Diagnostic value of a "wide-range" quantitative nested real-time PCR assay for varicella zoster virus myelitis.
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.
Department of Neurology, Nagaoka-Nishi Hospital, Nagaoka, Japan. nrd27501@nifty.com
Teruyuki
T
Takahashi
Masato
M
Tamura
Toshiaki
T
Takasu
D000368:Aged; D000369:Aged, 80 and over; D002555:Cerebrospinal Fluid / Q000821:virology; D020804:Encephalitis, Varicella Zoster / Q000175:diagnosis* / Q000821:virology*; D005260:Female; D014645:Herpesvirus 3, Human / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000379:methods*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012015:Reference Standards; D012680:Sensitivity and Specificity
cerebrospinal fluid (CSF); internal control; myelitis; varicella zoster virus (VZV); wide-range quantitative nested real-time (QNRT) PCR assay