Immunoprecipitation of herpes simplex virus type 1 antigens with different antisera and human cerebrospinal fluids

Laboratory diagnosis of common herpesvirus infections of the central nervous system by a multiplex PCR assay

A sensitive multiplex PCR assay for single-tube amplification that detects simultaneous herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), varicella-zoster virus (VZV), human cytomegalovirus (CMV), and Epstein-Barr virus (EBV) is reported with particular emphasis on how the method was optimized and carried out and its sensitivity was compared to previously described assays. The assay has been used on a limited number of clinical samples and must be thoroughly evaluated in the clinical context. A total of 86 cerebrospinal fluid (CSF) specimens from patients which had the clinical symptoms of encephalitis, meningitis or meningoencephalitis were included in this study. The sensitivity of the multiplex PCR was determined to be 0.01 and 0.03 50% tissue culture infective doses/the reciprocal of the highest dilution positive by PCR for HSV-1 and HSV-2 respectively, whereas for VZV, CMV and EBV, 14, 18, and 160 ag of genomic DNA were detected corresponding to 48, 66, and 840 genome copies respectively. Overall, 9 (10.3%) of the CSF samples tested were positive in the multiplex PCR. HSV-1 was detected in three patients (3.5%) with encephalitis, VZV was detected in four patients (4.6%) with meningitis, HSV-2 was detected in one neonate (1.16%), and CMV was also detected in one neonate (1.16%). None of the samples tested was positive for the EBV genome. None of the nine positive CSF samples presented herpesvirus coinfection in the central nervous system. Failure of DNA extraction or failure to remove any inhibitors of DNA amplification from CSF samples was avoided by the inclusion in the present multiplex PCR assay of alpha-tubulin primers. The present multiplex PCR assay detects simultaneously five different herpesviruses and sample suitability for PCR in a single amplification round of 40 cycles with an excellent sensitivity and can, therefore, provide an early, rapid, reliable noninvasive diagnostic tool allowing the application of antiviral therapy on the basis of a specific viral diagnosis. The results of this preliminary study should prompt a more exhaustive analysis of the clinical value of the present multiplex PCR assay.

A combined indirect ELISA and immunoblotting for the detection of intrathecal herpes simplex virus IgG antibody synthesis in patients with herpes simplex virus encephalitis

A combined indirect ELISA and immunoblotting assay was used for the detection of intrathecal synthesis of IgG antibodies to herpes simplex virus (HSV) in patients with HSV encephalitis (HSVE). By using these two assays as well as three markers for blood-brain barrier, leakage can be easily excluded. A total of 21 sera and 24 cerebrospinal fluid (CSF) samples from 11 patients with HSVE were examined. For seven patients more than one pair of serum and CSF were available. For one patient IgG antibodies began to be detectable in CSF after the sixth day from the onset of the disease. In the other 10 patients the intrathecal synthesis of HSV IgG antibodies was detected later than the sixth day and reached high optical density (OD) values after the 10th day from the onset of disease, at the earliest. In contrast, intrathecal HSV antibody synthesis was not found in specimens taken from 20 patients with acute meningitis who composed our negative control group. The use of a combined indirect ELISA and of an immunoblotting assay on a single dilution of serum and CSF for HSV IgG synthesis in the central nervous system (CNS) allowed the diagnosis of HSVE after the first week of disease.

Compartment-specific immunolocalization of conserved epitopes of the glycoprotein gB of herpes simplex virus type 1 and bovine herpes virus type 2 in infected cells

Monoclonal antibodies directed against a surface glycoprotein of the bovine herpes virus type 2 (BHV-2, bovine herpes mammillitis virus) recognize also determinants of the major glycoprotein gB of the human herpes simplex virus type 1 (HSV-1). Cross-reacting antigens of the virions and in infected cells were localized with immunocytochemical methods, immunofluorescence as well as pre-embedding and cryoultramicrotomy immune electron microscopy. All antibodies stain to different degrees cell free BHV-2 and HSV-1 virions. In the cell two predominant staining patterns could be observed indicating that expression of epitopes is dependent upon the cell compartment: (i) staining of cytoplasmic membranes and enveloped particles within membrane systems and (ii) staining of intranuclear antigens. Antibodies tagging intranuclear antigens react with moderately dense material or with the periphery of nucleocapsids. This unexpected result is interpreted in terms of two hypotheses: (1) presence of common epitopes on two entirely different herpesvirus proteins conserved in HSV-1 and BHV-2 and (2) transport of gB or its precursor into the nucleus.

