ORCID Profile
0000-0001-6306-4405
Current Organisation
University of Tasmania
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Publisher: Wiley
Date: 07-1992
DOI: 10.1111/J.1365-3083.1992.TB02945.X
Abstract: Athymic, nude mice, which normally succumb to virus infection, can resolve infection with recombinant vaccinia virus (rVV) engineered to express IL-2. We have demonstrated that interferon-gamma (IFN-gamma) produced by natural killer (NK) cells and other immunocytes in response to the virus-encoded interleukin-2 (IL-2) is crucial to recovery. Here, we extend this work to show that nude mice, when primed intravenously with rVV co-expressing both IL-2 and an influenza virus haemagglutinin (HA) gene, are also protected following challenge with a lethal dose of homologous influenza virus. A substantial increase in the number of influenza virus-reactive antibody-secreting cells producing antibody of the IgM isotype, but not of the IgG or IgA isotypes, was found in spleens and lungs of the protected mice. Treatment with monoclonal antibodies to IFN-gamma or to the NK marker, as GM1, at challenge and thereafter, led to their death however, though the specific IgM antibody response was unaffected. These data suggest that both specific antibody and non-specific antiviral reactivity are important elements of the protective response and show that this immunization strategy may be used to protect severely immunocompromised in iduals.
Publisher: Proceedings of the National Academy of Sciences
Date: 22-05-2001
Abstract: We inoculated BALB/c mice deficient in STAT6 (STAT6 −/− ) and their wild-type (wt) littermates (STAT6 +/+ ) with the natural mouse pathogen, ectromelia virus (EV). STAT6 −/− mice exhibited increased resistance to generalized infection with EV when compared with STAT6 +/+ mice. In the spleens and lymph nodes of STAT6 −/− mice, T helper 1 (Th1) cytokines were induced at earlier time points and at higher levels postinfection when compared with those in STAT6 +/+ mice. Elevated levels of NO were evident in plasma and splenocyte cultures of EV-infected STAT6 −/− mice in comparison with STAT6 +/+ mice. The induction of high levels of Th1 cytokines in the mutant mice correlated with a strong natural killer cell response. We demonstrate in genetically susceptible BALB/c mice that the STAT6 locus is critical for progression of EV infection. Furthermore, in the absence of this transcription factor, the immune system defaults toward a protective Th1-like response, conferring pronounced resistance to EV infection and disease progression.
Publisher: Elsevier BV
Date: 08-2000
DOI: 10.1016/S0952-7915(00)00109-6
Abstract: Viruses that successfully replicate within the host have devised strategies to subvert or evade the challenges posed by the innate and adaptive immune responses. Many investigators are now beginning to dissect the erse and complex interactions involving chemokines, chemokine receptors and viral infection. In recent years, much attention has been focused on the role of chemokines in antiviral defense.
Publisher: Cold Spring Harbor Laboratory
Date: 23-12-2019
DOI: 10.1101/2019.12.22.883728
Abstract: Excessive tumor necrosis factor (TNF) is known to cause significant pathology. Paradoxically, deficiency in TNF (TNF -/- ) also caused significant pathology during respiratory ectromelia virus (ECTV) infection, a surrogate mouse model for smallpox. TNF -/- mice succumbed to fulminant disease whereas wild-type mice, and those expressing only transmembrane TNF, recovered. TNF deficiency did not affect viral load or leukocyte recruitment but caused severe lung pathology and excessive production of the cytokines IL-6, IL-10, TGF-β, and IFN-γ. Blockade of these cytokines reduced lung pathology concomitant with induction of protein inhibitor of activated STAT3 (PIAS3) and/or suppressor of cytokine signaling 3 (SOCS3), factors that inhibit STAT3 activation. Short-term inhibition of STAT3 activation in ECTV-infected TNF -/- mice with an inhibitor reduced lung pathology. TNF is essential for regulating inflammation and its deficiency exacerbates ECTV infection as a consequence of significant lung pathology caused by dysregulation of inflammatory cytokine production, in part via overactivation of STAT3.
Publisher: MDPI AG
Date: 23-01-2023
DOI: 10.3390/V15020318
Abstract: Influenza pneumonia is a severe complication caused by inflammation of the lungs following infection with seasonal and pandemic strains of influenza A virus (IAV), that can result in lung pathology, respiratory failure, and death. There is currently no treatment for severe disease and pneumonia caused by IAV. Antivirals are available but are only effective if treatment is initiated within 48 h of onset of symptoms. Influenza complications and mortality are often associated with high viral load and an excessive lung inflammatory cytokine response. Therefore, we simultaneously targeted the virus and inflammation. We used the antiviral oseltamivir and the anti-inflammatory drug etanercept to d en TNF signaling after the onset of clinical signs to treat pneumonia in a mouse model of respiratory IAV infection. The combined treatment down-regulated the inflammatory cytokines TNF, IL-1β, IL-6, and IL-12p40, and the chemokines CCL2, CCL5, and CXCL10. Consequently, combined treatment with oseltamivir and a signal transducer and activator of transcription 3 (STAT3) inhibitor effectively reduced clinical disease and lung pathology. Combined treatment using etanercept or STAT3 inhibitor and oseltamivir d ened an overlapping set of cytokines. Thus, combined therapy targeting a specific cytokine or cytokine signaling pathway and an antiviral drug provide an effective treatment strategy for ameliorating IAV pneumonia. This approach might apply to treating pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Publisher: Elsevier BV
Date: 1998
Abstract: The results of this study demonstrate that murine cytomegalovirus (MCMV) induces polyclonal B cell activation in mice during the acute phase of primary infection. First flow cytometric analysis revealed that surface expression of CD45R, IgM, and IgK by splenocytes from MCMV-infected mice was significantly reduced with a concomitant increase in the frequency of surface IgG-expressing cells. Second, ELIspot assays demonstrated that the changes revealed by flow cytometry were paralleled by increases in the numbers of IgG-producing cells, especially those secreting IgG2a. Third, the IgG antibodies from MCMV-infected animals reacted against a variety of self and foreign antigens. MCMV-induced B cell activation was independent of CD4+ T-cell-mediated help and CD40, since activation was observed in two models of mice deficient for this T cell subset and in mice deficient for CD40. Reverse transcription-polymerase chain reaction analysis showed that mRNA transcripts for the cytokines IL-6, IL-10, and IFN-gamma were rapidly induced following infection with MCMV, but only IL-6 and IFN-gamma proteins were detectable by ELISA. In addition, the numbers of cells producing IL-6 and IFN-gamma were significantly increased in the spleen. The magnitude of the polyclonal B cell activation response was diminished by 50% in IL-6-deficient mice but not in mice lacking IFN-gamma. In the absence of IFN-gamma, surface expression and serum levels of IgG2a were reduced while IgG1 expression was increased.
Publisher: Springer Science and Business Media LLC
Date: 18-09-2019
DOI: 10.1038/S41590-019-0492-0
Abstract: Resisting and tolerating microbes are alternative strategies to survive infection, but little is known about the evolutionary mechanisms controlling this balance. Here genomic analyses of anatomically modern humans, extinct Denisovan hominins and mice revealed a TNFAIP3 allelic series with alterations in the encoded immune response inhibitor A20. Each TNFAIP3 allele encoded substitutions at non-catalytic residues of the ubiquitin protease OTU domain that diminished IκB kinase-dependent phosphorylation and activation of A20. Two TNFAIP3 alleles encoding A20 proteins with partial phosphorylation deficits seemed to be beneficial by increasing immunity without causing spontaneous inflammatory disease: A20 T108A I207L, originating in Denisovans and introgressed in modern humans throughout Oceania, and A20 I325N, from an N-ethyl-N-nitrosourea (ENU)-mutagenized mouse strain. By contrast, a rare human TNFAIP3 allele encoding an A20 protein with 95% loss of phosphorylation, C243Y, caused spontaneous inflammatory disease in humans and mice. Analysis of the partial-phosphorylation A20 I325N allele in mice revealed diminished tolerance of bacterial lipopolysaccharide and poxvirus inoculation as tradeoffs for enhanced immunity.
