EHV-1 glycoprotein D (EHV-1 gD) is required for virus entry and cell-cell fusion, and an EHV-1 gD deletion mutant induces a protective immune response in mice

In this study, Equus caballus major histocompatibility complex class I (MHC-I) was identified as a cellular entry receptor for the alphaherpesvirus equine herpesvirus type 1 (EHV-1). This novel EHV-1 receptor was discovered using a cDNA library from equine macrophages. cDNAs from this EHV-1-susceptible cell type were inserted into EHV-1-resistant B78H1 murine melanoma cells, these cells were infected with an EHV-1 lacZ reporter virus, and cells that supported virus infection were identified by X-Gal (5-bromo-4-chloro-3-indolyl-␤-D-galactopyranoside) staining. Positive cells were subjected to several rounds of purification to obtain homogeneous cell populations that were shown to be uniformly infected with EHV-1. cDNAs from these cell populations were amplified by PCR and then sequenced. The sequence data revealed that the EHV-1-susceptible cells had acquired an E. caballus MHC-I cDNA. Cell surface expression of this receptor was verified by confocal immunofluorescence microscopy. The MHC-I cDNA was cloned into a mammalian expression vector, and stable B78H1 cell lines were generated that express this receptor. These cell lines were susceptible to EHV-1 infection while the parental B78H1 cells remained resistant to infection. In addition, EHV-1 infection of the B78H1 MHC-I-expressing cell lines was inhibited in a dose-dependent manner by an anti-MHC-I antibody.

Section: Discussionmentioning

confidence: 99%

“…While these electrostatic interactions mediate virus binding, they do not trigger the entry of the virus into cells. For entry to proceed, a secondary triggering event mediated by gD must occur (10,14). After entry is initiated, EHV-1 enters cells either by directly fusing with the plasma membrane or via endocytosis (17).…”

mentioning

confidence: 99%

Equus caballus Major Histocompatibility Complex Class I Is an Entry Receptor for Equine Herpesvirus Type 1

Kurtz

Singletary

Kelly

et al. 2010

“…PRV and BHV-1 together with EHV-1 and Varicella-zoster virus form the Varicellovirus genus within the Alphaherpesvirinae subfamily (30). Whereas the functions of several individual EHV-1 envelope proteins, such as glycoprotein B (gB), gC, gD, gE, and gM, have been analyzed in some detail (4,18,(20)(21)(22), studies on the functions of the putative gE/gI, gH/gL, or gM/UL49.5 complexes have not yet been performed.…”

mentioning

confidence: 99%

The Gene 10 (UL49.5) Product of Equine Herpesvirus 1 Is Necessary and Sufficient for Functional Processing of Glycoprotein M

Rudolph¹,

Seyboldt²,

Granzow

et al. 2002

The functional cooperation of equine herpesvirus 1 (EHV-1) glycoprotein M (gM) and the gene 10 (UL49.5) product was analyzed. Transient-transfection experiments using gM and UL49.5 expression plasmids as well as RK13 cell lines constitutively expressing UL49.5 (RK49.5) or gM (RKgM) demonstrated that the endo-␤-N-acetylglucosaminidase H (endo H)-resistant mature form of gM was detectable only after coexpression of the two proteins. Deletion of the EHV-1 UL49.5-homologous gene 10 in strain KyA resulted in a small-plaque phenotype and up to 190-fold-reduced virus titers. The growth defects of the mutant KyA⌬49.5 virus, which were very similar to those of a gM-negative KyA virus, could be completely compensated for by growth of the mutant virus on RK49.5 cells or by repairing the deletion of gene 10 in the revertant virus KyA⌬49.5R. Analysis of cells infected with the UL49.5-negative EHV-1 demonstrated that gM was not transported to the trans-Golgi network in the absence of the UL49.5 product. In contrast, gM was efficiently transported and processed to the endo H-resistant mature form in KyA⌬49.5-infected RK49.5 cells. Furthermore, radioimmunoprecipitation experiments demonstrated that gM maturation was observed only if a 10,000-M r protein was coprecipitated with gM in KyA-or KyA⌬49.5R-infected cells or virions. This protein was absent in cells infected with Ky⌬49.5 or KyA⌬gM, suggesting that it was the EHV-1 UL49.5 product. Taken together, our results demonstrate that the expression of the EHV-1 UL49.5 product is necessary and sufficient for gM processing and that it is required for efficient virus replication.

