Identification of a variant B-specific neutralizing epitope on glycoprotein H of human herpesvirus-6.

Takeda, Kunio; Haque, Muzammel; Sunagawa, Tomimasa; Okuno, Toshiomi; Isegawa, Yuji; Yamanishi, Koichi

doi:10.1099/0022-1317-78-9-2171

Cited by 30 publications

(29 citation statements)

References 50 publications

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“…Of these, gH and gL appear to play prominent roles in the membrane fusion events that initiate HHV-6 infectivity, based on inhibitory activities of specific antibodies (7)(8)(9)(10)(11)(12). As in other herpesviruses, these glycoproteins form a heterodimeric complex, with gL being required for correct folding, intracellular maturation, and surface expression of gH (9,(12)(13)(14)(15)(16).…”

Section: Human Herpesvirus 6 (Hhv-6)mentioning

confidence: 99%

“…We also examined the effects of depleting two other HHV-6 glycoproteins, gp82-gp105 and gB; all three glycoproteins are known to play critical roles in viral infectivity, as shown by the neutralizing activities of specific antibodies to gH (7)(8)(9)(10)(11)(12), gB (17), or gp82-gp105 (19). We first analyzed the products of direct immunoprecipitation from the lysate of a mixture of HHV-6-infected HSB-2 cells and CD46-expressing NIH 3T3 cells (Fig.…”

Section: Hhv-6 Gh Binding To Cd46mentioning

confidence: 99%

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Interaction of Glycoprotein H of Human Herpesvirus 6 with the Cellular Receptor CD46

Santoro

Greenstone

Insinga³

et al. 2003

Journal of Biological Chemistry

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Human herpesvirus 6 (HHV-6) employs the complement regulator CD46 (membrane cofactor protein) as a receptor for fusion and entry into target cells. Like other known herpesviruses, HHV-6 encodes multiple glycoproteins, several of which have been implicated in the entry process. In this report, we present evidence that glycoprotein H (gH) is the viral component responsible for binding to CD46. Antibodies to CD46 co-immunoprecipitated an ϳ110-kDa protein band specifically associated with HHV-6-infected cells. This protein was identified as gH by selective depletion with an anti-gH monoclonal antibody, as well as by immunoblot analysis with a rabbit hyperimmune serum directed against a gH synthetic peptide. In reciprocal experiments, a monoclonal antibody against HHV-6 gH was found to co-immunoprecipitate CD46. Studies using monoclonal antibodies directed against specific CD46 domains, as well as engineered constructs lacking defined CD46 regions, demonstrated a close correspondence between the CD46 domains involved in the interaction with gH and those previously shown to be critical for HHV-6 fusion (i.e. short consensus repeats 2 and 3).Human herpesvirus 6 (HHV-6) 1 is a member of the ␤-herpesvirus subfamily (reviewed in Ref. 1). Two major HHV-6 variants, A and B, have been defined that form two segregated clusters with unique genetic, biologic, and immunologic characteristics. Primary infection with HHV-6 B occurs almost universally in early childhood and has been etiologically linked to exanthema subitum. In adult life, HHV-6 infection and/or reactivation have been associated with a wide range of diseases, including multiple sclerosis, but most of these associations have yet to be substantiated by rigorous epidemiological studies. In immunocompromised people, including those infected with human immunodeficiency virus, HHV-6 B has been implicated as an opportunistic agent that may cause life-threatening respiratory tract and central nervous system infections, as well as bone marrow or organ graft failure. Moreover, HHV-6 may act as a cofactor to accelerate progression of human immunodeficiency virus disease.The best studied members of the herpesvirus family enter cells by direct fusion with the plasma membrane in a process involving binding of viral glycoproteins to specific protein receptors on the target cell (reviewed in Ref.2). Fusion is also facilitated by virus interactions with cell surface glycosaminoglycans. Recently, we identified CD46 (membrane cofactor protein) as a cellular receptor mediating fusion and entry for both HHV-6 variants (3). This glycoprotein also serves as a cellular receptor mediating critical events in the infectious process of other human pathogens, including binding/fusion/ entry of measles virus, pilus binding of different pathogenic Neisseriae, and adhesion of group A Streptococci (reviewed in Ref. 4). CD46 is a member of the regulators of complement activation (RCA) protein family. It is a type I transmembrane glycoprotein of 45-67 kDa, expressed on most or all human nucleated ce...