Publisher: Cold Spring Harbor Laboratory
Date: 10-02-2022
DOI: 10.1101/2022.02.09.479486
Abstract: Pneumonia is a severe complication caused by inflammation of the lungs following infection with seasonal and pandemic strains of influenza A virus (IAV) that can result in lung pathology, respiratory failure and death. There is currently no treatment available for severe disease and pneumonia caused by IAV. Antivirals are available, but they are far from satisfactory if treatment is not initiated within 48 hours of symptoms onset. Influenza complications and mortality are often associated with high viral load and excessive lung inflammatory cytokine response. Therefore, we simultaneously targeted IAV with the antiviral drug oseltamivir and inflammation with the anti-inflammatory drug etanercept, targeting TNF after the onset of clinical signs to treat IAV pneumonia effectively. The combined treatment effectively reduced lung viral load, lung pathology, morbidity and mortality during respiratory IAV infection in mice, contemporaneous with significant downregulation of the inflammatory cytokines TNF, IL-1β, IL-6, IL-12p40, chemokines CCL2, CCL5 and CXCL10 and d ened STAT3 activation. Consequently, combined therapy with oseltamivir and a STAT3 inhibitor also effectively reduced clinical disease and lung pathology. Combined treatment using either of the anti-inflammatory drugs and oseltamivir d ened an overlapping set of cytokines. Thus, combined therapy targeting a specific cytokine or cytokine signaling pathway plus an antiviral drug provides an effective treatment strategy for ameliorating IAV pneumonia. Effective treatment of IAV pneumonia required multiple doses of etanercept and a high dose of oseltamivir. This approach might apply to the treatment of pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Antivirals against influenza A virus (IAV) are ineffective in treating pneumonia if administered 48 h after onset of disease symptoms. The host inflammatory response and tissue damage caused by IAV are responsible for lung pathology. We reasoned that targeting both virus and inflammation would be more effective in reducing lung pathology and pneumonia, morbidity and mortality. The simultaneous treatment with an anti-inflammatory drug targeting TNF or STAT3, combined with the anti-IAV antiviral drug, oseltamivir, significantly improved clinical disease, reduced lung viral load and pathology, and protected mice from severe pneumonia. The combined treatment suppressed multiple pro-inflammatory cytokines and cytokine signaling pathways. Thus, after the onset of disease symptoms, both virus and inflammation must be targeted to treat IAV pneumonia effectively.
Publisher: Wiley
Date: 12-2003
Publisher: Proceedings of the National Academy of Sciences
Date: 08-2000
Abstract: Many pathogens causing diarrhea do so by modulating ion transport in the gut. Respiratory pathogens are similarly associated with disturbances of fluid balance in the respiratory tract, although it is not known whether they too act by altering epithelial ion transport. Here we show that influenza virus A/PR/8/34 inhibits the amiloride-sensitive Na + current across mouse tracheal epithelium with a half-time of about 60 min. We further show that the inhibitory effect of the influenza virus is caused by the binding of viral hemagglutinin to a cell-surface receptor, which then activates phospholipase C and protein kinase C. Given the importance of epithelial Na + channels in controlling the amount of fluid in the respiratory tract, we suggest that down-regulation of Na + channels induced by influenza virus may play a role in the fluid transport abnormalities that are associated with influenza infections.
Publisher: Wiley
Date: 08-03-2022
DOI: 10.1111/FEBS.15782
Abstract: Pneumonia is a serious complication associated with inflammation of the lungs due to infection with viral pathogens. Seasonal and pandemic influenza viruses, variola virus (agent of smallpox) and severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2 agent of COVID‐19) are some leading ex les. Viral pneumonia is triggered by excessive inflammation associated with dysregulated cytokine production, termed ‘cytokine storm’. Several cytokines have been implicated but tumour necrosis factor (TNF) plays a critical role in driving lung inflammation, severe lung pathology and death. Despite this, the exact role TNF plays in the aetiology and pathogenesis of virus infection‐induced respiratory complications is not well understood. In this review, we discuss the pathological and immunomodulatory roles of TNF in contributing to immunopathology and resolution of lung inflammation, respectively, in mouse models of influenza‐ and smallpox (mousepox)‐induced pneumonia. We review studies that have investigated d ening of inflammation on the outcome of severe influenza and orthopoxvirus infections. Most studies on the influenza model have evaluated the efficacy of treatment with anti‐inflammatory drugs, including anti‐TNF agents, in animal models on the day of viral infection. We question the merits of those studies as they are not transferable to the clinic given that in iduals generally present at a hospital only after the onset of disease symptoms and not on the day of infection. We propose that research should be directed at determining whether d ening lung inflammation after the onset of disease symptoms will reduce morbidity and mortality. Such a treatment strategy will be more relevant clinically.
Publisher: Wiley
Date: 12-2004
Publisher: The American Association of Immunologists
Date: 09-2009
Abstract: A strong cell-mediated immune response is critical for controlling viral infections and is regulated by a number of cytokines, including IL-12 and IL-18. Indeed, some viruses have evolved to specifically target these pathways to counter the host immune response. Orthopoxviruses, including ectromelia virus, encode immune evasion molecules that specifically target IL-18 and IFN-γ. We hypothesized that IL-12 and IL-18 are pivotal for induction of IFN-γ production and subsequent generation of an effective host response to ectromelia virus infection. In this study, we demonstrate that absence of both IL-12p40 and IL-18 resulted in increased susceptibility to infection that was associated with skewing of the cytokine response to Th2 and a reduction in NK and CTL responses. The decrease in CTL response correlated with a defect in CD8+ T cell proliferation and lower numbers of virus-specific CD8+ T cells. Lack of either IL-12p40 and/or IL-18 was also associated with reduced numbers of CD8+ T cells at sites of infection and with an increase in the numbers of splenic T regulatory cells. Taken together, our data indicate that IL-12p40 and IL-18 act in concert and play an important antiviral role through the up-regulation of IFN-γ production and cell-mediated immune responses.
Publisher: Humana Press
Date: 2000
Publisher: American Society for Microbiology
Date: 07-05-2020
DOI: 10.1128/MRA.00375-20
Abstract: Nontypeable Haemophilus influenzae (NTHi) is an important cause of human illness, including pneumonia and acute exacerbations of chronic obstructive pulmonary disease (COPD). We report here the draft genome of an isolate of NTHi collected from the sputum of a patient presenting with COPD in Tasmania, Australia.
Publisher: Wiley
Date: 2007
Publisher: Elsevier BV
Date: 03-2000
Publisher: Wiley
Date: 06-1992
Publisher: Wiley
Date: 10-1997
DOI: 10.1111/J.1600-065X.1997.TB01011.X
Abstract: In this review, we discuss two broad approaches we have taken to study the role of cytokines and chemokines in antiviral immunity. Firstly, recombinant vaccinia viruses were engineered to express genes encoding cytokines and chemokines of interest. Potent antiviral activity was mediated by many of these encoded factors, including IL-2, IL-12, IFN-gamma, TNF-alpha, CD40L, Mig and Crg-2. In some cases, host defense mechanisms were induced (IL-2, IL-12, Mig and Crg-2), whilst for others, a direct antiviral effect was demonstrated (IFN-gamma, TNF-alpha and CD40L). In sharp contrast, vector-directed expression of IL-4, a type 2 factor, greatly increased virus virulence, due to a downregulation of host type 1 immune responses. Our second experimental approach involved the use of strains of mice deficient for the production of particular cytokines or their receptors, often in combination with our engineered viruses. Mice deficient in either IFN-gamma, IFN-gamma R, IFN-alpha/beta R, TNFRs, CD40 or IL-6 were, in general, highly susceptible to poxvirus infection. Surprisingly, not only the TNFR1, but also the TNFR2, was able to mediate the antiviral effects of TNF-alpha in vivo, whilst the antiviral activity observed following CD40-CD40L interaction is a newly defined function which may involve apoptosis of infected cells. Through the use of perforin-deficient mice, we were able to demonstrate a requirement for this molecule in the clearance of some viruses, such as ectromelia virus, whilst for others, such as vaccinia virus, perforin was less important but IFN-gamma was essential.
