scholarly journals Intracellular Processing of Human Herpesvirus 6 Glycoproteins Q1 and Q2 into Tetrameric Complexes Expressed on the Viral Envelope

2004 ◽  
Vol 78 (15) ◽  
pp. 7969-7983 ◽  
Author(s):  
Pilailuk Akkapaiboon ◽  
Yasuko Mori ◽  
Tomohiko Sadaoka ◽  
Sayoko Yonemoto ◽  
Koichi Yamanishi
Keyword(s):  
Monoclonal Antibody ◽  
Endoplasmic Reticulum ◽  
Human Herpesvirus ◽  
Viral Envelope ◽  
Human Herpesvirus 6 ◽  
Pulse Period ◽  
Viral Particles ◽  
Infected Cells ◽  
Herpesvirus 6 ◽  
Additional Product

ABSTRACT Human herpesvirus 6 (HHV-6) glycoproteins H and L (gH and gL, respectively) and the 80-kDa form of glycoprotein Q (gQ-80K) form a heterotrimeric complex that is found on the viral envelope and that is a viral ligand for human CD46. Besides gQ-80K, the gQ gene encodes an additional product whose mature molecular mass is 37 kDa (gQ-37K) and which is derived from a different transcript. Therefore, we designated gQ-80K as gQ1 and gQ-37K as gQ2. We show here that gQ2 also interacts with the gH-gL-gQ1 complex in HHV-6-infected cells and in virions. To examine how these components interact in HHV-6-infected cells, we performed pulse-chase studies. The results demonstrated that gQ2-34K, which is endo-β-N-acetylglucosaminidase H sensitive and which is the precursor form of gQ2-37K, associates with gQ1-74K, which is the precursor form of gQ1-80K, within 30 min of the pulse period. After a 1-h chase, these precursor forms had associated with the gH-gL dimer. Interestingly, an anti-gH monoclonal antibody coimmunoprecipitated mainly gQ1-80K and gQ2-37K, with little gQ1-74K or gQ2-34K. These results indicate that although gQ2-34K and gQ1-74K interact in the endoplasmic reticulum, the gH-gL-gQ1-80K-gQ2-37K heterotetrameric complex arises in the post-endoplasmic reticulum compartment. The mature complex is subsequently incorporated into viral particles.

scholarly journals Discovery of a Second Form of Tripartite Complex Containing gH-gL of Human Herpesvirus 6 and Observations on CD46

2004 ◽  
Vol 78 (9) ◽  
pp. 4609-4616 ◽  
Author(s):  
Yasuko Mori ◽  
Pilailuk Akkapaiboon ◽  
Sayoko Yonemoto ◽  
Masato Koike ◽  
Masaya Takemoto ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Human Cytomegalovirus ◽  
Human Herpesvirus ◽  
Viral Envelope ◽  
Amino Terminus ◽  
Protein Species ◽  
Human Herpesvirus 6 ◽  
Glycoprotein H ◽  
Infected Cells ◽  
Herpesvirus 6

ABSTRACT The human herpesvirus 6 (HHV-6) glycoprotein H (gH)-glycoprotein L (gL) complex associates with glycoprotein Q (gQ) (Y. Mori, P. Akkapaiboon, X. Yang, and K. Yamanishi, J. Virol. 77:2452-2458, 2003), and the gH-gL-gQ complex interacts with human CD46 (Y. Mori, X. Yang, P. Akkapaiboon, T. Okuno, and K. Yamanishi, J. Virol. 77:4992-4999, 2003). Here, we show that the HHV-6 U47 gene, which is a positional homolog of the human cytomegalovirus glycoprotein O (gO) gene, encodes a third component of the HHV-6 gH-gL-containing envelope complex. A monoclonal antibody (MAb) against the amino terminus of HHV-6 gO reacted in immunoblots with protein species migrating at 120 to 130 kDa and 74 to 80 kDa in lysates of HHV-6-infected cells and with a 74- to 80-kDa protein species in purified virions. The 80-kDa form of gO was coimmunoprecipitated with an anti-gH MAb, but an anti-gQ MAb, which coimmunoprecipitated gH, did not coprecipitate gO. Furthermore, the gH-gL-gO complex did not bind to human CD46, indicating that the complex was not a ligand for CD46. These findings suggested that the viral envelope contains at least two kinds of tripartite complexes, gH-gL-gQ and gH-gL-gO, and that the gH-gL-gO complex may play a role different from that of gH-gL-gQ during viral infection. This is the first report of two kinds of gH-gL complexes on the viral envelope in a member of the herpesvirus family.

scholarly journals The Human Herpesvirus 6 U100 Gene Product Is the Third Component of the gH-gL Glycoprotein Complex on the Viral Envelope

