Race between virus and inflammasomes: inhibition or escape, intervention and therapy.

The inflammasome is a multiprotein complex that further regulates cell pyroptosis and inflammation by activating caspase-1. The assembly and activation of inflammasome are associated with a variety of diseases. Accumulative studies have shown that inflammasome is a key modulator of the host's defense response to viral infection. Indeed, it has been established that activation of inflammasome occurs during viral infection. At the same time, the host has evolved a variety of corresponding mechanisms to inhibit unnecessary inflammasome activation. Therefore, here, we review and summarize the latest research progress on the interaction between inflammosomes and viruses, highlight the assembly and activation of inflammosome in related cells after viral infection, as well as the corresponding molecular regulatory mechanisms, and elucidate the effects of this activation on virus immune escape and host innate and adaptive immune defenses. Finally, we also discuss the potential therapeutic strategies to prevent and/or ameliorate viral infection-related diseases via targeting inflammasomes and its products.

Nutraceuticals in Viral Infections: An Overview of the Immunomodulating Properties.

Nutraceuticals, including vitamin D, vitamin A, zinc, lactoferrin, polyphenols coenzyme Q, magnesium, and selenium, are implicated in the modulation of the complex molecular pathways involved in the immune response against viral pathogens. A common element of the activity of nutraceuticals is their ability to enhance the innate immune response against pathogens by acting on the major cellular subsets and inducing the release of pro-inflammatory cytokines and antimicrobial peptides. In some cases, this action is accompanied by a direct antimicrobial effect, as evidenced in the specific case of lactoferrin. Furthermore, nutraceuticals act through complex molecular mechanisms to minimize the damage caused by the activation of the immune system against pathogens, reducing the oxidative damage, influencing the antigen presentation, enhancing the differentiation and proliferation of regulatory T cells, driving the differentiation of lymphocyte subsets, and modulating the production of pro-inflammatory cytokines. In this paper, we review the main molecular mechanisms responsible for the immunomodulatory function of nutraceuticals, focusing on the most relevant aspects for the prevention and treatment of viral infections.

Fructans as Immunomodulatory and Antiviral Agents: The Case of Echinacea.

Throughout history, medicinal purposes of plants have been studied, documented, and acknowledged as an integral part of human healthcare systems. The development of modern medicine still relies largely on this historical knowledge of the use and preparation of plants and their extracts. Further research into the human microbiome highlights the interaction between immunomodulatory responses and plant-derived, prebiotic compounds. One such group of compounds includes the inulin-type fructans (ITFs), which may also act as signaling molecules and antioxidants. These multifunctional compounds occur in a small proportion of plants, many of which have recognized medicinal properties. Echinacea is a well-known medicinal plant and products derived from it are sold globally for its cold- and flu-preventative and general health-promoting properties. Despite the well-documented phytochemical profile of Echinacea plants and products, little research has looked into the possible role of ITFs in these products. This review aims to highlight the occurrence of ITFs in Echinacea derived formulations and the potential role they play in immunomodulation.

Vitamin D [1,25(OH)2D3] Differentially Regulates Human Innate Cytokine Responses to Bacterial versus Viral Pattern Recognition Receptor Stimuli.

Vitamin D plays multiple roles in regulation of protective and maladaptive immunity. Although epidemiologic studies link poor in vivo 25(OH)D status to increased viral respiratory infections, we poorly understand how vitamin D affects viral pattern recognition receptor (PRR)-driven cytokine production. In this study, we hypothesized that the biologically active metabolite of vitamin D, 1,25(OH)2D3, inhibits human proinflammatory and anti-inflammatory innate cytokine responses stimulated by representative bacterial or viral PRR ligands. Fresh PBMCs or CD14(+) monocytes were stimulated with TLR4, TLR7/8-selective ligands, or respiratory syncytial virus (RSV) ± 1,25(OH)2D3. Proinflammatory and anti-inflammatory responses resulting from TLR4 stimulation were inhibited ∼50% in the presence of 1,25(OH)2D3. Conversely, its usage at physiologic through pharmacologic concentrations inhibited neither proinflammatory nor anti-inflammatory responses evoked by viral PRR ligands or infectious RSV. This differential responsiveness was attributed to the finding that TLR7/8, but not TLR4, stimulation markedly inhibited vitamin D receptor mRNA and protein expression, selectively reducing the sensitivity of viral PRR responses to modulation. 1,25(OH)2D3 also enhanced expression of IkBa, a potent negative regulator of NF-κB and cytokine production, in TLR4-stimulated monocytes while not doing so upon TLR7/8 stimulation. Thus, 1,25(OH)2D3 inhibits both proinflammatory and a broad panel of anti-inflammatory responses elicited by TLR4 stimulation, arguing that the common view of it as an anti-inflammatory immune response modifier is an oversimplification. In viral responses, it consistently fails to modify TLR7/8- or RSV-stimulated innate cytokine production, even at supraphysiologic concentrations. Collectively, the data call into question the rationale for increasingly widespread self-medication with vitamin D supplements.

