Complex formation of class I transplantation antigens and a viral glycoprotein.

Class I transplantation antigens form complexes with a virus protein encoded in the early region E3 of the adenovirus-2 genome. The interaction between this viral glycoprotein, E19, and nascent human class I antigens has been examined by microinjecting purified mRNA into Xenopus laevis oocytes. Both E19 and the two class I antigen subunits, the heavy chain and beta 2-microglobulin (beta 2M), were efficiently translated. The heavy chains did not become terminally glycosylated, as monitored by endoglycosidase H digestion, and were not expressed on the oocyte surface unless they were associated with beta 2M. The E19 protein did not become terminally glycosylated, and we failed to detect this viral protein on the surface of the oocytes. Co-translation of heavy chain and E19 mRNA demonstrated that the two proteins associate intracellularly. However, neither protein appeared to be transported to the trans-Golgi compartment. Similar observations were made in adenovirus-infected HeLa cells. Heavy chains bound to beta 2M became terminally glycosylated in oocytes in the presence of low concentrations of E19. At high concentrations of the viral protein, no carbohydrate modifications and no cell surface expression of class I antigens were apparent. Thus, beta 2M and E19 have opposite effects on the intracellular transport of the heavy chains. These data suggest that adenovirus-2 may impede the cell surface expression of class I antigens to escape immune surveillance.

Download Full-text

Characterisation of antigenic MHC Class I-restricted T cell epitopes in the glycoprotein of Ebolavirus

10.1101/494021 ◽

2018 ◽

Author(s):

Jonathan Powlson ◽

Daniel Wright ◽

Antra Zeltina ◽

Mark Giza ◽

Morten Nielsen ◽

...

Keyword(s):

Immune Response ◽

T Cell ◽

Mhc Class I ◽

T Cell Responses ◽

Hla Typing ◽

Class I ◽

Human Populations ◽

T Cell Epitopes ◽

Viral Glycoprotein ◽

Cell Responses

Ebolavirus is a pathogen capable of causing highly lethal haemorrhagic fever in humans. The envelope-displayed viral glycoprotein is the primary target of humoral immunity induced by both natural exposure and vaccination. The epitopes targeted by B cells have been thoroughly characterised by functional and structural analyses of the glycoprotein, GP, yet there is a paucity of information regarding the cellular immune response to Ebolavirus. To date, no T cell epitopes in the glycoprotein have been characterised in detail in humans. A recent Phase I clinical trial of a heterologous prime-boost vaccination regime with viral vectors encoding filovirus antigens elicited strong humoral and T cell responses in vaccinees. Using samples from this trial, the most frequently recognised peptide pools were studied in more detail to identify the minimal epitopes recognised by antigen-specific T cells and associated HLA-restrictions. Using IFNγ ELISPOT and flow cytometry, we characterised nine highly immunogenic T cell epitopes located on both the GP1 and GP2 subunits of the Ebolavirus GP. Epitope mapping revealed the location of these epitopes as presented on the mature virion. HLA-typing on all participants, combined with in silico epitope analysis, determined the likely MHC class I restriction elements. Thirteen HLA-A and -B alleles were predicted to present the identified epitopes, suggesting promiscuous recognition and induction of a broad immune response. The glycoprotein of Ebolavirus is highly immunogenic, inducing both CD4+ and CD8+ T cell responses and we have shown here for the first time that these responses are associated with multiple HLA types. Delivery of this antigen using a heterologous prime-boost approach with ChAd3 and MVA is likely to be highly immunogenic in genetically diverse human populations, due to the induction of responses against multiple immunodominant epitopes.

Download Full-text

The Association between Class-I Transplantation Antigens and an Adenovirus Membrane Protein

Chemical Immunology and Allergy - Immunobiology of HLA Class-I and Class-II Molecules ◽

10.1159/000409864 ◽

2015 ◽

pp. 114-134

Author(s):

Svante P��bo ◽

Olle K�mpe ◽

Liv Severinsson ◽

Mats Andersson ◽

Carmen Fernandez ◽

...

Keyword(s):

Membrane Protein ◽

Class I ◽

Transplantation Antigens

Download Full-text

Immune response genes controlling responsiveness to major transplantation antigens. Specific major histocompatibility complex-linked defect for antibody responses to class I alloantigens.

