Evaluation of a transcription mediated amplification assay for detection of herpes simplex virus types 1 and 2 mRNA in clinical specimens.

BACKGROUND: Herpes simplex viruses (HSV) are double-stranded DNA human herpesviruses (HHVs) that have the capacity to cause significant morbidity and mortality in humans. Like HHV5 (Cytomegalovirus) and HHV8 (Kaposi's sarcoma virus), HSV type 1 (HSV-1), and HSV type 2 (HSV-2) (HHV1, HHV2) selectively package certain viral messenger RNAs inside mature virions, as well as expressing those mRNAs in infected cells.

OBJECTIVES: To evaluate the clinical and analytical performance of Aptima HSV 1&2 assay (AHSV), a newly developed automated real time transcription-mediated amplification (TMA) nucleic acid amplification test (NAAT) for HSV-1 and 2 UL42 mRNAs, compared to viral culture and HSV DNA NAAT.

STUDY DESIGN: Cutaneous and mucocutaneous lesion swab specimens from a population of symptomatic female and male subjects attending a U.S. public health clinic (n=758) were evaluated by shell vial culture with fluorescent antibody staining for HSV-1 and 2. Specimens were then tested with AHSV for HSV-1 and 2 on the Panther instrument. Specimens from subjects with discordant culture-TMA paired results were tested using an FDA-cleared test for HSV-1 and 2 viral DNA. Analytical performance of AHSV was evaluated using test panels consisting of laboratory strains of HSV-1 and 2 and a variety of non-target human DNA viruses.

RESULTS: Compared to culture, AHSV was sensitive and specific for detection of HSV-1 and 2 in patient lesion swab specimens, exhibiting clinical sensitivities of 98.2% (95% CI: 92.9-99.7) and 99.4% (95% CI: 96.0-99.9), respectively. Addition of HSV DNA NAAT discordant resolution testing results to culture results improved AHSV sensitivity for HSV-1 and 2-99.2% (95% CI: 94.7-99.9) and 100% (95% CI: 97.5-100), respectively. Clinical specificity of AHSV for HSV-1 and 2 detection was 97.8% (95% CI: 96.3-98.8) and 94.5% (95% CI: 92.2-96.1), respectively, compared to culture; and 99.5% (95% CI: 98.5-99.9) and 99.5% (95% CI: 98.3-99.7), respectively, compared to culture with discordant resolution. Analytical sensitivity (95% limit of detection) of AHSV for HSV-1 (McIntyre strain) was 28.9 TCID50/mL (95% FL: 23.4-37.9), and 0.54 TCID50/mL (95% FL: 0.42-0.75) for HSV-2 (MS strain). AHSV did not cross-react with laboratory strains of HHV-3, HHV-4, HHV-5, HHV-6, and four other non-HHV human DNA viruses.

CONCLUSIONS: Real time transcription-mediated amplification NAAT for HSV viral mRNA is a sensitive and specific method for detection of herpes simplex virus infection in symptomatic patients.