[Show abstract][Hide abstract] ABSTRACT: The human intestinal parasite Schistosoma mansoni causes a chronic disease, schistosomiasis or bilharzia. According to the current literature, the parasite induces vigorous immune responses that are controlled by Th2 helper cells at the expense of Th1 helper cells. The latter cell type is, however, indispensable for anti-viral immune responses. Remarkably, there is no reliable literature among 230 million patients worldwide describing defective anti-viral immune responses in the upper respiratory tract, for instance against influenza A virus or against respiratory syncitial virus (RSV). We therefore re-examined the immune response to a human isolate of S. mansoni and challenged mice in the chronic phase of schistosomiasis with influenza A virus, or with pneumonia virus of mice (PVM), a mouse virus to model RSV infections. We found that mice with chronic schistosomiasis had significant, systemic immune responses induced by Th1, Th2, and Th17 helper cells. High serum levels of TNF-a, IFN-c, IL-5, IL-13, IL-2, IL-17, and GM-CSF were found after mating and oviposition. The lungs of diseased mice showed low-grade inflammation, with goblet cell hyperplasia and excessive mucus secretion, which was alleviated by treatment with an anti-TNF-a agent (Etanercept). Mice with chronic schistosomiasis were to a relative, but significant extent protected from a secondary viral respiratory challenge. The protection correlated with the onset of oviposition and TNF-a-mediated goblet cell hyperplasia and mucus secretion, suggesting that these mechanisms are involved in enhanced immune protection to respiratory viruses during chronic murine schistosomiasis. Indeed, also in a model of allergic airway inflammation mice were protected from a viral respiratory challenge with PVM. Copyright: ß 2014 Scheer 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. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files. Funding: SS was supported by the Fonds National de la Recherche, Luxembourg (http://www.fnr.lu) (PHD-08-045-RE). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist.
[Show abstract][Hide abstract] ABSTRACT: Many pathogens trigger type I interferon (IFN-I) responses early after infection that confer protection until adaptive immunity is induced. Upon infection with vesicular stomatitis virus (VSV) Toll-like receptor (TLR) and RIG-I-like helicase (RLH) signaling platforms are indispensable for the induction of protective IFN-I. Hence, TLR- and RLH-ablated MyTrCa−/− mice challenged with VSV do not mount IFN-I responses and are inevitably susceptible to lethal VSV infection. To study the impact of the kinetics of IFN-I responses on the induction of adaptive immunity, we infected MyTrCa−/− mice with VSV and treated them 4, 8, 16, and 24 h after infection with recombinant IFN-αα (rIFN-α)α). Interestingly, under such conditions MyTrCa−/− mice mounted normal adaptive immune responses and approximately 76% of the mice survived. On the contrary, initiation of the rIFN-αα treatment scheme 4 h before VSV infection significantly prolonged survival, whereas reduced VSV-specific cytotoxic T-lymphocytes and basically no VSV neutralizing antibody responses were induced and 100% of the mice finally died. Long-term rIFN-α treatment for 9 days initiated 4 h after VSV infection promoted 100% survival of MyTrCa−/− mice and protective immunity was induced normally as verified by 100% of the animals surviving even a VSV re-challenge 3 weeks after discontinuation of the rIFN-α treatment. Initiation of the 9 days rIFN-α regimen 4 h prior to infection also rescued 100% of the mice, however, no adaptive immunity developed and 100% of the animals succumbed to re-challenge. In conclusion, long-term rIFN-α treatment initiated before virus infection prevented induction of protective adaptive immunity, whereas initiation of rIFN-α treatment hours after infection supported development of normal adaptive immunity and protective memory response. These observations have implications for immunotherapies and vaccination strategies, in particular for patients under long-term IFN-I therapy who are treated with live attenuated vaccines.
Cytokines Down Under 2014: From Bench To Beyond, Melbourne; 10/2014
[Show abstract][Hide abstract] ABSTRACT: Avian bornaviruses (ABVs) are a group of genetically diverse viruses within the Bornaviridae family that can infect numerous avian species and represent the causative agents of proventricular dilatation disease, an often fatal disease that is widely distributed in captive populations of parrots and related species. The current study was designed to assess the antigenic variability of the family Bornaviridae and to determine its impact on ABV diagnosis by employing fluorescent antibody assays. It was shown that polyclonal rabbit sera directed against recombinant bornavirus nucleoprotein, X protein, phosphoprotein, and matrix protein provided sufficient cross-reactivity for the detection of viral antigen from a broad range of bornavirus genotypes grown in cell culture. In contrast, a rabbit anti-glycoprotein serum and 2 monoclonal antibodies directed against nucleoprotein and phosphoprotein proteins reacted more specifically. Antibodies were readily detected in sera from avian patients infected with known ABV genotypes if cells persistently infected with a variety of different bornavirus genotypes were used for analysis. For all sera, calculated antibody titers were highest when the homologous or a closely related target virus was used for the assay. Cross-reactivity with more distantly related genotypes of other phylogenetic groups was usually reduced, resulting in titer reduction of up to 3 log units. The presented results contribute to a better understanding of the antigenic diversity of family Bornaviridae and further emphasize the importance of choosing appropriate diagnostic tools for sensitive detection of ABV infections.