2003 ◽  
Vol 77 (4) ◽  
pp. 2452-2458 ◽  
Author(s):  
Yasuko Mori ◽  
Pilailuk Akkapaiboon ◽  
Xuwei Yang ◽  
Koichi Yamanishi
Keyword(s):  
Viral Entry ◽  
Human Herpesvirus ◽  
Viral Envelope ◽  
Gene Products ◽  
Human Herpesvirus 6 ◽  
Glycoprotein Complex ◽  
The Third ◽  
Glycoprotein H ◽  
Infected Cells ◽  
Herpesvirus 6

ABSTRACT The human herpesvirus 6 (HHV-6) variant A U100 gene encodes the third component of the glycoprotein H (gH)-glycoprotein L (gL)-containing complex. Glycosidase digestion analysis showed that the U100 gene products are glycoproteins consisting of an 80-kDa protein with complex N-linked oligosaccharides and a 74-kDa protein with immature, high-mannose N-linked oligosaccharides. Based on these characteristics, we designated the U100 gene products glycoprotein Q (gQ). Only the 80-kDa form of gQ was coimmunoprecipitated with an anti-gH antibody, suggesting that the 80-kDa protein associates with the gH-gL complex in HHV-6-infected cells. Furthermore, the complex was detected in purified virions, suggesting that it may play an important role in viral entry.

scholarly journals Human Herpesvirus 6 Open Reading Frame U14 Protein and Cellular p53 Interact with Each Other and Are Contained in the Virion

2005 ◽  
Vol 79 (20) ◽  
pp. 13037-13046 ◽  
Author(s):  
Masaya Takemoto ◽  
Masato Koike ◽  
Yasuko Mori ◽  
Sayoko Yonemoto ◽  
Yumi Sasamoto ◽  
...  
Keyword(s):  
Western Blotting ◽  
Human Herpesvirus ◽  
Northern Blotting ◽  
Expression Vectors ◽  
Human Herpesvirus 6 ◽  
P53 Expression ◽  
Reading Frame ◽  
Viral Particles ◽  
Infected Cells ◽  
Herpesvirus 6

ABSTRACT A mass spectroscopic analysis of proteins from human herpesvirus 6 (HHV-6)-infected cells showed that the HHV-6 U14 protein coimmunoprecipitated with the tumor suppressor p53. The binding of U14 to p53 was verified by coimmunoprecipitation experiments in both Molt-3 cells infected with HHV-6 and 293 cells cotransfected with U14 and p53 expression vectors. Indirect immunofluorescence assays (IFAs) showed that by 18 h postinfection (hpi) U14 localized to the dot-like structures observed in both the nucleus and cytoplasm where p53 was partly accumulated. Despite Northern blotting evidence that U14 follows late kinetics, the U14 protein was detected immediately after infection (at 3 hpi) by IFA. In addition, by Western blotting, U14 was detected at 0 hpi or in the presence of cycloheximide which completely abolished the expression of IE1 protein. In addition to U14, p53 was detected at 0 hpi although it was not detected in mock-infected cells. Furthermore, both U14 and p53 were clearly detected in the viral particles by Western blotting and immunoelectron microscopy, supporting the idea that U14 and p53 are incorporated into virions. Our study provides the first evidence of the incorporation of cellular p53 into viral particles and suggests that p53 may play an important role in viral infection.

scholarly journals Viral Glycoproteins Accumulate in Newly Formed Annulate Lamellae following Infection of Lymphoid Cells by Human Herpesvirus 6

1998 ◽  
Vol 72 (12) ◽  
pp. 9738-9746 ◽  
Author(s):  
Giorgia Cardinali ◽  
Massimo Gentile ◽  
Mara Cirone ◽  
Claudia Zompetta ◽  
Luigi Frati ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Helix Pomatia ◽  
Human Herpesvirus ◽  
Viral Envelope ◽  
Lymphoid Cells ◽  
Annulate Lamellae ◽  
Human Herpesvirus 6 ◽  
Viral Glycoprotein ◽  
Nuclear Membranes ◽  
Herpesvirus 6

ABSTRACT Ultrastructural analysis of HSB-2 T-lymphoid cells and human cord blood mononuclear cells infected with human herpesvirus 6 revealed the presence, in the cell cytoplasm, of annulate lamellae (AL), which were absent in uninfected cells. Time course analysis of the appearance of AL following viral infection showed that no AL were visible within the first 72 h postinfection and that their formation correlated with the expression of the late viral glycoprotein gp116. The requirement of active viral replication for AL neoformation was further confirmed by experiments using inactivated virus or performed in presence of the viral DNA polymerase inhibitor phosphonoacetic acid. Both conventional electron microscopic examination and immunogold fracture labeling with anti-endoplasmic reticulum antibodies indicated a close relationship of AL with the endoplasmic reticulum and nuclear membranes. However, when the freeze-fractured cells were immunogold labeled with an anti-gp116 monoclonal antibody, AL membranes were densely labeled, whereas nuclear membranes and endoplasmic reticulum cisternae appeared virtually unlabeled, showing that viral envelope glycoproteins selectively accumulate in AL. In addition, gold labeling with Helix pomatia lectin and wheat germ agglutinin indicated that AL cisternae, similar to cis-Golgi membranes, contain intermediate, but not terminal, forms of glycoconjugates. Taken together, these results suggest that in this cell-virus system, AL function as a viral glycoprotein storage compartment and as a putative site of O-glycosylation.