[Stimulation of the antiviral innate immune response by pyrimidine biosynthesis inhibitors: a surprise of phenotypic screening]. / Activation de la réponse innée antivirale par des inhibiteurs de la biosynthèse des pyrimidines - Les surprises d'un criblage phénotypique.

RNA viruses are responsible for major human diseases such as flu, bronchitis, dengue, hepatitis C or measles. They also represent an emerging threat because of increased worldwide exchanges and human populations penetrating more and more natural ecosystems. Recent progresses in our understanding of cellular pathways controlling viral replication suggest that compounds targeting host cell functions, rather than the virus itself, could inhibit a large panel of RNA viruses. In particular, several academic laboratories and private companies are now seeking molecules that stimulate the host innate antiviral response. One appealing strategy is to identify molecules that induce the large cluster of antiviral genes known as Interferon-Stimulated Genes (ISGs). To reach this goal, we have developed a phenotypic assay based on human cells transfected with a luciferase reporter gene under control of an interferon-stimulated response element (ISRE). This system was used in a high-throughput screening of chemical libraries comprising around 54,000 compounds. Among validated hits, compound DD264 was shown to boost the innate immune response in cell cultures, and displayed a broad-spectrum antiviral activity. While deciphering its mode of action, DD264 was found to target the fourth enzyme of de novo pyrimidine biosynthesis, namely the dihydroorotate dehydrogenase (DHODH). Thus, our data unraveled a yet unsuspected link between pyrimidine biosynthesis and the innate antiviral response.

Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part I: Overview, vaccines for enteric viruses and Vibrio cholerae.

Efforts to develop vaccines for prevention of acute diarrhea have been going on for more than 40 y with partial success. The myriad of pathogens, more than 20, that have been identified as a cause of acute diarrhea throughout the years pose a significant challenge for selecting and further developing the most relevant vaccine candidates. Based on pathogen distribution as identified in epidemiological studies performed mostly in low-resource countries, rotavirus, Cryptosporidium, Shigella, diarrheogenic E. coli and V. cholerae are predominant, and thus the main targets for vaccine development and implementation. Vaccination against norovirus is most relevant in middle/high-income countries and possibly in resource-deprived countries, pending a more precise characterization of disease impact. Only a few licensed vaccines are currently available, of which rotavirus vaccines have been the most outstanding in demonstrating a significant impact in a short time period. This is a comprehensive review, divided into 2 articles, of nearly 50 vaccine candidates against the most relevant viral and bacterial pathogens that cause acute gastroenteritis. In order to facilitate reading, sections for each pathogen are organized as follows: i) a discussion of the main epidemiological and pathogenic features; and ii) a discussion of vaccines based on their stage of development, moving from current licensed vaccines to vaccines in advanced stage of development (in phase IIb or III trials) to vaccines in early stages of clinical development (in phase I/II) or preclinical development in animal models. In this first article we discuss rotavirus, norovirus and Vibrio cholerae. In the following article we will discuss Shigella, Salmonella (non-typhoidal), diarrheogenic E. coli (enterotoxigenic and enterohemorragic), and Campylobacter jejuni.

ICoVax 2013: the 3rd ISV Pre-conference Computational Vaccinology Workshop.

Following last year's computational vaccinology workshop in Shanghai, China, the third ISV Pre-conference Computational Vaccinology Workshop (ICoVax 2013) was held in Barcelona, Spain. ICoVax 2013 provided an international platform for the attendees to showcase their research and discuss problems and solutions in the development and application of computational vaccinology and vaccine informatics tools. The first of the three full-length papers presented at ICoVax discussed the discovery of viral "camouflage" through cross-conservation of T-cell epitopes using a tool called JanusMatrix. This important paper reports that viruses may camouflage their presence in the human body by incorporating sequences in their proteins that are highly cross-conserved at the T-cell receptor surface with human genome proteins, a discovery that has wide ranging implications for the development of vaccines against viruses that use the camouflage method. The other papers described a database for storing experimentally verified data on DNA vaccines and compared therapeutic targets of western drugs to Chinese herbal medicines for cardiovascular diseases. The short poster presentations covered various uses of informatics tools for processing the DNA and microRNA of pathogens to improve vaccine coverage, efficacy and development. A live (on-line) demonstration of the vaccine design toolkit, iVax, presented by Frances Terry of EpiVax, illustrated how computational vaccinology could be used in the design of next generation vaccines.

