Identification and typing of herpes simplex virus by enzyme immunoassay with monoclonal antibodies.

A double-antibody enzyme immunoassay was developed for the identification and typing of herpes simplex virus (HSV) by employing a polyclonal rabbit capture antiserum together with type-common and type 2-specific monoclonal antibodies as detectors. The test successfully identified 45 type I isolates and 30 type 2 isolates as HSVs. Compared with immunofluorescent staining and restriction endonuclease analysis, enzyme immunoassay correctly typed 45 type 1 and 30 type 2 HSV isolates. Enzyme immunoassay was 100% sensitive for identification of HSV as compared with cell culture and 100% specific for typing as compared with immunofluorescence and restriction endonuclease analysis. Electron microscopy analysis suggested that approximately 10(6) virus particles were required for the identification and typing of HSV by enzyme immunoassay.     

Typing of herpes simplex virus isolates with monoclonal antibodies and by nucleic acid spot hybridization

Fifty-one clinical isolates of herpes simplex virus (HSV) were typed by an enzyme immunoassay (EIA) using mouse monoclonal antibodies, by DNA spot hybridization, and by restriction enzyme analysis using restriction endonuclease Eco RI. Extracts of VERO cells infected with the isolates were used for coating microtitre plates or denatured and spotted onto nitrocellulose filters. Viral antigens passively adsorbed to microtitre plates were detected by an indirect EIA using mouse monoclonal antibodies specific for HSV type 1 (HSV-1) or HSV type 2 (HSV-2). Spotted DNA was hybridized with 32P-labeled probes containing Hind III/Sal I-fragments of either HSV-1 or HSV-2 DNA and bound radioactivity was detected by autoradiography and counted in a liquid scintillation counter. All the three methods gave identical results for the 51 isolates studied. Twenty-six isolates were identified as HSV-1 and 25 as HSV-2. An additional 30 specimens were tested only by EIA and hybridization. Results by both techniques were in complete agreement.     

Typing and subtyping of herpes simplex isolates by monoclonal fluorescence

The type specificity of 16 herpes simplex monoclonal antibodies was tested on 50 isolates previously typed by endonuclease restriction. A panel of antibodies was selected and used to type isolates from 50 primary and 50 recurrent genital infections. Sixty-four isolates from 18 patients followed up for six months were subtyped by using a larger panel of monoclonal antibodies and predominant HSV1 and HSV2 subtypes were demonstrated. In addition to confirming recurrences, four possible reinfections were identified. Type-specific differences in the location of viral antigens in infected cells were noted and a possible association of this finding with the type-specific differences in rates of recurrence of genital infections discussed.     

Identification and typing of herpes simplex viruses with monoclonal antibodies.

Monoclonal antibodies which reacted with type-specific antigens of herpes simplex virus type 2 or with antigens shared by herpes simplex virus types 1 and 2 were used in an indirect immunofluorescence assay to type virus isolates and to detect viral antigens in cells obtained from herpetic lesions. Complete concordance was obtained for 42 isolates typed by endonuclease restriction analysis of viral DNA and by indirect immunofluorescence with monoclonal antibodies. Examination of a limited number of ulcerative lesions revealed that indirect immunofluorescence and virus isolation were comparable in detecting herpes simplex virus. The results indicate that monoclonal antibodies can be used to accurately identify and type isolates of herpes simplex virus.     

Evaluation of three immunofluorescence assays for culture confirmation and typing of herpes simplex virus.

Three pairs of monoclonal antibodies, supplied in kits by Electro-Nucleonics, Inc. (ENI), The Syva Co., and Kallestad Laboratories, Inc. (KL), were evaluated for the laboratory confirmation and typing of herpes simplex virus (HSV). Of 108 coded HSV slide preparation, run in parallel with each monoclonal-antibody set, 103 were equivalent by the immunofluorescence assays. Among the five discordant isolates, three (2.8%) did not type with the KL monoclonal antibodies and two (1.9%) false-positive results occurred with the Syva typing system. All of the HSV clinical isolates tested were correctly typed with the ENI indirect immunofluorescence antigen detection system. Typing confirmation of the five discordant HSV isolates was performed by differential sensitivity to 5-bromo-2'-deoxyuridine and endonuclease cleavage analysis of the viral DNA. Use of the Syva and KL direct immunofluorescence antigen detection systems for the identification of HSV isolates is less time-consuming than use of the ENI indirect antigen detection system; however, sensitivity and specificity may be lost.     