[Show abstract][Hide abstract] ABSTRACT: Several studies indicated that TLR as well as retinoic acid-inducible gene I-like helicase (RLH) signaling contribute to vesicular stomatitis virus (VSV)-mediated triggering of type I IFN (IFN-I) responses. Nevertheless, TLR-deficient MyD88(-/-)Trif(-/-) mice and RLH-deficient caspase activation and recruitment domain adaptor inducing IFN-β (Cardif)(-/-) mice showed only marginally enhanced susceptibility to lethal VSV i.v. infection. Therefore, we addressed whether concomitant TLR and RLH signaling, or some other additional mechanism, played a role. To this end, we generated MyD88(-/-)Trif(-/-)Cardif(-/-) (MyTrCa(-/-)) mice that succumbed to low-dose i.v. VSV infection with similar kinetics as IFN-I receptor-deficient mice. Three independent approaches (i.e., analysis of IFN-α/β serum levels, experiments with IFN-β reporter mice, and investigation of local IFN-stimulated gene induction) revealed that MyTrCa(-/-) mice did not mount IFN-I responses following VSV infection. Of note, treatment with rIFN-α protected the animals, qualifying MyTrCa(-/-) mice as a model to study the contribution of different immune cell subsets to the production of antiviral IFN-I. Upon adoptive transfer of wild-type plasmacytoid dendritic cells and subsequent VSV infection, MyTrCa(-/-) mice displayed significantly reduced viral loads in peripheral organs and showed prolonged survival. On the contrary, adoptive transfer of wild-type myeloid dendritic cells did not have such effects. Analysis of bone marrow chimeric mice revealed that TLR and RLH signaling of radioresistant and radiosensitive cells was required for efficient protection. Thus, upon VSV infection, plasmacytoid dendritic cell-derived IFN-I primarily protects peripheral organs, whereas concomitant TLR and RLH signaling of radioresistant stroma cells as well as of radiosensitive immune cells is needed to effectively protect against lethal disease.
The Journal of Immunology 08/2014; · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Avian bornaviruses (ABV) are the causative agents of proventricular dilatation disease (PDD), a widely distributed disease of parrots. Distinct ABV lineages were also found in various non-psittacine avian species, such as canaries, but the pathogenic role of ABV in these species is less clear. Despite the wide distribution of ABV in captive parrots and canaries, its mode of transmission is poorly understood: both horizontal transmission via the urofaecal-oral route and vertical transmission are discussed to play a role. In this study we investigated pathology and horizontal transmission of ABV in domestic canaries (Serinus canaria forma domestica) and cockatiels (Nymphicus hollandicus), two natural host species commonly used for experimental ABV infections. ABV inoculation resulted in persistent infection of all inoculated animals from both species. ABV-infected cockatiels exhibited PDD-like symptoms, such as neurologic signs or shedding of undigested seeds. In contrast, infected domestic canaries did not develop clinical disease. Interestingly, we did not detect viral RNA in cloacal swabs and organ samples or ABV-specific antibodies in serum samples of contact-exposed sentinel birds from either species at any time during a four months observation period. Our results strongly indicate that horizontal transmission of ABV by direct contact is inefficient in immunocompetent fully fledged domestic canaries and cockatiels.