Publisher: Wiley
Date: 03-10-2018
DOI: 10.1002/CPMC.65
Abstract: Ectromelia virus (ECTV) is an orthopoxvirus that causes mousepox in mice. Members of the genus orthopoxvirus are closely related and include variola (the causative agent of smallpox in humans), monkeypox, and vaccinia. Common features of variola virus and ECTV further include a restricted host range and similar disease progression in their respective hosts. Mousepox makes an excellent small animal model for smallpox to investigate pathogenesis, vaccine and antiviral agent testing, host-virus interactions, and immune and inflammatory responses. The availability of a wide variety of inbred, congenic, and gene-knockout mice allows detailed analyses of the host response. ECTV mutant viruses lacking one or more genes encoding immunomodulatory proteins are being used in numerous studies in conjunction with wild-type or gene-knockout mice to study the functions of these genes in host-virus interactions. The methods used for propagation of ECTV in cell culture, purification, and quantification of infectious particles through viral plaque assay are described. © 2018 by John Wiley & Sons, Inc.
Publisher: Elsevier BV
Date: 05-1998
DOI: 10.1016/S0165-2427(98)00086-5
Abstract: Ectromelia virus (EV) is a natural mouse pathogen that causes a generalized infection termed mousepox, which, in the genetically resistant C57BL/6 (B6) mouse, is an inapparent disease. In contrast, BALB/c and A strain mice are highly susceptible one infectious virus particle can result in 100% mortality. The contribution of cytokines in the induction of protective immune responses and recovery from infection with EV in B6, BALB/c and A strain mice have been. In the spleen and lymph node (LN) of resistant B6 mice, IL-2, IFN-gamma and TNF-alpha were induced rapidly with large numbers of cells producing these cytokines. All three cytokines were virtually absent in BALB/c and A strain mice. No significant differences were found in the numbers of IL-4 producing cells in the spleen or LN of both resistant and susceptible mice. IFN-gamma-producing cells were detected in the spleen but not in the lymph node whereas IL-2-producing cells were detected only in the lymph node of B6 mice. Despite significant increases in the IFN-gamma mRNA levels in the LN of B6 mice, no protein was detected by immunocytochemistry. The mRNA levels of IL-2, TNF-alpha and IL-12 were also rapidly upregulated in LN of B6 mice. The rapid induction of type I cytokines strongly correlated with a potent antiviral CTL response in B6 mice. The absence of these cytokines also correlated with a complete absence or delayed induction of CTL responses to EV in both the BALB/c and A strain mice. IFN-gamma gene knock out mice on a B6 background were as susceptible to EV as the BALB/c and A strain mice.
Publisher: Proceedings of the National Academy of Sciences
Date: 17-02-2022
Abstract: Antivirals are ineffective in treating viral pneumonia if administered after 48 h post onset of disease symptoms. Lung pathology during respiratory viral infections is triggered by the host inflammatory response and tissue damage caused by replicating virus. Therefore, targeting both virus and inflammation would be more effective in treating pneumonia. Simultaneous treatment with an anti-inflammatory drug targeting TNF or STAT3 combined with an antiviral drug significantly improved clinical disease, reduced lung viral load and pathology and protected mice from severe pneumonia caused by respiratory ectromelia virus infection. The combined treatment suppressed multiple proinflammatory cytokines and cytokine-signaling pathways, including NF-κB and STAT3. Late after onset of symptoms, antiviral treatment alone cannot ameliorate viral pneumonia, as it cannot reduce inflammation effectively.
Publisher: Elsevier BV
Date: 05-1991
DOI: 10.1016/0882-4010(91)90081-K
Abstract: Vaccinia virus that expressed interleukin 2 (IL 2) was cleared from immunodeficient irradiated mice more efficiently than virus that did not express interleukin 2. These results extend the previously observed protection from nude mice to another model of immunodeficiency. No antibody or cytotoxic T lymphocyte response could be detected in sublethally irradiated mice that had been inoculated with IL 2-expressing vaccinia virus, but levels of splenic natural killer cell activity were elevated. Sublethally irradiated mice that had recovered from IL 2-plus hemagglutinin-expressing vaccinia virus were partially protected against both influenza virus and vaccinia virus. These results indicate that vaccinia virus-expressed IL 2 mediates clearance of primary viral infection via a mechanism that does not involve antibody or cytotoxic T lymphocytes. They also indicate that inclusion of lymphokine genes in live recombinant viral vaccine vectors may increase vaccine safety.
Publisher: Wiley
Date: 06-2002
Publisher: American Society for Microbiology
Date: 02-2014
DOI: 10.1128/JVI.02572-14
Abstract: Antibody production by B cells in the absence of CD4 T cell help has been shown to be necessary and sufficient for protection against secondary orthopoxvirus (OPV) infections. This conclusion is based on short-term depletion of leukocyte subsets in vaccinated animals, in addition to passive transfer of immune serum to naive hosts that are subsequently protected from lethal orthopoxvirus infection. Here, we show that CD4 T cell help is necessary for neutralizing antibody production and virus control during a secondary ectromelia virus (ECTV) infection. A crucial role for CD4 T cells was revealed when depletion of this subset was extended beyond the acute phase of infection. Sustained depletion of CD4 T cells over several weeks in vaccinated animals during a secondary infection resulted in gradual diminution of B cell responses, including neutralizing antibody, contemporaneous with a corresponding increase in the viral load. Long-term elimination of CD8 T cells alone delayed virus clearance, but prolonged depletion of both CD4 and CD8 T cells resulted in death associated with uncontrolled virus replication. In the absence of CD4 T cells, perforin- and granzyme A- and B-dependent effector functions of CD8 T cells became critical. Our data therefore show that both CD4 T cell help for antibody production and CD8 T cell effector function are critical for protection against secondary OPV infection. These results are consistent with the notion that the effectiveness of the smallpox vaccine is related to its capacity to induce both B and T cell memory. IMPORTANCE Smallpox eradication through vaccination is one of the most successful public health endeavors of modern medicine. The use of various orthopoxvirus (OPV) models to elucidate correlates of vaccine-induced protective immunity showed that antibody is critical for protection against secondary infection, whereas the role of T cells is unclear. Short-term leukocyte subset depletion in vaccinated animals or transfer of immune serum to naive, immunocompetent hosts indicates that antibody alone is necessary and sufficient for protection. We show here that long-term depletion of CD4 T cells over several weeks in vaccinated animals during secondary OPV challenge reveals an important role for CD4 T cell-dependent antibody responses in effective virus control. Prolonged elimination of CD8 T cells alone delayed virus clearance, but depletion of both T cell subsets resulted in death associated with uncontrolled virus replication. Thus, vaccinated in iduals who subsequently acquire T cell deficiencies may not be protected against secondary OPV infection.
Publisher: American Society for Microbiology
Date: 09-2006
DOI: 10.1128/JVI.01314-06
Publisher: Wiley
Date: 08-2002
Publisher: Elsevier BV
Date: 07-2017
Publisher: Wiley
Date: 09-03-2007
DOI: 10.1002/9780470062128.CH11
Abstract: There is increased interest in understanding protective immunity to smallpox for two principal reasons. First, it is the only disease that has been successfully eradicated using a live virus vaccine and, second, there exists a potential threat of intentional or unintentional release of variola virus, the causative agent of smallpox. Although mortality rates associated with smallpox were as high as 40%, a significant subset of those infected recovered. The basis of susceptibility or resistance, and the immune parameters associated with recovery, are still unknown. Animal models of poxvirus infections are being employed to understand what constitutes an effective host response. Ectromelia virus is closely related to variola virus and it causes a disease similar to smallpox in mice. This model is well established, resistant and susceptible strains of mice are defined and four genetic loci associated with resistance have been identified. Susceptibility to infec tion and disease severity is also influenced by virus immune evasion strategies. The outcome of infection is clearly dictated by several factors including host and viral genes, both of which influence the immune response. Here we present data on one virus-encoded immune modifier and its effect on the functions of two host genetic loci associ ated with resistance.
Publisher: Public Library of Science (PLoS)
Date: 09-03-2015
Publisher: Wiley
Date: 10-2017
DOI: 10.1038/ICB.1990.46
Abstract: The neurovirulent strain of vaccinia virus, VV-WR, or recombinants derived from VV-WR, cause highly productive infection of murine ovaries, but infection could be partially inhibited in vivo using an antiserum to asialo-GM1 (as-GM1). In vitro analysis by flow cytometry revealed that murine ovarian cells expressed a cell surface antigen identical to or cross-reactive with as-GM1. The capacity of VV-WR to infect murine ovaries appears to depend in part upon as-GM1 expression on ovarian cells.
