg) daily for 12 days prior to infection with H3N2 heterosubtypic virus (A/Philippines/82, 6 LD50). (C) A/PR/8/34 virus specific serum antibody levels. Virus- specific antibody levels were determined in sera collected prior to challenge infection. H1 VLP: Vaccination with H1 VLPs, H1 VLP+GP: Daily treatment with GP for 12 days from the day 1 post vaccination with H1 VLPs, Mock: unvaccinated mice infected with virus.
Ginseng polysaccharide has antiviral activity
It would be of interest to determine whether GP treatment has effects on viral growth. When influenza A/PR8 virus was mixed with GP at different concentrations, the amounts of viral growth as measured by a hemagglutination activity assay were moderately lower up to 50% in a dose-dependent manner (Fig. 8A). High amounts of GP concentrations (500, 1000 µg/ml) were required to exhibit an inhibition effect on a high dose A/PR8 virus of approximately 20,000 plaque forming units (PFU) per milliliter. To determine the effects of GP on the growth of a different strain, the 2009 H1N1 pandemic virus (A/California/2009) was tested (Fig. 8B). The concentration of A/California/2009 virus was approximately 4000 PFU per milliliter and GP amounts in a range of up to 200 µg/ml were tested. Approximately five-fold lower levels of A/California/2009 virus production were observed at the GP concentration of 200 µg per milliliter (Fig. 8B). Also, a similar pattern of virus growth inhibition was obtained when mixtures of A/California/2009 virus and GP were used to infect eggs (data not shown). Therefore, these results suggest that GP may have the anti-viral growth activity against influenza viruses in a dose-dependent but strain-independent pattern.
A) Effects of ginseng polysaccharide on influenza A/PR8 virus. A diluted influenza A/PR8 virus (approximately 20,000 plaque forming units/ml) was mixed with different concentrations of GP (0, 500, 1000 µg/mL) and cultured for 3 days. B) Effects of ginseng polysaccharide on 2009 H1N1 pandemic influenza A/California/2009 virus. A diluted influenza A/California/2009 virus (approximately 4,000 plaque forming units/ml) was mixed with different concentrations of GP (0, 100, 200 µg/mL) and cultured for 5 days. The growth of viruses (A/PR8 virus, A/California/2009 virus) was determined by hemagglutination activity using chicken red blood cells, and presented as percentages compared to the controls (the wells without GP).
Although GP has been known to have various immunomodulatory functions, its in vivo effects on viral infectious diseases are not very well studied. For the first time, we have investigated the effects of GP treatment on influenza virus infection in a mouse model. Intranasal or intravenous administration of mice with GP prior to infection conferred resistance to intranasal lethal infection by different influenza strains, resulting in increased survival rates but not preventing body weight loss. Also, naïve mice were partially protected when a lethal dose of influenza virus was mixed with GP prior to infection. Finally, intranasal pretreatment of vaccinated mice with GP improved their survival against heterosubtypic infection. Therefore, GP might have a preventive effect on influenza infection.
Intranasal administration with GP was tested in this study since influenza virus infects the host via the respiratory tract. The survival benefit against both H1N1 (A/PR8) and H3N2 (A/Philippines) viruses was observed with intranasal 25 mg/kg or intravenous 10 mg/kg doses. Higher doses of GP pretreatments did not increase the survival benefit. Although these dosage ranges used in our study were similar to those reported by a previous study demonstrating the beneficial effect of intravenous pretreatment with GP on decreasing septic complications by intraperitoneal infection with bacteria, variable optimum doses were previously reported depending on different septic models , . Also, we found that timing of pretreatments influenced the efficacy of survival. Pretreatment more than one day earlier decreased the survival benefit and treatment post influenza infection did not improve protective efficacy (data not shown). This is consistent with previous findings that GP or ginseng treatment close to septic infection or after lipopolysaccharide stimulation was less or not effective , . Further studies are needed to better understand the mechanisms by which pretreatments with GP exhibit survival benefit during influenza infection.
Pretreatment with GP resulted in lower lung viral titers than those observed in the untreated mice at day 4 post infection. This better control of lung viral replication observed was not because of increased anti-viral antibody immune responses in the GP treated group (data not shown). In support of this observation, beneficial effects of GP pre-treatment were also observed in B cell-deficient mice (data not shown). A possible mechanism is that GP may have anti-viral effects on influenza virus. Naïve mice infected with a mixture of a 2009 H1N1 influenza virus and GP showed improved survival compared to the control mice infected with the same dose of virus in PBS. Moderate decreases were observed in lung viral titers (approximately 2.5 fold) in the GP treated virus group. In this regard, it is interesting to note that the replication of influenza viruses mixed with GP was inhibited at moderate levels. However, the requirement of high concentration of GP indicates that the direct virucidal effects of GP are relatively weak and other additional mechanisms might be involved in vivo.