[Show abstract][Hide abstract] ABSTRACT: The transcription factor STAT1 is essential for interferon- (IFN) mediated immunity in humans and mice. STAT1 function is tightly regulated and both loss- and gain-of function mutations result in severe immune diseases. The two alternatively spliced isoforms, STAT1α and STAT1β, differ with regard to a C-terminal transactivation domain, which is absent in STAT1β. STAT1β is considered to be transcriptionally inactive and to be a competitive inhibitor of STAT1α. To investigate the functions of the STAT1 isoforms in vivo we generated mice deficient for either STAT1α or STAT1β. As expected, the functions of STAT1α and STAT1β in IFNα/β- and IFNλ-dependent antiviral activity are largely redundant. In contrast to the current dogma, however, we found that STAT1β is transcriptionally active in response to IFNγ. In the absence of STAT1α, STAT1β shows more prolonged IFNγ-induced phosphorylation and promoter binding. Both isoforms mediate protective, IFNγ-dependent immunity against the bacterium Listeria monocytogenes, although with remarkably different efficiencies. Our data shed new light on the potential contribution of the individual STAT1 isoforms to STAT1-dependent immune responses. The knowledge of STAT1β's function will help fine-tune diagnostic approaches and design more specific strategies to interfere with STAT1 activity.
Molecular and Cellular Biology 04/2014; · 5.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The type III interferon (IFN) receptor is preferentially expressed by epithelial cells. It is made of two subunits: IFNLR1, which is specific to IFN-lambda (IFN-λ) and IL10RB, which is shared by other cytokine receptors. Human hepatocytes express IFNLR1 and respond to IFN-λ. In contrast, the IFN-λ response of the mouse liver is very weak and IFNLR1 expression is hardly detectable in this organ. Here we investigated the IFN-λ response at the cellular level in the mouse liver and we tested whether human and mouse hepatocytes truly differ in responsiveness to IFN-λ. When monitoring expression of the IFN-responsive Mx genes by immunohistofluorescence, we observed that the IFN-λ response in mouse livers was restricted to cholangiocytes, which form the bile ducts, and that mouse hepatocytes were indeed not responsive to IFN-λ. The lack of mouse hepatocyte response to IFN-λ was observed in different experimental settings, including the infection with a hepatotropic strain of influenza A virus which triggered a strong local production of IFN-λ. With the help of chimeric mice containing transplanted human hepatocytes, we show that hepatocytes of human origin readily responded to IFN-λ in a murine environment. Thus, our data suggest that human but not mouse hepatocytes are responsive to IFN-λ in vivo. The non-responsiveness is an intrinsic property of mouse hepatocytes and is not due to the mouse liver micro-environment.
PLoS ONE 01/2014; 9(1):e87906. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Interferons (IFNs) are essential components of the antiviral defense system of vertebrates. In mammals, functional receptors for type III IFN (IFN-λ) are mainly found on epithelial cells and IFN-λ was demonstrated to play a crucial role in limiting viral infections of mucosal surfaces. To determine whether IFN-λ plays a similar role in birds, we produced recombinant chicken IFN-λ (chIFN-λ) and we used the replication-competent retroviral RCAS vector system to generate mosaic-transgenic chicken embryos that constitutively express chIFN-λ. We could demonstrate that chIFN-λ markedly inhibited replication of various virus strains, including highly pathogenic influenza A viruses, in ovo and in vivo, as well as in epithelium-rich tissue and cell culture systems. In contrast, chicken fibroblasts responded poorly to chIFN-λ. When applied in vivo to three-week-old chickens, recombinant chIFN-λ strongly induced the IFN-responsive Mx gene in epithelium-rich organs such as lung, trachea and intestinal tract. Correspondingly, these organs were found to express high transcript levels of the putative chIFN-λ receptor alpha chain (chIL28RA) gene. Transfection of chicken fibroblasts with a chIL28RA expression construct rendered these cells responsive to chIFN-λ treatment, indicating that receptor expression determines cell type specificity of IFN-λ action in chickens. Surprisingly, mosaic-transgenic chickens perished soon after hatching, demonstrating a detrimental effect of constitutive chIFN-λ expression. Our data highlight fundamental similarities between the IFN-λ systems of mammals and birds, and suggest that type III IFN might play a role in defending mucosal surfaces against viral intruders in most if not all vertebrates.
[Show abstract][Hide abstract] ABSTRACT: Avian bornaviruses (ABV) are known to be the causative agent of proventricular dilatation disease (PDD) in parrots and their relatives (Psittaciformes). A broad range of ABV genotypes has been detected not only in psittacine birds, but also in other avian species including canary birds (Serinus canaria forma domestica) and Bengalese finches (Lonchura striata f. dom.), which are both members of the order songbirds (Passeriformes). During this study 286 samples collected from captive and wild birds of various passerine species in different parts of Germany were screened for the presence of ABV. Interestingly, only three ABV-positive samples were identified by RT-PCR. They originated from one yellow-winged pytilia (Pytilia hypogrammica) and two black-rumped waxbills (Estrilda troglodytes) from a flock of captive estrildid finches in Saxony. The ABV isolates detected here were only distantly related to ABV isolates found in passerine species in Germany and Japan and form a new genotype tentatively called ABV-EF (for "estrildid finches").
