Myelitis is one of the rarest neurological complications of varicella zoster virus (VZV) infection. In this study, the authors remodeled the “wide‐range” quantitative nested real‐time (QNRT) polymerase chain reaction (PCR) assay to quantitatively detect a small amount of VZV‐DNA in cerebrospinal fluid (CSF). For use as a specific internal control “calibrator,” an original mutation‐VZV (MZ) plasmid was developed. The initial copy number of VZV‐DNA in CSF specimens was measured by the amplification rate of the MZ‐plasmid. For 17 consecutive CSF specimens collected from three elderly patients with VZV myelitis, the diagnostic value of the wide‐range QNRT‐PCR assay was evaluated and compared with other conventional PCR assays and enzyme immunoassay (EIA). The MZ‐plasmid demonstrated statistically uniform amplifications (F = 1.016) against a wide range (1–100,000) of copy numbers of mimic VZV‐DNA. The wide‐range QNRT‐PCR assay quantitatively and rapidly (within 48 hr) detected 5,863, 3,052, 958, and 6,721 copies/ml of VZV‐DNA in the CSF specimens collected from all patients in the acute phase. Additionally, there was a significant difference (*P = 0.023) in the copy number of VZV‐DNA between before and after acyclovir treatment. Other conventional single PCR assays all revealed negative results, but were nevertheless time‐consuming (7 days). The IgG EIA‐value for VZV was continually elevated throughout the clinical course of all patients. The MZ‐plasmid was thus regarded as an appropriate “calibrator” in the wide‐range QNRT‐PCR assay. This assay is a novel, rapid, accurate, quantitative, and highly sensitive technique, and will contribute as a reliable and useful clinical examination for the rapid diagnosis of VZV infection to central nervous system. J Med. Virol. 85:2042–2055, 2013. © 2013 Wiley Periodicals, Inc.
Teruyuki Takahashi, M. Tamura, T. Takasu
Journal of Medical Virology