Ginseng Protects Against Respiratory Syncytial Virus by Modulating Multiple Immune Cells and Inhibiting Viral Replication

Ginseng has been used in humans for thousands of years but its effects on viral infection have not been well understood. We investigated the effects of red ginseng extract (RGE) on respiratory syncytial virus (RSV) infection using in vitro cell culture and in vivo mouse models. RGE partially protected human epithelial (HEp2) cells from RSV-induced cell death and viral replication. In addition, RGE significantly inhibited the production of RSV-induced pro-inflammatory cytokine (TNF-α) in murine dendritic and macrophage-like cells. More importantly, RGE intranasal pre-treatment prevented loss of mouse body weight after RSV infection. RGE treatment improved lung viral clearance and enhanced the production of interferon (IFN-γ) in bronchoalveolar lavage cells upon RSV infection of mice. Analysis of cellular phenotypes in bronchoalveolar lavage fluids showed that RGE treatment increased the populations of CD8⁺ T cells and CD11c⁺ dendritic cells upon RSV infection of mice. Taken together, these results provide evidence that ginseng has protective effects against RSV infection through multiple mechanisms, which include improving cell survival, partial inhibition of viral replication and modulation of cytokine production and types of immune cells migrating into the lung.     

The novel adjuvant CoVaccineHT™ increases the immunogenicity of cell-culture derived influenza A/H5N1 vaccine and induces the maturation of murine and human dendritic cells in vitro

A candidate influenza H5N1 vaccine based on cell-culture-derived whole inactivated virus and the novel adjuvant CoVaccineHT™ was evaluated in vitro and in vivo. To this end, mice were vaccinated with the whole inactivated influenza A/H5N1 virus vaccine with and without CoVaccineHT™ and virus-specific antibody and cellular immune responses were assessed. The addition of CoVaccineHT™ increased virus specific primary and secondary antibody responses against the homologous and an antigenically distinct heterologous influenza A/H5N1 strain. The superior antibody responses induced with the CoVaccineHT™-adjuvanted vaccine correlated with the magnitude of the virus-specific CD4+ T helper cell responses. CoVaccineHT™ did not have an effect on the magnitude of the CD8+ T cell response. In vitro, CoVaccineHT™ upregulated the expression of co-stimulatory molecules both on mouse and human dendritic cells and induced the secretion of pro-inflammatory cytokines TNF-α, IL-6, IL-1β and IL-12p70 in mouse- and IL-6 in human dendritic cells. Inhibition experiments indicated that the effect of CoVaccineHT™ is mediated through TLR4 signaling. These data suggest that CoVaccineHT™ also will increase the immunogenicity of an influenza A/H5N1 vaccine in humans.     

Influence of the route of administration on immunomodulatory properties of bovine β-lactoglobulin-producing Lactobacillus casei

Because of their intrinsic immunomodulatory properties, some lactic acid bacteria were reported to modulate allergic immune responses in mice and humans. We recently developed recombinant strains of Lactobacillus casei that produce β-lactoglobulin (BLG), a major cow's milk allergen. Here, we investigated immunomodulatory potency of intranasal and oral administrations of recombinant lactobacilli on a subsequent sensitization of mice to BLG. Intranasal administration of the BLG-producing Lb. casei stimulated serum BLG-specific IgG2a and IgG1 responses, and fecal IgA response as well, but did not inhibit BLG-specific IgE production. In contrast, oral administration led to a significant inhibition of BLG-specific IgE production while IgG1 and IgG2a responses were not stimulated. After both oral and intranasal administrations, production of IL-17 cytokine by BLG-reactivated splenocytes was similarly enhanced, thus confirming the adjuvant effect of the Lb. casei strain. However, a mixed Th1/Th2 cell response was evidenced in BLG-reactivated splenocytes from mice intranasally pretreated, with enhanced secretions of Th1 cytokines (IFN-γ and IL-12) and Th2 cytokines (IL-4 and IL-5) whereas only production of Th1 cytokines, but not Th2 cytokines, was enhanced in BLG-reactivated splenocytes from mice orally pretreated. Our results show that the mode of administration of live bacteria may be critical for their immunomodulatory effects.     