Publisher: Wiley
Date: 10-2017
DOI: 10.1038/ICB.1990.44
Abstract: Vaccinia virus was shown to replicate in the ovaries of normal inbred mice and cause sufficient damage to ovarian follicles to decrease fertility of the mice. The mouse-adapted strain, VV-WR, had a greater affinity for growth in ovaries than the vaccine strains, VV-Elstree, VV-NYBH or VV-Copenhagen. Virus reached the ovaries after intravenous or intraperitoneal inoculation, but not after subcutaneous inoculation in the foot pad. Interleukin-2 (IL-2), when expressed by a recombinant vaccinia virus was able to decrease the titre of virus in the ovaries and prevent infertility. Both non-specific (natural killer cells) and antigen-specific mechanisms were active within the ovaries and may play a role in the IL-2-mediated clearance of vaccinia virus.
Publisher: American Society for Microbiology
Date: 04-2013
DOI: 10.1128/JVI.03038-12
Abstract: A pivotal role for antigen-specific recall responses to secondary virus infection is well established, but the contribution of innate immune cells to this process is unknown. Recovery of mice from a primary orthopoxvirus (ectromelia virus [ECTV]) infection requires the function of natural killer (NK) cells, granulocytes, plasmacytoid dendritic cells (pDC), T cells, and B cells. However, during a secondary challenge, resolution of infection is thought to be dependent on antibody but not T cell function. We investigated the contribution of NK cells, granulocytes, and pDC to virus control during a secondary virus challenge in mice that had been primed with an avirulent, mutant strain of ECTV. Mice depleted of NK cells, granulocytes, or pDC effectively controlled virus, as did mice depleted of both CD4 and CD8 T cell subsets. However, mice concurrently depleted of all three innate cell subsets had elevated virus load, but this was significantly exacerbated in mice also depleted of CD4 and/or CD8 T cells. Increased viral replication in mice lacking innate cells plus CD4 T cells was associated with a significant reduction in neutralizing antibody. Importantly, in addition to T-dependent neutralizing antibody responses, the function of CD8 T cells was also clearly important for virus control. The data indicate that in the absence of innate cell subsets, a critical role for both CD4 and CD8 T cells becomes apparent and, conversely, in the absence of T cell subsets, innate immune cells help contain infection.
Publisher: Microbiology Society
Date: 08-2020
Abstract: Nontypeable Haemophilus influenzae (NTHi) colonizes human upper respiratory airways and plays a key role in the course and pathogenesis of acute exacerbations of chronic obstructive pulmonary disease (COPD). Currently, it is not possible to distinguish COPD isolates of NTHi from other clinical isolates of NTHi using conventional genotyping methods. Here, we analysed the core and accessory genome of 568 NTHi isolates, including 40 newly sequenced isolates, to look for genetic distinctions between NTHi isolates from COPD with respect to other illnesses, including otitis media, meningitis and pneumonia. Phylogenies based on polymorphic sites in the core-genome did not show discrimination between NTHi strains collected from different clinical phenotypes. However, pan-genome-wide association studies identified 79 unique NTHi accessory genes that were significantly associated with COPD. Furthermore, many of the COPD-related NTHi genes have known or predicted roles in virulence, transmembrane transport of metal ions and nutrients, cellular respiration and maintenance of redox homeostasis. This indicates that specific genes may be required by NTHi for its survival or virulence in the COPD lung. These results advance our understanding of the pathogenesis of NTHi infection in COPD lungs.
Publisher: Rockefeller University Press
Date: 19-10-1998
Abstract: Viral infection often activates the interferon (IFN)-γ–inducible gene, nitric oxide synthase 2 (NOS2). Expression of NOS2 can limit viral growth but may also suppress the immune system and damage tissue. This study assessed each of these effects in genetically deficient NOS2−/− mice after infection with influenza A, a virus against which IFN-γ has no known activity. At inocula sufficient to cause consolidating pneumonitis and death in wild-type control mice, NOS2−/− hosts survived with little histopathologic evidence of pneumonitis. Moreover, they cleared influenza A virus from their lungs by an IFN-γ–dependent mechanism that was not evident in wild-type mice. Even when the IFN-γ–mediated antiviral activity was blocked in NOS2−/− mice with anti–IFN-γ mAb, such mice failed to succumb to disease. Further evidence that this protection was independent of viral load was provided by treating NOS2+/+ mice with the NOS inhibitor, Nω-methyl-l-arginine (l-NMA). l-NMA prevented mortality without affecting viral growth. Thus, host NOS2 seems to contribute more significantly to the development of influenza pneumonitis in mice than the cytopathic effects of viral replication. Although NOS2 mediates some antiviral effects of IFN-γ, during influenza infection it can suppress another IFN-γ–dependent antiviral mechanism. This mechanism was observed only in the complete absence of NOS2 activity and appeared sufficient to control influenza A virus growth in the absence of changes in cytotoxic T lymphocyte activity.
Publisher: Wiley
Date: 03-06-2018
DOI: 10.1111/IMCB.12163
Abstract: The role of the immunoproteasome is perceived as confined to adaptive immune responses given its ability to produce peptides ideal for MHC Class-I binding. Here, we demonstrate that the immunoproteasome subunit, LMP2, has functions beyond its immunomodulatory role. Using LMP2-deficient mice, we demonstrate that LMP2 is crucial for lymphocyte development and survival in the periphery. Moreover, LMP2-deficient lymphocytes show impaired degradation of key BH3-only proteins, resulting in elevated levels of pro-apoptotic BIM and increased cell death. Interestingly, LMP2 is the sole immunoproteasome subunit required for BIM degradation. Together, our results suggest LMP2 has important housekeeping functions and represents a viable therapeutic target for cancer.
Publisher: Cold Spring Harbor Laboratory
Date: 27-03-2019
DOI: 10.1101/589507
Abstract: Resisting or tolerating microbes are alternative strategies to survive infection, but little is known about the evolutionary mechanisms controlling this balance. Here, genomic analyses of anatomically modern humans, extinct Denisovan hominins, and mice revealed a series of missense variants in the immune response inhibitor A20 (encoded by TNFAIP3 ), substituting non-catalytic residues of the ubiquitin protease domain to diminish IκB-dependent phosphorylation and activation of A20. Two A20 variants with partial phosphorylation deficits appeared beneficial: one originating in Denisovans and introgressed in modern humans throughout Oceania, and another in a mouse strain resistant to Coxsackievirus. By contrast, a variant with 95% loss of phosphorylation caused spontaneous inflammatory disease in humans and mice. Analysis of the partial phosphorylation variant in mice revealed diminished tolerance of bacterial lipopolysaccharide or to poxvirus inoculation as trade-offs for enhanced immunity. Modern and ancient variants reveal a genetically tunable element for balancing immunity and microbial tolerance.
Publisher: MDPI AG
Date: 05-03-2018
DOI: 10.3390/V10030111
Publisher: Wiley
Date: 12-1999
DOI: 10.1046/J.1440-1711.1999.00858.X
Abstract: Today, 10 years after the discovery of IL-8, chemokines (chemotactic cytokines) are seen as the stimuli that largely control leucocyte migration. Chemokines are low molecular weight chemoattractant cytokines secreted by a variety of cells, including leucocytes, epithelial cells, endothelial cells, fibroblasts and numerous other cell types. They are produced in response to exogenous stimuli, such as viruses and bacterial LPS, and endogenous stimuli, such as IL-1, TNF and IFN. These factors mediate chemotaxis and leucocyte activation. They also regulate leucocyte extravasation from the blood and/or lymph vessel luminal surface to the tissue space, the site of inflammation. There is no doubt that chemokines and chemokine receptors are critical for defence against infectious pathogens. It is also clear that these pathogens have evolved to accommodate the workings of the host immune system. Survival of these infectious agents appears dependent upon strategies that can evade, suppress, counteract or otherwise confound the constellation of host responses to invading pathogens. In this regard, the chemokines and their receptors are a major target. Reviewed in the present paper are several ex les in which microbial pathogens have usurped the mammalian chemokine system to subvert the host immune response.
