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Herpes simplex virus type 2 (HSV-2) IgG index values in two immunoassays in relation to HSV-2 IgG inhibition assay

Harry E Prince1, Hollis J Batterman1, Dale A Schwab1

  • 1Quest Diagnostics Infectious Disease, Inc., San Juan, Capistrano, CA, USA.

Diagnostic Microbiology and Infectious Disease
|August 10, 2019
PubMed

Insights

Confirmatory testing for herpes simplex virus type 2 (HSV-2) IgG requires re-evaluation. Current guidelines may miss false-positive and indeterminate results, potentially leading to misdiagnosis of HSV-2 infection.

Area of Science:

  • Clinical Diagnostics
  • Virology
  • Immunology

Background:

  • Herpes simplex virus type 2 (HSV-2) diagnosis relies on serological assays.
  • Current CDC guidelines recommend confirmatory testing for low-positive indices (1.10-3.50) in the HerpeSelect® (HSLT) HSV-2 IgG screening assay.
  • The adequacy of this threshold for accurate HSV-2 diagnosis needs further investigation.

Purpose of the Study:

  • To evaluate the effectiveness of the current CDC guideline for confirmatory HSV-2 IgG testing.
  • To determine if the recommended low-positive index threshold adequately identifies false-positive and indeterminate results.
  • To assess the impact of this threshold on HSV-2 diagnosis accuracy across different screening assays.

Main Methods:

  • Retrospective review of 262 screen-positive sera (index >1.10) tested with the HSLT HSV-2 IgG assay.
  • Confirmatory testing using an inhibition of binding assay with recombinant gG2 and infected cell lysates.
  • Testing of samples using the Liaison® HSV-2 IgG assay to compare screening performance.

Main Results:

  • 20% of false-positive sera (n=124) and 39% using Liaison assay had an index >3.50.
  • 51% of indeterminate sera (n=63) had an index >3.50 in both HSLT and Liaison assays.
  • ≥75% of true-positive samples (n=75) exhibited indices >3.50 in both assays.

Conclusions:

  • Confirmatory testing limited to low-positive indices (1.10-3.50) may miss a significant proportion of false-positive and indeterminate HSV-2 IgG results.
  • The current confirmatory testing strategy risks misdiagnosis of HSV-2 infection.
  • Revising the confirmatory testing threshold may improve diagnostic accuracy for HSV-2.

Keywords:
Confirmatory testingHerpes simplex virus type 2IgG Inhibition assay

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