GP was also demonstrated to enhance the production of cytokines and reactive oxygen species by stimulating macrophages , . In a recent study, GP was shown to stimulate dendritic cells resulting in enhanced production of IFN-γ . In contrast, intravenous pretreatment of GP attenuated the production of serum pro- and anti-inflammatory cytokines after septic bacterial infection . Infection of mice with a mixture of virus and GP resulted in higher levels of the antiviral cytokine IFN-γ and lower levels of proinflammatory cytokine IL-6 compared to those in the mice infected with virus only. Taken together, this study and others suggest a mechanism that GP might have antiviral activity against influenza virus by modulating host cytokines.
Infection with pathogenic influenza virus was shown to induce significant cell death probably via apoptosis causing tissue damages as a pathogenic mechanism of influenza –. Constitutive ERK1/2 activation is known to be important for the viability of malignant tumor/cancer cells and the phosphorylation of ERK1/2 plays a critical role in activating genes involved in cell cycle regulation and survival –. In preliminary studies, we found that influenza infection of human lung epithelial cell line (A549) induced significantly lower levels of ERK1/2 phosphorylation, indicating apoptosis-mediated cell death due to influenza virus infection. Examination of influenza infected cells under the microscope showed substantial cytopathic effects (data not shown). Importantly, pretreatment with GP resulted in preventing the down-regulation of ERK1/2 phosphorylation due to the subsequent infection with influenza virus. GP treatment of human lung epithelial cell line did not change the constitutive phosphorylation of ERK1/2 after infection with influenza virus (data not shown). Consistent with our observation, GP was reported to significantly increase the viability of peritoneal macrophage cells . In addition, ginseng was shown to inhibit degradation of long-lived proteins and to stimulate protein synthesis similar to polypeptide growth factors . Thus, it is speculated that maintaining the cell viability under the condition of viral infection-induced stress might be an another alternative mechanism for the protective effects by GP.
It is highly significant to enhance the cross protective efficacy of vaccination considering that current influenza vaccines induce strain-specific protection. This study first demonstrated that heterosubtypic protection of vaccinated mice was observed in mice received GP treatment daily although treatment of vaccinated mice with GP did not affect the host humoral immune responses to the vaccine antigen. Most people who consume ginseng are not immunologically naïve and are either vaccinated or immune to certain infectious agents because of natural exposure. It is also considered that immunomodulatory effects by GP treatments might play an important role in the outcomes of survival after influenza viral infection. Therefore, normal consumption of ginseng containing GP in healthy individuals would have beneficial effects on preventing unexpected influenza infections.
Conceived and designed the experiments: DGY RWC SMK. Performed the experiments: DGY MCK MKP KMP BZW. Analyzed the data: DGY SMK. Contributed reagents/materials/analysis tools: FSQ JMS JJW YKC SMK. Wrote the paper: SMK.
- 1. Fouchier RA, Munster V, Wallensten A, Bestebroer TM, Herfst S, et al. (2005) Characterization of a novel influenza A virus hemagglutinin subtype (H16) obtained from black-headed gulls. J Virol 79: 2814–2822.RA FouchierV. MunsterA. WallenstenTM BestebroerS. Herfst2005Characterization of a novel influenza A virus hemagglutinin subtype (H16) obtained from black-headed gulls.J Virol7928142822
- 2. Solovyov A, Palacios G, Briese T, Lipkin WI, Rabadan R (2009) Cluster analysis of the origins of the new influenza A(H1N1) virus. Euro Surveill 14(21).A. SolovyovG. PalaciosT. BrieseWI LipkinR. Rabadan2009Cluster analysis of the origins of the new influenza A(H1N1) virus.Euro Surveill1421
