scholarly journals Deletion mutation analysis of the adenovirus type 2 E3-gp19K protein: identification of sequences within the endoplasmic reticulum lumenal domain that are required for class I antigen binding and protection from adenovirus-specific cytotoxic T lymphocytes.

1993 ◽  
Vol 67 (9) ◽  
pp. 5289-5298 ◽  
Author(s):  
T W Hermiston ◽  
R A Tripp ◽  
T Sparer ◽  
L R Gooding ◽  
W S Wold
Keyword(s):  
Endoplasmic Reticulum ◽  
T Lymphocytes ◽  
Cytotoxic T Lymphocytes ◽  
Mutation Analysis ◽  
Protein Identification ◽  
Adenovirus Type ◽  
Class I ◽  
Antigen Binding ◽  
Lumenal Domain

scholarly journals The Endoplasmic Reticulum Lumenal Domain of the Adenovirus Type 2 E3-19K Protein Binds to Peptide-Filled and Peptide-Deficient HLA-A*1101 Molecules

2005 ◽  
Vol 79 (21) ◽  
pp. 13317-13325 ◽  
Author(s):  
Hong Liu ◽  
Walter F. Stafford ◽  
Marlene Bouvier
Keyword(s):  
Endoplasmic Reticulum ◽  
Tertiary Structure ◽  
Analytical Ultracentrifugation ◽  
Expression System ◽  
Class I ◽  
Type I ◽  
Antigenic Peptides ◽  
Presentation Pathway ◽  
Lumenal Domain

ABSTRACT E3-19K is a type I membrane glycoprotein expressed by adenoviruses (Ads) to modulate host antiviral immune responses. We have developed an expression system for the endoplasmic reticulum lumenal domain (residues 1 to 100) of Ad type 2 E3-19K tagged with a C-terminal His6 sequence in baculovirus-infected insect cells. In this system, recombinant E3-19K is secreted into the culture medium. A characterization of soluble E3-19K by analytical ultracentrifugation and circular dichroism showed that the protein is monomeric and adopts a stable and correctly folded tertiary structure. Using a gel mobility shift assay and analytical ultracentrifugation, we showed that soluble E3-19K associates with soluble peptide-filled and peptide-deficient HLA-A*1101 molecules. This is the first example of a viral immunomodulatory protein that interacts with conformationally distinct forms of class I major histocompatibility complex molecules. The E3-19K/HLA-A*1101 complexes formed in a 1:1 stoichiometry with equilibrium dissociation constants (Kd ) of 50 ± 10 nM for peptide-filled molecules and of about 10 μM for peptide-deficient molecules. A temperature-dependent proteolysis study revealed that the association of E3-19K with peptide-deficient HLA-A*1101 molecules stabilizes the binding groove. Importantly, our studies showed that peptide-deficient HLA-A*1101 molecules sequestered by E3-19K are capable of binding antigenic peptides and maturing into peptide-filled molecules. This firmly establishes that E3-19K does not block binding of antigenic peptides. Together, our results suggest that Ads have evolved to exploit the late and early stages of the class I antigen presentation pathway.

scholarly journals The many roads to cross-presentation

2005 ◽  
Vol 202 (10) ◽  
pp. 1313-1318 ◽  
Author(s):  
Tom A.M. Groothuis ◽  
Jacques Neefjes
Keyword(s):  
Endoplasmic Reticulum ◽  
T Lymphocytes ◽  
Mhc Class I ◽  
Cytotoxic T Lymphocytes ◽  
Class I ◽  
Cross Presentation ◽  
Peptide Loading ◽  
The Many ◽  
Mhc Class I Molecules

Cross-presentation of extracellular antigens by MHC class I molecules is required for priming cytotoxic T lymphocytes (CTLs) at locations remote from the site of infection. Various mechanisms have been proposed to explain cross-presentation. One such mechanism involves the fusion of the endoplasmic reticulum (ER) with the endosomal-phagosomal system, in which the machinery required for peptide loading of MHC class I molecules is introduced directly into the phagosome. Here, we discuss the evidence for and against the ER-phagosome concept as well as other possible mechanisms of cross-presentation.

scholarly journals Human Transporters Associated with Antigen Processing (Taps) Select Epitope Precursor Peptides for Processing in the Endoplasmic Reticulum and Presentation to T Cells

1999 ◽  
Vol 190 (9) ◽  
pp. 1227-1240 ◽  
Author(s):  
Grégoire Lauvau ◽  
Kazuhiro Kakimi ◽  
Gabriele Niedermann ◽  
Marina Ostankovitch ◽  
Patricia Yotnda ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
T Lymphocytes ◽  
Antigen Presentation ◽  
Mhc Class I ◽  
Cytotoxic T Lymphocytes ◽  
Antigen Processing ◽  
High Efficiency ◽  
Class I ◽  
Aminopeptidase Activity