Typing of herpes simplex virus types 1 and 2 by immunoblotting analysis using polyclonal antisera to herpes simplex virus glycoproteins

Herpes simplex virus (HSV) isolates were differentiated by immunoblotting analysis using a mixture of polyclonal antisera directed against HSV type 1 (HSV-1) and HSV type 2 (HSV-2) glycoprotein fractions (gB/gC of HSV-1 and gC/gE/84-kDa protein of HSV-2), since the mixed antisera recognized viral polypeptides with different molecular weights in HSV-1- and HSV-2-infected cells. Results of typing by immunoblotting analysis were consistent with those obtained by restriction endonuclease analysis of DNAs extracted from 10 HSV isolates. These results suggest that the immunoblotting technique will be applicable to reliable typing of HSV isolates using polyclonal antisera showing the difference in reaction patterns between HSV-1- and HSV-2-infected cells.     

Typing of herpes simplex virus by capture biotin-streptavidin enzyme-linked immunosorbent assay and comparison with restriction endonuclease analysis and immunofluorescence method using monoclonal antibodies.

A sensitive enzyme-linked immunosorbent capture assay using biotin and streptavidin (capture B/SA ELISA) was developed using type-specific monoclonal antibodies for typing of herpes simplex virus. Rabbit anti-herpes simplex virus immunoglobulin G was used as the capturing antibody, and biotin-linked type-1-specific mouse monoclonal antibody or rabbit type-1- or type-2-specific polyclonal antibody served as the detecting antibody. The captured antigen was detected by an ELISA with alkaline phosphatase-conjugated streptavidin, which reacted with biotin molecules on the detector antibody. The capture B/SA ELISA was compared with other methods for efficiency and reliability in typing. Results obtained by restriction endonuclease digestion of the radiolabeled viral genome were used to determine the type (1 or 2) of clinical isolates. These results were then used as a reference for determining the accuracy of the capture B/SA ELISA, as well as that of the immunofluorescence method, both of which are easily adaptable for use in the clinical laboratory. The three methods were in perfect agreement. It was determined that both the capture B/SA ELISA and the immunofluorescence method using monoclonal antibodies provided typing results with 100% specificity and 100% sensitivity and thus were accurate and reliable. However, the ELISA was the method of choice because of its simplicity, rapidity, and use of nonradioisotopic reagents.     

Serotyping of herpes simplex virus isolates: A comparison of BVDU sensitivities,indirect immunofluorescence with monoclonal antibodies,and indirect immunofluorescence with cross-adsorbed rabbit antibodies

Four methods for typing of herpes simplex virus (HSV) isolates were compared for 43 recent clinical isolates and 3 reference strains of HSV, These isolates were subjected to indirect immunofluorescence using both monoclonal antibodies and cross-adsorbed rabbit antisera. Sensitivity to E-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) was also examined.All isolates which fluoresced with HSV-1 monoclonals were found to be sensitive to BVDU with ID₅₀'s ranging from 0.001 to 0.006 μg/ml. All isolates labelled as HSV-2 using monoclonal antibodies had ID₅₀'s to BVDU ranging from 0.4 to 3.5 μg/ml. Results of typing with rabbit cross-adsorbed antisera were less accurate, however. When dilutions were predetermined according to manufacturer's instructions, only 3 of 22 isolates (14%) of HSV-1 were correctly typed. HSV-2 isolates were correctly labelled in 24 of 26 situations (92%).When fluorescence dilution endpoints were compared, however, 21 of 22(95%) HSV-1 isolates had fluorescence endpoints at a greater dilution with HSV-1 antiserum. Twenty-three of 24 HSV-2 isolates were also correctly typed (96%).     

Identification and typing of herpes simplex virus types 1 and 2 by monoclonal antibodies, sensitivity to the drug (E)-5-(2-bromovinyl)-2'-deoxyuridine, and restriction endonuclease analysis of viral DNA

With development of antiviral drugs, the need to identify a virus as to drug sensitivity becomes increasingly of importance. The compound (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) has been shown to be much more inhibitory to the replication of herpes simplex virus type 1 (HSV-1) and varicella-zoster virus as opposed to herpes simplex virus type 2 (HSV-2). We have typed over 170 isolates, using an immunofluorescent technique and sensitivity to the drug BVDU. These results were then compared to the typing of isolates by analysis of viral DNA after restriction endonuclease digestion (EcoRI). Without exception the results were in agreement between the monoclonal antibody results and sensitivity to the drug BVDU. Furthermore, the typing with monoclonal antibodies was also in excellent agreement with the DNA analysis. Only those isolates inhibited with BVDU showed DNA characteristics of HSV-1 and reacted only with the S-200 antibody. On the other hand, those isolates which reacted with the monoclonal antibody S-141 were insensitive to BVDU, and again this was in agreement with the DNA analysis. These results could provide the basis for developing a diagnostic test using the two monoclonal antibodies to type either isolates or direct smears and to use the results as a basis for possible drug therapy.     