[Show abstract][Hide abstract] ABSTRACT: Interferons (IFNs) are a group of cytokines with a well-established antiviral function. They can be induced by viral infection, are secreted and bind to specific receptors on the same or neighbouring cells to activate the expression of hundreds of IFN stimulated genes (ISGs) with antiviral function. Type I IFN has been known for more than half a century. However, more recently, type III IFN (IFNλ, IL-28/29) was shown to play a similar role and to be particularly important at epithelial surfaces. Here we show that airway epithelia, the primary target of influenza A virus, produce both IFN I and III upon infection, and that induction of both depends on the RIG-I/MAVS pathway. While IRF3 is generally regarded as the transcription factor required for initiation of IFN transcription and the so-called "priming loop", we find that IRF3 deficiency has little impact on IFN expression. In contrast, lack of IRF7 reduced IFN production significantly, and only IRF3(-/-)IRF7(-/-) double deficiency completely abolished it. The transcriptional response to influenza infection was largely dependent on IFNs, as it was reduced to a few upregulated genes in epithelia lacking receptors for both type I and III IFN (IFNAR1(-/-)IL-28Rα(-/-)). Wild-type epithelia and epithelia deficient in either the type I IFN receptor or the type III IFN receptor exhibit similar transcriptional profiles in response to virus, indicating that none of the induced genes depends selectively on only one IFN system. In chimeric mice, the lack of both IFN I and III signalling in the stromal compartment alone significantly increased the susceptibility to influenza infection. In conclusion, virus infection of airway epithelia induces, via a RIG-I/MAVS/IRF7 dependent pathway, both type I and III IFNs which drive two completely overlapping and redundant amplification loops to upregulate ISGs and protect from influenza infection.
[Show abstract][Hide abstract] ABSTRACT: The induction of an interferon-induced antiviral state is a powerful cellular response against viral infection that limits viral spread. Here we show that a pre-existing antiviral state inhibits replication of influenza A viruses in human A549 cells by preventing transport of the viral genome to the nucleus and the interferon-induced MxA protein is necessary but not sufficient for this process. This represents a previously unreported antiviral function of MxA against influenza A virus infection.
[Show abstract][Hide abstract] ABSTRACT: Influenza A viruses circulating in humans from ∼1950 to ∼1987 featured a non-structural (NS1) protein with a C-terminal extension of seven amino acids. The biological significance of this NS1 elongation remained elusive. We observed that replication kinetics of wild-type A/Hong Kong/01/68 (H3N2) and a mutant encoding a truncated NS1 were indistinguishable in most experimental systems. However, wild-type virus out-competed the mutant during mixed infections, suggesting that the NS1 extension conferred minor growth advantages.
[Show abstract][Hide abstract] ABSTRACT: We established a reverse genetics system for Nyamanini virus (NYMV) and recovered GFP-expressing virus from full-length cDNA. Using this technology, we assessed the functions of two poorly characterized viral genes. NYMV lacking open reading frame 2 (ORF2) could not be rescued, whereas virus lacking ORF4 was replication-competent. ORF4-deficient NYMV readily established a persisting non-cytolytic infection but failed to produce infectious viral particles, supporting the view that ORF4 represents an essential factor for NYMV particle assembly.
[Show abstract][Hide abstract] ABSTRACT: The ability of vaccines to induce T cell responses is crucial for preventing diseases caused by viruses or bacteria. Nanoparticles (NPs) are considered an efficient tool for inducing potent immune responses. In this study, we describe a novel vaccination approach with biodegradable calcium phosphate (CaP) NPs that serve as carrier of immunoactive TLR9 ligand (CpG) combined with a viral Ag from the influenza A virus hemagglutinin. Functionalized CaP NPs were efficiently taken up by dendritic cells in vivo and elicited a potent T cell-mediated immune response in immunized mice with high numbers of IFN-γ-producing CD4(+) and CD8(+) effector T cells. Most importantly, both i.p. and intranasal immunization with these NPs offered protection in a mouse model of influenza virus infection. This study demonstrates the great potential of CaP NPs as a novel vaccination tool that offers substantial flexibility for several infection models.
