Comparison of the Simplexa HSV1 & 2 Direct kit and laboratory-developed real-time PCR assays for herpes simplex virus detection

Background: Rapid detection and differentiation of herpes simplex viruses (HSV) is important for patient management and treatment, especially in HSV meningoencephalitis.

Objectives: Results of Simplexa HSV1 & 2 Direct kit (Focus Diagnostics), an FDA-cleared sample-to-result method providing results in ∼ 75 min, were compared to those of laboratory-developed real-time PCR assays (LDT) for detection of HSV1 and HSV2.

Study design: Samples tested included 168 cerebral spinal fluid (CSF) collected prospectively and 150 tested retrospectively: 81 from clinical testing and 69 from subjects in a neonatal herpes study; and 53 plasma and sera. Each sample was tested by both methods on the same day.

Results: Three of 318 CSF had invalid Simplexa Direct results and negative LDT results. Three neonatal samples with low HSV viral loads by LDT could not be typed; two were HSV2 positive and one was negative by Simplexa Direct. Of 312 CSF with valid, type-specific results, HSV1 was detected in 16 by LDT and in 17 by Simplexa Direct; HSV2 was detected in 48 by LDT and in 49 by Simplexa Direct. Concordance rates were 98.4% (κ 0.84) and 97.1% (κ 0.89) for HSV1 and HSV2, respectively. Positive percent agreements were 87.5% for HSV1 and 91.7% for HSV2. Two and four CSF were positive only by LDT and three and five were positive only by Simplexa Direct for HSV1 and HSV2, respectively.

Conclusions: Simplexa HSV1 & 2 assay performed well compared to an established LDT. The faster turn-around-time compared to LDT will allow for more rapid antiviral treatment and better patient management.