The type of adjuvant strongly influences the T-cell response during nanoparticle-based immunization.

Potent vaccines require the ability to effectively induce immune responses. Especially for the control of infectious diseases with intracellular pathogens, like viruses or bacteria, potent T-cell responses are indispensable. Several delivery systems such as nanoparticles have been considered to boost the immunogenicity of pathogen derived peptides or subunits for the induction of potent T-cell responses. Since they can be further functionalized with immunostimulants, like Toll-like receptor (TLR) agonists, they improve the response by enhanced activation of the innate immune system. Currently, TLR agonists like unmethylated CpG oligonucleotides and the synthetic dsRNA derivate polyriboinosinic acid-polyribocytidylic acid (poly[I:C]) are widely used as vaccine adjuvants. CpG and poly(I:C) trigger different TLRs and therefore show differential signal transduction. Recently, we established biodegradable calcium phosphate (CaP) nanoparticles as potent T cell inducing vaccination vehicles. In this commentary we discuss the role of CpG and poly(I:C) for the effective induction of virus-specific T cells during immunization with CaP nanoparticles. The presented results underline the importance of the right formulation of vaccines for specific immunization purpose.

The second messenger phosphatidylinositol-5-phosphate facilitates antiviral innate immune signaling.

Innate immune receptors, notably Toll-like receptors (TLRs) and RIG-I-like receptors (RLRs), sense viral infection and activate transcription factors, including interferon regulatory factor-3 (IRF3), to induce type I interferon (IFN). We demonstrate that the lipid phosphatidylinositol-5-phosphate (PtdIns5P) is increased upon viral infection and facilitates type I IFN production by binding to IRF3 and its upstream kinase TBK1 and promoting TBK1-mediated IRF3 phosphorylation and activation. Additionally, we determine that PtdIns5P is produced through the kinase PIKfyve, which phosphorylates PtdIns to generate PtdIns5P. Accordingly, PIKfyve knockdown or pharamoclogical inhibition decreases PtdIns5P levels and type I IFN production after TLR or RLR stimulation, and results in increased viral replication. A synthetic PtdIns5P, C8-PtdIns5P, promotes IRF3 phosphorylation and cytokine production in dendritic cells and acts as an adjuvant to boost immune responses in immunized mice. Thus, PtdIns5P produced during viral infection is a second messenger that targets the TBK1-IRF3 axis to elicit antiviral immunity.

Regulators of innate immunity as novel targets for panviral therapeutics.

Interferons (IFNs) have long been used as an immunomodulatory therapy for a large array of acute and chronic viral infections. However, IFN therapies have been plagued by severe side effects. The discovery of pathogen recognition receptors (PRR) rejuvenated the interest for immunomodulatory therapies. The successes obtained with Toll-like receptor (TLR) agonists in activating immune cells and as adjuvant for prophylactic vaccines against different viruses paved the way to targeted immunomodulatory therapy. Better characterization of pathogen-induced immune disorders and newly discovered regulators of innate immunity have now the potential to specifically withdraw prevailing subversion mechanisms and to transform antiviral treatments by introducing panviral therapeutics with less adverse effects than IFN therapies.

21 Days head-down bed rest induces weakening of cell-mediated immunity - Some spaceflight findings confirmed in a ground-based analog.

Several studies indicate a weakening of cell-mediated immunity (CMI) and reactivation of latent herpes viruses during spaceflight. We tested the hypothesis that head-down bed rest (HDBR), a ground-based analog of spaceflight, mimics the impact of microgravity on human immunity. Seven healthy young males underwent two periods of 3 weeks HDBR in the test facility of the German Aerospace Center. As a nutritional countermeasure aimed against bone demineralisation, 90 mmol potassium bicarbonate (KHCO(3)) was administered daily in a crossover design. Blood samples were drawn on five occasions. Whole blood was stimulated with antigen i.e. Candida albicans, purified protein derivative (PPD) tuberculin, tetanus toxoid and Cytomegalovirus (CMV) (CMV-QuantiFERON). Flow cytometric analysis included CD4(+)CD25(+)CD127(-)FOXP3(+) regulatory T cells (Tregs), γδ T cells, B cells, NK cells and dendritic cells. In one of the two bed rest periods, we observed a significant decrease in production of interleukin-2 (IL-2), interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) following phytohemagglutinin (PHA) stimulation, with a rapid normalization being observed after HDBR. The cytokine levels showed a V-shaped pattern that led to a relativeTh2-shift in cytokine balance. Only three individuals responded to the specific T cell antigens without showing signs of an altered response during HDBR, nor did we observe reactivation of CMV or Epstein-Barr virus (EBV). Of unknown significance, dietary supplementation with KHCO(3) counteracted the decrease in IL-2 levels during HDBR, while there was no impact on other immunological parameters. We conclude that discrete alterations in CMI may be induced by HDBR in selected individuals.