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Section: Human Herpesvirus 6 (Hhv-6)mentioning

confidence: 99%

Section: Hhv-6 Gh Binding To Cd46mentioning

confidence: 99%

Interaction of Glycoprotein H of Human Herpesvirus 6 with the Cellular Receptor CD46

Santoro

Greenstone

Insinga³

et al. 2003

Journal of Biological Chemistry

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“…The cells were then stimulated for 2 or 3 days with phytohemagglutinin (5 g/ml) in RPMI 1640 medium containing 10% fetal calf serum (FCS). To prepare virus stocks, HHV-6B HST (54) and HHV-6A U1102 (Downing et al, Letter) were propagated in stimulated CBMCs as previously described (48). When more than 80% of the cells exhibited a cytopathic effect, the infected cells were lysed by freezing, thawed twice, and spun at 1,500 ϫ g for 10 min.…”

Section: Cells and Virusesmentioning

confidence: 99%

Expression of Human Herpesvirus 6B rep within Infected Cells and Binding of Its Gene Product to the TATA-Binding Protein In Vitro and In Vivo

Mori

Dhepakson

Shimamoto

et al. 2000

J Virol

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We have characterized the human herpesvirus 6B (HHV-6B) rep gene, which is a homologue of the adenoassociated virus type 2 rep and is unique in the herpesvirus family. Three transcripts, 9.0, 5.0, and 2.7 kb (the major transcript), were detected by Northern blotting using an HHV-6B rep probe under late conditions. We investigated the expression kinetics of the rep gene using cycloheximide (CHX) and phosphonoformic acid (PFA), which are inhibitors of protein synthesis and viral DNA synthesis, respectively. The 5.2-kb transcript was mainly detected in the absence of protein biosynthesis upon infection, and none of the 9.0-, 5.0-, and 2.7-kb transcripts detected under the late conditions were detected in the presence of CHX and PFA. Sequences obtained from a cDNA library showed that the 5.0-and 2.7-kb transcripts were spliced from two and three exons, respectively, and the 2.7-kb transcript was more abundant. Immunohistochemistry using an antibody raised against the HHV-6 rep gene product (REP) revealed that REP was mainly present in the nucleus of MT-4 cells within 24 h after infection with HHV-6B. Using pull-down assays, coimmunoprecipitation, and a mammalian two hybrid system, we showed that HHV-6 REP binds to a transcription factor, human TATA-binding protein, through its N-terminal region.Human herpesvirus 6 (HHV-6) is a recently isolated member of the herpesvirus family (44), which causes exanthem subitum as a primary infection (54). Thereafter, HHV-6 establishes a latent infection, but it can be reactivated during immunosuppression and has been recovered from immunodeficient individuals

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“…Human cytomegalovirus also has two gH/gL complexes: gH/gL/UL128-131 and gH/gL/gO. These complexes were shown previously to be related to viral cell tropism for entry processes (33)(34)(35)47).Because reactivated HHV-6B, and not HHV-6A, causes several diseases in immunocompromised patients (49), and as primary infection by HHV-6B also causes diseases in infants (16,48), it is essential to identify the viral and cellular molecules mediating HHV-6B infection.Several MAbs against the HHV-6B glycoproteins gH and gB that neutralize the virus have been established (40,41). Although the MAb that recognizes gp82-gp105 (gQ1) was shown previously to have neutralizing activity against HHV-6A (32), it is still unknown whether HHV-6B gQ1 functions in viral entry.…”

mentioning

confidence: 99%

“…Several MAbs against the HHV-6B glycoproteins gH and gB that neutralize the virus have been established (40,41). Although the MAb that recognizes gp82-gp105 (gQ1) was shown previously to have neutralizing activity against HHV-6A (32), it is still unknown whether HHV-6B gQ1 functions in viral entry.…”

mentioning

confidence: 99%

Analysis of a Neutralizing Antibody for Human Herpesvirus 6B Reveals a Role for Glycoprotein Q1 in Viral Entry