scholarly journals Immunosuppressive effect of human herpesvirus 6 on T-cell functions: suppression of interleukin-2 synthesis and cell proliferation [published erratum appears in Blood 1995 Jul 1;86(1):418]

Blood ◽  
1995 ◽  
Vol 85 (5) ◽  
pp. 1263-1271 ◽  
Author(s):  
L Flamand ◽  
J Gosselin ◽  
I Stefanescu ◽  
D Ablashi ◽  
J Menezes
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocyte ◽  
Peripheral Blood ◽  
Cellular Proliferation ◽  
Interleukin 2 ◽  
Human Herpesvirus ◽  
Human Herpesvirus 6 ◽  
Infected Cells ◽  
Herpesvirus 6

Human herpesvirus-6 (HHV-6), the etiologic agent of roseola, is ubiquitous, establishes latency in the host, and can infect a variety of immunocompetent cells, with CD4+ T lymphocytes being the targets in which it replicates most efficiently. The present study was undertaken to learn more about specific immunobiologic effects of HHV-6 infection on T-lymphocyte functions. Our data demonstrate that infection of peripheral blood mononuclear cells (PBMC) by HHV-6 results in suppression of T-lymphocyte functions, as evidenced by reduced interleukin-2 (IL-2) synthesis and cellular proliferation. In fact, HHV- 6-infected PBMC secreted 50% less IL-2 than mock-infected cells after mitogenic stimulation with OKT3 antibody or phytohemmaglutinin (PHA). The inhibition of IL-2 by HHV-6 was also observed in enriched T-cell cultures, suggesting a direct effect of this virus on this cell type. Messenger RNA (mRNA) analysis by reverse-transcriptase polymerase chain reaction (PCR) indicated that HHV-6 diminishes IL-2 mRNA levels in mitogen-stimulated peripheral blood T cells. These results were also confirmed by Northern blot using the leukemic T-cell line Jurkat. This inhibitory effect of HHV-6 did not require infectious virus, as the use of UV-irradiated HHV-6 produced similar results. Moreover, HHV-6- infected PBMC showed up to an 85% reduction in their mitogen-driven proliferative response, as compared with sham-infected cells. Proliferation of both CD4+ and CD8+ T cells was affected by HHV-6. Taken together, our data show that infection of T cells by HHV-6 results in immune suppression characterized by a downregulation of IL-2 mRNA and protein synthesis accompanied by diminished cellular proliferation.

scholarly journals In vitro cellular tropism of human B-lymphotropic virus (human herpesvirus-6).

1988 ◽  
Vol 167 (5) ◽  
pp. 1659-1670 ◽  
Author(s):  
P Lusso ◽  
P D Markham ◽  
E Tschachler ◽  
F di Marzo Veronese ◽  
S Z Salahuddin ◽  
...  
Keyword(s):  
T Cell ◽  
T Lymphocytes ◽  
Cell Population ◽  
Mononuclear Cells ◽  
Human Herpesvirus ◽  
Human Herpesvirus 6 ◽  
Infected Cells ◽  
Cellular Tropism ◽  
Herpesvirus 6

We investigated the cellular tropism of human B-lymphotropic virus (HBLV) (also designated Human Herpesvirus-6) in vitro by infecting fresh MN cells from normal human adult peripheral blood, umbilical cord blood, bone marrow, tonsil, and thymus. Cultures from all the sources examined contained infectable cells, as shown by the appearance of characteristic enlarged, round-shaped, short-lived cells expressing HBLV-specific markers. Detailed immunological analysis demonstrated that the vast majority of these cells expressed T cell-associated antigens (i.e., CD7, CD5, CD2, CD4, and to a lesser extent, CD8). The CD3 antigen and the TCR-alpha/beta heterodimer were not detectable on the surface membrane, but were identified within the cytoplasm of HBLV-infected cells, by both immunofluorescence and radioimmunoprecipitation assay. A proportion of the HBLV-infected cell population also expressed the CD15 and class II MHC DR antigens. By means of immunoselection procedures it was possible to show that a consistent proportion of HBLV-infectable cells were contained within the CD3-depleted immature T cell population, while the depletion of CD2+ cells completely abrogated the infectability of the cultures. Northern blot analysis confirmed the T cell origin of HBLV-infected cells, demonstrating the expression of full size TCR-alpha and -beta chain mRNA. In addition to fresh T cells, HBLV was able to infect normal T lymphocytes expanded in vitro with IL-2 for greater than 30 d. These results indicate that HBLV is selectively T cell tropic in the course of the in vitro infection of normal mononuclear cells and may therefore be directly involved in the pathogenesis of T cell related hematological disorders. In particular, in light of the cytopathic effect exerted in vitro on CD4+ T lymphocytes, a possible role of HBLV in immune deficiency conditions should be considered.

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