Faculty Opinions recommendation of Specific recognition of the viral protein UL18 by CD85j/LIR-1/ILT2 on CD8+ T cells mediates the non-MHC-restricted lysis of human cytomegalovirus-infected cells.

CD8+ T-cell responses to pathogens are directed against infected cells that present pathogen-encoded peptides on MHC class-I molecules. Although natural responses are polyclonal, the spectrum of peptides that qualify for epitopes is remarkably small even for pathogens with high coding capacity. Among those few that are successful at all, a hierarchy exists in the magnitude of the response that they elicit in terms of numbers of CD8+ T cells generated. This led to a classification into immunodominant and non-immunodominant or subordinate epitopes, IDEs and non-IDEs, respectively. IDEs are favored in the design of vaccines and are chosen for CD8+ T-cell immunotherapy. Using murine cytomegalovirus as a model, we provide evidence to conclude that epitope hierarchy reflects competition on the level of antigen recognition. Notably, high-avidity cells specific for non-IDEs were found to expand only when IDEs were deleted. This may be a host’s back-up strategy to avoid viral immune escape through antigenic drift caused by IDE mutations. Importantly, our results are relevant for the design of vaccines based on cytomegaloviruses as vectors to generate high-avidity CD8+ T-cell memory specific for unrelated pathogens or tumors. We propose the deletion of vector-encoded IDEs to avoid the suppression of epitopes of the vaccine target.

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Infection of CD8+CD45RO+ Memory T-Cells by HIV-1 and Their Proliferative Response

The Open AIDS Journal ◽

10.2174/1874613600802010043 ◽

2008 ◽

Vol 2 (1) ◽

pp. 43-57 ◽

Cited By ~ 7

Author(s):

Naveed Gulzar ◽

Sowyma Balasubramanian ◽

Greg Harris ◽

Jaime Sanchez-Dardon ◽

Karen F.T. Copeland

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Proliferative Response ◽

Cell Infection ◽

Cellular Target ◽

Potential Reservoir ◽

Infected Cells ◽

Hiv 1

CD8+ T-cells are involved in controlling HIV-1 infection by eliminating infected cells and secreting soluble factors that inhibit viral replication. To investigate the mechanism and significance of infection of CD8+ T-cells by HIV-1in vitro, we examined the susceptibility of these cells and their subsets to infection. CD8+ T-cells supported greater levels of replication with T-cell tropic strains of HIV-1, though viral production was lower than that observed in CD4+ T-cells. CD8+ T-cell infection was found to be productive through ELISA, RT-PCR and flow cytometric analyses. In addition, the CD8+CD45RO+ memory T-cell population supported higher levels of HIV-1 replication than CD8+CD45RA+ naïve T-cells. However, infection of CD8+CD45RO+ T-cells did not affect their proliferative response to the majority of mitogens tested. We conclude, with numerous lines of evidence detecting and measuring infection of CD8+ T-cells and their subsets, that this cellular target and potential reservoir may be central to HIV-1 pathogenesis.

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#16: Enterovirus D68 Visualized in the Anterior Horn of the Spinal Cord of a Pediatric Patient with Flaccid Paralysis

Journal of the Pediatric Infectious Diseases Society ◽

10.1093/jpids/piab031.015 ◽

2021 ◽

Vol 10 (Supplement_2) ◽

pp. S8-S8

Author(s):

Matthew R Vogt ◽

Peter F Wright ◽

William F Hickey ◽

Kelli L Boyd ◽

James E Crowe

Keyword(s):