- 3. Dawood FS, Jain S, Finelli L, Shaw MW, Lindstrom S, et al. (2009) Emergence of a novel swine-origin influenza A (H1N1) virus in humans. N Engl J Med 360: 2605–2615.FS DawoodS. JainL. FinelliMW ShawS. Lindstrom2009Emergence of a novel swine-origin influenza A (H1N1) virus in humans.N Engl J Med36026052615
- 4. Itoh Y, Shinya K, Kiso M, Watanabe T, Sakoda Y, et al. (2009) In vitro and in vivo characterization of new swine-origin H1N1 influenza viruses. Nature 460(7258): 1021–1025.Y. ItohK. ShinyaM. KisoT. WatanabeY. Sakoda2009In vitro and in vivo characterization of new swine-origin H1N1 influenza viruses.Nature460725810211025
- 5. Naffakh N, van der Werf S (2009) April 2009: an outbreak of swine-origin influenza A(H1N1) virus with evidence for human-to-human transmission. Microbes Infect 11: 725–728.N. NaffakhS. van der Werf2009April 2009: an outbreak of swine-origin influenza A(H1N1) virus with evidence for human-to-human transmission.Microbes Infect11725728
- 6. Moscona A (2005) Oseltamivir resistance–disabling our influenza defenses. N Engl J Med 353: 2633–2636.A. Moscona2005Oseltamivir resistance–disabling our influenza defenses.N Engl J Med35326332636
- 7. Kim KH, Lee YS, Jung IS, Park SY, Chung HY, et al. (1998) Acidic polysaccharide from Panax ginseng, ginsan, induces Th1 cell and macrophage cytokines and generates LAK cells in synergy with rIL-2. Planta Med 64: 110–115.KH KimYS LeeIS JungSY ParkHY Chung1998Acidic polysaccharide from Panax ginseng, ginsan, induces Th1 cell and macrophage cytokines and generates LAK cells in synergy with rIL-2.Planta Med64110115
- 8. Lee YS, Chung IS, Lee IR, Kim KH, Hong WS, et al. (1997) Activation of multiple effector pathways of immune system by the antineoplastic immunostimulator acidic polysaccharide ginsan isolated from Panax ginseng. Anticancer Res 17: 323–331.YS LeeIS ChungIR LeeKH KimWS Hong1997Activation of multiple effector pathways of immune system by the antineoplastic immunostimulator acidic polysaccharide ginsan isolated from Panax ginseng.Anticancer Res17323331
- 9. Han SK, Song JY, Yun YS, Yi SY (2005) Ginsan improved Th1 immune response inhibited by gamma radiation. Arch Pharm Res 28: 343–350.SK HanJY SongYS YunSY Yi2005Ginsan improved Th1 immune response inhibited by gamma radiation.Arch Pharm Res28343350
- 10. Song JY, Akhalaia M, Platonov A, Kim HD, Jung IS, et al. (2004) Effects of polysaccharide ginsan from Panax ginseng on liver function. Arch Pharm Res 27: 531–538.JY SongM. AkhalaiaA. PlatonovHD KimIS Jung2004Effects of polysaccharide ginsan from Panax ginseng on liver function.Arch Pharm Res27531538
- 11. Song JY, Han SK, Bae KG, Lim DS, Son SJ, et al. (2003) Radioprotective effects of ginsan, an immunomodulator. Radiat Res 159: 768–774.JY SongSK HanKG BaeDS LimSJ Son2003Radioprotective effects of ginsan, an immunomodulator.Radiat Res159768774
- 12. Song JY, Han SK, Son EH, Pyo SN, Yun YS, et al. (2002) Induction of secretory and tumoricidal activities in peritoneal macrophages by ginsan. Int Immunopharmacol 2: 857–865.JY SongSK HanEH SonSN PyoYS Yun2002Induction of secretory and tumoricidal activities in peritoneal macrophages by ginsan.Int Immunopharmacol2857865
- 13. Ernst E (2010) Panax ginseng: An Overview of the Clinical Evidence. J Ginseng Res 34: 259–263.E. Ernst2010Panax ginseng: An Overview of the Clinical Evidence.J Ginseng Res34259263
- 14. Yuan CS, Wang CZ, Wicks SM, Qi LW (2010) Chemical and pharmacological studies of saponins with a focus on American ginseng. Journal of ginseng research 34: 160–167.CS YuanCZ WangSM WicksLW Qi2010Chemical and pharmacological studies of saponins with a focus on American ginseng.Journal of ginseng research34160167
- 15. Han Y, Son SJ, Akhalaia M, Platonov A, Son HJ, et al. (2005) Modulation of radiation-induced disturbances of antioxidant defense systems by ginsan. Evid Based Complement Alternat Med 2: 529–536.Y. HanSJ SonM. AkhalaiaA. PlatonovHJ Son2005Modulation of radiation-induced disturbances of antioxidant defense systems by ginsan.Evid Based Complement Alternat Med2529536