Ginseng and Salviae herbs play a role as immune activators and modulate immune responses during influenza virus infection

We have investigated the adjuvant roles of common herbal medicines (ginseng, Salviae) and their effects on early immune responses during influenza virus infection in a mouse model. Intranasal co-administration with inactivated influenza virus A (PR8) and ginseng or Salviae extract increased the levels of influenza virus specific antibodies and neutralizing activities compared to immunization with PR8 alone, and provided protective immunity. Salviae co-administration significantly enhanced IFN-gamma and IL-2 cytokine producing splenocytes while ginseng induced high levels of IL-4 and IL-5 cytokine producing cells after challenge infection. Cells expressing an early activation marker CD69 and levels of a pro-inflammatory cytokine IL-6 were highly elevated in lungs from na?ve mice during challenge virus infection, which might be a mechanism in lung inflammation leading to death. In contrast, immunized mice that were co-administered ginseng or Salviae modulated CD69 expressing immune cells, did not produce IL-6, and showed significant enhancement of influenza virus specific IgA antibody in lungs after challenge virus infection. Therefore, these results indicate that both ginseng and Salviae play a role as mucosal adjuvants against influenza virus as well as immuno-modulators during influenza virus infection.     

Immunostimulatory Effects of Live Lactobacillus sakei K040706 on the CYP-Induced Immunosuppression Mouse Model

Our previous studies have shown that heat-killed Lactobacillus sakei K040706 exerts immunostimulatory and anti-inflammatory activities in macrophages, cyclophosphamide (CYP)-treated mice, and dextran sulfate sodium–induced colitis mice. However, the immunostimulatory effects of live Lactobacillus sakei K040706 (live K040706) against CYP-induced immunosuppression and its underlying molecular mechanisms remain unknown. Therefore, we investigated the immunostimulatory effects of live K040706 (10⁸ or 10⁹ colony forming unit (CFU)/day, p.o.) in CYP-induced immunosuppressed mice. Oral administration of live K040706 prevented the CYP-induced decreases in body weight, thymus index, natural killer (NK) cell activity, T and B cell proliferation, and cytokine (interferon (IFN)-γ, interleukin (IL)-2, and IL-12) production. The administration of live K040706 also exerted positive effects on the gut microbiota of CYP-induced mice, resulting in a microbiota composition similar to that of normal mice. Moreover, live K040706 significantly enhanced IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF) production in the splenocytes and Peyer’s patch (PP) cells of mice and increased bone marrow (BM) cell proliferation. Taken together, our data indicate that live K040706 may effectively accelerate recovery from CYP-induced immunosuppression, leading to activation of the immune system. Therefore, live K040706 may serve as a potential immunomodulatory agent against immunosuppression.     

α-Galactosylceramide potently augments M2e-induced protective immunity against highly pathogenic H5N1 avian influenza virus infection in mice

A new form of influenza A vaccine that can provide broadly cross-protective immunity is central in developing strategies to prepare for the next global flu pandemic. The ectodomain of the M2 protein (M2e) is an attractive target for developing such a kind of vaccine and several approaches have been proposed to overcome its poor immunogenicity nature. Here, we show change to the poor immunogenic characteristic of this antigen. This study demonstrates that α-galactosylceramide, which is an immunomodulatory glycolipid, can greatly enhance the protective immunity induced by M2e peptide absorbed in alum adjuvant. Mice were fully protected against highly pathogenic H5N1 avian influenza virus infection, exhibiting significantly reduced morbidity and lung viral titer after supplementing with α-galactosylceramide. α-Galactosylceramide simultaneously augmented the IgG1 and IgG2a antibody responses. In addition, mice immune sera showed enhanced abilities in binding to native M2 proteins on virus infected cells. The adjuvant also modulated the cytokine release of mice upon infection, upregulated the expressions of IFN-γ, IL-4 and several proinflammatory cytokines. In conclusion, we believe that M2e-peptide supplemented with α-galactosylceramide in alum adjuvant would be a promising vaccine formulation to combat the next influenza pandemic.     

Korean Red Ginseng Extract Inhibits IL-8 Expression via Nrf2 Activation in Helicobacter pylori-Infected Gastric Epithelial Cells