Spinal Cord ◽

T Cells ◽

Antigen Presentation ◽

Motor Neurons ◽

Cd8 T Cells ◽

Viral Protein ◽

The United States ◽

Anterior Horn ◽

Viral Rna ◽

Enterovirus D68

Abstract Background Acute flaccid myelitis (AFM) is a polio-like paralyzing illness of children. AFM incidence is increasing during every other year outbreaks that occur in the United States simultaneously with outbreaks of enterovirus D68 (EV-D68) infection. Demonstrating that EV-D68 directly causes AFM has been challenging due to rare detection of the virus in the cerebrospinal fluid (CSF) of patients despite frequent detection at nonsterile sites. Murine studies have shown that EV-D68 can infect spinal cord anterior horn motor neurons and cause paralysis, similar to poliovirus. However, a key outstanding question is whether EV-D68 causes AFM in humans by direct viral pathogenesis or by indirect host immunopathogenesis. Methods We investigated the pathogenesis of AFM using tissues from a previously reported case of a 5-year-old boy who presented in fall 2008 with four days of progressive limb and voice weakness followed by incontinence, apnea, and death. He had a CSF pleocytosis of 2094/µL with EV-D68 identified in the CSF by sequencing of the VP1 gene. We designed probes for in situ hybridization (ISH) based on this sequence to stain formalin fixed paraffin embedded tissues from his autopsy. For immunohistochemistry (IHC) we used both commercial polyclonal anti-EV-D68 antibodies and our own human monoclonal antibodies that stain virus infected cells in vitro. Immunophenotyping was done by IHC. To analyze gene transcription in the inflammatory transcriptome of these infected areas of spinal cord we used the GeoMx platform from Nanostring. Results We identified EV-D68 in the anterior horn of the patient’s spinal cord, corresponding to the location of motor neuron cell bodies. This area was highly inflamed, with an infiltrate of CD8 T cells and many macrophages. Viral RNA (see figure) and viral protein was visualized in motor neurons but not supporting cells using ISH and IHC, respectively. Viral RNA but not viral protein was detected rarely in the lungs in macrophages, which had extensive inflammatory infiltrate. The infiltrate was predominantly composed of macrophages with a CD8 T cell component as well. The transcriptome of cells in the inflamed tissue was enriched for genes involved in antigen presentation on MHC. Conclusions Deaths in AFM patients are rare and often distant from initial presentation, but this patient died four days after onset of weakness, allowing us to directly demonstrate that EV-D68 can infect the human spinal cord. Motor neurons but not neural support cells are directly infected by EV-D68 with a corresponding infiltrate of macrophages and CD8 T cells. Antigen presentation processes are upregulated in inflamed tissues. Therefore, both direct viral pathology and immune factors likely contribute to AFM disease in EV-D68 infection.

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Cytomegalovirus inhibition of extrinsic apoptosis determines fitness and resistance to cytotoxic CD8 T cells

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1914667117 ◽

2020 ◽

Vol 117 (23) ◽

pp. 12961-12968 ◽

Cited By ~ 3

Author(s):

M. Zeeshan Chaudhry ◽

Rosaely Casalegno-Garduno ◽

Katarzyna M. Sitnik ◽

Bahram Kasmapour ◽

Ann-Kathrin Pulm ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Antigen Presentation ◽

Cd8 T Cells ◽

Cell Function ◽

Death Receptor ◽

Cd8 T Cell ◽

Cytotoxic T Cell ◽

Caspase 8 ◽

Infected Cells

Viral immune evasion is currently understood to focus on deflecting CD8 T cell recognition of infected cells by disrupting antigen presentation pathways. We evaluated viral interference with the ultimate step in cytotoxic T cell function, the death of infected cells. The viral inhibitor of caspase-8 activation (vICA) conserved in human cytomegalovirus (HCMV) and murine CMV (MCMV) prevents the activation of caspase-8 and proapoptotic signaling. We demonstrate the key role of vICA from either virus, in deflecting antigen-specific CD8 T cell-killing of infected cells. vICA-deficient mutants, lacking either UL36 or M36, exhibit greater susceptibility to CD8 T cell control than mutants lacking the set of immunoevasins known to disrupt antigen presentation via MHC class I. This difference is evident during infection in the natural mouse host infected with MCMV, in settings where virus-specific CD8 T cells are adoptively transferred. Finally, we identify the molecular mechanism through which vICA acts, demonstrating the central contribution of caspase-8 signaling at a point of convergence of death receptor-induced apoptosis and perforin/granzyme-dependent cytotoxicity.