Nanobodies®: new ammunition to battle viruses.

In 1989, a new type of antibody was identified, first in the sera of dromedaries and later also in all other species of the Camelidae family. These antibodies do not contain a light chain and also lack the first constant heavy domain. Today it is still unclear what the evolutionary advantage of such heavy chain-only antibodies could be. In sharp contrast, the broad applicability of the isolated variable antigen-binding domains (VHH) was rapidly recognized, especially for the development of therapeutic proteins, called Nanobodies(®). Here we summarize first some of the unique characteristics and features of VHHs. These will next be described in the context of different experimental therapeutic applications of Nanobodies against different viruses: HIV, Hepatitis B virus, influenza virus, Respiratory Syncytial virus, Rabies virus, FMDV, Poliovirus, Rotavirus, and PERVs. Next, the diagnostic application of VHHs (Vaccinia virus, Marburg virus and plant Tulip virus X), as well as an industrial application (lytic lactococcal 936 phage) will be described. In addition, the described data show that monovalent Nanobodies can possess unique characteristics not observed with conventional antibodies. The straightforward formatting into bivalent, multivalent, and/or multispecific Nanobodies allowed tailoring molecules for potency and cross-reactivity against viral targets with high sequence diversity.

Human dendritic cells promote an antiviral immune response when stimulated by CVT-E002.

OBJECTIVES: There is interest in developing new compounds to enhance the immune response to airway virus infections. CVT-E002 is a patented ginseng extract shown to decrease symptoms of virus infection in clinical trials. We hypothesized that the mechanism for this antiviral effect could be through modulation of dendritic cells leading to enhanced T-cell activation. METHODS: Human monocyte-derived dendritic cells (moDC) exposed to CVT-E002 (or not) were co-cultured with autologous T cells, with or without virus (respiratory syncytial virus or parainfluenza virus). Effects of CVT-E002 on cell function were determined through flow cytometry, 5-bromo-2'-deoxyuridine (BrdU) incorporation and ELISA. KEY FINDINGS: moDC cultured with CVT-E002 or virus induced greater activation of T cells, as measured by CD25 expression and BrdU incorporation, compared with untreated moDC. Responding T cells were CD4+CD45RO+. Co-cultures of CVT-E002 treated moDC with T cells responded with increased release of Th1-type cytokines (interferon-gamma, tumour necrosis factor and interleukin-12). CVT-E002-treated moDC showed increased expression of CD83, CD80 and CD86. Lipopolysaccharide levels were not detected in CVT-E002 and antagonists for Toll-like receptor-4 did not inhibit CVT-E002-induced moDC maturation. CONCLUSIONS: CVT-E002 induced moDC maturation, which caused increased memory T-cell activation and Th1-type cytokine response.

Sociocultural and epidemiological aspects of HIV/AIDS in Mozambique

Background: A legacy of colonial rule coupled with a devastating 16-year civil war through 1992 left Mozambique economically impoverished just as the human immunodeficiency virus (HIV) epidemic swept over southern Africa in the late 1980s. The crumbling Mozambican health care system was wholly inadequate to support the need for new chronic disease services for people with the acquired immunodeficiency syndrome (AIDS). Methods: To review the unique challenges faced by Mozambique as they have attempted to stem the HIV epidemic, we undertook a systematic literature review through multiple search engines (PubMed, Google Scholar™, SSRN, AnthropologyPlus, AnthroSource) using Mozambique as a required keyword. We searched for any articles that included the required keyword as well as the terms 'HIV' and/or 'AIDS', 'prevalence', 'behaviors', 'knowledge', 'attitudes', 'perceptions', 'prevention', 'gender', drugs, alcohol, and/or 'health care infrastructure'. Results: UNAIDS 2008 prevalence estimates ranked Mozambique as the 8th most HIV-afflicted nation globally. In 2007, measured HIV prevalence in 36 antenatal clinic sites ranged from 3% to 35%; the national estimate of was 16%. Evidence suggests that the Mozambican HIV epidemic is characterized by a preponderance of heterosexual infections, among the world's most severe health worker shortages, relatively poor knowledge of HIV/AIDS in the general population, and lagging access to HIV preventive and therapeutic services compared to counterpart nations in southern Africa. Poor education systems, high levels of poverty and gender inequality further exacerbate HIV incidence. Conclusions: Recommendations to reduce HIV incidence and AIDS mortality rates in Mozambique include: health system strengthening, rural outreach to increase testing and linkage to care, education about risk reduction and drug adherence, and partnerships with traditional healers and midwives to effect a lessening of stigma.

