Supportive Data

The following validation data supports the use of this assay for clinical testing.

Accuracy/Diagnostic Sensitivity and Specificity:

LightCycler polymerase chain reaction (PCR) (primers, directed to varicella-zoster virus [VZV], gene 29) was compared with shell vial cell cultures for the detection of VZV from 253 dermal specimens. Twenty-three specimens (9.1%) were positive for VZV by LightCycler PCR and the shell vial cell culture assay. An additional 21 specimens exclusively yielded VZV DNA. These discrepant specimens were resolved as true-positive results by confirmation of results by PCR using primers directed to another gene of VZV. Importantly, there were no instances in which VZV was recovered by the shell vial assay and not detected by LightCycler PCR (specificity, 100%). Of 100 cerebrospinal fluid specimens tested by both conventional PCR and LightCycler PCR, VZV DNA was detected in 49 specimens by both methods; 1 specimen was positive only by the conventional PCR assay. Fifty specimens were found to be negative for VZV DNA by both techniques.

Supplemental Data (Spiking Studies):

To supplement the above data, 30 negative specimens each various specimen type were spiked with VZV plasmid at the limit of detection (10-20 targets/microliter). The spiked specimens were run in a blinded fashion along with approximately 30 negative (non-spiked) specimens each of various specimen types; 90% to 100% of the spiked specimens were positive and 100% of the non-spiked specimens were negative.

Analytical Sensitivity/Limit of Detection:

The limit of detection of this assay is 10 to 20 DNA target copies per microliter in specimen matrix.

Analytical Specificity:

No PCR signal was obtained from extracts of 27 bacterial, viral, and fungal isolates that could be found as normal flora in sites normally tested for this organism or that could cause similar symptoms.

Precision:

Interassay precision was 100%, and intraassay precision was 97%.

Reportable Range:

This test is a qualitative assay, and results are reported as negative or positive for targeted VZV DNA.