Helicobacter pylori (H. pylori) causes gastric diseases by increasing reactive oxygen species (ROS) and interleukin (IL)-8 expression in gastric epithelial cells. ROS and inflammatory responses are regulated by the activation of nuclear factor erythroid-2-related factor 2 (Nrf2) and the expression of Nrf2 target genes, superoxide dismutase (SOD) and heme oxygenase-1 (HO-1). We previously demonstrated that Korean red ginseng extract (RGE) decreases H. pylori-induced increases in ROS and monocyte chemoattractant protein 1 in gastric epithelial cells. We determined whether RGE suppresses the expression of IL-8 via Nrf2 activation and the expression of SOD and HO-1 in H. pylori-infected gastric epithelial AGS cells. H. pylori-infected cells were treated with RGE with or without ML385, an Nrf2 inhibitor, or zinc protoporphyrin (ZnPP), a HO-1 inhibitor. Levels of ROS and IL-8 expression; abundance of Keap1, HO-1, and SOD; levels of total, nuclear, and phosphorylated Nrf2; indices of mitochondrial dysfunction (reduction in mitochondrial membrane potential and ATP level); and SOD activity were determined. As a result, RGE disturbed Nrf2–Keap1 interactions and increased nuclear Nrf2 levels in uninfected cells. H. pylori infection decreased the protein levels of SOD-1 and HO-1, as well as SOD activity, which was reversed by RGE treatment. RGE reduced H. pylori-induced increases in ROS and IL-8 levels as well as mitochondrial dysfunction. ML385 or ZnPP reversed the inhibitory effect of RGE on the alterations caused by H. pylori. In conclusion, RGE suppressed IL-8 expression and mitochondrial dysfunction via Nrf2 activation, induction of SOD-1 and HO-1, and reduction of ROS in H. pylori-infected cells.     

Short-term supplementation with active hexose correlated compound improves the antibody response to influenza B vaccine

Administration of bioactive nutritional supplements near or at the time of immunization has been a recent approach to stimulate human immune response to vaccination. Active hexose correlated compound (AHCC), a mushroom extract, has been shown to protect mice against lethal primary influenza infection. Moreover, when AHCC was administered pre-vaccination in mice, they showed improved protection from lethal avian flu infection when compared to mice vaccinated alone. In this study, we hypothesized that AHCC will also improve the immune responses of healthy individuals to influenza vaccine. A randomized controlled study was performed with 30 healthy adults to evaluate the effects of AHCC supplementation on the immune response to the 2009-2010 seasonal influenza vaccine. Blood was drawn pre-vaccination and 3 wk post-vaccination. Immediately post-vaccination, the AHCC group began supplementation with AHCC (3 g/d). Flow cytometric analysis of lymphocyte subpopulations revealed that AHCC supplementation increased NKT cells (P < .1), and CD8 T cells (P < .05) post-vaccination compared to controls. Analysis of antibody production 3 weeks post-vaccination revealed that AHCC supplementation significantly improved protective antibody titers to influenza B, while the improvement was not significant in the control group. Overall, our study showed that AHCC supplementation improved some lymphocyte percentages and influenza B antibody titers over the control. Future studies are required to determine the kinetics of AHCC supplementation to improve the overall response to influenza vaccination.     

Iron deficiency reduces serum and in vitro secretion of interleukin-4 in mice independent of altered spleen cell proliferation

Iron deficiency, a worldwide public health problem in children and adult women, impairs innate and cell-mediated immunity including interferon-γ secretion. Its effects on interleukin (IL)-4 have not been well investigated. Interleukin-4, a cytokine primarily secreted by TH2 lymphocytes, regulates B-cell proliferation and the switching of immunoglobulin (Ig)M to IgE subtypes; the latter is involved in the defense against helminth infection. Considering the fact that interferon-γ is a potent inhibitor of IL-4, we hypothesize that iron deficiency would increase the secretion of IL-4 and IgE. We measured IL-4 in serum and supernatant of concanavalin A and anti-CD3 antibody-treated spleen cells from iron-deficient, control, pair-fed DBA and C57BL/6 mice (20-24/group) and iron-replete mice for 3, 7, and 14 days (8-13/group). Feeding the low-iron diet (5 ppm vs 50 ppm for the control diet) for 2 months significantly reduced the mean levels of hemoglobin, hematocrit, liver iron stores, thymus weight, and induced splenomegaly in both strains of mice (P < .001). Iron deficiency, and not pair-feeding, reduced plasma IL-4 levels (P < .05), although it did not significantly affect IgE levels. Iron deficiency, especially when associated with thymus atrophy, reduced in vitro IL-4 secretion by activated spleen cells, cell proliferation, and percentage of CD4⁺IL-4⁺ cells (P < .05). Impaired cell proliferation did not fully explain reduced in vitro IL-4 secretion because iron-deficient mice with a normal thymus weight had a normal ³H-thymidine uptake but decreased supernatant IL-4. It was likely due to low percentage of CD4⁺IL-4⁺. Iron repletion improved IL-4 measurements. Data suggest that iron deficiency has generalized negative effects on T-cell function. Unaltered plasma IgE may be due to other cytokines (ie, IL-13) that also modulate its secretion.     