- 16. Ahn JY, Choi IS, Shim JY, Yun EK, Yun YS, et al. (2006) The immunomodulator ginsan induces resistance to experimental sepsis by inhibiting Toll-like receptor-mediated inflammatory signals. Eur J Immunol 36: 37–45.JY AhnIS ChoiJY ShimEK YunYS Yun2006The immunomodulator ginsan induces resistance to experimental sepsis by inhibiting Toll-like receptor-mediated inflammatory signals.Eur J Immunol363745
- 17. Ahn JY, Song JY, Yun YS, Jeong G, Choi IS (2006) Protection of Staphylococcus aureus-infected septic mice by suppression of early acute inflammation and enhanced antimicrobial activity by ginsan. FEMS Immunol Med Microbiol 46: 187–197.JY AhnJY SongYS YunG. JeongIS Choi2006Protection of Staphylococcus aureus-infected septic mice by suppression of early acute inflammation and enhanced antimicrobial activity by ginsan.FEMS Immunol Med Microbiol46187197
- 18. Quan FS, Huang C, Compans RW, Kang SM (2007) Virus-like particle vaccine induces protective immunity against homologous and heterologous strains of influenza virus. J Virol 81: 3514–3524.FS QuanC. HuangRW CompansSM Kang2007Virus-like particle vaccine induces protective immunity against homologous and heterologous strains of influenza virus.J Virol8135143524
- 19. Lim YJ, Na HS, Yun YS, Choi IS, Oh JS, et al. (2009) Suppressive effects of ginsan on the development of allergic reaction in murine asthmatic model. Int Arch Allergy Immunol 150: 32–42.YJ LimHS NaYS YunIS ChoiJS Oh2009Suppressive effects of ginsan on the development of allergic reaction in murine asthmatic model.Int Arch Allergy Immunol1503242
- 20. Park JD, Shin HJ, Kwak YS, Wee JJ, Song YB, et al. (2006) Partial chemical structure and immunomodulating antitumor activities of RGAP (Red ginseng Acidic polysaccharide) from Korean red ginseng. The 9th International Symposium on Ginseng 390–409.JD ParkHJ ShinYS KwakJJ WeeYB Song2006Partial chemical structure and immunomodulating antitumor activities of RGAP (Red ginseng Acidic polysaccharide) from Korean red ginseng.The 9th International Symposium on Ginseng390409
- 21. Nakaya TA, Kita M, Kuriyama H, Iwakura Y, Imanishi J (2004) Panax ginseng induces production of proinflammatory cytokines via toll-like receptor. J Interferon Cytokine Res 24: 93–100.TA NakayaM. KitaH. KuriyamaY. IwakuraJ. Imanishi2004Panax ginseng induces production of proinflammatory cytokines via toll-like receptor.J Interferon Cytokine Res2493100
- 22. Quan FS, Compans RW, Nguyen HH, Kang SM (2008) Induction of heterosubtypic immunity to influenza virus by intranasal immunization. J Virol 82: 1350–1359.FS QuanRW CompansHH NguyenSM Kang2008Induction of heterosubtypic immunity to influenza virus by intranasal immunization.J Virol8213501359
- 23. Quan FS, Compans RW, Cho YK, Kang SM (2007) Ginseng and Salviae herbs play a role as immune activators and modulate immune responses during influenza virus infection. Vaccine 25: 272–282.FS QuanRW CompansYK ChoSM Kang2007Ginseng and Salviae herbs play a role as immune activators and modulate immune responses during influenza virus infection.Vaccine25272282
- 24. Quan FS, Kim YC, Vunnava A, Yoo DG, Song JM, et al. (2010) Intradermal vaccination with influenza virus-like particles by using microneedles induces protection superior to that with intramuscular immunization. J Virol 84: 7760–7769.FS QuanYC KimA. VunnavaDG YooJM Song2010Intradermal vaccination with influenza virus-like particles by using microneedles induces protection superior to that with intramuscular immunization.J Virol8477607769
- 25. Quan FS, Steinhauer D, Huang C, Ross TM, Compans RW, et al. (2008) A bivalent influenza VLP vaccine confers complete inhibition of virus replication in lungs. Vaccine 26: 3352–3361.FS QuanD. SteinhauerC. HuangTM RossRW Compans2008A bivalent influenza VLP vaccine confers complete inhibition of virus replication in lungs.Vaccine2633523361
- 26. Rhule A, Navarro S, Smith JR, Shepherd DM (2006) Panax notoginseng attenuates LPS-induced pro-inflammatory mediators in RAW264.7 cells. J Ethnopharmacol 106: 121–128.A. RhuleS. NavarroJR SmithDM Shepherd2006Panax notoginseng attenuates LPS-induced pro-inflammatory mediators in RAW264.7 cells.J Ethnopharmacol106121128