Molecular biological characterization of equine herpesvirus type 1 (EHV-1) isolates from ruminant hosts

Isolates of equine herpesvirus type 1 (EHV-1) originating from affected antelope and cattle were compared with reference EHV-1 and EHV-4 isolates and were characterized. Based on cross-neutralization, DNA restriction profiles and blot-hybridization data these isolates could be characterized as EHV-1. One isolate (from an antelope) with a different restriction profile showed significant DNA homology with EHV-1, partial homology with EHV-4, and little or no homology with EHV-2 and HSV-1 DNAs. Blot hybridization revealed differences in DNA restriction fragments located at the termini of two isolates and size heterogeneity in the unique long/internal repeat junction fragment (UL/IR) of one isolate.

Conservation of a gene cluster including glycoprotein B in bovine herpesvirus type 2 (BHV-2) and herpes simplex virus type 1 (HSV-1)

A library of subgenomic fragments of bovine herpesvirus type 2 (BHV-2) DNA was constructed in the expression cloning vector lambda gt11 and screened with monoclonal antibodies to the glycoprotein gb BHV-2, which is homologous to glycoprotein gB (gB-1) of herpes simplex virus type 1 (HSV-1). Lambda gt11 clones containing gB BHV-2-specific sequences were used to identify lambda EMBL3 vectors with DNA inserts which contained the complete gB BHV-2 gene. Nucleotide sequencing revealed that the gB BHV-2 gene is highly conserved compared to gB-1. The amino acid sequences and the predicted secondary structures of both glycoproteins are very similar. Two further open reading frames (ORF) in close vicinity to the gene encoding gB BHV-2 showed considerable homology to HSV-1 genes. They code for the major DNA-binding protein (dbp) of BHV-2 and a putative 72-kDa polypeptide. The gene of the latter protein corresponding to ICP18.5 of HSV-1 is interspersed between the ORFs of gB BHV-2 and the dbp of BHV-2. All three genes map in the unique long region of the genome. Their homology and the colinear arrangement compared to HSV-1 indicate a close relationship between the two viruses.

Common epitopes of glycoprotein B map within the major DNA-binding proteins of bovine herpesvirus type 2 (BHV-2) and herpes simplex virus type 1 (HSV-1)

Bovine herpesvirus 2 (BHV-2) specifies a glycoprotein of 130 kDa (gB BHV-2) which shows extensive homology to glycoprotein B (gB-1) of herpes simplex virus 1 (HSV-1). The BHV-2-specific 130-kDa glycoprotein is able to induce cross-reacting antibodies, some of which even cross-neutralize HSV-1. In order to determine the genome localization of gB BHV-2 and in order to identify conserved antigenic domains in both glycoproteins, we established libraries of subgenic fragments of BHV-2 and HSV-1 DNA in the prokaryotic expression vector lambda gt11 and screened them with cross-reacting monoclonal antibodies which allowed us to identify recombinant lambda gt11 clones expressing gB fusion protein. Nucleotide sequencing of inserted DNA fragments within these recombinant lambda gt11 clones revealed that they originated from the carboxy-terminal part of the major DNA-binding proteins (dbp) of BHV-2 (dbp BHV-2) and its counterpart ICP8 in HSV-1. Antisera raised against the beta-galactosidase fusion protein of recombinant phage lambda-113/2 coding for an 84 amino acid (aa) polypeptide originating from dbp BHV-2 neutralized infectivity of BHV-2 and HSV-1 in the presence of complement and precipitated [3H] glucosamine-labeled gB BHV-2 and gB-1. This antiserum also reacts with ICP8 and presumably with dbp BHV-2. Two hypotheses are discussed to explain this unexpected result: (i) epitopes in the carboxy-terminal part of gB BHV-2 and gB-1 are similar to antigenic determinants in the amino-terminal region of the gBs, thus providing cross-reacting antibody-binding sites; (iii) during gene expression a carboxy-terminal part of dbp BHV-2 and ICP8 genes might be spliced to the amino-terminal region of the glycoproteins gB BHV-2 and gB-1.

Monoclonal antibodies directed against a 130K glycoprotein of bovine herpesvirus 2 cross-react with glycoprotein B of herpes simplex virus

Envelope proteins of bovine herpesvirus type 2 (BHV-2) and herpes simplex virus types 1 and 2 (HSV-1, -2) share cross-reacting determinants. Monoclonal antibodies directed against epitopes of a 130K glycoprotein of BHV-2 detect determinants on the surface of infected cells and react either with cytoplasmic or nuclear antigens. Biological and biochemical characterization of the proteins recognized by these antibodies revealed that the BHV-2 specific 130K glycoprotein and the gB of HSV share common epitopes. Some of them are involved in the neutralization of HSV and BHV-2.