Plasmodium berghei ANKA Infection in ICR Mice as a Model of Cerebral Malaria

Background

Animal models with various combination of host-parasite have long been employed to study malaria pathogenesis. Here, we describe the combination of Plasmodium berghei ANKA infection in inbred ICR mice as a model of cerebral malaria (CM).

Methods

Infection in mice was initiated by intraperitoneal injection of 2 x 10⁷ (0.2ml) parasitized red blood cells (PRBCs).

Results

This model can produce a severe degree of infection presented by the high degree of parasitaemia followed by death 6-7 days post infection. Severe anemia, splenomegaly, hepatomegaly and discolourations of major organs were observed. Histopathological findings revealed several important features mimicking human CM including, microvascular sequestration of PRBCs in major organs, particularly in the brain, hypertrophy and hyperplasia of the kupffer cells in the liver, pulmonary edema and hyaline membrane formation in the lungs and haemorrhages in the kidney''s medulla and cortex. Proinflammatory cytokines TNFα, IFNγ, IL-1, IL-6 and IL-18, and anti-inflammatory cytokine IL-10 were all found to be elevated in the plasma of infected mice.

Conclusion

This model can reproduce many of the important features of CM and therefore can be used as a tool to advance our understanding of the disease pathogenesis.     

A broad protection provided by matrix protein 2 (M2) of avian influenza virus

To prevent a future influenza A virus subtype pandemic outbreak, developing a broad-spectrum vaccine would be highly beneficial. The ion channel protein M2 is highly conserved in a diverse number of influenza A virus subtypes. This distinguishing characteristic makes M2 an attractive vaccine target for a broadly protective vaccine. We expressed a full-length M2 protein which was C-terminally fused to a small peptide in Escherichia coli. Because this recombinant M2 (rM2) protein forms multimeric complexes with high molecular weight, it serves as a potential immunogen. Antibodies induced by the rM2 protein prevented the replication of different subtypes of influenza A virus both in vitro and in vivo. Animal study demonstrated that rM2 immunization protected mice against influenza A virus infection via limiting replication of virus progeny in vivo and attenuating lung damage. As such, the M2 protein is a highly potential candidate for next generation vaccine development with the capability of protecting against various influenza A virus subtypes.     

Bovine colostrum enhances natural killer cell activity and immune response in a mouse model of influenza infection and mediates intestinal immunity through toll-like receptors 2 and 4

Oral administration of bovine colostrum affects intestinal immunity, including an increased percentage of natural killer (NK) cells. However, effects on NK cell cytotoxic activity and resistance to infection as well as a potential mechanism remain unclear. Therefore, we investigated the effects of bovine colostrum (La Belle, Inc, Bellingham, WA) on the NK cytotoxic response to influenza infection and on toll-like receptor (TLR) activity in a primary intestinal epithelial cell culture. We hypothesized that colostrum would increase NK cell activity and that TLR-2 and TLR-4 blocking would reduce interleukin 6 production by epithelial cells in response to contact stimulation with colostrum. Four-month-old female C57BL/6 mice were supplemented with 1 g of colostrum per kilogram of body weight before and after infection with influenza A virus (H1N1). Animals were assessed for weight loss, splenic NK cell activity, and lung virus titers. Colostrum-supplemented mice demonstrated less reduction in body weight after influenza infection, indicating a less severe infection, increased NK cell cytotoxicity, and less virus burden in the lungs compared with controls. Colostrum supplementation enhanced NK cell cytotoxicity and improved the immune response to primary influenza virus infection in mice. To investigate a potential mechanism, a primary culture of small intestine epithelial cells was then stimulated with colostrum. Direct activation of epithelial cells resulted in increased interleukin 6 production, which was inhibited with TLR-2 and TLR-4 blocking antibodies. The interaction between colostrum and immunity may be dependent, in part, on the interaction of colostrum components with innate receptors at the intestinal epithelium, including TLR-2 and TLR-4.     