- 27. Shin JY, Song JY, Yun YS, Yang HO, Rhee DK, et al. (2002) Immunostimulating effects of acidic polysaccharides extract of Panax ginseng on macrophage function. Immunopharmacol Immunotoxicol 24: 469–482.JY ShinJY SongYS YunHO YangDK Rhee2002Immunostimulating effects of acidic polysaccharides extract of Panax ginseng on macrophage function.Immunopharmacol Immunotoxicol24469482
- 28. Kim MH, Byon YY, Ko EJ, Song JY, Yun YS, et al. (2009) Immunomodulatory activity of ginsan, a polysaccharide of panax ginseng, on dendritic cells. Korean J Physiol Pharmacol 13: 169–173.MH KimYY ByonEJ KoJY SongYS Yun2009Immunomodulatory activity of ginsan, a polysaccharide of panax ginseng, on dendritic cells.Korean J Physiol Pharmacol13169173
- 29. Tumpey TM, Lu X, Morken T, Zaki SR, Katz JM (2000) Depletion of lymphocytes and diminished cytokine production in mice infected with a highly virulent influenza A (H5N1) virus isolated from humans. J Virol 74: 6105–6116.TM TumpeyX. LuT. MorkenSR ZakiJM Katz2000Depletion of lymphocytes and diminished cytokine production in mice infected with a highly virulent influenza A (H5N1) virus isolated from humans.J Virol7461056116
- 30. Maruoka S, Hashimoto S, Gon Y, Nishitoh H, Takeshita I, et al. (2003) ASK1 regulates influenza virus infection-induced apoptotic cell death. Biochem Biophys Res Commun 307: 870–876.S. MaruokaS. HashimotoY. GonH. NishitohI. Takeshita2003ASK1 regulates influenza virus infection-induced apoptotic cell death.Biochem Biophys Res Commun307870876
- 31. Mok CK, Lee DC, Cheung CY, Peiris M, Lau AS (2007) Differential onset of apoptosis in influenza A virus H5N1- and H1N1-infected human blood macrophages. J Gen Virol 88: 1275–1280.CK MokDC LeeCY CheungM. PeirisAS Lau2007Differential onset of apoptosis in influenza A virus H5N1- and H1N1-infected human blood macrophages.J Gen Virol8812751280
- 32. Schultz-Cherry S, Dybdahl-Sissoko N, Neumann G, Kawaoka Y, Hinshaw VS (2001) Influenza virus ns1 protein induces apoptosis in cultured cells. J Virol 75: 7875–7881.S. Schultz-CherryN. Dybdahl-SissokoG. NeumannY. KawaokaVS Hinshaw2001Influenza virus ns1 protein induces apoptosis in cultured cells.J Virol7578757881
- 33. Brydon EW, Morris SJ, Sweet C (2005) Role of apoptosis and cytokines in influenza virus morbidity. FEMS Microbiol Rev 29: 837–850.EW BrydonSJ MorrisC. Sweet2005Role of apoptosis and cytokines in influenza virus morbidity.FEMS Microbiol Rev29837850
- 34. Armstrong L, Hughes O, Yung S, Hyslop L, Stewart R, et al. (2006) The role of PI3K/AKT, MAPK/ERK and NFkappabeta signalling in the maintenance of human embryonic stem cell pluripotency and viability highlighted by transcriptional profiling and functional analysis. Hum Mol Genet 15: 1894–1913.L. ArmstrongO. HughesS. YungL. HyslopR. Stewart2006The role of PI3K/AKT, MAPK/ERK and NFkappabeta signalling in the maintenance of human embryonic stem cell pluripotency and viability highlighted by transcriptional profiling and functional analysis.Hum Mol Genet1518941913
- 35. Chen PY, Sun JS, Tsuang YH, Chen MH, Weng PW, et al. (2010) Simvastatin promotes osteoblast viability and differentiation via Ras/Smad/Erk/BMP-2 signaling pathway. Nutr Res 30: 191–199.PY ChenJS SunYH TsuangMH ChenPW Weng2010Simvastatin promotes osteoblast viability and differentiation via Ras/Smad/Erk/BMP-2 signaling pathway.Nutr Res30191199
- 36. Lim TS, Na K, Choi EM, Chung JY, Hwang JK (2004) Immunomodulating activities of polysaccharides isolated from Panax ginseng. J Med Food 7: 1–6.TS LimK. NaEM ChoiJY ChungJK Hwang2004Immunomodulating activities of polysaccharides isolated from Panax ginseng.J Med Food716
- 37. Lu ZQ, Dice JF (1985) Ginseng extract inhibits protein degradation and stimulates protein synthesis in human fibroblasts. Biochem Biophys Res Commun 126: 636–640.ZQ LuJF Dice1985Ginseng extract inhibits protein degradation and stimulates protein synthesis in human fibroblasts.Biochem Biophys Res Commun126636640