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DNA Immunization Using Highly Conserved Murine Cytomegalovirus Genes Encoding Homologs of Human Cytomegalovirus UL54 (DNA Polymerase) and UL105 (Helicase) Elicits Strong CD8 T-Cell Responses and Is Protective against Systemic Challenge

Journal of Virology ◽

10.1128/jvi.00633-07 ◽

2007 ◽

Vol 81 (14) ◽

pp. 7766-7775 ◽

Cited By ~ 21

Author(s):

Christopher S. Morello ◽

Laura A. Kelley ◽

Michael W. Munks ◽

Ann B. Hill ◽

Deborah H. Spector

Keyword(s):

T Cells ◽

T Cell ◽

Dna Polymerase ◽

Human Cytomegalovirus ◽

Cd8 T Cells ◽

T Cell Responses ◽

Cd8 T Cell ◽

Murine Cytomegalovirus ◽

Dna Immunization ◽

Cell Responses

ABSTRACT Human cytomegalovirus (HCMV) establishes a lifelong infection with the potential for reinfection or viral transmission even in the presence of strong and diverse CD8 T-lymphocyte responses. This suggests that the CMVs skew the host T-cell response in order to favor viral persistence. In this study, we hypothesized that the essential, nonstructural proteins that are highly conserved among the CMVs may represent a novel class of T-cell targets for vaccine-mediated protection due to their requirements for expression and sequence stability, but that the observed subdominance of these antigens in the CMV-infected host results from the virus limiting the T-cell responses to otherwise-protective specificities. We found that DNA immunization of mice with the murine CMV (MCMV) homologs of HCMV DNA polymerase (M54) or helicase (M105) was protective against virus replication in the spleen following systemic challenge, with the protection level elicited by the M54 DNA being comparable to that of DNA expressing the immunodominant IE1 (pp89). Intracellular gamma interferon staining of CD8 T cells from mice immunized with either the M54 or M105 DNAs showed strong primary responses that recalled rapidly after viral challenge. M54- and M105-specific CD8 T cells were detected after the primary MCMV infection, but their levels were not consistently above the background level. The conserved, essential proteins of the CMVs thus represent a novel class of CD8 T-cell targets that may contribute to a successful HCMV vaccine strategy.

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Characterization of the Interaction between the Matrix Protein of Vesicular Stomatitis Virus and the Immunoproteasome Subunit LMP2

Journal of Virology ◽

10.1128/jvi.01753-15 ◽

2015 ◽

Vol 89 (21) ◽

pp. 11019-11029 ◽

Cited By ~ 7

Author(s):

Frauke Beilstein ◽

Linda Obiang ◽

Hélène Raux ◽

Yves Gaudin

Keyword(s):

T Cells ◽

Immune System ◽

Mhc Class I ◽

Vesicular Stomatitis Virus ◽

Cd8 T Cells ◽

Matrix Protein ◽

Catalytic Subunit ◽

The Matrix ◽

Infected Cells ◽

Vesicular Stomatitis

ABSTRACTThe matrix protein (M) of vesicular stomatitis virus (VSV) is involved in virus assembly, budding, gene regulation, and cellular pathogenesis. Using a yeast two-hybrid system, the M globular domain was shown to interact with LMP2, a catalytic subunit of the immunoproteasome (which replaces the standard proteasome catalytic subunit PSMB6). The interaction was validated by coimmunoprecipitation of M and LMP2 in VSV-infected cells. The sites of interaction were characterized. A single mutation of M (I96A) which significantly impairs the interaction between M and LMP2 was identified. We also show that M preferentially binds to the inactive precursor of LMP2 (bearing an N-terminal propeptide which is cleaved upon LMP2 maturation). Furthermore, taking advantage of a sequence alignment between LMP2 and its proteasome homolog, PSMB6 (which does not bind to M), we identified a mutation (L45R) in the S1 pocket where the protein substrate binds prior to cleavage and a second one (D17A) of a conserved residue essential for the catalytic activity, resulting in a reduction of the level of binding to M. The combination of both mutations abolishes the interaction. Taken together, our data indicate that M binds to LMP2 before its incorporation into the immunoproteasome. As the immunoproteasome promotes the generation of major histocompatibility complex (MHC) class I-compatible peptides, a feature which favors the recognition and the elimination of infected cells by CD8 T cells, we suggest that M, by interfering with the immunoproteasome assembly, has evolved a mechanism that allows infected cells to escape detection and elimination by the immune system.IMPORTANCEThe immunoproteasome promotes the generation of MHC class I-compatible peptides, a feature which favors the recognition and the elimination of infected cells by CD8 T cells. Here, we report on the association of vesicular stomatitis virus (VSV) matrix protein (M) with LMP2, one of the immunoproteasome-specific catalytic subunits. M preferentially binds to the LMP2 inactive precursor. The M-binding site on LMP2 is facing inwards in the immunoproteasome and is therefore not accessible to M after its assembly. Hence, M binds to LMP2 before its incorporation into the immunoproteasome. We suggest that VSV M, by interfering with the immunoproteasome assembly, has evolved a mechanism that allows infected cells to escape detection and elimination by the immune system. Modulating this M-induced immunoproteasome impairment might be relevant in order to optimize VSV for oncolytic virotherapy.

