Typing of clinical herpes simplex virus isolates with mouse monoclonal antibodies to herpes simplex virus types 1 and 2: comparison with type-specific rabbit antisera and restriction endonuclease analysis of viral DNA

A total of 122 clinical isolates of herpes simplex virus (HSV) from 107 patients were typed by using an indirect immunoperoxidase technique with commercially available type-specific rabbit antisera, recently developed mouse monoclonal antibodies to HSV types 1 and 2, and restriction endonuclease analysis of viral DNA. With the commercially available type-specific rabbit antisera, 34% of clinical HSV isolates were of indeterminate type; 63% of them were typed as HSV type 1 and 37% as HSV type 2 by using monoclonal antibody and restriction enzyme typing systems. Typing by immunofluorescence assay with the monoclonal antibodies gave identical results to those obtained by restriction enzyme analysis. Simultaneous infection with both HSV types was demonstrated by monoclonal antibody typing in five isolates from three patients. These findings were subsequently confirmed by plaque purification and restriction endonuclease analysis of viral DNA. Monoclonal antibodies were as sensitive as restriction enzyme analysis for the typing of clinical HSV isolates. Because of their simplicity, they are more amenable to use in clinical laboratories than is restriction endonuclease analysis.     

Studies on herpes simplex virus type 1 glycoproteins using monoclonal antibodies

Monoclonal antibodies against herpes simplex virus type 1 glycoproteins were isolated and utilized to study the synthesis and processing of glycoproteins B, C, and D (gB, gC, gD, respectively). Monoclonal antibodies against both gB and gD had higher virus-neutralizing activity when compared to that of gC. Differences among these glycoproteins were observed in their time of appearance in the virus-infected cells. The presence of gD was detected at a very early stage of infection when compared to gB and gC. The localization of these glycoproteins during their synthesis and processing was studied.     

Serological analysis of herpes simplex virus types 1 and 2 with monoclonal antibodies.

A panel of monoclonal antibodies to herpes simplex virus glycoproteins was used for serological analysis of 130 strains. Based on specific immunological determinants, strains of each serotype clustered into subgroups. Monoclonal antibodies were suitable reagents for serotyping and have potential application to epidemiology of herpes simplex virus infections.     

Type-common and type-specific monoclonal antibodies to herpes simplex virus types 1 and 2.

Seventeen monoclonal antibodies (Mabs) reacting specifically with the cells infected with herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2) were characterized by a variety of immunological tests such as radioimmunoprecipitation, immunoblotting and virus-neutralization. The majority of Mabs was directed against glycoprotein B (anti-gB), six reacted with glycoprotein C (anti-gC) and one with glycoprotein G (anti-gG). Six anti-gB Mabs reacted with both types of HSV (anti-gB-1,2), two anti-gB and all the six anti-gC Mabs have been specific for HSV-1 (anti-gB-1 and anti-gC-1). The remaining two anti-gB Mabs and the anti-gG have been specific to HSV-2 (anti-gB-2 and anti-gG). Only three out of the seventeen examined Mabs neutralized the virus.     

Antibody response to herpes simplex virus glycoproteins gB and gD

The antibody response to herpes simplex virus (HSV) glycoproteins B and D was evaluated using these cloned glycoproteins in an ELISA assay and compared to a standard Western blotting procedure. The ELISA assay appeared to be more sensitive for detecting gB and gD antibodies. Antibodies to gB but not gD were detected in the acute sera of patients presenting with their first episode of true primary genital herpes. The geometric mean HSV gB titer (log 2) was also significantly higher than the geometric mean gD titer in the convalescent sera of these patients (7.9 +/- 0.7 vs. 5.5 +/- 0.9, P less than .003). A cross-reaction between HSV gB and varicella zoster virus (VZV) gp II was demonstrated. Thus, it is possible that a previous VZV infection could prime the immune system to respond rapidly and more vigorously to HSV gB. Indeed, in this report we demonstrated a significant correlation between the VZV ELISA absorbance and the titer to HSV gB and also detected a higher VZV ELISA absorbance and HSV gB titer in the acute sera of patients with a true primary HSV infection compared to other HSV seronegative VZV seropositive patients. Use of this quantitative assay should allow further investigation into the relationship of the immune response to these important targets and the clinical course of HSV disease.     