Evaluation of two immunofluorescence assays with monoclonal antibodies for typing of herpes simplex virus.

An indirect immunofluorescence assay and a direct immunofluorescence assay were evaluated for typing clinical isolates of herpes simplex virus (HSV). The indirect immunofluorescence assay (Electro-Nucleonics, Inc.) correctly identified 16 HSV type 2 (HSV-2) isolates, but failed to identify 4 of 14 HSV-1 isolates because of background fluorescence and instability of reagents. Forty-nine HSV-1 isolates were correctly typed by direct immunofluorescence assay (Kallestad Laboratories, Inc.), but 1 of 39 HSV-2 isolates did not react with the HSV-2 type-specific antibody conjugate.     

Typing of herpes simplex virus with type-specific human immunoglobulin M in an indirect immunofluorescence assay.

Sera from nine individuals with suspected primary herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) infection were screened to identify those containing HSV type-specific immunoglobulin M (IgM). Selected sera were then utilized in an IgM-specific indirect immunofluorescent-antibody HSV-typing assay (patent pending). To evaluate the procedure, 29 HSV isolates were grown in cultures of continuous human amnion cells, fixed, and used as substrates for indirect immunofluorescence. Determination of virus type was based on intensity of fluorescence of the substrate with HSV-1- and HSV-2-specific antisera after staining with fluorescein-conjugated anti-human IgM. Typing of the isolates by restriction endonuclease digestion showed that of 29, 18 were HSV-2 and 11 were HSV-1. Results by IgM-specific indirect immunofluorescent-antibody assay were identical to those by restriction endonuclease digestion for 27 of the isolates; 2 isolates failed to replicate adequately in the test cells. The IgM-specific indirect immunofluorescent-antibody procedure appears to be a simple, rapid, and accurate technique which could be of use to clinical virology laboratories.     

Comparison of neutralization and DNA restriction enzyme methods for typing clinical isolates of human adenovirus.

Sixty-five adenovirus isolates collected over a 3.5-year period were typed by both standard microneutralization techniques and restriction endonuclease digestion of viral DNA. Of the 65 isolates, 47 (72.3%) representing six adenovirus types could be typed by microneutralization. Eighteen isolates demonstrated partial neutralization with standard antisera to two or more adenovirus serotypes and thus could not be definitively typed. DNA analysis permitted typing of 64 of the 65 isolates (98.5%) (including four isolates which contained mixtures of two adenovirus types), and 12 different types were identified. Neutralization and DNA typing disagreed for five isolates, and in each case, digestion with multiple restriction endonucleases and DNA hybridization studies were consistent with the type assigned by DNA analysis. In addition, the DNA analysis method allowed the identification of genomic variants (genome types) of five adenovirus types. We conclude that typing clinical isolates of adenovirus by restriction endonuclease digestion of viral DNA can be done rapidly, provides additional epidemiological and typing information, and provides fewer ambiguous results than does typing by neutralization.     

Detection and direct typing of herpes simplex virus by polymerase chain reaction

A method for the detection and direct typing of herpes simplex virus (HSV) by the polymerase chain reaction (PCR) technique has been developed. One common upstream primer and two type-specific downstream primers were prepared to amplify DNA from the HSV type 1 and type 2 DNA polymerase gene. Using these three primers simultaneously in the PCR reaction mixtures, both types of HSV DNA were amplified to produce products of different sizes. By direct gel analysis, the products of standard HSV type 1 and type 2 strains had the predictive sizes of 469 and 391 base pairs, respectively, and the difference in molecular mass enabled us to type the HSV strain. A total of 24 strains (type 1; 16 and type 2; 8 strains) were examined by PCR, and the results were consistent with those determined by immunofluorescence using type-specific monoclonal antibodies. No specific amplification was observed using other herpes virus or human genomic DNAs. The PCR method was then applied to clinical specimens. Of 15 samples obtained from oral lesions of children with herpetic gingivostomatitis, all (100%) were HSV positive by PCR, compared with 13 (86.7%) using standard cell culture methods. Three specimens from vulvar lesions of women with genital herpes were positive using both PCR and cell cultures. There was complete agreement in the typing of HSV strains using the PCR method or virus isolation. On the basis of these results, it is suggested that DNA amplification and typing by PCR is particularly useful for material from which virus isolation might be difficult.     

