Browsing by Subject "Vaccinia"

Now showing 1 - 4 of 4
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    Primary Human Macrophages Serve as Vehicles for Vaccinia Virus Replication and Dissemination
    (American Society for Microbiology (ASM), 2014-06) Byrd, Daniel; Shepherd, Nicole; Lan, Jie; Hu, Ningjie; Amet, Tohti; Yang, Kai; Desai, Mona; Yu, Qigui; Department of Microbiology & Immunology, IU School of Medicine
    Human monocytic and professional antigen-presenting cells have been reported only to exhibit abortive infections with vaccinia virus (VACV). We found that monocyte-derived macrophages (MDMs), including granulocyte macrophage colony-stimulating factor (GM-CSF)-polarized M1 and macrophage colony-stimulating factor (M-CSF)-polarized M2, but not human AB serum-derived cells, were permissive to VACV replication. The titers of infectious virions in both cell-free supernatants and cellular lysates of infected M1 and M2 markedly increased in a time-dependent manner. The majority of virions produced in permissive MDMs were extracellular enveloped virions (EEV), a secreted form of VACV associated with long-range virus dissemination, and were mainly found in the culture supernatant. Infected MDMs formed VACV factories, actin tails, virion-associated branching structures, and cell linkages, indicating that MDMs are able to initiate de novo synthesis of viral DNA and promote virus release. VACV replication was sensitive to inhibitors against the Akt and Erk1/2 pathways that can be activated by VACV infection and M-CSF stimulation. Classical activation of MDMs by lipopolysaccharide (LPS) plus gamma interferon (IFN-γ) stimulation caused no effect on VACV replication, while alternative activation of MDMs by interleukin-10 (IL-10) or LPS-plus-IL-1β treatment significantly decreased VACV production. The IL-10-mediated suppression of VACV replication was largely due to Stat3 activation, as a Stat3 inhibitor restored virus production to levels observed without IL-10 stimulation. In conclusion, our data demonstrate that primary human macrophages are permissive to VACV replication. After infection, these cells produce EEV for long-range dissemination and also form structures associated with virions which may contribute to cell-cell spread. IMPORTANCE Our results provide critical information to the burgeoning fields of cancer-killing (oncolytic) virus therapy with vaccinia virus (VACV). One type of macrophage (M2) is considered a common presence in tumors and is associated with poor prognosis. Our results demonstrate a preference for VACV replication in M2 macrophages and could assist in designing treatments and engineering poxviruses with special considerations for their effect on M2 macrophage-containing tumors. Additionally, this work highlights the importance of macrophages in the field of vaccine development using poxviruses as vectors. The understanding of the dynamics of poxvirus-infected foci is central in understanding the effectiveness of the immune response to poxvirus-mediated vaccine vectors. Monocytic cells have been found to be an important part of VACV skin lesions in mice in controlling the infection as well as mediating virus transport out of infected foci.
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    VIRAL MODULATION OF MHC CLASS II-MEDIATED ANTIGEN PRESENTATION
    (2009-06-24T12:57:08Z) Wang, Nan; Blum, Janice Sherry, 1957-; He, Johnny J.; Kaplan, Mark H.; Gallagher, Patricia J.; Harrington, Maureen A.
    Vaccinia virus (VV) has been used as a vaccine, yet safety concerns remain due to its viral immunoevasive properties. Among these, VV infection of antigen presentation cells (APC) perturbs MHC class II-mediated antigen (Ag) presentation. The goals of this project include: 1) to define mechanisms by which VV disrupts class II presentation; and 2) to examine whether disruption of the class II pathway by VV alters T cell responses in vitro and in vivo. A significant reduction in the expression of the class II chaperone, invariant chain (Ii), was observed during the late stage of VV infection. Yet surface expression of MHC class II molecules was maintained along with cell viability. To examine whether VV acts solely to disrupt host protein synthesis, B cells were treated with an inhibitor of translation-cycloheximide (CHX). Like VV, CHX negatively regulated Ii protein expression and class II presentation. Ii proteolysis also contributed in part to reduce Ii expression in VV infected and CHX treated APC. Yet only VV infection altered lysosomal protease expression, potentially influencing Ii degradation. Over-expression or ectopic-expression of Ii partially protected cells from VV-induced class II dysfunction. These studies suggest VV destabilizes class II molecules by disrupting Ii expression. To examine the presentation of viral Ags by class II, CD4 T cells from VV-primed mice were used. Viral proteins were presented by class II shortly after APC exposure to low concentrations of VV. The presentation of VV Ags correlated temporally with reductions in exogenous peptide presentation. At higher MOI (≥ 1), class II presentation of VV Ags was reduced. To examine the in vivo effects of VV on Ag presentation, a mouse model of ovalbumin-induced airway hypersensitivity was used. Th2 cytokine production was reduced, while a novel inflammatory cytokine Interleukin-17 (IL-17) production was enhanced in asthmatic VV-infected mice. In health mice, repeated VV infections lead to enhanced CD8 T cell production of Interferon-γ (IFN-γ) and IL-17. Finally, antibodies to a viral protein H3 were generated and shown to preserve class II presentation. Together these studies suggest VV disruption of the class II pathway may blunt T cell responses to VV.
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    Virus-encoded ectopic CD74 enhances poxvirus vaccine efficacy
    (Wiley Blackwell (Blackwell Publishing), 2014-04) Walline, Crystal C.; Deffit, Sarah N.; Wang, Nan; Guindon, Lynette M.; Crotzer, Victoria L.; Liu, Jianyun; Hollister, Kristin; Eisenlohr, Laurence C.; Brutkiewicz, Randy R.; Kaplan, Mark H.; Blum, Janice S.; Department of Microbiology & Immunology, IU School of Medicine
    Vaccinia virus (VV) has been used globally as a vaccine to eradicate smallpox. Widespread use of this viral vaccine has been tempered in recent years because of its immuno-evasive properties, with restrictions prohibiting VV inoculation of individuals with immune deficiencies or atopic skin diseases. VV infection is known to perturb several pathways for immune recognition including MHC class II (MHCII) and CD1d-restricted antigen presentation. MHCII and CD1d molecules associate with a conserved intracellular chaperone, CD74, also known as invariant chain. Upon VV infection, cellular CD74 levels are significantly reduced in antigen-presenting cells, consistent with the observed destabilization of MHCII molecules. In the current study, the ability of sustained CD74 expression to overcome VV-induced suppression of antigen presentation was investigated. Viral inhibition of MHCII antigen presentation could be partially ameliorated by ectopic expression of CD74 or by infection of cells with a recombinant VV encoding murine CD74 (mCD74-VV). In contrast, virus-induced disruptions in CD1d-mediated antigen presentation persisted even with sustained CD74 expression. Mice immunized with the recombinant mCD74-VV displayed greater protection during VV challenge and more robust anti-VV antibody responses. Together, these observations suggest that recombinant VV vaccines encoding CD74 may be useful tools to improve CD4⁺ T-cell responses to viral and tumour antigens.