Herpesvirus simiae (B virus): replication of the virus and identification of viral polypeptides in infected cells

The events and products of replication of Herpesvirus simiae (B virus) in Vero cells were studied. The time course of the synthetic events of DNA replication and protein synthesis were found to be similar to the processes of the herpes simplex viruses and SA 8. Infectious progeny virus were detected by 4 hours post infection and were first found extracellularly between 6 and 8 hours post infection (PI). As in the case of SA 8, all cell lines tested were permissive for lytic infection by B virus. Analyses of B virus-infected cells by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) revealed approximately 50 infected cell polypeptides (ICP) ranging in molecular weight from about 26,000 to 239,000 daltons. The kinetics of synthesis of the ICPs were also identified. At least nine glucosamine-containing glycopeptides were noted ranging from 133,000 to 29,000 daltons.

Detection of viral antigens in cerebrospinal fluid of patients with herpes simplex virus encephalitis

Thirty-two cerebrospinal fluid (CSF) samples from eighteen patients with confirmed herpes simplex encephalitis (HSE) were assayed by an indirect enzyme-linked immunosorbent assay (ELISA) for the presence of viral antigens. The results are expressed as an antigen ratio distinguishing between herpes simplex virus (HSV) antigens containing samples and negative samples. Judged by this criterion a positive result was obtained in 33% of the patients. Overall, 25% of the CSF samples from HSE patients were positive. In one out of 33 control patients with other neurological disorders a positive antigen ratio was found. Two or more CSF samples were available from eleven patients. In six of these, the second or later samples showed a decreased antigen ratio when compared to the first CSF sample. An increase of the anti-HSV antibody titer was seen in the CSF of five of these six patients. Five out of six patients with a decreasing antigen ratio had an unfavorable outcome of their encephalitis, while a favorable outcome was seen in four of the five patients with an increasing or steady antigen ratio. A decrease of the antigen ratio in the course of HSE can be explained by the presence of immune complexes in CSF and may indicate a poor prognosis.

Detection of viral antigens in cerebrospinal fluid of rabbits with experimental herpes simplex virus type 1 encephalitis

We investigated several methods for the rapid diagnosis of herpes simplex virus induced encephalitis in a rabbit model. The corneas of twenty-two rabbits were infected with herpes simplex virus type 1 (HSV-1) and diagnosis of Herpes encephalitis was made by virus isolation, immunofluorescent and peroxidase staining of brain biopsies, demonstration of anti-HSV IgM in cerebrospinal fluid (CSF) and by an indirect enzyme-linked immunosorbent assay (ELISA), designed for detection of viral antigens. With the last method we were able to demonstrate viral antigens in cerebrospinal fluid six days post infection, before clinical signs of encephalitis appeared. In three rabbits this was before anti-HSV IgM appeared in the CSF. Virus was isolated from brain samples of 67 per cent of the animals which died from Herpes encephalitis. Nine rabbits received cortisone before infection, resulting in markedly lower antibody titers and a higher lethality, 77 per cent, as compared to 46 per cent in nontreated rabbits. For rapid diagnosis of Herpes encephalitis in rabbits, demonstration of herpes simplex virus antigens in CSF by means of an indirect ELISA is superior to the other methods investigated.

The immune response to herpes simplex virus: comparison of the specificity and relative titers of serum antibodies directed against viral polypeptides following primary herpes simplex virus type 1 infections

Employing an immunoblotting technique, the polypeptide specificity and relative titers of anti-HSV IgG reactive with denaturation-resistant epitopes on HSV proteins were determined in patients experiencing primary HSV-1 infections at various anatomical sites. Early sera from previously seronegative patients with primary HSV-1 infections were found to have comparatively low levels of antibody directed against the major viral glycoprotein antigens (gB, gC, and gD) relative to titers present in sera of individuals with long-standing, latent orofacial HSV-1 infections. Patients with primary infections did however have high titers of antibody directed against a series of low molecular weight HSV polypeptide antigens. These antigens were found to be antigenically related to a structural component of virion nucleocapsids. At later times postinfection, titers of antibodies directed against other viral polypeptides including the major glycoproteins increased to levels more closely approximating those observed in latently infected individuals. These results indicate that the anti-HSV IgG detected by immunoblot analysis which appears earliest following primary infection is not directed against the known major infected cell or virion glycoprotein surface antigens but rather against an internal capsid protein of HSV.