Advax delta inulin adjuvant overcomes immune immaturity in neonatal mice thereby allowing single–dose influenza vaccine protection

Neonates are at high risk for influenza morbidity and mortality due to immune immaturity and lack of priming by prior influenza virus exposure. Inactivated influenza vaccines are ineffective in infants under six months and to provide protection in older children generally require two doses given a month apart. This leaves few options for rapid protection of infants, e.g. during an influenza pandemic. We investigated whether Advax™, a novel polysaccharide adjuvant based on delta inulin microparticles could help overcome neonatal immune hypo-responsiveness. We first tested whether it was possible to use Advax to obtain single-dose vaccine protection of neonatal pups against lethal influenza infection. Inactivated influenza A/H1N1 vaccine (iH1N1) combined with Advax™ adjuvant administered as a single subcutaneous immunization to 7-day-old mouse pups significantly enhanced serum influenza-specific IgM, IgG1, IgG2a and IgG2b levels and was associated with a 3–4 fold increase in the frequency of splenic influenza-specific IgM and IgG antibody secreting cells. Pups immunized with Advax had significantly higher splenocyte influenza-stimulated IFN-γ, IL-2, IL-4, and IL-10 production by CBA and a 3–10 fold higher frequency of IFN-γ, IL-2, IL-4 or IL-17 secreting T cells by ELISPOT. Immunization with iH1N1 + Advax induced robust protection of pups against virus challenge 3 weeks later, whereas pups immunized with iH1N1 antigen alone had no protection. Protection by Advax-adjuvanted iH1N1 was dependent on memory B cells rather than memory T cells, with no protection in neonatal μMT mice that are B-cell deficient. Hence, Advax adjuvant overcame neonatal immune hypo-responsiveness and enabled single-dose protection of pups against otherwise lethal influenza infection, thereby supporting ongoing development of Advax™ as a neonatal vaccine adjuvant.     

Ingenol Protects Human T Cells From HIV-1 Infection

Objectives

Many natural compounds have been investigated as drug candidates to prevent human immunodeficiency virus (HIV) with low cytotoxicity. We tested whether ingenol from Euphorbia ingens exerts anti-HIV effects in human T cell lines.

Methods and Results

Ingenol effectively maintained high cell viability (CD₅₀, >1 mM) in H9 and MT4 T cells. The efficacy of ingenol to inhibit HIV-1 infection was dose dependent. ED₅₀ for 100 and 200 TCID₅₀ of HIV-1 was 5.06 and 16.87 μM, respectively. Gag p24 antigen production in ingenol-treated MT4 cells was reduced by 24.5% on day 6 post-infection. While p24 antigen was reduced in ingenol-treated cells, levels of cytokines such as TNF-α and IL-6 and chemokines such as RANTES and MCP-1 were increased. dUTP level related to late apoptotic events was increased on day 2 post-infection of HIV by ingenol treatment, whereas expression of annexin V was unchanged. Reduced levels of iNOS and ZAP-70 after HIV infection were recovered by ingenol treatment.

Conclusion

Ingenol helps T cells to survive longer against viremia after HIV-1 infection, without exerting cytotoxic effects. Ingenol can be considered a safe and efficacious candidate for immune-boosting therapy for AIDS patients.     

Subunit vaccines based on recombinant yeast protect against influenza A virus in a one-shot vaccination scheme

Here we report on new subunit vaccines based on recombinant yeast of the type Kluyveromyces lactis (K. lactis), which protect mice from a lethal influenza A virus infection. Applying a genetic system that enables the rapid generation of transgenic yeast, we have developed K. lactis strains that express the influenza A virus hemagglutinin, HA, either individually or in combination with the viral M1 matrix protein. Subcutaneous application of the inactivated, but otherwise non-processed yeast material shows a complete protection of BALB/c mice in prime/boost and even one-shot/single dose vaccination schemes against a subsequent, lethal challenge with the cognate influenza virus. The yeast vaccines induce titers of neutralizing antibodies that are readily comparable to those induced by an inactivated virus vaccine. These data suggest that HA and M1 are produced with a high antigenicity in the yeast cells. Based on these findings, multivalent, DIVA-capable, yeast-based subunit vaccines may be developed as promising alternatives to conventional virus-based anti-flu vaccines for veterinary applications.     

Impact of immunization against SpyCEP during invasive disease with two streptococcal species: Streptococcus pyogenes and Streptococcus equi

Currently there is no licensed vaccine against the human pathogen Streptococcus pyogenes. The highly conserved IL-8 cleaving S. pyogenes cell envelope proteinase SpyCEP is surface expressed and is a potential vaccine candidate. A recombinant N-terminal part of SpyCEP (CEP) was expressed and purified. AntiCEP antibodies were found to neutralize the IL-8 cleaving activity of SpyCEP. CEP-immunized mice had reduced bacterial dissemination from focal S. pyogenes intramuscular infection and intranasal infection. We also identified a functional SpyCEP-homolog protease SeCEP, expressed by the equine pathogen Streptococcus equi, which was able to cleave both human and equine IL-8. CEP-immunized mice also demonstrated reduced bacterial dissemination from S. equi intramuscular infection. Therefore immunization against SpyCEP may provide protection against other streptococci species with homologous proteases.     