Kawabata

Oyaizu

Maeki

et al. 2011

J Virol

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Human herpesvirus 6 (HHV-6) is a T cell-tropic betaherpesvirus. HHV-6 can be classified into two variants, HHV-6A and HHV-6B, based on differences in their genetic, antigenic, and growth characteristics and cell tropisms. The function of HHV-6B should be analyzed more in its life cycle, as more than 90% of people have the antibodies for HHV-6B but not HHV-6A. It has been shown that the cellular receptor for HHV-6A is human CD46 and that the viral ligand for CD46 is the envelope glycoprotein complex gH/gL/gQ1/gQ2; however, the receptor-ligand pair used by HHV-6B is still unknown. In this study, to identify the glycoprotein(s) important for HHV-6B entry, we generated monoclonal antibodies (MAbs) that inhibit infection by HHV-6B. Most of these MAbs were found to recognize gQ1, indicating that HHV-6B gQ1 is critical for virus entry. Interestingly, the recognition of gQ1 by the neutralizing MAb was enhanced by coexpression with gQ2. Moreover, gQ1 deletion or point mutants that are not recognized by the MAb could nonetheless associate with gQ2, indicating that although the MAb recognized the conformational epitope of gQ1 exposed by the gQ2 interaction, this epitope was not related to the gQ2 binding domain. Our study shows that HHV-6B gQ1 is likely a ligand for the HHV-6B receptor, and the recognition site for this MAb will be a promising target for antiviral agents.Human herpesvirus 6 (HHV-6) was first isolated from patients with lymphocytic disorders in1986 (36) and was subsequently shown to be the causative agent of exanthem subitum (ES) (48). Currently, HHV-6 can be classified into two variants, HHV-6A and HHV-6B, based on differences in genetic, antigenic, and growth characteristics and cell tropisms (1,5,7,8). HHV-6B causes infant ES, and more than 90% of people have antibodies (Abs) against HHV-6B (31, 38), while the pathogenesis of HHV-6A is still unknown. Recently, it was shown that a reactivation of HHV-6B causes encephalitis in immunocompromised hosts (13,45,46) and possibly enhances the severity of drug-induced sensitivity syndrome (14).Human CD46, a regulator of the complement activation receptor expressed on all nuclear cells, is a receptor for HHV-6 (37), and its viral ligand is the envelope glycoprotein complex gH/gL/gQ1/gQ2 (3, 28). Although this complex can bind CD46 (28), those of some clinical isolates, including laboratory strains of HHV-6B, do not bind it (24, 26). The gQ gene is unique because it is conserved only among HHV-6A, HHV-6B, and 15,19). Recently, we successfully reconstituted a virus from the HHV-6 genome (43) and found that HHV-6 gQ1 is essential for virus growth and probably for entry.As monoclonal antibodies (MAbs) against gH and gB inhibit virus-induced cell fusion and infection, gH and gB are thought to be fusogenic candidates (39). In addition, as it is common to herpesviruses generally, gH homologues expressed on viral envelopes form a complex with gL homologues (18,20,21).In addition to gH/gL/gQ1/gQ2, another gH/gL complex, gH/ gL/gO, is present in the viral envelopes of both ...

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Identification of a variant B-specific neutralizing epitope on glycoprotein H of human herpesvirus-6.

Cited by 30 publications

References 50 publications

Interaction of Glycoprotein H of Human Herpesvirus 6 with the Cellular Receptor CD46

Interaction of Glycoprotein H of Human Herpesvirus 6 with the Cellular Receptor CD46

Expression of Human Herpesvirus 6B rep within Infected Cells and Binding of Its Gene Product to the TATA-Binding Protein In Vitro and In Vivo

Analysis of a Neutralizing Antibody for Human Herpesvirus 6B Reveals a Role for Glycoprotein Q1 in Viral Entry

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