Publisher: American Society for Microbiology
Date: 07-2006
DOI: 10.1128/JVI.00115-06
Abstract: Renewed interest in smallpox and the need for safer vaccines have highlighted our lack of understanding of the requirements for protective immunity. Since smallpox has been eradicated, surrogate animal models of closely related orthopoxviruses, such as ectromelia virus, have been used to establish critical roles for CD8 T cells in the control of primary infection. To study the requirements for protection against secondary infection, we have used a prime-challenge regime, in which avirulent ectromelia virus was used to prime mice that were then challenged with virulent ectromelia virus. In contrast to primary infection, T cells are not required for recovery from secondary infection, since gene knockout mice deficient in CD8 T-cell function and wild-type mice acutely depleted of CD4, CD8, or both subsets were fully protected. Protection correlated with effective virus control and generation of neutralizing antibody. Notably, primed mice that lacked B cells, major histocompatibility complex class II, or CD40 succumbed to secondary infection. Thus, antibody is essential, but CD4 or CD8 T cells are not required for recovery from secondary poxvirus infection.
Publisher: Proceedings of the National Academy of Sciences
Date: 09-2009
Abstract: A remarkable feature of the adaptive immune system is the speed at which small numbers of antigen-specific lymphocytes can mediate a successful immune response. Rapid expansion of T and B lymphocyte clones that have receptors specific for a particular antigen is one of the primary means by which a swift response is generated. Although much of this clonal expansion is caused by the ision of antigen-specific cells, here we demonstrate an additional mechanism by which the pool of effector T cells against a viral infection can quickly enlarge. Our data show that virus-specific CD8 + cytotoxic T lymphocytes (CTL) can transfer their T cell receptors (TCR) to recipient CTL of an unrelated specificity that, as a consequence, gain the antigen specificity of the donor T cell. This process occurs within minutes via membrane exchange and results in the recipient CTL acquiring the ability to recognize and eliminate cells targeted by the donor TCR, while still retaining the antigen specificity of its own TCR. Such receptor sharing allows rapid, proliferation-independent expansion of virus-specific T cell clones of low frequency and plays a highly significant antiviral role that can protect the host from an otherwise lethal infection.
Publisher: The American Association of Immunologists
Date: 15-02-2004
DOI: 10.4049/JIMMUNOL.172.4.1996
Abstract: Dendritic cells (DCs) play a central role in initiating immune responses. Despite this, there is little understanding how different DC subsets contribute to immunity to different pathogens. CD8α+ DC have been shown to prime immunity to HSV. Whether this very limited capacity of a single DC subset priming CTL immunity is restricted to HSV infection or is a more general property of anti-viral immunity was examined. Here, we show that the CD8α+ DCs are the principal DC subset that initiates CTL immunity to s.c. infection by influenza virus, HSV, and vaccinia virus. This same subset also dominated immunity after i.v. infection with all three viruses, suggesting a similar involvement in other routes of infection. These data highlight the general role played by CD8α+ DCs in CTL priming to viral infection and raises the possibility that this DC subset is specialized for viral immunity.
Publisher: Public Library of Science (PLoS)
Date: 23-12-2015
Publisher: Wiley
Date: 04-2000
DOI: 10.1046/J.1440-1711.2000.00894.X
Abstract: MuMig (monokine induced by gamma interferon) and Crg-2 (cytokine responsive gene) are chemokines of the CXC subfamily. They share activity as T and NK cell chemoattractants. Crg-2 has been shown to be inducible by IFN, TNF, IL-1 and LPS, whereas the expression of MuMig is thought to be strictly dependent on IFN-gamma. In the present study, the kinetics of expression of the genes for MuMig and Crg-2 were analysed by northern blot analysis in organs of normal mice and in groups of gene knockout mice deficient in IFN-gamma (IFN-gamma-/-) or receptors for IFN-alpha/beta and IFN-gamma (double R-/- DR-/-) after vaccinia virus infection. MuMig mRNA was not expressed in IFN-gamma-/- mice in all organs examined, whereas Crg-2 mRNA levels were marginally reduced. In contrast, MuMig and Crg-2 mRNA transcripts were completely abolished in the DR-/- mice.
Publisher: Wiley
Date: 12-01-2010
DOI: 10.1038/ICB.2009.110
Abstract: Smallpox was a deadly disease when it was rife yet despite its eradication more than 30 years ago, the possibility of accidental or intentional release has driven research in search of better definitions of correlates of protective immunity. Mousepox, a disease caused by ectromelia virus (ECTV), is arguably one of the best surrogate small animal models for smallpox. Correlates of protection in mousepox are well defined during primary infection, whereas those in a secondary infection, which have definite relevance to vaccination strategies, are less well understood. We previously established that neutralizing antibody (Ab), which is generated far more rapidly during a secondary infection compared with a primary infection, has a key role during a secondary virus challenge. In this study, we show that the route of immunization or the use of homologous or heterologous virus vaccines for immunization does not influence the ability of mice to control high-dose virulent ECTV challenge or to mount a substantial secondary neutralizing Ab response. In contrast, the recall cytotoxic T lymphocyte (CTL) responses generated under these regimes of immunization were varied and did not correlate with virus control. Furthermore, unlike the recall Ab response that was generated rapidly, the kinetics of the secondary antiviral CTL response was no different to a primary infection and peaked only at day 8 post-challenge. This finding further underscores the importance of Ab in conferring protection during secondary poxvirus infection. This information could potentially prove useful in the design of safer and more efficacious vaccines against poxviruses or other diseases using poxvirus vectors.
Publisher: American Society for Microbiology
Date: 07-2006
DOI: 10.1128/JVI.00427-06
Abstract: Mouse models of orthopoxvirus disease provide great promise for probing basic questions regarding host responses to this group of pathogens, which includes the causative agents of monkeypox and smallpox. However, some essential tools for their study that are taken for granted with other mouse models are not available for these viruses. Here we map and characterize the initial CD8 + T-cell determinants for poxviruses in H-2 d -haplotype mice. CD8 + T cells recognizing these three determinants make up around 40% of the total responses to vaccinia virus during and after resolution of infection. We then use these determinants to test if predicted conservation across orthopoxvirus species matches experimental observation and find an unexpectedly cross-reactive variant peptide encoded by ectromelia (mousepox) virus.
Publisher: Springer Science and Business Media LLC
Date: 09-03-2020
Publisher: Hindawi Limited
Date: 28-04-2020
DOI: 10.1111/CMI.13206
Publisher: Springer Science and Business Media LLC
Date: 17-03-2013
DOI: 10.1038/NI.2555
Abstract: Spleen-resident dendritic cell (DC) populations occupy sentinel positions for the capture and presentation of blood-borne antigens. Here we found a difference in expression of the chemotactic receptor EBI2 (GPR183) on splenic DC subsets and that EBI2 regulated the positioning and homeostasis of DCs in the spleen. EBI2 and its main ligand, 7α,25-OHC, were required for the generation of the splenic CD4(+) DC subset and the localization of DCs in bridging channels. Absence of EBI2 from DCs resulted in defects in both the activation of CD4(+) T cells and the induction of antibody responses. Regulated expression of EBI2 on DC populations is therefore critical for the generation and correct positioning of splenic DCs and the initiation of immune responses.
Publisher: Rockefeller University Press
Date: 28-12-2004
DOI: 10.1084/JEM.20041912
Abstract: The large size of poxvirus genomes has stymied attempts to identify determinants recognized by CD8+ T cells and greatly impeded development of mouse smallpox vaccination models. Here, we use a vaccinia virus (VACV) expression library containing each of the predicted 258 open reading frames to identify five peptide determinants that account for approximately half of the VACV-specific CD8+ T cell response in C57BL/6 mice. We show that the primary immunodominance hierarchy is greatly affected by the route of VACV infection and the poxvirus strain used. Modified vaccinia virus ankara (MVA), a candidate replacement smallpox vaccine, failed to induce responses to two of the defined determinants. This could not be predicted by genomic comparison of viruses and is not due strictly to limited MVA replication in mice. Several determinants are immunogenic in cowpox and ectromelia (mousepox) virus infections, and immunization with the immunodominant determinant provided significant protection against lethal mousepox. These findings have important implications for understanding poxvirus immunity in animal models and bench-marking immune responses to poxvirus vaccines in humans.
