(P270) Detection of Herpes Simplex Virus DNA from Vaginal Swabs at Time of Delivery Using Three PCR Detection Platforms

Background: Neonatal herpes simplex virus (HSV) infection is acquired at delivery in ~85% of cases, most commonly from exposure in the maternal genital tract to asymptomatically shed virus. Detection of HSV DNA in vaginal swabs at delivery could enable interventions to prevent vertical transmission during labor. No rapid molecular diagnostic test is approved in the U.S. for the detection of HSV shedding at delivery or in the absence of clinically apparent lesions.

Methods: Women presenting for delivery without clinically apparent HSV genital lesions were enrolled in this NIH-funded study. Vaginal swabs were collected for detection of HSV DNA by standard PCR using a laboratory developed test, by a research-use-only HSV cartridge developed by Cepheid for its GeneXpert platform, and by a CE-IVD marked (Europe) and TGA cleared (Australia) PCR assay by SpeeDx for use in people with active HSV lesions. Receipt of acyclovir, valacyclovir, or famciclovir within the preceding 14 days was exclusionary.

Results: 12,500 women enrolled, of whom 12,431 had vaginal specimens collected. Samples from 6,658 subjects were randomly selected for testing by standard PCR and Xpert PCR, 204 (3.1%; 95% CI: 2.7, 3.5) of which were positive for HSV DNA of any copy number or Ct value. These 204 samples and a matching number negative by both assays then were tested by SpeeDx PCR. Of these 408 samples, 169 were positive by standard PCR (positive ≥ 200 copies/mL), Xpert PCR (positive ≤ 37.0 Ct values), and/or SpeeDx PCR (positive ≤ 37.0 Ct values) (Figure). 85.8% (95% CI: 79.6, 90.7) of the 169 samples were positive by SpeeDx PCR, compared with 65.1% (95% CI: 57.4, 72.3) and 74.0% (95% CI: 66.7, 80.4) for Xpert and standard PCRs, respectively. For the 92 samples positive by all three assays, median viral load by standard PCR was 22,990.55 copies/mL (range: 208 to 54,317,000 copies/mL); median Ct values were 22.065 (range: 10.11 to 28.56) for SpeeDx PCR and 32.1 (range: 24.0 to 37.0) for Xpert PCR (p< 0.0001).

Conclusions: Of the assays tested, SpeeDx PCR was the most frequently positive for HSV DNA among women without HSV lesions at the time of delivery.