Bovine herpesvirus 1: differentiation of IBR- and IPV-viruses and identification and functional role of their major immunogenic components

Infectious Bovine Rhinotracheitis (IBR) and Infectious Pustular Vulvovaginitis (IPV) virus strains of Bovine Herpesvirus 1 (BHV-1) can be differentiated by restriction endonuclease digestion of their DNAs. Antigens and polypeptide patterns of isolates of these different clinical entities are almost identical. Page analysis of immunoprecipitates revealed three major immunogenic components in BHV-1 infected cells. These are glycoproteins with apparent molecular weights of 93,000 (GP93), 74,000 (GP74) and 69,000 daltons (GP69), respectively. Bovine convalescent sera and antisera, which are directed against individual precipitates derived from crossed immunoelectrophoresis, contain antibodies reacting with one or more of these glycoproteins. The experiments with these antisera demonstrate that GP74 and possibly GP93, both structural components of the BHV-1 virion, induce neutralizing antibodies, whereas GP69, a non-structural protein, does not.

Plaque/focus immunoassay: a simple method for detecting antiviral monoclonal or other antibodies and viral antigens in cells

A new, simple enzyme-linked immunosorbent assay (ELISA) is described which is performed directly on infected and fixed cell cultures in microtitre plates. It permits large scale screening of antiviral monoclonal antibodies and differentiation of specific antibodies from those usually responsible for high background reactions in other ELISA techniques. Time consuming purification of antigens is thus avoided. The plaque/focus immunoassay is also applicable to titration of antibodies in patients' sera and antigens in lytically or non-lytically virus-infected cells. It may also be used to localize antigens in different cell compartments. This immunoassay requires no special equipment and results may be evaluated either with the naked eye or using a light microscope.

The structure of the Rous sarcoma virus glycoprotein complex: in vitro phenotypic mixing of rous sarcoma virus

Gp 85 the major envelope glycoprotein of Rous sarcoma virus can be released from intact by virus treatment with 2-mercaptoethanol. Attempts were made to reassociate released gp 85 to 2-mercaptoethanol treated virus. In order to study the biological activity and to analyse the reaction product with biochemical methods gp 85 from a subgroup different from the recipient virus was used. Successful in vitro phenotypic mixing could be shown. The biochemical analysis, however, revealed that no reassociation of gp 85 and gp 35 could be obtained. The biological activity was due to a strong association of whole gp 85-gp 35 molecules derived from the gp 85 preparation to the recipient virus. These molecules were present as a minor contamination in the gp 85 preparation.

Evidence for a Gp85-related glycoprotein in cells transformed by the Bryan high titer strain of Rous sarcoma virus

The Bryan High Titer strain of Rous Sarcoma Virus (BH-RSV) is a deletion mutant in the env-gene coding for the viral envelope glycoproteins gp35 and gp85. In this report experimental evidence is described that cells, transformed by BH-RSV, express a glycoprotein immunologically related to gp85. Animals bearing BH-RSV induced tumors produce antibodies reacting with gp85 of nondefective RSV. Lysates of a BH-RSV transformed quail cell line, R(-):Q, inhibit the immunoprecipitation of gp85 by antibodies against the group-specific determinant of gp85. In R(-):Q cell lysates and in the culture supernatant a glycoprotein of an apparent molecular weight 40,000 (gp40) is found that reacts with monospecific antisera against gp85 of nondefective RSV. In newly synthesized BH-RSV a gp40 associated with the virion is detectable but is easily lost during purification of the virus. Further, a 95k glycoprotein and a 95k phosphoprotein are specifically precipitated from R(-):Q cells by an antiserum against gp85. From these results we conclude that the deletion of the env-gene is incomplete such that part of gp85, bearing group-specific antigenic determinants, is expressed in BH-RSV transformed cells. Analysis of BH-RSV particles freshly harvested from R(-):Q cells reveals that they contain almost exclusively the gag-precursor pr76 and little or no processed gag-proteins. Therefore the R(-):Q cell line seems to be suitable for the study of virus maturation occurring after the budding process.