Induction of multiple pro-inflammatory cytokines by respiratory viruses and reversal by standardized Echinacea, a potent antiviral herbal extract.

Several viruses associated with upper respiratory diseases have been shown to stimulate the secretion of pro-inflammatory cytokines, including chemokines, sometimes in the absence of viral cytopathology. We evaluated the ability of a standardized preparation of the popular herbal medicine Echinacea (Echinaforce, an ethanol extract of herb and roots of E. purpurea, and containing known concentrations of marker compounds) to inhibit the viral induction of various cytokines in a line of human bronchial epithelial cells (BEAS-2B), and in two other human cell lines. All of the viruses tested, rhinoviruses 1A and 14, influenza virus, respiratory syncytial virus, adenovirus types 3 and 11, and herpes simplex virus type 1, induced substantial secretion of IL-6 and IL-8 (CXCL8), in addition to several other chemokines, depending on the virus, although only viable viruses were able to do this. In every case however Echinacea inhibited this induction. The Echinacea preparation also showed potent virucidal activity against viruses with membranes, indicating the multi-functional potential of the herb. These results support the concept that certain Echinacea preparations can alleviate "cold and flu" symptoms, and possibly other respiratory disorders, by inhibiting viral growth and the secretion of pro-inflammatory cytokines.

The interaction between early life upper respiratory tract infection and birth during the pollen season on rye-sensitized hay fever and ryegrass sensitization--a birth cohort study.

Studies on early life viral respiratory infection and subsequent atopic disease in childhood have conflicting findings. Animal models show that viral respiratory infection in conjunction with allergen presentation can enhance sensitization. This prospective study assesses the influence of an upper respiratory tract infection (URI) in the first month of life and the season of birth on the development of hay fever and ryegrass allergen sensitization in childhood. From a Tasmanian cohort born during 1988 and 1989, a group of 498 children were followed up at 8 yr and another different group of 415 children were followed up at 16 yr. The ryegrass pollen season in Tasmania occurs in November and December. Forty-four (9.6%) children in Follow-up sample 1 and 47 (12.5%) children in Follow-up sample 2 were born in the pollen season. The parental report of an early upper respiratory tract infection (EURI) was documented prospectively by a home interview at 1 month of age (median age 5.1 wk). Sensitization to ryegrass and house dust mite (HDM) was determined at 8 yr of age by skin prick testing and at 16 yr by ImmunoCap. Ryegrass sensitized hay fever was defined as a positive response to a question on hay fever plus the presence of ryegrass allergy. For children tested at age 8 and born in the pollen season, a EURI by postnatal interview was associated with an increased risk of ryegrass sensitization (OR 5.80 95% CI 1.07, 31.31) but not for children with a EURI born outside the pollen season (OR 0.62 95% CI 0.35, 1.08). Similarly, EURI was significantly associated with early onset (< or = 8 yr) ryegrass sensitized hay fever for children born in the pollen season (AOR 4.78 95% CI 1.17, 19.47) but was not associated with early onset ryegrass sensitized hay fever for children born outside the pollen season (AOR 0.76 95% CI 0.43, 1.33). These findings suggest that early life viral URI interacts with ryegrass allergen exposure in the development of ryegrass allergen sensitization and ryegrass sensitized hay fever symptoms.

Portal to the interior: viral pathogenesis and natural compounds that restore mucosal immunity and modulate inflammation.

Most antigens, particularly viruses, enter the body through the mucosal epithelia where they are carried by afferent lymphatics to regional lymph nodes for presentation to the immune system. Although they share immunological similarities, immune processes that protect the mucosa are distinct from innate and acquired immunity. The barrier formed by the intestinal mucosa is the most studied, with its microenvironment having a marked influence on both local and systemic immune responses. A healthy microenvironment and resilient neighboring tissue provide protection against inflammation known to dampen mucosal immunity, promote carcinogenesis, contribute to systemic inflammatory processes, and result in autoimmune diseases. Numerous natural substances improve this microenvironment and thereby enhance immunity against microbial infections. Since mucosal immunity forms the first line of defense against many commonly transmitted pathogens, restoring and maintaining mucosal immunity is critical for disease prevention and intervention. This article discusses the nature of mucosal immunity and its relationship to viral infections and other conditions, and reviews natural compounds that help restore mucosal immunity.