Herpes Simplex and Varicella Zoster Viruses

Is Extraction Required for Dermal and Anogenital Specimens?

December 2009

First, we needed to examine why extraction was done for HSV and VZV PCR testing. We decided to focus specifically on dermal and anogenital samples, since these comprise the bulk of the samples that we receive for HSV and VZV PCR testing.

In these cases, the main purpose of extraction is to purify viral DNA remove inhibiting substances. Since HSV and VZV DNA is typically abundant in anogenital and dermal samples, and samples collected on a swab contain very few, if any, inhibiting substances, we hypothesized that extraction served little purpose, other than removing the phenol red pH indicator from the M5 media. We know that the phenol red can interfere with the detection of the PCR product, but if samples are not submitted in M5, then extraction may not be necessary.

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Jump to section:

• Introduction
• The Viruses
• Laboratory Diagnosis
• HSV/VZV Real-time PCR Sample Workflow
• Is Extraction Required for Dermal and Anogenital Specimens?
• Direct Processing in Neutralization Buffer: An Alternative to MagNA Pure Extraction
• Match Up Identifying Information
• Remove Swab from the Culturette Tube
• Heat Swab in Neutralization Buffer
• Sample is Ready for PCR
• A New Workflow for Dermal and Anogenital Swabs
• Direct Processing in Neutralization Buffer: Comparable to DNA Extraction?
• Comparison of Detection - HSV
• Results: Comparison of Amplification Cycle Threshold
• Comparison of Detection - VZV
• Results: Comparison of Amplification Crossing Points
• Questions and Answers
• Questions and Answers
• M5 Media vs Culturette Tubes: Experiment
• M5 Media vs Culturette Tubes: Results
• Conclusions
• Questions?