Journal of Experimental Medicine ◽

10.1084/jem.155.1.303 ◽

1982 ◽

Vol 155 (1) ◽

pp. 303-320 ◽

Cited By ~ 30

Author(s):

G W Butcher ◽

J R Corvalán ◽

D R Licence ◽

J C Howard

Keyword(s):

Major Histocompatibility Complex ◽

Antibody Response ◽

Antibody Responses ◽

Class I ◽

Control Analysis ◽

Major Histocompatibility ◽

Histocompatibility Complex ◽

Transplantation Antigens ◽

Ir Genes

We have identified two major histocompatibility complex (MHC)-linked Ir genes that control the antibody response made by rats against class I major alloantigens. We have named these genes Ir-RT1Aa and Ir-RT1Ac. These Ir genes determine responsiveness of the immunized animal in a typical codominant fashion. There is no evidence so far for trans-complementation between low-responder haplotypes. Detailed studies of Ir-RT1Aa indicate that it controls the antibody response to at least two distinct alloantigenic determinants on RT1Aa molecules. These class I molecules thus behave like hapten-carrier conjugates when the response against the carrier is under Ir gene control. Analysis of the origin of alloantibody-forming cells in tetraparental radiation chimeras indicates that Ir-RT1Aa must control the provision of effective help to B cells. In many respects therefore, the properties of Ir-RT1Aa are broadly similar to those described for Ir genes controlling antibody responses to conventional antigens. The existence of apparently conventional Ir genes controlling the antibody response to major alloantigens strongly suggest that the processing of these transmembrane molecules by host antigen-presenting cells is a prerequisite for immune induction, and that it is the MHC of the responder rather than that of the allograft to which T helper cells are restricted in alloimmune responses in vivo.

Download Full-text

Class-I-Restricted Human Cytotoxic T Lymphocytes Directed against Minor Transplantation Antigens and Their Possible Role in Organ Transplantation (Part 1 of 2)

Chemical Immunology and Allergy - Immunobiology of HLA Class-I and Class-II Molecules ◽

10.1159/000318415 ◽

1984 ◽

pp. 44-58 ◽

Cited By ~ 1

Author(s):

Els Goulmy

Keyword(s):

T Lymphocytes ◽

Organ Transplantation ◽

Cytotoxic T Lymphocytes ◽

Class I ◽

Transplantation Antigens

Download Full-text

MARCH8 Restricts Ebola Virus Replication by Blocking the Viral Glycoprotein Processing and Glycosylation

Proceedings ◽

10.3390/proceedings2020050123 ◽

2020 ◽

Vol 50 (1) ◽

pp. 123

Author(s):

Changqing Yu ◽

Sunan Li ◽

Omid Madadgar ◽

Iqbal Ahmad ◽

Xianfeng Zhang ◽

...

Keyword(s):

Cell Surface ◽

Fusion Protein ◽

Fusion Proteins ◽

Ebola Virus ◽

Class I ◽

Class Iii ◽

Viral Glycoprotein ◽

E3 Ligases ◽

Glycosylation Sites ◽

Hiv 1

Ebola virus (EBOV) glycoprotein (GP) is a class I fusion protein whose maturation is dependent on furin-mediated processing. EBOV-GP is heavily glycosylated, with glycans constituting ~50% of its molecular mass. Compared with 15 N-linked glycosylation sites, EBOV-GP1 has ~80 potential O-linked glycosylation sites in the mucin-like domain (MLD), suggesting that O-linked glycans are dominated. The membrane-associated RING-CH (MARCH) family consists of 11 members that are RING-finger ubiquitin E3 ligases. Recently, human MARCH1, MARCH2, and MARCH8 were reported to inhibit HIV-1 replication by targeting its Env. Here, we show that human MARCH8 also inhibits EBOV replication by blocking GP incorporation into virions via downregulating its cell surface expression. To understand how the downregulation occurs, we investigated EBOV-GP subcellular localization, processing, glycosylation, and intracellular trafficking in the presence of human MARCH8. We find that MARCH8 interacts with GP and retains GP in the Golgi. MARCH8 also interacts with the homoB domain of furin that blocks its convertase activity. In consequence, MARCH8 blocks GP processing in an MLD-independent manner. Consistently, MARCH8 also blocks the O-linked, but not the N-linked glycosylation of GP. Importantly, in the presence of MARCH8, the shedding of GP1 but not the secreted GP (sGP) is blocked, suggesting that MARCH8 targets the GP1 C-terminal region. The MARCH8 activity is extended to its orthologs from Bos taurus and mice, and its paralogs MARCH1 and MARCH2. In addition, MARCH8 inhibits the processing of two other class I fusion proteins, including HIV-1 Env and IAV HA, and it triggers the degradation of the class III fusion protein VSV-G. We conclude that MARCH8 exerts a very broad and conserved antiviral activity by inhibiting the maturation of class I fusion proteins, which blocks their secretion to the cell surface and incorporation into virions. It should also target class III fusion proteins by triggering their degradation.

Download Full-text