Human herpesvirus 7 U47 gene products are glycoproteins expressed in virions and associate with glycoprotein H

The function of the human herpesvirus 7 (HHV-7) U47 gene, which is a positional homologue of the genes encoding glycoprotein O (gO) in human cytomegalovirus (HCMV) and human herpesvirus 6 (HHV-6), was analysed. A monoclonal antibody (mAb) against the U47 gene product reacted in immunoblots with proteins migrating at 49 and 51 kDa in lysates of HHV-7-infected cells and with 49 and 51 kDa proteins in partially purified virions. Digestion of the 49 and 51 kDa proteins with endoglycosidase H and peptide N-glycosidase F indicated that the U47-encoded proteins were modified with N-linked oligosaccharides. Therefore, the U47 gene and its product were named gO, as in HCMV and HHV-6. In addition, the anti-gO mAb co-immunoprecipitated glycoprotein H (gH) in HHV-7-infected cells, indicating an association between HHV-7 gO and gH. The results suggest that the HHV-7 gO–gH complex might have a similar function to that in HCMV or HHV-6, such as cell–cell fusion in virus infection.

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

Journal of Virology ◽

10.1128/jvi.78.9.4609-4616.2004 ◽

2004 ◽

Vol 78 (9) ◽

pp. 4609-4616 ◽

Cited By ~ 57

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.

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

Journal of Virology ◽

10.1128/jvi.77.4.2452-2458.2003 ◽

2003 ◽

Vol 77 (4) ◽

pp. 2452-2458 ◽

Cited By ~ 45

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.

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

Journal of Virology ◽

10.1128/jvi.78.15.7969-7983.2004 ◽

2004 ◽

Vol 78 (15) ◽

pp. 7969-7983 ◽

Cited By ~ 61

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.

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A monoclonal antibody that neutralizes Epstein-Barr virus, human cytomegalovirus, human herpesvirus 6, and bacteriophage T4 DNA polymerases.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.87.20.7963 ◽

1990 ◽

Vol 87 (20) ◽

pp. 7963-7967 ◽

Cited By ~ 2

Author(s):

C. H. Tsai ◽

M. V. Williams ◽

R. Glaser

Keyword(s):

Monoclonal Antibody ◽

Human Cytomegalovirus ◽

Epstein Barr Virus ◽

Bacteriophage T4 ◽

Dna Polymerases ◽

Human Herpesvirus ◽

Human Herpesvirus 6 ◽

Barr Virus ◽

Herpesvirus 6 ◽

Epstein Barr

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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 ◽

10.1182/blood.v85.5.1263.bloodjournal8551263 ◽

1995 ◽

Vol 85 (5) ◽

pp. 1263-1271 ◽

Cited By ~ 106

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.

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The Human Cytomegalovirus UL74 Gene Encodes the Third Component of the Glycoprotein H-Glycoprotein L-Containing Envelope Complex

Journal of Virology ◽

10.1128/jvi.72.10.8191-8197.1998 ◽

1998 ◽

Vol 72 (10) ◽

pp. 8191-8197 ◽

Cited By ~ 113

Author(s):

Mary T. Huber ◽

Teresa Compton

Keyword(s):

Amino Acid ◽

Human Cytomegalovirus ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Open Reading Frames ◽

Protein Species ◽

Gene Encoding ◽

Peptide Backbone ◽

Glycoprotein H ◽

Infected Cells

ABSTRACT The human cytomegalovirus (HCMV) gCIII envelope complex is composed of glycoprotein H (gH; gpUL75), glycoprotein L (gL; gpUL115), and a third, 125-kDa protein not related to gH or gL (M. T. Huber and T. Compton, J. Virol. 71:5391–5398, 1997; L. Li, J. A. Nelson, and W. J. Britt, J. Virol. 71:3090–3097, 1997). Glycosidase digestion analysis demonstrated that the 125-kDa protein was a glycoprotein containing ca. 60 kDa of N-linked oligosaccharides on a peptide backbone of 65 kDa or less. Based on these biochemical characteristics, two HCMV open reading frames, UL74 and TRL/IRL12, were identified as candidate genes for the 125-kDa glycoprotein. To identify the gene encoding the 125-kDa glycoprotein, we purified the gCIII complex, separated the components by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and subjected gH and the 125-kDa glycoprotein to amino acid microsequence analysis. Microsequencing of an internal peptide derived from purified 125-kDa glycoprotein yielded the amino acid sequence LYVGPTK. A FASTA search revealed an exact match of this sequence to amino acids 188 to 195 of the predicted product of the candidate gene UL74, which we have designated glycoprotein O (gO). Anti-gO antibodies reacted in immunoblots with a protein species migrating at ca. 100 to 125 kDa in lysates of HCMV-infected cells and with 100- and 125-kDa protein species in purified virions. Anti-gO antibodies also immunoprecipitated the gCIII complex and recognized the 125-kDa glycoprotein component of the gCIII complex. Positional homologs of the UL74 gene were found in other betaherpesviruses, and comparisons of the predicted products of the UL74 homolog genes demonstrated a number of conserved biochemical features.

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Polyvalent and monoclonal antibodies identify major immunogenic proteins specific for human herpesvirus 7-infected cells and have weak cross-reactivity with human herpesvirus 6

Journal of General Virology ◽

10.1099/0022-1317-75-10-2719 ◽

1994 ◽

Vol 75 (10) ◽

pp. 2719-2727 ◽

Cited By ~ 24

Author(s):

L. Foa-Tomasi ◽

E. Avitabile ◽

L. Ke ◽

G. Campadelli-Fiume

Keyword(s):

Monoclonal Antibodies ◽

Human Herpesvirus ◽

Cross Reactivity ◽

Human Herpesvirus 6 ◽

Infected Cells ◽

Herpesvirus 6 ◽

Immunogenic Proteins

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

Journal of Experimental Medicine ◽

10.1084/jem.167.5.1659 ◽

1988 ◽

Vol 167 (5) ◽

pp. 1659-1670 ◽

Cited By ~ 217

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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