Typing of herpes simplex virus strains by analyzing the viral DNA using restriction endonucleases

Analysis of the products of viral DNAs cleavage by restrictive endonucleases showed the strains of herpes simplex virus Us and L2 used for herpes vaccine manufacture to belong to type 1 and the VN strain to type 2 of herpes simplex virus. This method is found to be optimal for typing of herpes simplex virus strains.     

Comparison of foldback sequences of herpes simplex virus types 1 and 2 DNA

The DNAs of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) were separately denatured and allowed to renature briefly. The intrastand foldback structures that resulted from base pairing of inverted repeated sequences on otherwise single-stranded (ss) DNA were visualized in the electron microscope. The two genomes were found to contain similar size classes of small duplex stem DNA sequences. However, HSV-2 DNA appeared to possess an additional, larger size class of foldback structures not found on HSV-1 DNA. Both HSV DNAs were found to contain stem-plus-loop structures; the larger stem-plus-loop structures of the two genomes had similar stem lengths but dissimilar loop lengths. Thus, a comparison of the genomes of HSV-1 and HSV-2 showed that they possessed similar size classes of foldback sequences.     

Discrimination of antibody to herpes B virus from antibody to herpes simplex virus types 1 and 2 in human and macaque sera

The antigenic cross-reactive characteristics of herpes B virus and herpes simplex virus (HSV) type 1 (HSV-1) and HSV-2 are responsible for false-positive diagnoses by serological assays in humans and macaques. In the present study, we developed a fluorometric indirect enzyme-linked immunosorbent assay (ELISA) with recombinant herpes B virus glycoprotein D (gD) and HSV-1 and HSV-2 gG (gG-1 and gG-2, respectively) to discriminate between the three primate herpesvirus infections. The secreted form of gD, gDdTM, was used to detect antibody to herpes B virus gD. Sera positive for herpes B virus, HSV-1, and HSV-2 showed specific reactions to gD, gG-1, and gG-2, respectively. Sera collected from humans and rhesus macaques were investigated for the presence of antibodies to the recombinant proteins of the three herpesviruses. The results suggested that the approach is able to discriminate between herpes B virus and HSV infections. The ELISA was also found to be able to detect infections with multiple primate herpesviruses and may have the potential to identify a subsequent infection in individuals that have already been infected with another herpesvirus. In addition, we found evidence of a greater cross-reactivity of herpes B virus with HSV-1 than with HSV-2. It is suggested that the ELISA with the recombinant antigens is useful not only for the serodiagnosis of primate herpesvirus infections but also for elucidation of the seroprevalence of herpesviruses in humans and primates.     

Immunogenicity of herpes simplex virus type 1 glycoproteins expressed in vaccinia virus recombinants

Vaccinia virus recombinants expressing glycoproteins B (vgB11), D (VgD52), E (gE/7.5 and gE/4B), G (gG-vac), H (gH-vac), and I (gI-vac) of HSV-1 were used to compare the protective response to these individual glycoproteins in the mouse. Glycoprotein D induced the best neutralizing antibody titers and the most increased rates of HSV clearance from the ear as well as good protection from the establishment of latent HSV infections in the sensory ganglia. Glycoprotein B also induced good neutralizing antibody titers and as great a protection from the establishment of latency as gD although the rate of virus clearance from the ear was not as great as after immunization with gD. Glycoprotein E induced weak neutralizing antibody but gG, gH, and gI did not show a neutralizing antibody response. At higher challenge doses of virus (10(6) PFU HSV-1 in the ear), gE induced a protective response by increasing the rate of virus clearance and reducing the acute infection of ganglia as compared to negative control immunized mice. However there was no protection from the establishment of latent infections after immunization with gE. No protective response was seen to gG, gH, or gl.     

O-glycosidic carbohydrate-peptide linkages of herpes simplex virus glycoproteins

Summary Electrophoretically purified HSV-specified glycoproteins with radiolabelled carbohydrates were subjected to mild alkaline borohydride treatment (0.5m NaOH and 0.5m NaBH₄). The treatment liberated significant amounts of the labelled oligosaccharides. The latter demonstrated molecular weights of about 3,000 as determined by gel filtration. The glycoproteins involved probably belong to the gA/gB complex or gC. The results suggest that HSV specified glycoproteins contain oligosaccharides linked with an O-glycosidic bond to a threonine or serine residue of the polypeptide.With 3 Figures     

A host range difference between herpes simplex virus types 1 and 2.