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Host ER–parasitophorous vacuole interaction provides a route of entry for antigen cross-presentation in Toxoplasma gondii–infected dendritic cells

Journal of Experimental Medicine ◽

10.1084/jem.20082108 ◽

2009 ◽

Vol 206 (2) ◽

pp. 399-410 ◽

Cited By ~ 115

Author(s):

Romina S. Goldszmid ◽

Isabelle Coppens ◽

Avital Lev ◽

Pat Caspar ◽

Ira Mellman ◽

...

Keyword(s):

T Cells ◽

Dendritic Cells ◽

Toxoplasma Gondii ◽

Mhc Class I ◽

Cd8 T Cells ◽

Parasitophorous Vacuole ◽

Host Cells ◽

Class I ◽

Cross Presentation ◽

Infected Cells

Toxoplasma gondii tachyzoites infect host cells by an active invasion process leading to the formation of a specialized compartment, the parasitophorous vacuole (PV). PVs resist fusion with host cell endosomes and lysosomes and are thus distinct from phagosomes. Because the parasite remains sequestered within the PV, it is unclear how T. gondii–derived antigens (Ag’s) access the major histocompatibility complex (MHC) class I pathway for presentation to CD8+ T cells. We demonstrate that recruitment of host endoplasmic reticulum (hER) to the PV in T. gondii–infected dendritic cells (DCs) directly correlates with cross-priming of CD8+ T cells. Furthermore, we document by immunoelectron microscopy the transfer of hER components into the PV, a process indicative of direct fusion between the two compartments. In strong contrast, no association between hER and phagosomes or Ag presentation activity was observed in DCs containing phagocytosed live or dead parasites. Importantly, cross-presentation of parasite-derived Ag in actively infected cells was blocked when hER retrotranslocation was inhibited, indicating that the hER serves as a conduit for the transport of Ag between the PV and host cytosol. Collectively, these findings demonstrate that pathogen-driven hER–PV interaction can serve as an important mechanism for Ag entry into the MHC class I pathway and CD8+ T cell cross-priming.

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Broadly targeted human cytomegalovirus-specific CD4+ and CD8+ T cells dominate the memory compartments of exposed subjects

Journal of Experimental Medicine ◽

10.1084/jem.20050882 ◽

2005 ◽

Vol 202 (5) ◽

pp. 673-685 ◽

Cited By ~ 900

Author(s):

Andrew W. Sylwester ◽

Bridget L. Mitchell ◽

John B. Edgar ◽

Cara Taormina ◽

Christian Pelte ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Human Cytomegalovirus ◽

Cd8 T Cells ◽

Viral Infections ◽

Infectious Agent ◽

Cross Reactivity ◽

T Cell Response ◽

Open Reading Frames ◽

Human T Cell

Human cytomegalovirus (HCMV) infections of immunocompetent hosts are characterized by a dynamic, life-long interaction in which host immune responses, particularly of T cells, restrain viral replication and prevent disease but do not eliminate the virus or preclude transmission. Because HCMV is among the largest and most complex of known viruses, the T cell resources committed to maintaining this balance have never been characterized completely. Here, using cytokine flow cytometry and 13,687 overlapping 15mer peptides comprising 213 HCMV open reading frames (ORFs), we found that 151 HCMV ORFs were immunogenic for CD4+ and/or CD8+ T cells, and that ORF immunogenicity was influenced only modestly by ORF expression kinetics and function. We further documented that total HCMV-specific T cell responses in seropositive subjects were enormous, comprising on average ∼10% of both the CD4+ and CD8+ memory compartments in blood, whereas cross-reactive recognition of HCMV proteins in seronegative individuals was limited to CD8+ T cells and was rare. These data provide the first glimpse of the total human T cell response to a complex infectious agent and will provide insight into the rules governing immunodominance and cross-reactivity in complex viral infections of humans.

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