Antigen presentation by major histocompatibility complex (MHC) class I molecules requires peptide supply by the transporters associated with antigen processing (TAPs), which select substrates in a species- and, in the rat, allele-specific manner. Conflicts between TAPs and MHC preferences for COOH-terminal peptide residues in rodent cells strongly reduce the efficiency of MHC class I antigen presentation. Although human TAP is relatively permissive, some peptide ligands for human histocompatibility leukocyte antigen class I molecules are known to possess very low TAP affinities; the significance of these in vitro findings for cellular antigen presentation is not known. We studied two naturally immunodominant viral epitopes presented by HLA-A2 that display very low affinities for human TAP. Low TAP affinities preclude minimal epitope access to the endoplasmic reticulum (ER) and assembly with HLA-A2 in vitro, as well as presentation by minigene-expressing cells to cytotoxic T lymphocytes. However, NH2-terminally but not COOH-terminally extended epitope variants with higher TAP affinities assemble in vitro and are presented to cytotoxic T lymphocytes with high efficiency. Thus, human TAP can influence epitope selection and restrict access to the ER to epitope precursors. Analysis of TAP affinities of a panel of viral epitopes suggests that TAP selection of precursors may be a common phenomenon for HLA-A2–presented epitopes. We also analyzed HLA-A2–eluted peptides from minigene-expressing cells and show that an NH2-terminally extended variant with low A2 binding affinity undergoes ER processing, whereas another with high affinity is presented unmodified. Therefore, the previously reported aminopeptidase activity in the ER can also act on TAP-translocated peptides.

scholarly journals Retention of adenovirus E19 glycoprotein in the endoplasmic reticulum is essential to its ability to block antigen presentation.

1991 ◽  
Vol 174 (6) ◽  
pp. 1629-1637 ◽  
Author(s):  
J H Cox ◽  
J R Bennink ◽  
J W Yewdell
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Antigen Presentation ◽  
Viral Proteins ◽  
Genetically Engineered ◽  
Class I ◽  
Wild Type ◽  
Histocompatibility Complex ◽  
Infected Cells ◽  
Lumenal Domain

The E3/19K glycoprotein of adenovirus functions to diminish recognition of adenovirus-infected cells by major histocompatibility complex class I-restricted cytotoxic T lymphocytes (CTLs) by binding intracellular class I molecules and preventing them from reaching the plasma membrane. In the present study we have characterized the nature of the interaction between E3/19K and the H-2Kd (Kd) molecule. An E3/19K molecule genetically engineered to terminate six residues from its normal COOH terminus (delta E19), was found to associate with Kd in a manner indistinguishable from wild-type E3/19K. Unlike E3/19K, however, delta E19 was transported through the Golgi complex to the plasma membrane, where it could be detected biochemically and immunocytochemically using a monoclonal antibody specific for the lumenal domain of E3/19K. Importantly, delta E19 also differed from E3/19K in being unable to prevent the presentation of Kd-restricted viral proteins to CTLs. This is unlikely to be due to delta E19 having a lower avidity for Kd than E3/19K, since delta E19 was able to compete with E3/19K for Kd binding, both physically, and functionally in nullifying the E3/19K blockade of antigen presentation. These findings indicate that the ability of E3/19K to block antigen presentation is due solely to its ability to retain newly synthesized class I molecules in the endoplasmic reticulum.

scholarly journals High frequency of cross-reactive cytotoxic T lymphocytes elicited during the virus-induced polyclonal cytotoxic T lymphocyte response.

1993 ◽  
Vol 177 (2) ◽  
pp. 317-327 ◽  
Author(s):  
S R Nahill ◽  
R M Welsh
Keyword(s):  
T Lymphocytes ◽  
Virus Infection ◽  
Cytotoxic T Lymphocytes ◽  
High Frequency ◽  
Class Ii ◽  
Class I ◽  
Direct Stimulation ◽  
Ctl Response ◽  
Cd4 Cell ◽  
Stimulation Of

Polyclonal stimulation of CD8+ cytotoxic T lymphocytes (CTL) occurs during infection with many viruses including those not known to transform CTL or encode superantigens. This polyclonal CTL response includes the generation of high levels of allospecific CTL directed against many class I haplotypes. In this report we investigated whether the allospecific CTL generated during an acute lymphocytic choriomeningitis virus (LCMV) infection of C57BL/6 mice were stimulated specifically by antigen recognition or nonspecifically by polyclonal mechanisms possibly involving lymphokines or superantigens. An examination of the ability of different strains of mice to induce high levels of CTL specific for a given alloantigen showed that most, but not all, strains generated high levels of allospecific CTL, and that their abilities to generate them mapped genetically to the major histocompatibility complex locus, exclusive of the class II region. This indicated that the virus-induced allospecific CTL generation was independent of the class II allotype, and mice depleted of CD4+ cells generated allospecific CTL, indicating independence of class II-CD4+ cell interactions and resulting CD4+ cell-secreted lymphokines. FACS staining with a variety of V beta-binding antibodies did not show a superantigen-like depletion or enrichment of any tested V beta + subset during infection. Several experiments provided evidence in support of direct stimulation of CD8+ cells via the T cell receptor: (a) both virus- and allo-specific killing were enriched within a given V beta subpopulation; (b) relative CTL precursor frequencies against different class I alloantigens changed during the course of virus infection; (c) the relative levels of virus-induced, allospecific CTL-mediated lysis at day 8 after infection did not parallel the CTL precursor frequencies before infection; and (d) limiting dilution analyses of day 8 LCMV-infected spleen cells stimulated by virus-infected syngeneic peritoneal exudate cells (PEC) revealed not only the expected virus-specific CTL clones, but also a high frequency of clones that were cross-reactive with allogeneic and virus-infected syngeneic targets. In addition to the virus cross-reactive allospecific CTL clones, virus-infected PEC also stimulated the generation of some allospecific clones that did not lyse virus-infected fibroblasts. Surprisingly, LCMV-infected PEC were much more efficient at stimulating allospecific CTL clones from day 8 LCMV-infected splenocytes than were allogeneic stimulators. These results indicate that at least part of the polyclonal allospecific CTL response elicited by acute virus infection is a consequence of the selective expansion of many clones of allospecific CTL which cross-react with virus-infected cells.(ABSTRACT TRUNCATED AT 400 WORDS)

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