The infectivities of several strains of herpes simplex virus type 1 and type 2 were measured by plating on established human and Chinese hamster cell lines. Whereas all the type 1 strains reproducibly showed a 10(4)-fold lower titre on the Chinese hamster cells, the type 2 strains showed only a 10- to 100-fold lower titre. This host range difference has been used in the analysis of recombinants between type 1 and type 2 viruses.     

Simultaneous detection of herpes simplex virus types 1 and 2 by real-time PCR and Pyrosequencing.

BACKGROUND: Up to 80% of the US adult population has been exposed to herpes simplex virus (HSV) type 1, primarily during childhood. Also, approximately 20% of the US population has contracted genital herpes from HSV-2 infections. Clinical symptoms can present as fever, headache, malaise, myalgia, and cold sores/lesions that cause pain, itching, dysuria, and vaginal or urethral discharge. A recurrence of infection is common. HSV culturing is characterized by low sensitivity with variable success rates due to shipping conditions. OBJECTIVE: To design and validate a real-time PCR assay capable of simultaneously detecting each HSV subtype. STUDY DESIGN: ATCC-purchased HSV-1 and HSV-2 positive samples and HSV-1 and HSV-2 infected clinical specimens were assayed simultaneously with shared amplification primers and subtype-specific probes against the HSV glycoprotein B gene on a Rotor-Gene 3000 platform. Separately, two PCR reactions were performed in which one primer contained a 5' biotin modification. Single-stranded DNA from the amplicon was purified and Pyrosequenced. RESULTS: The quantitative range of the assay extended from 10(8) through 10(0) copies of each virus (r(2) > 0.991) and specificity was determined by non-amplification of 37 different human pathogens, including other herpesviruses such as VZV, CMV, and EBV. Sensitivity and specificity values of 100% were calculated by concordance analysis between the real-time PCR and the DNA Pyrosequencing results (HSV-1: n = 119, HSV-2: n = 120). Application of this assay to 4581 cervical swab specimens collected from women visiting physicians primarily in six states provided detection rates of 3.1% for HSV-1 and 7.6% for HSV-2. The average age of women infected with HSV-1 was 29.5 versus 35.6 for HSV-2. CONCLUSIONS: This procedure was demonstrated as both highly sensitive and specific for the detection of HSV-1 and HSV-2 in a single reaction. Also, the integration of Pyrosequencing analysis permitted an innovative and rapid verification for each subtype.     

Comparative examination of the polypeptides of herpes simplex virus: types 1 and 2

Polypeptides synthesized during productive infection of HSV-1 and HSV-2 were found to possess distinct characteristics in regard to localization within the cell, DNA-binding properties, and phosphorylation after synthesis. Continuous labeling for 14 hr or pulse-labeling at successive periods during the replicative cycle with radioactive precursors revealed two types of polypeptide localization: (a) selective accumulation or enhancement within the cytoplasm or nucleus with barely detectable concentrations elsewhere and (b) accumulation in significant concentrations within both cytoplasm and nucleus showing little selective enhancement. Of the polypeptides made during HSV-1 infection 22 were phosphorylated as compared with 16 phosphoproteins specified by HSV-2. Phosphorylation was also implicated in the generation of the four molecular forms comprising the ICP 5–8 complex. Twenty-three polypeptides with affinity for DNA were detected after either type of infection. Sufficient comparisons were made to provide a basis for the tentative listing of 20 polypeptides of HSV-1 with corresponding polypeptides of HSV-2.     