Publisher: Wiley
Date: 10-2000
DOI: 10.1034/J.1600-065X.2000.17720.X
Abstract: The biological roles of two interferon-inducible chemokines, monokine induced by gamma interferon (Mig) and cytokine responsive gene (Crg-2), in the immune response against vaccinia virus (VV) and ectromelia virus (EV) infections are discussed. To investigate their antiviral effects in vivo, the expression profiles of these chemokines during the course of VV or EV infections were first established. Mig and Crg-2 were induced in multiple organs at high levels early after infection with VV. Both chemokines were rapidly induced in popliteal lymph nodes of C57BL/6 mice but not in BALB/c mice following infection with EV. Secondly, recombinant vaccinia viruses (rVV) encoding Mig or Crg-2 were constructed to investigate the immunobiology of infection in athymic, nude and euthymic, normal mice. Finally, the EV model in combination with recombinant Mig and Crg-2 proteins was used to test their effects on viral replication and immune responses in vivo. The results of these investigations demonstrate that the mechanisms of Mig- and Crg-2-induced viral clearance involve natural killer cells and interferons.
Publisher: Wiley
Date: 04-1998
Publisher: American Society for Microbiology
Date: 04-2007
DOI: 10.1128/JVI.01927-06
Abstract: Ectromelia virus (ECTV), a natural mouse pathogen and the causative agent of mousepox, is closely related to variola virus (VARV), which causes smallpox in humans. Mousepox is an excellent surrogate small-animal model for smallpox. Both ECTV and VARV encode a multitude of host response modifiers that target components of the immune system and that are thought to contribute to the high mortality rates associated with infection. Like VARV, ECTV encodes a protein homologous to the ectodomain of the host gamma interferon (IFN-γ) receptor 1. We generated an IFN-γ binding protein (IFN-γbp) deletion mutant of ECTV to study the role of viral IFN-γbp (vIFN-γbp) in host-virus interaction and also to elucidate the contribution of this molecule to the outcome of infection. Our data show that the absence of vIFN-γbp does not affect virus replication per se but does have a profound effect on virus replication and pathogenesis in mice. BALB/c mice, which are normally susceptible to infection with ECTV, were able to control replication of the mutant virus and survive infection. Absence of vIFN-γbp from ECTV allowed the generation of an effective host immune response that was otherwise diminished by this viral protein. Mice infected with a vIFN-γbp deletion mutant virus, designated ECTV-IFN-γbp Δ , produced increased levels of IFN-γ and generated robust cell-mediated and antibody responses. Using several strains of mice that exhibit differential degrees of resistance to mousepox, we show that recovery or death from ECTV infection is determined by a balance between the host's ability to produce IFN-γ and the virus' ability to d en its effects.
Publisher: Wiley
Date: 09-10-2007
Abstract: Even though smallpox has been eradicated, the threat of accidental or intentional release has highlighted the fact there is little consensus about correlates of protective immunity or immunity against re-infection with the causative poxvirus, variola virus (VARV). As the existing vaccine for smallpox has unacceptable rates of side effects and complications, new vaccines are urgently needed. Surrogate animal models of VARV infection in humans, including vaccinia virus (VACV) and ectromelia virus (ECTV) infection in mice, monkeypox virus (MPXV) infection in macaques have been used as tools to dissect the immune response to poxviruses. Mousepox, caused by ECTV, a natural mouse pathogen, is arguably the best surrogate small-animal model, as it shares many aspects of virus biology, pathology and clinical features with smallpox in humans. The requirements for recovery from a primary ECTV infection have been well characterized and include type I and II interferons, natural killer cells, CD4T cells, CD8T cell effector function and antibody. From a vaccine standpoint, it is imperative that the requirements for recovery from secondary infection are also identified. We have investigated host immune parameters in response to a secondary ECTV infection, and have identified that interferon and CD8T cell effector functions are not essential however, T- and B-cell interaction and antibody are absolutely critical for recovery from a secondary challenge. The central role of antibody has been also been identified in the secondary response to other poxviruses. These findings have important clinical implications and would greatly assist the design of therapeutic interventions and new vaccines for smallpox.
Publisher: SAGE Publications
Date: 07-2017
DOI: 10.1177/096368979900800404
Abstract: The rejection mechanisms for fetal proislet allografts and pig proislet xenografts in mice are characterized by different intragraft cytokine mRNA profiles and cellular responses. Allograft rejection is predominantly CD8 T-cell-dependent and is associated with a Th1-type cytokine pattern (i.e., IFN-γ, IL-2 but no IL-4 or IL-5 mRNA). In contrast, xenograft rejection is CD4 T-cell-dependent and is accompanied by a strong Th2-type response (i.e., enhanced expression of IL-4 and IL-5 mRNA) and by marked eosinophil accumulation at the graft site. We have now examined and compared the regulatory role of IFN-γ in both proislet allograft and xenograft rejection processes. The histopathology and intragraft cytokine mRNA profile of BALB/c (H-2 d ) proislet allografts were examined in IFN-γ-deficient and wild-type C57BL/6J recipient mice. The survival of pig proislet xenografts was also assessed in IFN-γ –/– and wild-type hosts. Both proislet allografts and xenografts were acutely rejected in IFN-γ –/– and wild-type mice. Unlike the conventional allograft reaction, which lacks eosinophil infiltration, the rejection of proislet allografts in IFN-γ-deficient hosts correlated with intragraft expression of IL-4 and IL-5 mRNA (i.e., a Th2-type response) and eosinophil recruitment. The rejection of proislet allografts and xenografts can therefore occur by IFN-γ-independent pathways IFN-γ, however, regulates the pathology of the allograft reaction but not the xenograft response. The immune destruction of proislet allografts is not prevented by Th2 cytokine gene expression instead, the latter correlated with the recruitment of unconventional inflammatory cells (eosinophils), which may play an accessory role in effecting graft injury. Significantly, the Th1-to-Th2-like switch resulted in the novel conversion of an allograft rejection reaction into a xenograft-like rejection process.
Publisher: Wiley
Date: 16-01-2007
Abstract: Variola virus, the causative agent of smallpox, is a member of the poxvirus family and one of the most virulent human pathogens known. Although smallpox was eradicated almost 30 years ago, it is not understood why the mortality rates associated with the disease were high, why some patients recovered, and what constitutes an effective host response against infection. As variola virus infects only humans, our current understanding of poxvirus infections comes largely from historical clinical data from smallpox patients and from animal studies using closely related viruses such as ectromelia, myxoma and monkeypox. The outcome of an infection is determined by a complex interaction between the type of immune response mounted by the host and by evasion mechanisms that the virus has evolved to subvert it. Disease pathogenesis is also a function of both host and viral factors. Poxviruses are not only cytopathic, causing host tissue damage, but also encode an array of immunomodulatory molecules that affect the severity of disease. The ability of the host to control virus replication is therefore critical in limiting tissue damage. However, in addition to targeting virus, the immune response can inadvertently damage the host to such a degree that it causes illness and even death. There is growing evidence that many of the symptoms associated with serious poxvirus infections are a result of a 'cytokine storm' or sepsis and that this may be the underlying cause of pathology.
Publisher: Microbiology Society
Date: 11-2006
Abstract: NOS2 gene-deficient (NOS2 −/− ) mice are less susceptible than wild-type (NOS2 +/+ ) mice to infection with Influenza A virus . Virus titres in the lungs of influenza-infected NOS2 −/− mice are significantly lower than those in NOS2 +/+ mice, with enhanced viral clearance in NOS2 −/− mice dependent on gamma interferon (IFN- γ ). The current study was undertaken to ascertain the role of specific components of the immune response in promoting virus clearance in influenza-infected NOS2 −/− mice. Levels of T cell- and natural killer cell-mediated cytotoxicity in the lungs of virus-infected mice were not significantly different between NOS2 +/+ and NOS2 −/− mice. However, virus-infected NOS2 −/− mice produced higher levels of virus-specific IgG2a antibody. Furthermore, more viable B cells and plasmablasts, along with greater levels of IFN- γ , were found in NOS2 −/− splenocyte cultures stimulated with B-cell mitogens. In addition to the early reduction in virus titres, clinical symptoms and proinflammatory cytokine production were attenuated in NOS2 −/− mice. Thus, NOS2 −/− B cells are capable of responding rapidly to influenza virus infection by proliferating and preferentially producing antibody of the IgG2a subtype. The relationship between viral load and the development of immunopathology is discussed.
