Herpes simplex virus (HSV) glycoprotein h is partially processed in a cell line that expresses the glycoprotein and fully processed in cells infected with deletion or is mutants in the known hsv glycoproteins

Foà-Tomasi, Laura; Avitabile, Elisa; Boscaro, Ambra; Brandimarti, Renato; Gualandri, Rita; Manservigi, Roberto; Dall'olioj, Fabio; Serafini-Cessij, Franca; Campadelli-Fiume, Gabriella

doi:10.1016/0042-6822(91)90061-f

Cited by 35 publications

(22 citation statements)

References 34 publications

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“…3). As expected, surface expression of gH2-WT required coexpression of gL2, confirming previous observations with HSV-1 that gL is required for the transport of gH out of the ER (8,9,19,22,25,35,37). When the four deletion mutants were coexpressed with gL, all were detected on the cell surface.…”

Section: Resultssupporting

confidence: 71%

“…It is well established that for HSV and most other herpesviruses, transport, cell surface expression, and incorporation of gH into the virion envelope require the formation of a complex with gL (8,22,34,35). gH expressed in the absence of gL remains trapped in the ER (9,19,25,37). However, there have been several instances reported in the literature in which mutant forms of gH or gL form a complex yet are still not transported to the cell surface FIG.…”

Section: Discussionmentioning

confidence: 99%

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N-Terminal Mutants of Herpes Simplex Virus Type 2 gH Are Transported without gL but Require gL for Function

Cairns

Friedman

Lou

et al. 2007

J Virol

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Glycoprotein H (gH) is conserved among all herpesviruses and is essential for virus entry and cell fusion along with gL, gB, and, in most alphaherpesviruses, gD. Within the gH/gL heterodimer, it is thought that gH accounts for the fusion function and gL acts as a chaperone for the folding and transport of gH. Here, we found that the N terminus of gH2 contains important elements involved in both its folding and its transport. Our conclusions are based on the phenotypes of a series of gH deletion mutants in which the signal sequence (residues 1 to 18) was retained and N-terminal residues were removed up to the number indicated. The first mutant, gH2⌬29 (deletion of residues 19 to 28), like wild-type (WT) gH, required gL for both transport and function. To our surprise, two other mutants (gH2⌬64 and gH2⌬72) were transported to the cell surface independent of gL but were nonfunctional, even when complexed with gL. Importantly, a fourth mutant (gH2⌬48) was transported independent of gL but was functional only when complexed with gL. Using a panel of monoclonal antibodies against gH2, we found that when gH2⌬48 was expressed alone, its antigenic structure differed from that of gH2⌬48/gL or gH2-WT/gL. Mutation of gH2 residue R39, Y41, W42, or D44 allowed gL-independent transport of gH. Our results also show that gL is not merely required for gH transport but is also necessary for the folding and function of the complex. Since gH2⌬64/gL and gH2⌬72/gL were nonfunctional, we hypothesized that residues critical for gH/gL function lie within this deleted region. Additional mutagenesis identified L66 and L72 as important for function. Together, our results highlight several key gH residues: R39, Y41, W42, and D44 for gH transport and L66 and L72 for gH/gL structure and function.Glycoprotein H (gH) is conserved among all herpesviruses and is essential for virus entry. The herpes simplex virus (HSV) gH/gL heterodimer represents the functional form of these proteins (22,35,39). This heterodimer is an essential component of the core fusion machinery that also includes gB (41). Four glycoproteins (gB, gD, gH, and gL) as well as a gD receptor are required for entry into most alphaherpesviruses, including HSV (42). The current hypothesis is that the gDreceptor complex is required to stabilize the virus-cell interaction and also acts as a trigger for fusion that requires gB and/or gH/gL. The crystal structures of gD (5, 26) and gB (21) have been solved. The structure of gB closely resembles those of other known fusion proteins, most notably the vesicular stomatitis virus G protein (38), leaving open the question of the precise role of gH/gL.In HSV, the formation of the gH/gL complex is necessary for protein localization both in the virion envelope and on the cell surface (22,35,39). When gH is expressed in the absence of gL, it remains in the endoplasmic reticulum (ER) (22,25). When gL, which lacks a transmembrane domain, is expressed in the absence of gH, it is secreted from cells (8,22,35). It is hypothesized that gL harbors a chap...

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Section: Resultssupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

N-Terminal Mutants of Herpes Simplex Virus Type 2 gH Are Transported without gL but Require gL for Function

Cairns

Friedman

Lou

et al. 2007

J Virol

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“…Alternatively, deletion of parts of the primary sequence of gH in combination with expression in mammalian cells could result in a conformational change in some important epitopes on gH leading to the loss of antibody binding sites. Lack of reactivity of gH specific antibodies with recombinant protein derived from mammalian systems has been described for other herpesviruses (Foa-Tomasi et al, 1991;Forrester et al, 1991;Gompels & Minson, 1989;Roberts eta]., 1991;Yaswen et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

Glycoprotein H of human cytomegalovirus is a major antigen for the neutralizing humoral immune response