Fusion activity of lipid-anchored envelope glycoproteins of herpes simplex virus type 1

Expression of the herpes simplex virus type 1 (HSV-1) glycoproteins gB, gD, gH, and gL is necessary and sufficient to cause cell fusion. To identify the requirements for a membrane-spanning domain in HSV-1 glycoprotein-induced cell fusion, we created gB, gD, and gH mutants with transmembrane and cytoplasmic domains replaced by a glycosylphosphatidylinositol (gpi)-addition sequence. The corresponding gBgpi, gDgpi, and gHgpi proteins were expressed with wild-type efficiency at the cell surface and were linked to the plasma membrane via a gpi anchor. The gDgpi mutant promoted cell fusion near wild-type gD levels when co-expressed with gB, gH, and gL in a cell-mixing fusion assay, indicating that the gD transmembrane and cytoplasmic domains were not required for fusion activity. A plasma membrane link was required for fusion because a gD mutant lacking a transmembrane and cytoplasmic domain was nonfunctional for fusion. The gDgpi mutant was also able to cooperate with wild-type gB, gH, and gL to form syncytia, albeit at a size smaller than those formed in the wild-type situation. The gBgpi and gHgpi mutants were unable to promote fusion when expressed with the other wild-type viral glycoproteins, highlighting the requirement of the specific transmembrane and cytoplasmic domains for gB and gH function.     

Evaluation of mixed infection cases with both herpes simplex virus types 1 and 2

Herpes simplex virus type 1 (HSV-1) is isolated principally from the upper half of the body innervated by the trigeminal ganglia whereas herpes simplex virus type 2 (HSV-2) is generally isolated from the lower half of the body innervated by the sacral ganglia. However, recent reports suggest that HSV-1 and HSV-2 can each infect both the upper and lower half of the body causing a variety of symptoms and there is a possibility that HSV-1 and HSV-2 infections can occur simultaneously with both causing symptoms. HSV type in clinical isolates from 87 patients with genital herpes and 57 with ocular herpes was determined by the polymerase chain reaction (PCR), and six cases of mixed infection with both HSV-1 and HSV-2 were identified. Of the six cases, three were patients with genital herpes and three were ocular herpes patients. Analysis of the copy number of the HSV-1 and HSV-2 genome by a quantitative real time PCR demonstrated that HSV-1 was dominant at a ratio of approximately 100:1 in the ocular infections. In contrast, the HSV-2 genome was present at a 4-40 times higher frequency in isolates from genital herpes patients. There was no obvious difference between the clinical course of mixed infection and those of single HSV-1 or HSV-2 infections. This study indicated that the frequency of mixed infection with both HSV-1 and HSV-2 is comparatively higher than those of previous reports. The genome ratio of HSV-1 and HSV-2 reflects the preference of each HSV type for the target organ.     

Monoclonal antibodies to herpes simplex virus type 1 glycoproteins show that epitope location influences virus neutralization

Three monoclonal antibodies, G8D1 , C2D2 , and TI57 , reacting with herpes simplex virus type 1 glycoproteins have been characterised according to the location of their epitope and ability to neutralize infective virus. Immune electron microscopy and a blocking radioimmunoassay were used to locate the epitopes. The results indicate that the epitope recognised by G8D1 is located on the surface of the glycoprotein fringe, whereas those recognized by C2D2 and TI57 are interior with respect to this. Only G8D1 has neutralizing activity alone, whereas C2D2 can neutralize when antiglobulin is added. Thus, epitope location and density determine the neutralizing capacity of individual antibody molecules.     

Typing of Clostridium difficile by western immunoblotting with 10 different antisera.

Western blotting (immunoblotting) with antisera against each of 10 reference serogroups was evaluated as a means of typing Clostridium difficile. A total of 164 clinical isolates of C. difficile were tested. Variations in band profiles in each serogroup were used to type isolates into subserogroups. This technique was useful for an epidemiological investigation.     

Increased susceptibility to infection with herpes simplex virus types 1 and 2 of cold-adapted L cells.

L cells (L-As subline) have been adapted to a temperature of 4 degrees C. In the cold-adapted cells, designated LC3, greater amounts of infectious herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) were synthesized than in the original L-As cells or in another control L-cell line. Two strains of HSV-1 reached higher infectious titres in LC3 cells grown at 36 degrees C than in those grown at 32 degrees C. The HSV-2 strain tested replicated in LC-3 cells grown at 32 degrees C better than at higher temperature. Increased reproduction of HSV in LC3 cells was not due to enhanced adsorption of virions on the cells as compared with control L cells. The multiplication of cold-adapted LC3 cells was and was not more intensive than of L-As and control L cells, respectively. The virological results are confronted with known physiological properties of cold-adapted cells.