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Review: Three very
different US FDA-licensed herpes simplex virus type-specific
serology tests based on glycoproteins gG-1 and/or gG-2 are available
for diagnosis of genital herpes.
Performance and use of HSV
type-specific serology test kits.
Ashley RL
Herpes. 2002;9:38-45
Summary:
Question
What are the performance data of three FDA-licensed HSV type-specific
serology tests?
Study Selection Criteria
Currently available, United States Food and Drug Administration-licensed,
HSV type-specific serology tests based on glycoproteins gG-1 and/or gG-2
were evaluated.
Data Extraction
The evidence for the performance and use of three test kits was evaluated.
The POCkit HSV-2 (Diagnology, Belfast, UK) is a point of care test for HSV
type 2 antibodies. HerpeSelect (Focus Technologies, formerly MRL
Diagnostics, Cypress, CA) is an enzyme-linked immunosorbent assay for
HSV-1 or HSV-2 that can be semi-automated for high throughput. HerpeSelect
Immunoblot (Focus Technologies) is a nitrocellulose strip immunoblot that
detects and distinguishes HSV-1, HSV-2, and type-common antibodies. The
FDA has limited the use of these three tests to adults. These commercial
kits were evaluated against the gold standard HSV glycoprotein gG-based
tests, including Western blot, that distinguish between antibodies to
HSV-1 and HSV-2. All the tests use an enzyme-catalyzed color change as the
test signal.
Results
A description and the performance of the
three tests reviewed are presented in the table.
Test results are obtained for the POCkit test and the immunoblot by
visualizing a color change, which can be a subjective end-point, or, for
the ELISA, by recording an optical density, which is less subjective. For
the ELISA assay, to assure that results are reproducible, a calibration
sample is provided against which patient results are normalized.
| Characteristics of
FDA-approved HSV type-specific serology test kits |
| Test |
Antigen |
Application |
Sensitivity
(%) |
Specificity
(%) |
| HSV-1 |
HSV-2 |
HSV-1 |
HSV-2 |
POCkitTM
HSV-2 |
Lectin-purified
native gG-2 |
Point-of-care
or laboratory, 10 minute test |
NA** |
not given |
NA** |
not given |
HerpeSelect®
gG-1 or gG-2
ELISA |
Recombinant
gG-1 or gG-2 |
Laboratory,
optical density reader required |
91-96 |
96-100 |
92-95 |
96-97 |
HerpeSelect®
Immunoblot |
Recombinant
gG-1 or gG-2 |
Laboratory
or CLIA certified clinic |
99-100 |
97-100 |
93-95 |
94-98 |
*Sensitivity and
specificity are against the Western blot assay performed on samples
from antenatal and STD population
**Not applicable |
Conclusions
HSV-1 tests cannot distinguish between oral
and genital HSV-1 infections. Nearly all patients with HSV-2 antibody have
genital herpes. An HSV-2 positive serology does not rule out concomitant
genital infection with HSV-1. For patients lacking symptoms or sexual
history indicating genital herpes, confirmation of a positive test should
be considered. Testing a second sample at a later date or requesting a
different gG-based test on the positive sample is advisable.
For correspondence: Rhoda L. Ashley,
University of Washington, Children's Hospital and Regional Medical Center,
4800 Sand Point Way NE, Seattle, WA 98105. E-mail address: rashle@chmc.org
.
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