Seroepidemiology of herpes simplex virus and restriction endonuclease cleavages analysis of herpes simplex virus type 2 in Okinawa

A seroepidemiologic study of herpes simplex virus (HSV) in Okinawa was performed. A total of 423 serum samples were collected from all over Okinawa, and the positivity rate of antibody against HSV was measured using a passive hemagglutination method. The sero-positive rate for HSV in age groups of over 40 years was 100%. Seven HSV type 2 (HSV 2) isolates were obtained in Okinawa, and DNA preparations from Vero cells infected with the isolates were analyzed using five restriction endonucleases: Bam HI, Hind III, Kpn I, Bgl II and Eco RI. Variations in the genomic region were demonstrated in five of the isolates. Such variations have not been reported previously in HSV 2 in mainland Japan. This is the first report of a seroepidemiologic study of HSV and restriction endonuclease cleavage analysis of HSV 2 in Okinawa, is a subtropical island where HSV is endemic.     

Enzyme-linked immunosorbent assay for detection and typing of herpes simplex virus

An enzyme-linked immunosorbent assay for herpes simplex virus was tested using commercially available peroxidase-conjugated and unconjugated rabbit antibodies to herpes simplex virus type 1 and type 2 (DAKO immunoglobulins A/S, Copenhagen, Denmark). One hundred and thirty-seven clinical specimens from vesicles and superficial cutaneous lesions were tested and the results compared with virus isolation. In addition 210 herpes simplex virus isolates were typed. Forty-four specimens yielded herpes simplex virus both in the enzyme-linked immunosorbent assay and in tissue culture and 79 were negative in both tests. Fourteen were positive in isolation but negative in the enzyme-linked immunosorbent assay. Seventy-three isolates were typed as herpes simplex virus type 1 and 137 as herpes simplex virus type 2. The enzyme-linked immunosorbent assay was found to be rapid and easy to perform but less sensitive than conventional isolation in routine diagnostic work. For typing of isolates it was found to be a useful method for distinguishing herpes simplex virus type 1 and type 2.     

Comparison of biological, biochemical, immunological, and immunochemical techniques for typing herpes simplex virus isolates.

In this study, 102 herpes simplex virus isolates were typed by cell culture selection (chicken embryo cells and guinea pig embryo cells [CE/GPE]), (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) sensitivity, plaque reduction neutralization, and indirect immunofluorescence staining techniques. The percentages of agreement between the typing methods were as follows: BVDU sensitivity versus CE/GPE, 99% (99/102); CE/GPE and BVDU sensitivity versus neutralization, 32% (33/102); CE/GPE and BVDU sensitivity versus indirect immunofluorescence staining 17% (17/102). Results were easy to interpret when the CE/GPE and BVDU sensitivity systems were used. In contrast, when type-specific antisera prepared commercially were used, results were often obscure, even contradictory, because of antibody cross-reactions. Therefore, this study suggests that immunological and immunochemical methods that use presently available commercially prepared antisera cannot reliably differentiate herpes simplex virus type 1 from type 2.     

Antibody response to type-common and type-unique epitopes of herpes simplex virus polypeptides

Herpes simplex virus type 1 (HSV1) and type 2 (HSV2) polypeptides with type-common and type-unique epitopes were identified using cross-adsorbed hyperimmune rabbit sera and Western blotting techniques. Twelve HSV1 and fourteen HSV2 polypeptides with type-specific epitopes were identified. Cross-adsorbed human sera reacted to a subset of the type-specific epitopes defined by rabbit sera. Human sera with both HSV1- and HSV2-specific antibodies were identified by their reaction to HSV1-type-specific epitopes after adsorption with HSV2, and HSV2-type-specific epitopes after adsorption with HSV1. Mixing experiments demonstrated the sensitivity of this assay for detecting HSV2-type-specific antibody in the presence of HSV1 antibody. This technique has proven useful in the study of immune response to individual HSV polypeptides during human HSV infections, while the presence of these type-unique epitopes on HSV polypeptides allows for the detection of type-specific antibodies in human sera.     