Publisher: American Society for Microbiology
Date: 07-2006
DOI: 10.1128/JVI.00116-06
Abstract: To understand the correlates of protective immunity against primary variola virus infection in humans, we have used the well-characterized mousepox model. This is an excellent surrogate small-animal model for smallpox in which the disease is caused by infection with the closely related orthopoxvirus, ectromelia virus. Similarities between the two infections include virus replication and transmission, aspects of pathology, and development of pock lesions. Previous studies using ectromelia virus have established critical roles for cytokines and effector functions of CD8 T cells in the control of acute stages of poxvirus infection. Here, we have used mice deficient in B cells to demonstrate that B-cell function is also obligatory for complete virus clearance and recovery of the host. In the absence of B cells, virus persists and the host succumbs to infection, despite the generation of CD8 T-cell responses. Intriguingly, transfer of naive B cells or ectromelia virus-immune serum to B-cell-deficient mice with established infection allowed these animals to clear virus and fully recover. In contrast, transfer of ectromelia virus-immune CD8 T cells was ineffective. Our data show that mice deficient in CD8 T-cell function die early in infection, whereas those deficient in B cells or antibody production die much later, indicating that B-cell function becomes critical after the effector phase of the CD8 T-cell response to infection subsides. Strikingly, our results show that antibody prevents virus from seeding the skin and forming pock lesions, which are important for virus transmission between hosts.
Publisher: Rockefeller University Press
Date: 11-1990
Abstract: Athymic nude mice recover from an infection with recombinant vaccinia virus (VV) encoding murine interleukin 2 (IL-2), but treatment with a mAb to IL-2 accentuated infection. Administration of a mAb against interferon gamma (IFN-gamma) to mice infected with the IL-2-encoding virus completely prevented the IL-2-induced mechanisms of recovery. Both asialo-GM1+ (NK) and asialo-GM1- (non-NK) cells were participants in the IFN-gamma-mediated recovery of nude mice from infection with the IL-2-encoding VV recombinant. Depletion of asialo-GM1+ cells exacerbated infection, though not as much as anti-IFN-gamma mAb. In vitro, both asialo-GM1+ and asialo-GM1- nude mouse splenocytes produced IFN-gamma in response to IL-2.
Publisher: The American Association of Immunologists
Date: 06-2011
Abstract: Parasite burden predicts disease severity in malaria and risk of death in cerebral malaria patients. In murine experimental cerebral malaria (ECM), parasite burden and CD8+ T cells promote disease by mechanisms that are not fully understood. We found that the majority of brain-recruited CD8+ T cells expressed granzyme B (GzmB). Furthermore, gzmB−/− mice harbored reduced parasite numbers in the brain as a consequence of enhanced antiparasitic CD4+ T cell responses and were protected from ECM. We showed in these ECM-resistant mice that adoptively transferred, Ag-specific CD8+ T cells migrated to the brain, but did not induce ECM until a critical Ag threshold was reached. ECM induction was exquisitely dependent on Ag-specific CD8+ T cell-derived perforin and GzmB, but not IFN-γ. In wild-type mice, full activation of brain-recruited CD8+ T cells also depended on a critical number of parasites in this tissue, which in turn, was sustained by these tissue-recruited cells. Thus, an interdependent relationship between parasite burden and CD8+ T cells dictates the onset of perforin/GzmB-mediated ECM.
Publisher: American Society for Microbiology
Date: 07-2012
DOI: 10.1128/JVI.06636-11
Abstract: Egress of wrapped virus (WV) to the cell periphery following vaccinia virus (VACV) replication is dependent on interactions with the microtubule motor complex kinesin-1 and is mediated by the viral envelope protein A36. Here we report that ectromelia virus (ECTV), a related orthopoxvirus and the causative agent of mousepox, encodes an A36 homologue (ECTV-Mos-142) that is highly conserved despite a large truncation at the C terminus. Deleting the ECTV A36R gene leads to a reduction in the number of extracellular viruses formed and to a reduced plaque size, consistent with a role in microtubule transport. We also observed a complete loss of virus-associated actin comets, another phenotype dependent on A36 expression during VACV infection. ECTV ΔA36R was severely attenuated when used to infect the normally susceptible BALB/c mouse strain. ECTV ΔA36R replication and spread from the draining lymph nodes to the liver and spleen were significantly reduced in BALB/c mice and in Rag-1-deficient mice, which lack T and B lymphocytes. The dramatic reduction in ECTV ΔA36R titers early during the course of infection was not associated with an augmented immune response. Taken together, these findings demonstrate the critical role that subcellular transport pathways play not only in orthopoxvirus infection in an in vitro context but also during orthopoxvirus pathogenesis in a natural host. Furthermore, despite the attenuation of the mutant virus, we found that infection nonetheless induced protective immunity in mice, suggesting that orthopoxvirus vectors with A36 deletions may be considered another safe vaccine alternative.
Publisher: The American Association of Immunologists
Date: 15-07-2012
Abstract: Tight regulation of virus-induced cytotoxic effector CD8+ T cells is essential to prevent immunopathology. Naturally occurring effector CD8+ T cells, with a KLRG1hi CD62Llo phenotype typical of short-lived effector CD8+ T cells (SLECs), can be found in increased numbers in autoimmune-prone mice, most notably in mice homozygous for the san allele of Roquin. These SLEC-like cells were able to trigger autoimmune diabetes in a susceptible background. When Roquin is mutated (Roquinsan), effector CD8+ T cells accumulate in a cell-autonomous manner, most prominently as SLEC-like effectors. Excessive IFN-γ promotes the accumulation of SLEC-like cells, increases their T-bet expression, and enhances their granzyme B production in vivo. We show that overexpression of IFN-γ was caused by failed posttranscriptional repression of Ifng mRNA. This study identifies a novel mechanism that prevents accumulation of self-reactive cytotoxic effectors, highlighting the importance of regulating Ifng mRNA stability to maintain CD8+ T cell homeostasis and prevent CD8-mediated autoimmunity.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-09-1993
Abstract: Interferons (IFNs) induce antiviral activity in many cell types. The ability of IFN-gamma to inhibit replication of ectromelia, vaccinia, and herpes simplex-1 viruses in mouse macrophages correlated with the cells' production of nitric oxide (NO). Viral replication was restored in IFN-gamma-treated macrophages exposed to inhibitors of NO synthase. Conversely, epithelial cells with no detectable NO synthesis restricted viral replication when transfected with a complementary DNA encoding inducible NO synthase or treated with organic compounds that generate NO. In mice, an inhibitor of NO synthase converted resolving ectromelia virus infection into fulminant mousepox. Thus, induction of NO synthase can be necessary and sufficient for a substantial antiviral effect of IFN-gamma.
Publisher: American Society for Microbiology
Date: 15-03-2019
DOI: 10.1128/JVI.01795-18
Abstract: Neutralizing antibody response is the best-known correlate of long-term protective immunity for most of the currently licensed clinically effective viral vaccines. However, the host immune and viral factors that are critical for the induction of robust and durable antiviral humoral immune responses are not well understood. Our study provides insight into the dynamics of key cellular mediators of germinal center reaction during live virus infections and the influence of viral replicative capacity on the magnitude of antiviral antibody response and effector function. The significance of our study lies in two key findings. First, the systemic spread of even poorly replicating or nonreplicating viruses to mimic the spread of antigens from replicating viruses due to escalating antigen concentration is fundamental to the induction of durable antibody responses. Second, the T FH :T FR ratio may be used as an early predictor of protective antiviral humoral immune responses long before memory responses are generated.