The Journal of Immunology 05/2013; · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nyamanini virus (NYMV) and Midway virus (MIDWV) are unclassified tick-borne agents that infect land birds and seabirds, respectively. The recent molecular characterization of both viruses confirmed their already known close serological relationship and revealed them to be nonsegmented, single- and negative-stranded RNA viruses that are clearly related to, but quite distinct from, members of the order Mononegavirales (bornaviruses, filoviruses, paramyxoviruses, and rhabdoviruses). A third agent, soybean cyst nematode virus 1 (SbCNV-1, previously named soybean cyst nematode nyavirus), was recently found to be an additional member of this new virus group. Here, we review the current knowledge about all three viruses and propose classifying them as members of a new mononegaviral family, Nyamiviridae.
Archives of Virology 05/2013; · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The innate host defense against influenza virus is largely dependent on the type I interferon (IFN) system. However, surprisingly little is known about the cellular source of IFN in the infected lung. To clarify this question, we employed a reporter mouse that contains the firefly luciferase gene in place of the IFN-β coding region. IFN-β-producing cells were identified either by simultaneous immunostaining of lungs for luciferase and cellular markers or by generating conditional reporter mice that express luciferase exclusively in defined cell types. Two different strains of influenza A virus were employed that either do or do not code for nonstructural protein 1 (NS1) which strongly suppresses innate immune responses of infected cells. We found that epithelial cells and CD11c(-) lung macrophages that represent the prime host cells for influenza viruses showed vigorous IFN-β responses which, however, were severely reduced and delayed if the infecting virus was able to produce NS1. Interestingly, CD11c(+) cell populations that were either expressing or lacking macrophage markers produced the bulk of IFN-β at 48 h post infection with wild-type influenza A virus. Our results demonstrate that the virus-encoded IFN-antagonistic factor NS1 disarms specifically epithelial cells and lung macrophages which otherwise would serve as main mediators of the early response against infection by influenza virus.
[Show abstract][Hide abstract] ABSTRACT: Avian bornavirus (ABV) was identified in 2008 as the causative agent of proventricular dilatation disease (PDD) in psittacine birds. In addition, ABV variants were detected in wild waterfowl and in a canary bird. PDD-like diseases were also reported in various other avian species, but it remains unknown whether ABV is involved. In this study we detected ABV in 12 of 30 tested canary bird flocks (40%), indicating a wide distribution of ABV in captive canary birds in Germany. Sequence analysis identified several distinct ABV genotypes which differ markedly from the genotypes present in psittacine birds. Some canaries naturally infected with ABV exhibited gastrointestinal and neurological symptoms which resembled PDD in psittacines, while others did not show signs of disease. Canaries experimentally inoculated with ABV developed infections of the brain and various other organs. The experimentally infected canaries transmitted the virus to sentinel birds kept in the same aviary, but did not show any clinical signs during a five month observation period. Embryonated eggs originating from ABV-infected hens contained ABV-specific RNA, but virus could not be re-isolated from embryonic tissue. These results indicate that ABV is widely distributed in canary birds and due to its association to clinical signs should be considered as a potential pathogen of this species.
[Show abstract][Hide abstract] ABSTRACT: Resistance of influenza A viruses to neuraminidase inhibitors can arise through mutations in the neuraminidase (NA) gene. We show here that a Q136K mutation in the NA of the 2009 pandemic H1N1 virus confers a high degree of resistance to zanamivir. Resistance is accompanied by reduced amounts of NA molecules in viral particles and reduced intrinsic enzymatic activity of mutant NA. Interestingly, the Q136K mutation strongly impairs viral fitness in the guinea pig transmission model.
[Show abstract][Hide abstract] ABSTRACT: STAT1-deficient mice are more susceptible to infection with SARS-Coronavirus (SARS-CoV) than type I IFN receptor-deficient mice. We used mice lacking functional receptors for both type I and type III IFN (dKO) to evaluate the possibility that type III IFN plays a decisive role in SARS-CoV protection. We found that viral peak titres in lungs of dKO and STAT1-deficient mice were similar but significantly higher than in wild-type mice. The kinetics of viral clearance from the lung was also comparable in dKO and STAT1-deficient mice. Surprisingly, however, infected dKO mice remained healthy, whereas infected STAT1-deficient mice developed liver pathology and eventually succumbed to neurological disease. Our data suggest that the failure of STAT1-deficient mice to efficiently control initial SARS-CoV replication in the lung is due to impaired type I and type III IFN signaling, whereas the failure to control subsequent systemic viral spread is due to unrelated defects in STAT1-deficient mice.
Journal of General Virology 09/2012; · 3.13 Impact Factor