“…Using gD deletion mutants of these viruses, investigators previously established that viral particles lacking envelope gD fail to penetrate target cells while maintaining the ability to attach to the cell surface (10)(11)(12)(13)(14). Not all viruses in the subfamily Alphaherpesvirinae, however, have or express the gD gene.…”

Section: Discussionmentioning

confidence: 99%

“…A key role of gD homologs in cell entry was established for all known alphaherpesviruses expressing the protein, including herpes simplex virus 1 (HSV-1), pseudorabies virus (PRV), bovine herpesvirus 1 (BHV-1), and equine herpesvirus 1 (EHV-1). Investigations of deletion mutants of these viruses showed that gD is essential for virus penetration into target cells (10)(11)(12)(13)(14). Numerous studies showing complete inhibition of virus cell entry by monoclonal gD antibodies, soluble recombinant gD protein, or soluble gD receptors further confirmed the crucial role of gD in in vitro infectivity of alphaherpesviruses (15)(16)(17)(18).…”

mentioning

confidence: 99%

B Virus (Macacine herpesvirus 1) Glycoprotein D Is Functional but Dispensable for Virus Entry into Macaque and Human Skin Cells

Perelygina

Patrusheva

Vasireddi

et al. 2015

Glycoprotein D (gD) plays an essential role in cell entry of many simplexviruses. B virus (Macacine herpesvirus 1) is closely related to herpes simplex virus 1 (HSV-1) and encodes gD, which shares more than 70% amino acid similarity with HSV-1 gD. Previously, we have demonstrated that B virus gD polyclonal antibodies were unable to neutralize B virus infectivity on epithelial cell lines, suggesting gD is not required for B virus entry into these cells. In the present study, we confirmed this finding by producing a B virus mutant, BV-⌬gDZ, in which the gD gene was replaced with a lacZ expression cassette. Recombinant plaques were selected on complementing VD60 cells expressing HSV-1 gD. Virions lacking gD were produced in Vero cells infected with BV⌬gDZ. In contrast to HSV-1, B virus lacking gD was able to infect and form plaques on noncomplementing cell lines, including Vero, HEp-2, LLC-MK2, primary human and macaque dermal fibroblasts, and U373 human glioblastoma cells. The gD-negative BV-⌬gDZ also failed to enter entry-resistant murine B78H1 cells bearing a single gD receptor, human nectin-1, but gained the ability to enter when phenotypically supplemented with HSV-1 gD. Cell attachment and penetration rates, as well as the replication characteristics of BV-⌬gDZ in Vero cells, were almost identical to those of wild-type (wt) B virus. These observations indicate that B virus can utilize gD-independent cell entry and transmission mechanisms, in addition to generally used gD-dependent mechanisms. A lphaherpesviruses share a strategy to enter host cells (1-3). Initial cell attachment of free virions is mediated by glycoprotein C (gC) and/or gB binding to cell surface heparan sulfate (4). This interaction facilitates specific binding of gD to one of several cellular receptors. To date, five gD receptors have been identified, including herpesvirus entry mediator (HVEM, or HveA), nectin-1 (HveC), nectin-2 (HveB), poliovirus receptor (PVR, or HveD), and 3-O-sulfated heparin sulfate (5-8). Receptor binding induces a conformational change in gD and subsequent transition into an active state. Activated gD then induces gB and gH-gL conformational changes, which trigger fusion between viral and cellular membranes (9). A key role of gD homologs in cell entry was established for all known alphaherpesviruses expressing the protein, including herpes simplex virus 1 (HSV-1), pseudorabies virus (PRV), bovine herpesvirus 1 (BHV-1), and equine herpesvirus 1 (EHV-1). Investigations of deletion mutants of these viruses showed that gD is essential for virus penetration into target cells (10)(11)(12)(13)(14). Numerous studies showing complete inhibition of virus cell entry by monoclonal gD antibodies, soluble recombinant gD protein, or soluble gD receptors further confirmed the crucial role of gD in in vitro infectivity of alphaherpesviruses (15)(16)(17)(18). Experiments demonstrating that vaginal infection of experimental animals with HSV-1 and HSV-2 could be prevented by pretreatment of a virus inoculum with gD-specific anti...