Publisher: American Society for Microbiology
Date: 04-2001
DOI: 10.1128/IAI.69.4.2636-2642.2001
Abstract: A rodent respiratory experimental model has proved useful for investigating the immune mechanisms responsible for clearance of bacteria from the lungs. Immunohistochemical studies in immune and nonimmune rats have identified the cellular kinetics of response to bacterial pulmonary infection for CD8 + , CD4 + , and γδ + T cells B cells and the expression of major histocompatibility complex class II (MHC-II). During the course of bacterial clearance, there was no apparent proliferation or extravasation of lymphocytes, nor was there increased expression of MHC-II in nonimmune animals despite an influx of polymorphonuclear leukocytes, whereas in immunized animals there was an early influx of CD8 + and γδ + T cells, followed by enhanced expression of the MHC-II marker, cellular infiltration by polymorphonuclear leukocytes, and finally an increased number of CD4 + T cells. Depletion of CD8 + T cells confirmed their vital contribution in the preprimed immune response to pulmonary infection by significantly decreasing the animals' ability to clear bacteria following challenge.
Publisher: Rockefeller University Press
Date: 06-1995
Abstract: IFN-gamma-induced nitric oxide (NO) in the murine macrophage-derived cell line RAW 264.7 was previously shown to inhibit replication of the poxviruses ectromelia and vaccinia (VV) and HSV-1. In the current study we demonstrate that murine macrophages activated as a consequence of VV infection express inducible nitric oxide synthase. These activated macrophages were resistant to infection with VV and efficiently blocked the replication of VV and HSV-1 in infected bystander cells of epithelial and fibroblast origin. This inhibition was arginine dependent, correlated with nitrite production in cultures, and reversible by the NOS inhibitor N omega-monomethyl-L-arginine. NO-mediated inhibition of VV replication was studied by treatment of virus-infected human 293 cells with the NO donor S-nitroso-N-acetyl-penicillamine. Using a VV-specific DNA probe, antibodies specific for temporally expressed viral proteins, and transmission electron microscopy, we have shown that NO inhibited viral late gene protein synthesis, DNA replication, and virus particle formation, but not expression of the early proteins that were analyzed. Putative enzymatic targets of NO were identified by reversing the NO-mediated inhibition of VV replication in the 293 cells with exogenous ferrous sulfate and L-cysteine. Reversal of inhibition may derive from the capacity of these reagents to protect or regenerate nonheme iron or thiol groups, respectively, which are essential for the catalytic activities of enzymes susceptible to inactivation by NO.
Publisher: Proceedings of the National Academy of Sciences
Date: 25-08-2005
Abstract: IFN function is critical for recovery from most primary viral infections, including poxvirus infection. In contrast, very little is known about the requirement for IFN function in mediating recovery from a secondary virus infection. We have used ectromelia virus (ECTV), an orthopoxvirus very closely related to variola virus, to investigate the importance of IFN function in recovery from a secondary infection. Variola virus, the causative agent of smallpox in humans, and ECTV, which causes mousepox in mice, both encode receptor homologs that are thought to interfere with host IFN function. Using a prime-challenge regime, in which avirulent ECTV is used to prime mice deficient in type I/II IFN function or IFN regulatory factor 1 (IRF-1) and then challenging the mice with a virulent strain, we show that IFN function is redundant for virus clearance during a secondary ECTV infection. A neutralizing Ab response is generated in a secondary infection, even in the absence of IFN function, although when present, IFN strongly influences the neutralizing titer and subtype of IgG that is produced. Importantly, the depletion of CD8 + T lymphocytes during a secondary challenge in IFN-deficient mice does not affect their capacity to clear ECTV, indicating that Ab is critical for the control of a secondary infection.
Publisher: Proceedings of the National Academy of Sciences
Date: 07-06-2004
Abstract: Ectromelia virus (ECTV), a natural mouse pathogen and an orthopoxvirus, has been used to investigate the correlation between polarized type 1 or type 2 immune responses and resistance to disease in poxvirus infections by using well defined resistant and susceptible mouse strains. Our data show that distinct differences exist in the cytokine profiles expressed in resistant and susceptible mice infected with ECTV. Resistant C57BL/6 mice generate a type 1 cytokine response [IFN-γ, IL-2, and tumor necrosis factor (TNF)], within the first few days of infection, which is associated with strong cytotoxic T lymphocyte response (CTL) and recovery from ECTV infection. Susceptible strains of mice (BALB/c and A/J) on the other hand generate a type 2 cytokine response (IL-4 but little or no IFN-γ and IL-2), which is associated with a weak or an absent CTL response, resulting in uncontrolled virus replication and death. Although deletion of IL-4 function alone did not change the outcome of infection in susceptible mice, the loss of IFN-γ function in resistant mice abrogated natural killer (NK) cell and CTL effector functions resulting in fulminant disease and 100% mortality. Therefore, a clear link exists between the early production of specific type 1 cytokines, in particular, IFN-γ, the nature of the cellular immune response, and disease outcome in this virus model. This finding in the mousepox model raises the possibility that inappropriate cytokine responses may result in increased susceptibility to smallpox in humans.
Publisher: Proceedings of the National Academy of Sciences
Date: 12-10-2020
Abstract: Viruses have coevolved with their hosts and developed strategies to d en, evade, or subvert the host immune response to provide an advantage to the virus. We show that ectromelia virus (ECTV) encodes a TNF receptor (TNFR) homolog, which provides an advantage to the host and virus by d ening TNF levels and inflammation. Infection of ECTV-resistant mice with a mutant virus lacking viral TNFR (vTNFR) caused significant lung pathology and death due to secretion of excessive levels of TNF and other inflammatory cytokines. In vitro, recombinant vTNFR from ECTV and other orthopoxviruses bound to membrane-associated TNF and down-regulated inflammatory gene expression through reverse signaling. vTNFR benefits the host by enabling survival, potentially facilitating virus spread, which should advantage the virus.
Publisher: Korean Academy of Medical Sciences
Date: 2000
Publisher: Proceedings of the National Academy of Sciences
Date: 22-06-2020
Abstract: Excessive tumor necrosis factor (TNF) production during some respiratory viral infections is associated with lung pathology and death. We show here that deficiency in TNF also causes significant pathology during respiratory poxvirus infection of mice but has no effect on viral load. TNF deficiency causes increased production of interleukin (IL)-6, IL-10, transforming growth factor beta, and interferon gamma and overactivation of STAT3 signaling. Cytokine blockade, or STAT3 inactivation, ameliorates lung pathology in TNF-deficient mice. The membrane form of TNF alone is necessary and sufficient for regulating inflammation and the prevention of lung pathology. Targeting specific cytokines or cytokine signaling pathways to can ameliorate lung inflammation during respiratory viral infections but the timing and duration of the interventive measures are critical.
Publisher: Wiley
Date: 08-2004
Publisher: Cold Spring Harbor Laboratory
Date: 25-02-2020
DOI: 10.1101/2020.02.24.963520
Abstract: Ectromelia virus (ECTV) causes mousepox, a surrogate mouse model for smallpox caused by variola virus in humans. Both viruses encode tumor necrosis factor receptor (TNFR) homologs termed cytokine response modifier (Crm) proteins, containing a TNF-binding domain and a chemokine-binding domain termed smallpox virus-encoded chemokine receptor (SECRET) domain. Infection of ECTV-resistant C57BL/6 mice with an ECTV CrmD deletion mutant resulted in uniform mortality due to excessive TNF secretion and dysregulated inflammatory cytokine production but viral load was not affected. CrmD d ened lung pathology, leukocyte recruitment and inflammatory cytokines including TNF, IL-6, IL-10 and IFN-γ. Blockade of IL-6, IL-10R or TNF function with monoclonal antibodies reduced lung pathology and provided 60-100% protection from an otherwise lethal infection. IFN-γ caused lung pathology only when both the TNF-binding and SECRET domains were deleted but it was neither necessary nor sufficient to cause pathology when only the CrmD SECRET domain was expressed by virus.
Publisher: Public Library of Science (PLoS)
Date: 21-03-2013
Publisher: Public Library of Science (PLoS)
Date: 11-12-2014
Publisher: Springer Science and Business Media LLC
Date: 19-07-2013
DOI: 10.1038/NI0813-876E
No related grants have been discovered for Gunasegaran Karupiah.