Evaluation of immune responses and analysis of the effect of vaccination of the Leishmania major recombinant ribosomal proteins L3 or L5 in two different murine models of cutaneous leishmaniasis

Four new antigenic proteins located in Leishmania ribosomes have been characterized: S4, S6, L3 and L5. Recombinant versions of the four ribosomal proteins from Leishmania major were recognized by sera from human and canine patients suffering different clinical forms of leishmaniasis. The prophylactic properties of these proteins were first studied in the experimental model of cutaneous leishmaniasis caused by L. major inoculation into BALB/c mice. The administration of two of them, LmL3 or LmL5 combined with CpG-oligodeoxynucleotides (CpG-ODN) was able to protect BALB/c mice against L. major infection. Vaccinated mice showed smaller lesions and parasite burden compared to mice inoculated with vaccine diluent or vaccine adjuvant. Protection was correlated with an antigen-specific increased production of IFN-γ paralleled by a decrease of the antigen-specific IL-10 mediated response in protected mice relative to non-protected controls. Further, it was demonstrated that BALB/c mice vaccinated with recombinant LmL3 or LmL5 plus CpG-ODN were also protected against the development of cutaneous lesions following inoculation of L. braziliensis. Together, data presented here indicate that LmL3 or LmL5 ribosomal proteins combined with Th1 inducing adjuvants, may be relevant components of a vaccine against cutaneous leishmaniasis caused by distinct species.     

Heat-Killed Enterococcus faecalis EF-2001 Ameliorates Atopic Dermatitis in a Murine Model

Recent reports have shown the immunomodulatory effect of heat-killed lactic acid bacteria. Atopic dermatitis (AD) is an allergic skin disease, caused by immune dysregulation among other factors. The aim of this study was to assess the effect of heat-killed Enterococcus faecalis EF-2001 (EF-2001) on AD. We established an in vivo AD model by repeated local exposure of Dermatophagoides farinae extract (DFE; house dust mite extract) and 2,4-dinitrochlorobenzene (DNCB) to the ears of mice. After oral administration of EF-2001 for four weeks, the epidermal and dermal ear thickness, mast cell infiltration, and serum immunoglobulin levels were measured. In addition, the gene expression levels of pathogenic cytokines in the ears, lymph nodes, and splenocytes were assayed. EF-2001 attenuated AD symptoms based on the ear thickness, histopathological analysis, and serum immunoglobulin levels. Moreover, EF-2001 decreased the DFE/DNCB-induced expression of various pathogenic cytokines in the ears, lymph nodes, and splenocytes. These results suggest that EF-2001 has therapeutic potential in the treatment of AD owing to its immunomodulatory effects.     

Echinacea purpurea aerial extract alters course of influenza infection in mice

Influenza infection is a major clinical problem and Echinacea purpurea, a widely consumed botanical product, is purported to alter the course of respiratory infections including influenza. Mice infected with WSN influenza A and treated with E. purpurea polysaccharide extract had less weight loss than untreated mice but similar pulmonary viral titers. Echinacea-treated mice had lower systemic and pulmonary KC and IL-10 levels and lower systemic IFN-γ levels following influenza infection. These suggest that E. purpurea alters the clinical course of influenza infection in mice through modulation of cytokines and not direct antiviral activity.     

Enhancement of T cell-mediated immune responses to whole inactivated influenza virus by chloroquine treatment in vivo

Current influenza vaccines induce poor cross-reactive CD8+ T cell responses. Cellular immunity is generally specific for epitopes that are remarkably conserved among different subtypes, suggesting that strategies to improve the cross-presentation of viral antigens by dendritic cells (DC) could elicit a broadly protective immune response. Previous studies have shown that limited proteolysis within the endocytic pathway can favorably influence antigen processing and thus immune responses. Herein, we demonstrate that chloroquine improves the cross-presentation of non-replicating influenza virus in vitro and T cell responses in mice following a single administration of inactivated HI-X31 virus. CD8+ T cells were also recruited to lymph nodes draining the site of infection and able to reduce viral load following pulmonary challenge with the heterologous PR8 virus. These findings may have implications for vaccination strategies aimed at improving the cross-presentation capacity of DCs and thus the size of effector and memory CD8+ T cells against influenza vaccines.