Urban

Klein

et al. 1996

Journal of General Virology

105

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A recombinant baculovirus expressing glycoprotein H (gpUL75) of human cytomegalovirus was used to examine the humoral immune response in naturally infected individuals. Recombinant baculovirus infected insect cells produced two forms of gH with molecular masses of 78-82 kDa and 94 kDa. The 94 kDa polypeptide was modified by high mannose oligosaccharide side-chains as shown by reduction in molecular mass after treatment with endoglycosidases H and F. The 78-82 kDa protein represented the non-glycosylated precursor which was resistant to the enzymes. In contrast to gH expressed in mammalian cells, the recombinant baculovirus expressed gH was transported to the cell surface. Glycoprotein H produced in insect cells was reactive with human convalescent sera and all tested neutralizing monoclonal antibodies recognizing either linear or conformational epitopes. Antibodies reacting with insect cell derived gH were detected in 96% of HCMV seropositive human sera. Using insect cells infected with the gH expressing recombinant baculovirus as immunoabsorbent, between 0% and 58% of the total virus neutralizing activity was removed from sera of individuals with a past HCMV infection, gH must therefore be considered a major antigen for the induction of neutralizing antibodies during natural infection.

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“…Sialic acids have a stabilizing effect on glycoproteins and enzymatic desialylation often results in significant changes in the structure and function of these proteins (13,27,40,46,47,58,82). Previous studies have shown that gC, gD, and gH are sialylated but the specific linkages and possible functions of sialic acids on these proteins have not been determined (11,22,25,51,61,68). The goal of the present study was to determine whether sialylation of HSV-1 envelope proteins is important for infectivity.…”

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confidence: 99%

Sialic Acid on Herpes Simplex Virus Type 1 Envelope Glycoproteins Is Required for Efficient Infection of Cells

Teuton

Brandt

2007

J Virol

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Herpes simplex virus type 1 (HSV-1) envelope proteins are posttranslationally modified by the addition of sialic acids to the termini of the glycan side chains. Although gC, gD, and gH are sialylated, it is not known whether sialic acids on these envelope proteins are functionally important. Digestion of sucrose gradient purified virions for 4 h with neuraminidases that remove both ␣2,3 and ␣2,6 linked sialic acids reduced titers by 1,000-fold. Digestion with a ␣2,3-specific neuraminidase had no effect, suggesting that ␣2,6-linked sialic acids are required for infection. Lectins specific for either ␣2,3 or ␣2,6 linkages blocked attachment and infection to the same extent. In addition, the mobility of gH, gB, and gD in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels was altered by digestion with either ␣2,3 specific neuraminidase or nonspecific neuraminidases, indicating the presence of both linkages on these proteins. The infectivity of a gC-1-null virus, ⌬gC2-3, was reduced to the same extent as wild-type virus after neuraminidase digestion, and attachment was not altered. Neuraminidase digestion of virions resulted in reduced VP16 translocation to the nucleus, suggesting that the block occurred between attachment and entry. These results show for the first time that sialic acids on HSV-1 virions play an important role in infection and suggest that targeting virion sialic acids may be a valid antiviral drug development strategy.Herpes simplex virus type 1 (HSV-1) is a widespread human pathogen with 70 to 90% of the adults in the United States testing seropositive for the virus (92). The most common manifestation is mucous membrane infection resulting in ulcerative lesions that are usually self-limiting in immunocompetent individuals. However, serious illnesses, including lethal neonatal HSV, encephalitis, and blinding keratitis, can occur (43,49,83,92). Primary and recurrent infections in the immunocompromised, such as transplant recipients, those on chemotherapy, or those infected with human immunodeficiency virus (HIV) can be life-threatening (64,80,94). A number of antivirals are approved for HSV-1 treatment (21, 39, 60), but they are not completely effective. One significant problem in dealing with HSV infections is the ability of the virus to persist in the host as a latent infection (65). None of the currently available antivirals can eliminate a latent infection. Preventing the establishment of a persistent infection, which could be accomplished either by blocking infection or the establishment of latency, would be an ideal strategy for dealing with this virus.The development of agents to block HSV infection requires a greater understanding of HSV entry. Infection is initiated by the binding of viral glycoprotein C (gC) or gB to cell surface heparan sulfate proteoglycans (37,73,74). After attachment, gD can bind to any of several cellular receptors including herpes virus entry mediator, nectin-1, nectin-2, or 3-O-sulfated heparan sulfate (17,30,54,70,84), triggering a conformational change...

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Herpes simplex virus (HSV) glycoprotein h is partially processed in a cell line that expresses the glycoprotein and fully processed in cells infected with deletion or is mutants in the known hsv glycoproteins

Cited by 35 publications

References 34 publications

N-Terminal Mutants of Herpes Simplex Virus Type 2 gH Are Transported without gL but Require gL for Function

N-Terminal Mutants of Herpes Simplex Virus Type 2 gH Are Transported without gL but Require gL for Function

Glycoprotein H of human cytomegalovirus is a major antigen for the neutralizing humoral immune response

Sialic Acid on Herpes Simplex Virus Type 1 Envelope Glycoproteins Is Required for Efficient Infection of Cells

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