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An ELISA using a
recombinant baculovirus-expressed fragment of the HSV-2 glycoprotein
G can reliably detect HSV-2 type-specific antibodies.
Use of a fragment
of glycoprotein G-2 produced in the baculovirus expression system
for detecting herpes simplex virus type 2-specific antibodies.
Ikoma M, Liljeqvist J-A, Groen J,
Glazenburg KL, The TH, Welling-Wester S.
Journal of Clinical
Microbiology 2002;40:2526-2532.
Summary:
Question
What is the performance of an ELISA using a baculovirus-expressed fragment
of the HSV-2 gG protein compared to a commercial EIA for the detection of
HSV-2 specific antibodies?
Design
This study describes a direct comparison of a newly developed
enzyme-linked immunosorbent assay (ELISA) with a commercially available
EIA for the identification of HSV-2 antibodies in serum.
Participants
Two hundred sixty-seven serum samples from different sources, including
128 from patients with culture proven HSV-2; 20 sera, collected at a
sexually transmitted diseases outpatient clinic, that were discordant in a
previous comparison study of commercial HSV immunoassays; and 119 from
medical students, previously tested for HSV antibodies, and selected to
include only HSV negative and HSV-2 positive samples were analyzed.
Description of Tests and Diagnostic
Standard
Three recombinant baculoviruses expressing 1) a fragment of the HSV-2
glycoprotein G, gG-2281-594His, containing amino acid residues
281 to 594, 2) a fragment of the HSV-1 glycoprotein G, gG-1t26-189His,
containing amino acid residues 26 to 189, and 3) a fragment of the HSV-1
glycoprotein D, gD-11-313, were constructed. The fragments were
expressed, purified, and used in an ELISA assay. An extract of HSV-1
infected Vero cells was also used as an antigen in the ELISA. Serum
samples were diluted 1:50 for testing. Antibodies were detected with
peroxidase-conjugated rabbit anti-immunoglobulin G (Dako, Glostrup,
Denmark). A sample was characterized as HSV positive when the serum
reacted with at least one of two type-common antigens (gD-11-313
or HSV-1 infected Vero cell extract). The sera were typed as type 1, type
2, or positive for both if they reacted against the type-specific antigens
(gG-2281-594His or gG-1t26-189His). Sera that
reacted only with HSV type-common antigens and not with type-specific
antigens were designated not typed. All samples were also tested with the
HSV-2-specific gG-2-based EIA (Gull Laboratories, Meridian Bioscience,
Inc., Cincinnati, Ohio).
Main Outcome Measures
The sensitivity and specificity of the ELISA using the
baculovirus-expressed antigens compared to the commercial EIA for the
detection of HSV-2-specific antibodies were determined.
Main Results
The reactivities of the 267 sera in the HSV-2 specific assays are shown in
the table. The sensitivity and specificity of the new assay were 91.5 and
95.5%, respectively, compared to the Gull assay.
| Reactivities
of human sera in a gG-2281-594His-based ELISA compared
with the Gull EIA IgG kit |
| Gull
EIA result |
Number
of samples with reactivity in the gG-2281-594His-based
ELISA |
| HSV-2
and type- common positive |
HSV-2
negative |
HSV
type-common positive only |
Total |
| HSV-2
positive, type-common negative |
Negative |
| Positive |
97 |
3 |
4 |
2 |
106 |
| Negative |
7 |
0 |
143 |
6 |
156 |
| Indeterminate |
3 |
0 |
2 |
0 |
5 |
| Total |
107 |
3 |
149 |
8 |
267 |
Authors' Conclusions
The sensitivity and specificity of the ELISA
using antigens expressed by recombinant baculoviruses were slightly lower
than those of the commercial EIA, which is based on affinity-purified
complete gG-2.
Source of funding: Not given.
For correspondence: Sytske Welling-Wester,
Department of Medical Microbiology, University of Groningen, Hanzeplein 1,
9713 GZ Groningen, The Netherlands. E-mail address: s.welling-wester@med.rug.nl.
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