The mapping of linear epitopes of B virus (Cercopithecine herpesvirus 1 and herpes B virus) glycoprotein D (gD) was accomplished by screening the constructed gD epitope library with serum from B virus-infected macaques. The immunodominant epitope, gD (362-370), was identified within the C-terminal region of B virus gD that was highly conserved among 19 B virus clinical isolates but was not present in either herpes simplex virus (HSV)-1 or HSV-2 gD. A substantial percentage of serum samples from macaques (95%) and humans (80%) infected with B virus contained antibodies to this epitope. Antibodies against HSV types 1 or 2 did not react with this epitope; thus, gD (362-370) has unique potential to detect B virus-specific antibody responses in human serum, even in the presence of antibodies to HSV-1 and HSV-2.

B virus (cercopithecine herpesvirus 1) is the only deadly alphaherpesvirus that is zoonotically transmissible from macaques to humans. The detection of humoral immune responses is the method of choice for the rapid identification of B virus-infected animals. We evaluated the diagnostic potential of recombinant B virus glycoproteins for the detection of immunoglobulin G (IgG) antibodies in monkey and human sera. Glycoproteins B, C, and E and secreted (sgG) and membrane-associated (mgG) segments of glycoprotein G (gG) were expressed in the baculovirus expression system, while gD was expressed in CHO cells. We developed recombinant protein-based IgG enzyme-linked immunosorbent assays (ELISAs) and compared their diagnostic efficacies by using B virus antibody-negative (n ‫؍‬ 40) and -positive (n ‫؍‬ 75) macaque sera identified by a whole antigenbased ELISA and Western blotting. The diagnostic sensitivities of the gB-, gC-, gD-, and mgG-ELISAs were 100, 97.3, 88.0, and 80.0%, respectively. The specificities of the gB-, gC-, and gD-ELISAs and of the mgG-ELISA were 100 and 97.5%, respectively. In contrast, the sensitivities and specificities of sgG-and gE-ELISAs were low, suggesting that sgG and gE are less effective diagnostic antigens. Sera from nonmacaque monkeys crossreacted with gB, gC, and gD, and only baboon sera reacted weakly with mgG. Human herpes simplex virus type 1 (HSV-1)-and HSV-2-positive sera pools reacted with gB and gD, whereas sera from B virus-infected individuals reacted with all four antigens. These data indicate that gB, gC, gD, and mgG have a high diagnostic potential for B virus serodiagnosis in macaques, whereas mgG may be a valuable antigen for discrimination between antibodies induced by B virus and those induced by other, closely related alphaherpesviruses, including HSV-1 and -2.Human infection with B virus (also called cercopithecine herpesvirus 1, monkey B virus, and herpes B virus) is the most feared occupational hazard among individuals working with macaque monkeys, since fatality is often the outcome of infection, which proceeds in the absence of effective antiviral therapy (25,56). The use of macaques in research has been steadily growing over the last decade and is expected to rise quickly in the near future due to the increasing demands for these animals for use in HIV/AIDS investigations, vaccine trials, drug testing, and research into bioterrorism agents. As macaque usage increases, frequencies of human exposures to B virus are increasing as well. Rapid and accurate diagnostic tests are urgently needed to aid in the early identification of clinical cases, which is essential for a timely initiation of antiviral therapies in zoonotically infected humans. In addition to human diagnostics, enhanced assays are required for monitoring specific-pathogen-free (SPF) macaque colonies established by the National Institutes of Health for the breeding of B virusfree animals (55), as these animals often demonstrate only very low levels of antibody.Unfortunately, a direct diagnosis of infectio...

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...

Genes encoding glycoproteins gB, gC, gD, gE, and gG of herpes B virus (species Cercopithecine herpesvirus 1) were cloned into mammalian expression vector pcDNA3.1/V5-His. Abilities of the plasmid constructs to express recombinant glycoproteins were confirmed by Western blot analysis of transfected CHO-K1 and COS-7 cells. Antibody production was induced in rabbits by intramuscular injections with the expression constructs at four-weekly intervals. Antibodies to gB were detected after the second DNA inoculation, while it took an additional plasmid injection to induce responses to gC, gD and gE. The gG plasmid failed to stimulate antibody production. Antisera ELISA titers varied greatly depending on the gene, with gB inducing highest (21,000) and gE inducing lowest (60) antibody titer. The induced antibodies were predominantly conformation-dependent. The gB, gC, and gD antisera contained HSV cross-neutralizing antibodies, but only gB antisera contained B virus neutralizing antibodies. The gB antisera cross-reacted with HSV antigens in Western blot, ELISA, dot-blot, plaque immunostaining and immunoprecipitation assays, whereas gD and gC antisera were mostly B virus-specific. Thus, polyclonal antibodies to B virus glycoproteins can be generated by DNA immunization and used as diagnostic and research reagents.

Bvirus (Macacine herpesvirus 1) is an enveloped, doublestranded DNA virus belonging to the genus Simplexvirus of the subfamily Alphaherpesvirinae. B virus generally produces either mild disease or asymptomatic infection in monkeys of the Macaca genus, which are natural reservoir hosts. Similar to human herpes simplex viruses (HSV), B virus in natural host animals initially infects mucosal or skin epidermal and dermal cells and then enters nerve terminals of the sensory neurons subserving these sites. Subsequently, B virus travels in a retrograde direction to the dorsal root ganglion, where it can establish a latent lifelong infection with periodic reactivation (1, 2). B virus infections of the central nervous system (CNS) are extremely rare in the natural host and are usually associated with immunosuppression or intercurrent diseases (3, 4). In most human cases, B virus spreads to the CNS, causing an acute ascending paralysis and encephalomyelitis with an ϳ80% mortality rate if not treated in a timely manner. Postmortem examinations reveal focal neuronal lesions occasionally seen in parietal neurons, but far more often in the brainstem and cervical spinal cord, which are primary sites of virus recovery (5-11). The molecular basis for the differences in neurovirulence between HSV and B virus in humans remains a mystery despite the fact that specific molecular differences between these two viruses have been identified (12)(13)(14)(15)(16)(17)(18)(19).B virus is genetically and immunologically closely related to HSV, and some aspects of cell entry and cell-to-cell transmission of B virus and HSV are conserved (14,(20)(21)(22)(23). The specific interactions of glycoprotein D (gD) with cognate cellular receptors, viz., herpesvirus entry mediator (HVEM), nectin-1, and nectin-2, as well as one of the several isoforms of 3-O-sulfated heparan