Comparative evaluation of four commercially available monoclonal antibodies for culture confirmation of herpes simplex virus infection.

Four fluorescein isothiocyanate-labelled monoclonal antibody typing reagents were compared for intensity of fluorescence and sensitivity in confirming herpes simplex virus (HSV) in cell culture. A total of 125 (50 HSV type 1 [HSV-1] and 75 HSV-2) specimens positive for HSV were concurrently stained with type-specific monoclonal antibodies from Bartels (Bartels Immunodiagnostic Supplies, Inc., Bellevue, Wash.), Kallestad (Pathfinder; Kallestad Diagnostics, Chaska, Minn.), Diagnostic Products Corp. (DPC) (PathoDx; DPC, Los Angeles, Calif.), and Syva (Microtrak; Syva Co., Palo Alto, Calif.). Fifty cultured specimens not displaying HSV-associated cytopathic effect were also stained. Each of the four reagents confirmed the 50 negative cultures and 125 positive cultures. One HSV-1-positive culture was missed by the Kallestad antibody. Ten HSV-1 isolates displayed dull fluorescence when stained with the Syva HSV-2 reagent. The other three reagents stained only the HSV-1 well with these 10 specimens. The Syva and Bartels stains were brighter, in general, than the Kallestad and DPC stains. However, the Kallestad and DPC stains were brilliant enough to allow interpretation without hesitation. The differences in intensity and background staining emphasize the need for laboratories to routinely perform quality checks on their reagents and to test new products which become commercially available.     

Differentiation of herpes simplex virus types 1 and 2 in clinical samples by a real-time taqman PCR assay

While the clinical manifestations of HSV-1 and -2 overlap, the site of CNS infection, complications, response to antivirals, frequency of antiviral resistance, and reactivation rate on mucosal surfaces varies between HSV-1 and -2. Detection of HSV DNA by PCR has been shown to be the most sensitive method for detecting HSV in clinical samples. As such, we developed a PCR-based assay to accurately distinguish HSV-1 from HSV-2. Our initial studies indicated the assay using type specific primers was slightly less efficient for detecting HSV-1 and -2 DNA than the high throughput quantitative PCR assay we utilize that employs type common primers to gB. We subsequently evaluated the type specific assay on 3,131 specimens that had HSV DNA detected in the type common PCR assay. The typing results of these specimens were compared with the monoclonal antibody staining results of culture isolates collected from the same patients at the same time, and the HSV serologic status of the patient. The typing assay accurately identified both HSV-1 and -2 with a specificity of >99.5% and was significantly more sensitive than typing by culture and subsequent monoclonal antibody assays. Complete concordance was seen between the typing assay and HSV serologic status of the patient. Dual (HSV-1 and -2) infection in clinical samples was recognized in 2.6% of clinical samples using the new typing assay. This assay, when used in combination with the type common assay, can now accurately type almost all mucosal and visceral HSV isolates by molecular techniques.     

Detection and typing of herpes simplex viruses by using recombinant immunoglobulin fragments produced in bacteria.

Thirty-seven bacterial clones producing human recombinant monoclonal antibody Fab fragments (rFabs) reactive to herpes simplex virus (HSV) antigens were selected from a human combinatorial antibody library constructed in a phage-display vector by a panning procedure against an HSV lysate. Thirty-four of the HSV-specific rFabs were able to specifically recognize HSV-infected cells in indirect immunofluorescence (IF) assays; of these, 25 recognized cells infected by either HSV type 1 (HSV-1) or HSV-2, while 9 recognized only HSV-1-infected cells. One HSV type-common rFab (rFab H37) and one HSV-1-specific rFab (rFab H85) were further evaluated as reagents for viral detection and typing by IF staining in 134 HSV-positive (72 HSV-1 and 62 HSV-2) viral cultures from clinical specimens. The results obtained with these two rFabs were fully consistent with those obtained with a commercial preparation of fluorescein-labeled anti-HSV type-specific murine monoclonal antibodies. The detection sensitivity with the type-common rFab in indirect IF assays was higher overall than that provided by the type-specific murine monoclonal antibodies. Preparations of rFabs suitable for IF staining can be easily and inexpensively obtained in a clinical microbiology laboratory from Escherichia coli cultures. Similar HSV-specific rFabs, therefore, could be advantageous for in vitro diagnostic purposes.