Assay of type-specific and type-common antibodies to herpes simplex virus types 1 and 2 in human sera

A reliable and reproducible method for determining specific reactivity to herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) in human sera has been developed. Human sera were used to immunoprecipitate HSV-specific glycoprotein antigens from both HSV-1- and HSV-2-infected cell extracts. The viral glycoproteins precipitated from these extracts were then analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to detect specific reactivity of the sera with distinct type-specific antigens of HSV-1, HSV-2, or both as well as with type-common glycoprotein antigens. By examining a large number of human sera, this method was found to be more reliable than the standard microneutralization test in discriminating between single-positive (positive for HSV-1 or HSV-2) and double-positive (positive for HSV-1 and HSV-2) sera.

gA and gB glycoproteins of herpes simplex virus type 1: two forms of a single polypeptide

Utilizing a combination of preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sodium dodecyl sulfate-hydroxylapatite column chromatography, we have separated and purified the gA and gB glycoproteins of the major virus-specific glycoprotein region from herpes simplex virus type 1-infected cells. By using purified antigen preparations, antisera specific to each of these glycoproteins were produced. Immunoprecipitation from detergent extracts of infected cells and radioimmune precipitation of the purified antigens have shown that the anti-gA and anti-gB sera each recognize both the gA and the gB glycoproteins. The anti-gA serum was also shown to neutralize virus despite the presence of only minute quantities of the gA glycoprotein in virions. Pulse-chase studies have indicated that the gA and gB glycoproteins are synthesized from a common precursor polypeptide. Together, these data demonstrate that the gA and gB glycoproteins of herpes simplex virus type 1 are antigenically similar but not identical and probably represent two different forms of the same polypeptide which differ in their degree of glycosylation.

Preparation and characterization of specific antisera to individual glycoprotein antigens comprising the major glycoprotein region of herpes simplex virus type 1

The major glycoprotein complex (VP123) of herpes simplex virus type 1 resolved by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis was purified and further fractionated into two major and two minor components by chromatography of the isolated VP123 region on SDS-hydroxylapatite columns. The two major components (gC and gA/gB) were purified free of other polypeptides and used to prepare specific antisera to these glycoproteins. Radioimmune precipitation demonstrated that these antisera were specific for the antigens used in their production. These two antisera as well as an anti-VP123 serum were further characterized by immunoprecipitation, neutralization, and membrane immunofluorescence techniques. Results indicate that both of the major glycoprotein antigens are expressed on the surface of virions as well as on the surface of infected cells.

Participation of three major glycoprotein antigens of herpes simplex virus type 1 early in the infectious cycle as determined by antibody-dependent cell-mediated cytotoxicity

Tissue culture cells infected with herpes simplex virus type 1 synthesize three major glycoprotein antigens (Ag-11, Ag-8, and Ag-6), which have been characterized by crossed immunoelectrophoresis. The three viral antigens have been identified as a mixture of gA and gB (Ag-11), gD (Ag-8), and gC (Ag-6). Recent findings have shown that antibodies directed to each of the three antigens individually are able to mediate antibody-dependent cell-mediated cytotoxicity when tissue culture cells late in the infectious cycle (18 h postinfection) are used. In this work, antibody-dependent cell-mediated cytotoxicity was applied to study the time postinfection at which the individual viral antigens first made their appearance at the cell surface. All three viral antigens (Ag-11, Ag-8, and Ag-6) could be demonstrated as newly synthesized from 3 to 4 h postinfection, and the quantities of the antigens at the surfaces of the infected cells increased with time postinfection. The use of cycloheximide and ultraviolet-inactivated virus demonstrated that input virus could be detected by antibody-dependent cell-mediated cytotoxicity during the first 2 h postinfection, but the cytotoxicity caused by input virus remained constant with time postinfection. In conclusion, these observations demonstrate the participation of individual herpes simplex virus surface antigens in antibody-dependent cell-mediated cytotoxicity attack on cells early in infection.

The cerebrospinal fluid of rabbits infected with Borna disease virus

Rabbits were inoculated intracerebrally with Borna disease virus infected brain suspension or tissue culture extracts. In 30 per cent of the diseased animals infectious virus was present in the cerebrospinal fluid (CSF). The CSF had increased numbers of lymphocytes and an elevation of the protein concentration, mainly due to an increase in gamma-globulins, was measured. The gamma-globulins were of oligoclonal character and reacted with a borna disease virus specific antigen of infected brains or tissue culture cells. The antibody titers in the CSF were of similar level to those in the serum. In comparison, those of the CSF of naturally infected horses always exceeded the serum titers. Injection of tracer substances revealed that no drastic damage to the blood-brain barrier was caused during the disease. The results suggest that antibodies detected in the CSF are locally produced. The significance of these findings for the pathogenesis of Borna disease is discussed.